JP3902536B2 - Variable length data encoding method and variable length data encoding apparatus - Google Patents

Variable length data encoding method and variable length data encoding apparatus Download PDF

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JP3902536B2
JP3902536B2 JP2002344079A JP2002344079A JP3902536B2 JP 3902536 B2 JP3902536 B2 JP 3902536B2 JP 2002344079 A JP2002344079 A JP 2002344079A JP 2002344079 A JP2002344079 A JP 2002344079A JP 3902536 B2 JP3902536 B2 JP 3902536B2
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encoding
signal
variable length
data
image
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JP2003230095A (en
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渉 猪羽
隆幸 菅原
勝義 西谷
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日本ビクター株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a configuration of a semi-disclosed type contents signal encoder for encoding contents of an encoding object while ensuring a prescribed security level for the object. <P>SOLUTION: A variable length encoding table 14 is obtained by assigning a prescribed code work to each data value of the number of time series data obtained resulting from applications of orthogonal transform to supplied image and audio signals, an exchanging variable length encoding table 15 is generated by exchanging different code words in which the number of time series data is assigned as the same number among the code words described in the variable length encoding table 14, a CPU 16 generates an encoding selection signal to identify which of the variable length encoding table or the exchanging variable length encoding table 15 a VLC (Variable Length Coding) unit 121 for variable length encoding and outputs the selection signal with a compression encoding signal to realize the configuration of the contents signal encoding apparatus. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to compression encoding of digital image signals or digital audio signals, and decoding of compression-encoded signals. In particular, the present invention decodes digital data without deterioration by a decoding device, or decodes digital data. The present invention relates to a variable-length data encoding method and a variable-length data encoding apparatus for supplying decoded data having different quality for each user so as to be slightly deteriorated in stages.
[0002]
[Prior art]
When an analog video signal is transmitted or recorded and reproduced, the reproduced video signal is deteriorated according to the quality of the transmission path or recording medium, and is reproduced by the original video signal and the user side. There is a slight difference in image quality between video signals.
[0003]
Similarly, when an analog acoustic signal is transmitted or recorded and reproduced, the reproduced acoustic signal is deteriorated according to the quality of the transmission path or recording medium, and the original acoustic signal and the user reproduce it. There is a slight difference in sound quality between sound signals.
[0004]
As such, it occurs between the copyright owner who owns the video signal and / or the audio signal (hereinafter, these signals may be referred to as content signals) and the user who reproduces the content signal. Due to the difference in quality, the rights business relating to the content signal owned by the copyright holder is protected, and the content business is normally operated.
[0005]
In recent years, digital signal processing technology has been developed, and content signals using the same can be broadcasted, communicated, or supplied to users through recording media with reduced quality degradation of the content signal. For this reason, the difference between the quality of the content owned by the copyright holder and the quality of the content played back on the user side is reduced, and normal operation of business using content owned by the copyright holder is becoming difficult. is there.
[0006]
Therefore, encryption technology and conditional access technology have been developed to supply content only to users who have a specific contract, and content has been supplied using them. Signals processed by encryption and conditional access can be selected for either normal playback or no playback at all. It is used in such a way that content is supplied only to specific users.
[0007]
In addition, when the content of the copyright holder is transmitted or supplied to the user by a recording medium, and the user uses the content for the second time, information for identifying the right holder of the content is digitally watermarked. A method for embedding in content information has also been developed. In this case, the quality of the content is less deteriorated when the content is secondarily used, and the protection of the content by the digital watermark is actually used only for specifying the content owner. .
[0008]
In this way, digital transmission technology has been developed for content transmission and recording / reproduction technology with little quality degradation. Then, there is a demand for the development of a signal technology for protecting copyright holders in order to carry out a preferable content business, which incorporates a technology related to the protection of a preferable copyright that an analog signal has in the digital technology.
[0009]
Here, the MPEG (moving picture experts group) video and MPEG audio technology will be described first as to the compression coding and decoding technology of the content signal, and then the content is added to the encoded compression coded signal. An encoding technique according to a content disclosure method for realizing suitable encoding for business will be described.
[0010]
First, MPEG video technology will be described.
The so-called MPEG video method that efficiently encodes a moving image signal such as a television signal is widely used as a signal transmitted in a digital satellite broadcast, a DVD (Digital versatile Disc), a digital tape recorder, and a communication network. It is planned to be adopted for digital terrestrial broadcasting from 2003.
[0011]
In other words, the MPEG video standard is JTC1 / SC2 (Joint Technical Committee 1 / Sub committee 2) of ISO / IEC (International Organization for Standardization / International Electrotechnical Commission) in 1988; / This is an international standard created by a deliberation started by an organization that examines video coding standards, established in the expert group 2).
[0012]
SC2 which is the deliberation group is continuing the activity to establish standards for encoding video and audio signals as SC29, and the international standard established by MPEG people is also commonly called the MPEG standard. ing.
[0013]
The MPEG1 (MPEG Phase 1) standard, first established by MPEG, is an encoding standard for moving image signals accompanied by acoustic signals for storage media recorded at a transmission rate of about 1.5 Mbps. JPEG (Joint Photographic Coding Experts Group) for video coding and ISDN (Integrated Services Digital Network) video conferencing and H.264 video compression for low transfer rates. This is a coding standard using the basic technology of H.261 (CCITT SGXV, standardized by the current ITU-T SG15).
[0014]
In this way, MPEG1 was established as ISO / IEC11172 in August 1993, and many discs encoded and recorded according to the MPEG1 standard have been commercialized.
[0015]
In addition, MPEG2 (MPEG Phase 2), which was subsequently enacted, was established as ISO / IEC 13818 and “H.262” in November 1994 for the purpose of general-purpose standards to support various applications such as communication and broadcasting. It was done.
[0016]
These MPEG1 and MPEG2 encoding schemes are composed of a plurality of encoding techniques, and these techniques convert a “frame” image constituting a moving image into blocks of 16 × 16 pixels called “macroblocks”. The encoding process is performed by dividing the image into two.
[0017]
For each macroblock unit, the encoding process obtains a motion amount called a “motion vector” between a reference image and a to-be-encoded image that are separated by a predetermined number of frames in the future or in the past in time. A “motion-compensated prediction” technique that encodes an encoded image from a reference image based on a quantity, and an error signal of the motion-compensated prediction or the encoded image itself, DCT (one of orthogonal transform techniques) Discrete Cosine Transform (Discrete Cosine Transform) is used to convert image information into frequency information, and to perform compression encoding so that only visually significant information is obtained from the converted frequency domain information. And the two image encoding elemental technologies.
[0018]
There are three modes of prediction in motion compensated prediction in the case of prediction from both the past, the future, and the past future, and these three modes are switched for each macroblock composed of 16 pixel × 16 pixel data. Can be used.
[0019]
In addition, as picture types given to the frame of the input image, three types of pictures are defined: I (Intra-coded), P (Predictive-coded), and B (Bidirectionally predictive-coded).
[0020]
The I picture is a picture that is encoded without performing motion prediction, but the P picture has two modes of prediction from the past and encoding without performing prediction, and the B picture has the future. There are four MC (Motion Compensation) modes that perform prediction from the past, prediction from the past, prediction from both past and future directions, and intra-frame coding without performing prediction.
[0021]
Motion compensation using these future or past images is performed by pattern-matching the motion region for each macroblock to obtain a motion vector with half-pel (1/2 of the inter-pixel distance) accuracy, and the obtained motion The input image signal is encoded with reference to a reference image formed by moving the future or past reference image position in the vector direction corresponding to the vector amount.
[0022]
The direction of the motion vector thus determined includes a horizontal direction and a vertical direction, and the vector information is transmitted as additional information of the macroblock together with the MC mode.
[0023]
Of the picture data thus made, the three types of pictures I, P, and B are arranged and transmitted in a predetermined order starting from the I picture, and before the next I picture from that I picture. A set of pictures (frame images) up to a certain picture is called a GOP (Group Of Picture). In encoding performed by a normal storage medium or the like, a GOP is configured by about 15 pictures.
[0024]
The I picture and the P and B pictures encoded as motion compensated pictures are DCT, that is, orthogonal transforms in which an integral transformation using a cosine function as an integral kernel is discretely transformed into a finite space.
[0025]
In the orthogonal transformation, the macroblock is divided into DCT blocks of 8 pixels × 8 pixels and the two-dimensional DCT is performed. However, since the frequency component of the image data is generally low and the high frequency is small, the image data is low by performing DCT. The energy can be expressed by being compressed by a conversion coefficient whose energy is concentrated in the frequency band.
[0026]
The DCT image data (DCT coefficient) is quantized by a quantizer. In other words, the DCT coefficient is obtained by dividing by a predetermined quantized value by the quantizer, and the quantized value is obtained as a quantized value obtained by weighting a two-dimensional frequency of 8 pixels × 8 pixels with visual characteristics. The quantization value is a scalar multiplied by a predetermined quantization scale.
[0027]
Further, the quantized value is multiplied by an inverse quantized value obtained at the time of decoding the encoded image data, so that the characteristic due to the quantized value given at the time of encoding is canceled at the time of decoding.
[0028]
Next, the configuration of an MPEG encoder that performs encoding and decoding by such a method will be described.
FIG. 47 shows the configuration of the MPEG encoder and outlines its operation.
[0029]
The MPEG encoder 50 includes an input terminal 51, an adder 52, a DCT unit 53, a quantizer 54, a VLC (variable length coding) unit 55, a buffer 56, a code amount controller 57, an inverse quantizer 61, and an inverse DCT. And an adder 63, an image memory 64, and a motion compensation predictor 65.
[0030]
First, the moving image signal supplied to the input terminal 51 is supplied to the motion compensation predictor 65 and the adder 52. In the adder 52, the signal supplied from the motion compensation predictor 65 is inverted in polarity and added and added. The signal obtained is supplied to the DCT unit 53.
[0031]
In the DCT unit 53, the supplied image signal is subjected to the discrete cosine transform, and the DCT transform coefficient obtained by the conversion is supplied to the quantizer 54, and the quantized signal is quantized based on the predetermined quantized value. The quantized quantized data is supplied to the inverse quantizer 61 and the VLC unit 55.
[0032]
In the VLC unit 55, the supplied quantized data is variable-length encoded, but the direct current (DC) component obtained by DCT conversion of the quantized value is subjected to DPCM (differential pulse code modulation) modulation. Made.
[0033]
The alternating current (AC) component is obtained while zigzag scan is performed in the order of the data of the high frequency component than the data of the low frequency component, and the obtained data has a run length of zero and an effective coefficient value. As one event, Huffman coding is performed by assigning codes with shorter code lengths in descending order of appearance probability.
[0034]
The Huffman-encoded data, which is the variable-length encoding, is temporarily stored in the buffer 56, and the temporarily stored data is output as encoded data output at a predetermined transfer rate.
[0035]
Then, the generated code amount for each macroblock of the output data is supplied to the code amount controller 57, compared with a preset target code amount, and the difference from the generated code amount obtained by the comparison. Is supplied to the quantizer 54. The quantizer 54 controls the code amount so that encoded data of a predetermined transfer rate is obtained by changing the value of the quantization scale based on the code amount of the difference.
[0036]
On the other hand, the image data quantized by the quantizer 54 is supplied to the inverse quantizer 61 for inverse quantization. The inversely quantized data is supplied to the inverse DCT unit 62 where the inverse DCT is performed, and the inversely DCTed data is supplied to the adder 63.
[0037]
The adder 63 adds the reference image supplied from the motion compensation predictor 65, and a signal obtained by the addition is supplied to the image memory 64 and temporarily stored therein. The temporarily stored image data is used as a reference decoded image for calculating a difference image in the motion compensated predictor 65, so that it is output as encoded data with motion compensation from the MPEG encoder 50. Has been made.
[0038]
The encoded data output in this way is supplied to the MPEG decoder and decoded.
FIG. 48 shows the configuration of the MPEG decoder and outlines its operation.
[0039]
The MPEG decoder 70 shown in the figure includes an encoded data input terminal 71, a buffer 72, a VLD unit 73, an inverse quantizer 74, an inverse DCT unit 75, an adder 76, an image memory 77, and a motion compensation predictor 78. Consists of.
[0040]
First, the encoded data supplied to the input terminal 71 is temporarily stored in the buffer 72, and the encoded data temporarily stored therein is supplied to a VLD (variable length decoding) unit 73 as necessary.
[0041]
In the VLD unit 73, variable length decoding of the data encoded by the VLC unit 55 is performed, and data relating to the direct current (DC) component and the alternating current (AC) component is obtained.
[0042]
Among the obtained data, AC component data is obtained as quantized data arranged in an 8 × 8 matrix in the zigzag scan order from the same low frequency to high frequency components as in the MPEG encoder 50. The obtained quantized data is supplied to the inverse quantizer 74.
[0043]
In the inverse quantizer 74, inverse quantization is performed based on the above-described quantization matrix arrangement, and data obtained by the inverse quantization is supplied to the inverse DCT device 75. There, an inverse DCT operation is performed to obtain image data as decoded data.
[0044]
The obtained image data is temporarily stored in the image memory 77, and the temporarily stored image data is supplied to the motion compensation predictor 78. The image data is used as a reference decoded image for calculating a difference image in motion compensation prediction.
[0045]
Thus, the image data constituting the moving image is encoded and transmitted or recorded by the MPEG encoder 50, and the received or reproduced encoded data is decoded by the MPEG decoder 70 as moving image information. It is made to be obtained. Such a technique is used in both MPEG1 and MPEG2, but in any case, it enables transmission of a video signal that is less affected by noise and non-linearity in the transmission path.
[0046]
Then, in connection with the copyright protection of the image signal encoded in this way, the image data encoded using a plurality of types of encoding modes is permitted to reproduce the encoded data based on the input security data or There is a method of determining non-permission and decoding an image signal encoded according to the determination result (see, for example, Patent Document 1).
[0047]
The encoding and decoding of the image signal has been described above.
Next, compression coding of an audio signal will be described using MPEG-2 AAC (Advanced Audio Coding) as an example.
FIG. 49 shows the configuration of an MPEG-2 AAC encoding apparatus that compresses and encodes a digital audio signal, and its operation will be described.
[0048]
The audio signal encoding apparatus 400 shown in the figure includes an auditory psychological analyzer 401, an MDCT (Modified Discrete Cosine Transform) unit 402, a scale factor calculator 403, a quantizer 404, a codebook selector 405, and a variable length encoder. 406, a minimum code amount detector 407, a code amount determiner 408, and a bit stream generator 409.
[0049]
First, the MPEG-2 AAC audio encoding device obtains a re-frequency spectrum by performing FFT (Fast Fourier Transform) processing on the input digital audio signal by the psychoacoustic analyzer 401, and based on that, the auditory psychological analyzer 401 obtains a re-frequency spectrum. The amount of masking performed is calculated, and the allowable quantization noise power for each preset frequency band is calculated.
[0050]
On the other hand, the MDCT unit 402 obtains spectrum data by performing MDCT on the supplied audio signal. The data is called MDCT coefficient. Then, based on the window selection information determined by the auditory psychological analyzer 401, a long or short conversion block length is selected. The MDCT calculation is executed while overlapping the calculation block length by 50%.
[0051]
When the window selection is selected as a long window, the audio signal of 2048 samples is converted into 1024 MDCT coefficients, and when the window is a short window, 256 samples are converted into 128 MDCT coefficients.
[0052]
Next, the scale factor calculator 403 divides the audio signal into a plurality of scale factor bands in units of 1024 MDCT coefficients for each frequency band based on human auditory characteristics. The number of quantization steps (scale factor) of each scale factor band is set so that the quantization noise calculated in each scale factor band does not become larger than the allowable quantization noise power calculated by the psychoacoustic analyzer 401. Calculated.
[0053]
In the stippling in the figure, it is indicated that the processing is performed in units of scale factor bands. That is, the quantizer 404 performs quantization in units of scale factor bands. The scale factor calculator 403 obtains the MDCT coefficient for the signal in the scale factor band from the scale factor calculated there and the total number of quantization steps, and performs quantization based on the obtained coefficient value. . Further, the MDCT coefficient is quantized so that the number of bits necessary for quantization is kept within the number of usable bits and the total number of quantization steps is controlled.
[0054]
In the next codebook selector 405, a usable Huffman codebook is selected from the maximum absolute value of the quantized value.
FIG. 50 shows a table of the Huffman codebook used in MPEG-2 AAC.
[0055]
Then, the variable length encoder 406 selects and uses the Huffman codebook based on the maximum absolute value of the quantized value, and performs variable length encoding there. For example, when the maximum absolute value of the quantized value is 5, it is possible to use 7 or more Haman codebooks. The selected Huffman codebook is supplied to the variable length encoder 406.
[0056]
In the variable length encoder 406, the quantized value of the MDCT coefficient output from the quantizer 404 is subjected to variable length encoding using the Huffman codebook selected by the codebook selector 405. When a plurality of Huffman codebooks are selected, encoding is performed using each Huffman codebook, and the encoded result is supplied to the minimum code amount detector 407. Further, in the variable length encoder 406, the supplied scale factor is also subjected to variable length encoding, and the encoding result with reduced redundancy is supplied to the code amount determination unit 408.
[0057]
The minimum code amount detector 407 selects a Huffman codebook that generates the smallest code amount based on the respective encoding results encoded using each Huffman codebook, and selects the selected Huffman code. The code book and the encoding result are supplied to the code amount determination unit 408.
[0058]
In the code amount determination unit 408, it is determined whether the code amount generated by encoding is within the usable code amount, and if it exceeds the usable code amount, quantization is performed again to generate This is repeated until the code amount to be used is equal to or less than the usable code amount.
[0059]
The encoded data output satisfying the usable number of bits is supplied to the bit stream generator 409. There, they are multiplexed together with coding parameters such as sampling frequency and coding rate, generated as an AAC bit stream, and output from the audio signal coding apparatus.
[0060]
Next, an audio signal decoding apparatus that decodes the AAC bitstream encoded as described above will be described.
FIG. 51 shows a conventional example of an MPEG-2 AAC decoder that performs decoding corresponding to the MPEG-2 AAC encoder, and will be described below with reference to FIG.
[0061]
The audio signal decoding apparatus 420 shown in the figure includes a bit stream analyzer 421, a variable length decoder 422, an inverse quantizer 423, and an IMDCT (Inverse Modified Discrete Cosine transform) unit 424.
[0062]
First, in the MPEG-2 AAC decoder, an AAC bitstream obtained by multiplexing a plurality of signals is received by a bitstream analyzer 421 in each of encoding parameters such as sampling frequency and encoding rate, and encoded data. Separated into signals.
[0063]
The variable length decoder 422 receives encoded data and a scale factor and a quantization value as encoding parameters, and variable length decoding is performed based on the data. That is, a scale factor Huffman codebook is used as the scale factor, and the quantized value is based on the Huffman codebook number obtained from the bitstream analyzer 421 in units of scale factor bands. A codebook is selected and decrypted.
[0064]
Next, the decoded quantized value and scale factor are supplied to the inverse quantizer 423. There, the quantization value is inversely quantized for each scale factor band unit using the overall quantization step number and the scale factor which are one of the encoding parameters output from the bitstream analyzer 421, and MDCT A coefficient is calculated.
[0065]
The MDCT coefficient is input to the IMDCT unit 424, where it is subjected to inverse MDCT conversion to be converted into an audio signal and output from there.
As described above, the operation in which the digital audio signal is compression-coded by the audio signal encoding device and the encoded signal is decoded by the audio signal decoding device to obtain the digital audio signal has been described.
[0066]
Then, security information such as digital watermark information is included in the digital audio signal encoded by the audio signal decoding apparatus, and recorded on the optical disc using the SCMS (Serial Copy Management System) method, and also permitted by the security system. There is also an optical disc apparatus in which only a part of the encoded digital audio signal is recorded on the recording medium when the signal cannot be obtained (see, for example, Patent Document 2).
[0067]
[Patent Document 1]
JP 2000-175162 A
[Patent Document 2]
JP 2001-312853 A
[0068]
[Problems to be solved by the invention]
By the way, the transmission of content signals using high-quality compressed and encoded signals of MPEG1 and MPEG2 and audio signals and audio signals is preferable for the user. However, it is not always preferable for the copyright holder to promote the content business.
[0069]
Therefore, in comparison with the above-mentioned compression coding method using MPEG images and sounds with high coding quality, for example, when decoded by a normal decoding device, the digital content data in a semi-disclosure state slightly deteriorated like an analog system. To be obtained. There is a need for a compression encoding method for protecting digital contents data so that digital contents data without deterioration can be obtained when decoded by a predetermined decoding apparatus.
[0070]
As an encoding method for protecting the content business, a function for preventing unauthorized copying of content and unauthorized reproduction using an unauthorized player is provided. In addition, content that has undergone signal processing for security protection of content that prevents unauthorized reproduction is supplied to the market.
[0071]
On the other hand, there is also a method of performing security protection by directly performing encryption processing on a bit stream that is encoded data obtained by compressing and encoding content to be protected by, for example, MPEG.
[0072]
However, in this method, the encoded data that has been encrypted is decrypted only by a specific authorized user to obtain content data that does not deteriorate, but on the user side that is not subjected to the decryption process of encryption. There is a problem that no image or sound signal information relating to the content can be obtained.
[0073]
Therefore, the present invention provides a so-called Huffman code when performing variable-length coding on content data obtained by orthogonal transformation of content data performed by, for example, MPEG, and variable-length coding of coefficient value data obtained by orthogonal transformation. The VLC (variable length coding) table using the above is changed and used so that the quality of the reproduced image and the sound signal are different between a general decoder and a regular decoder.
[0074]
In the case of events with greatly different occurrence probabilities, the length of each code is generally different. If such a table is read, the amount of code increases and the coding efficiency may deteriorate. However, in the case of the present invention, especially when the VLC code is reread, codes that are events of the same length in the VLC code are reread, thereby preventing deterioration of the encoding efficiency and generating an absurd error signal. Also try to prevent.
[0075]
Further, the VLC code of the VLC table used by switching is configured by using a code in a VLC code system defined by, for example, MPEG video and MPEG AAC audio standards generally used in the market as international standards. Therefore, it is realized by a method having good consistency with a method used in the market as a content compression encoding method.
[0076]
Furthermore, an encoding selection signal for switching an event represented by a VLC code using a commonly used MPEG syntax is, for example, data, image or sound described in a user data recording area defined by MPEG. Transmission is possible by a plurality of methods such as mixed digital watermark data and additional data transmitted separately from image and audio data. Then, it is intended to provide a variable length data encoding method and a variable length data encoding device that are performed while ensuring a predetermined security level for a desired content to be encoded.
[0077]
[Means for Solving the Problems]
The present invention comprises the following means 1) or 2) in order to solve the above problems.
That is,
[0078]
1) Time-series data is obtained by performing data conversion, quantization, and arrangement by a predetermined method on a content signal including at least one of an image signal and an audio signal. In a variable length data encoding method for encoding compressed time series data to obtain a compressed encoded signal,
A first step (14) for obtaining a variable-length coding table described by assigning a predetermined code word to a plurality of data values of the time-series data;
Among the code words described in the variable length coding table, the number of the time-series data is allocated as the same number, and different code words are exchanged to create an exchange variable length coding table. A second step (15);
A third step (16) of generating an encoding selection signal that designates which one of the variable length coding table and the exchange variable length coding table is used to perform the variable length coding. )When,
A fourth step (12) for performing variable-length encoding of the time-series data using the specified encoding table and generating the compressed encoded signal;
A variable length data encoding method characterized by comprising:
2) A time series data is obtained by performing data conversion, quantization, and arrangement by a predetermined method for a content signal including at least one of an image signal and an audio signal. In a variable length data encoding device that encodes the time-series data to generate a compressed encoded signal,
Variable-length coding table obtaining means (14) for obtaining a variable-length coding table described by assigning a predetermined code word to a plurality of data values of the time-series data;
Among the code words described in the variable length coding table, the number of the time-series data is allocated as the same number, and different code words are exchanged to create an exchange variable length coding table. Exchange variable length coding table creation means (15);
Coding selection signal generating means for generating a coding selection signal that specifies which one of the variable length coding table and the exchange variable length coding table is used to perform the variable length coding. (16) and
Variable length encoding means (12) for performing variable length encoding of the time-series data using the specified encoding table and generating the compressed encoded signal;
A variable length data encoding apparatus comprising:
[0079]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the variable length data encoding method and variable length data encoding apparatus of the present invention will be described.
[0080]
Here, the signal to be encoded is a content signal including at least one of an image signal and / or an acoustic signal. First, an encoding method when the content signal is an image will be described based on a basic example thereof.
<First embodiment>
FIG. 1 shows a configuration of an image signal encoding apparatus (hereinafter also simply referred to as an encoding apparatus) according to a first embodiment equipped with the image signal encoding method, and will be described with reference to the drawings. To do.
[0081]
An image signal encoding apparatus 10 shown in FIG. 1 includes an image data converter 11, an MPEG encoder 12, a VLC table selector 13, a standard VLC table 14, a special VLC table 15, and a CPU 16. The MPEG encoder 12 includes a VLC unit 121.
[0082]
Next, the operation of the image signal encoding apparatus 10 will be described.
First, an input image signal to be encoded by the MPEG encoder 12 is supplied to the image data converter 11, where an encoding selection signal which is a VLC table switching signal described later supplied from the CPU 16 is used as digital watermark information. Supplied and embedded in the image signal.
[0083]
The encoding selection signal embedded in the image signal is output from the CPU 16, and the encoding selection signal output from the CPU 16 is also supplied to the VLC table 13. In the VLC table selector 13, the VLC table selected by the encoding selection signal among the VLC tables supplied from the standard VLC table 14 and the special VLC table 15 is supplied to the VLC unit 121. 12, compression coding based on the VLC table temporarily stored in the VLC unit 121 is performed.
[0084]
In other words, the MPEG encoder 12 is supplied with an image signal in which an encoding selection signal is embedded with a digital watermark. The image signal is compressed and encoded using the VLC table specified by the embedded encoding selection signal.
[0085]
In this way, when the encoding selection signal supplied from the CPU 16 is “0”, for example, the standard VLC table is selected and encoded, and when it is “1”, the special VLC table is selected and encoded. It is made like. Then, the encoding selection signal is converted by the image data converter 11, and is compressed and encoded by MPEG so as to be embedded in the image signal at the first position for every predetermined interval, for example, using a digital watermark technique. The encoded data is generated.
[0086]
Next, decoding of the generated encoded data will be described.
FIG. 2 shows the configuration of an image signal decoding apparatus (hereinafter also simply referred to as a decoding apparatus) according to the first embodiment equipped with a decoding method for the encoded data, and will be described below with reference to the drawings. .
[0087]
The image signal decoding apparatus 20 shown in FIG. 1 includes an MPEG decoder 22, a VLC table selector 23, a standard VLC table 24, a special VLC table 25, and an image digital watermark detector 26. The MPEG decoder 22 includes a VLC decoder 221.
[0088]
Next, the operation of the image signal decoding apparatus 20 will be described.
First, the encoded data compressed and encoded by the image signal encoding device 10 is supplied to the MPEG decoder 22. Here, the compression-coded signal is decoded using the value of the VLC table temporarily stored in the VLC decoder 221. The image signal obtained by the decoding is input to the image digital watermark detector 26.
[0089]
In the image digital watermark detector 26, an encoding selection signal embedded as digital watermark information is detected by an image data converter described later, and the encoded selection signal obtained by the detection is supplied to the VLC table selector 23. The
[0090]
The VLC table selector 23 selects the VLC table stored in the standard VLC table 24 or the special VLC table 25 based on the supplied encoding selection signal, that is, the encoding selection signal supplied from the CPU 16. This is supplied to the VLC decoder 221. The value of the VLC table is temporarily stored in the VLC decoder 221.
[0091]
Next, the VLC table temporarily stored in the VLC table 221 is used, and the MPEG decoder 22 decodes the supplied encoded data. The decoding is performed using the same VLC table as the VLC table temporarily stored in the VLC unit 121 of the MPEG encoder 12. Therefore, a high-quality image signal is obtained by decoding.
[0092]
As described above, in the image signal encoding device 10 and the image signal decoding device 20 in the first embodiment, the VLC table selected by the encoding selection signal embedded by the image digital watermark technique. Is used to perform compression coding and decoding of the compression-encoded data, so that a high-quality image signal is reproduced.
[0093]
On the other hand, if the image signal decoding device does not have a function of detecting image digital watermark information, or if the image signal decoding device does not have the information of the special VLC table, the standard VLC mounted in a normal MPEG decoder is used. Since the table is used for decoding, the image signal obtained by decoding is reproduced as an image signal including a distortion component based on the difference between the VLC tables.
[0094]
Using the above method, the copyright holder who owns the copyright of the content supplies image signals of different qualities to the special decoder that has the contractual relationship and the general decoder that does not have the contractual relationship. be able to. That is, by installing an image digital watermark detector and a special VLC table in a special decoder, image signals of different qualities are supplied to the general person and the special person.
[0095]
Even if the general public has an image signal decoding device equipped with a special VLC table, the digital watermark information embedded in the encoded data is the special information provided with the information related to the method of embedding the digital watermark information. Only a contractor who is in a special relationship can obtain an image signal without quality degradation.
[0096]
The digital watermark signal in which the predetermined information is embedded is, for example, a technique of embedding some information in an image and keeping it hidden. There are a plurality of methods for embedding the information. The image signal encoding device side and the image signal decoding device side use a predetermined digital watermarking method to mutually The transmission selection signal is transmitted.
[0097]
As an example that has been proposed as a digital watermarking method, for example, NTT is the SCIS'97 (1997 Symposium on Cryptography and Information Security; 1997, Symposium on Cryptography and Information Security) -31G "In digital video using DCT "Copyright information embedding method" has been announced. This method is proposed as an information embedding method based on changes in DCT (discrete cosine transform) coefficients, motion vectors, and quantization characteristics in MPEG (moving picture experts group) coding of information to be embedded. .
[0098]
In addition, SCIS '97 -26B has announced "Watermark Signature Method for Images Using PN Sequences" at National Defense University. This method follows the direct spreading method and spreads image signals using PN (pseudo noise) sequences. Has been proposed as a method for synthesizing signature information.
[0099]
It is possible to transmit the coding selection signal by using any of the proposed watermarking methods, and also by other watermarking methods in which the coding selection signal is embedded and transmitted by encryption processing. Realization is possible.
[0100]
As described above, by transmitting the encoded signal generated by the image signal encoding device based on the encoding selection signal transmitted by the digital watermark method or the like to the image signal decoding device, the image of different quality for each user can be obtained. The configurations and operations of the obtained image signal encoding device and decoding device have been described.
[0101]
An image to be transmitted with the encoding selection signal embedded is, for example, a first image of a GOP (Group of Picture) in a moving image, for example, or a first image at a predetermined interval is encoded using a standard VLC table. The second and subsequent images are encoded using the transmitted VLC table described in the digital watermark method. Furthermore, there is also a method of recording VLC table information described by digital watermark by encoding it using a standard VLC table for a predetermined time, for example, at a place where program software is started.
[0102]
As another method, there is a method of transmitting digital watermark information related to the VLC table by a portion that transmits a DC component of an image block obtained by DCT conversion of an image signal. In normal coding, the DC component is often quantized with a fixed bit length (for example, 8 bits) regardless of the quantization value, and therefore the redundancy of the portion is large. Therefore, for example, when the value of the DC component of the entire screen is set to “even” is set to 0 and “odd” is set to 1, digital watermark data can be transmitted.
[0103]
The encoding selection signal is transmitted using the above method. Then, when the same decoding VLC table as that at the time of encoding is used, an image with no deterioration is reproduced, and when a different VLC table is used, an image with a slight deterioration is reproduced. However, even when a different VLC table is used, an image in which a reproduced image generated thereby is not reproduced.
The configuration of the image signal encoding device and the image signal decoding device according to the first embodiment for transmitting the encoding selection signal by the digital watermark method and the operation of these devices have been described above.
Next, a method for transmitting the coding selection signal in the user data description area that can be defined and transmitted by the user will be described.
[0104]
<Second embodiment>
FIG. 3 shows the configuration of an image signal encoding apparatus according to the second embodiment equipped with the image signal encoding method, which will be described below with reference to the drawings.
The image signal encoding device 10a shown in FIG. 1 includes an MPEG encoder 12a, a VLC table selector 13, a standard VLC table 14, a special VLC table 15, and a CPU 16a. The MPEG encoder 12a includes a VLC unit 121 and user data. A description device 122 is included. In the figure, blocks having the same functions as those of the first embodiment are denoted by the same reference numerals.
[0105]
Next, the operation of the image signal encoding device 10a configured as described above will be described as different from the first embodiment.
That is, the image signal encoding device 10a supplies the encoding selection signal supplied from the CPU 16a to the user data description unit 122 of the MPEG encoder 12a, thereby describing the encoding selection signal in the user data area.
[0106]
The VLC table selector 13 supplies a VLC table based on the encoding selection signal supplied from the CPU 16 a to the VLC unit 121. The input image data is compression-encoded based on the encoding selection signal supplied from the CPU 16a, and the encoding in which the encoding selection signal is described in the user data area of the compression-encoded signal. The data is output from the image signal encoding device 10a as data.
[0107]
Next, description of the coding selection signal in the user data description area will be described.
FIG. 4 shows and describes the description format of the sequence header in the encoded data.
[0108]
In the same figure, the description syntax of the sequence header is shown. The sequence header describes a 32-bit sequence header code followed by a 12-bit horizontal image size and a 12-bit vertical image size.
Then, user data can be described in the User_data portion after the nextbits () == user_data_start_code with halftone dots.
[0109]
User data can also be described in the GOP layer.
FIG. 5 shows a description format of the encoded data in the GOP layer.
In the figure, the description part of the user data is shown with halftone dots as in FIG. That is, user data similar to the above can be described in the User_data portion after nextbits () == user_data_start_code.
[0110]
Such user data can be similarly described in the picture layer.
FIG. 6 shows a description format of a picture layer in encoded data. Similarly, user data can be described at the locations indicated by halftone dots.
[0111]
In this way, user data can be described in MPEG in the respective areas of the sequence header, GOP layer, and picture layer. Since user_data having other different contents may be described in the user_data description area, when describing an encoding selection signal that is a VLC table switching signal, for example, 32 bits such as “ffee2424” in hexadecimal display It is described following the header signal.
[0112]
That is, a 1-bit signal for selecting a VLC table such as “0” or “1” in binary notation is described following the header signal. Alternatively, the VLC table selection information is described by a byte-aligned 8-bit signal.
[0113]
As such, the encoding selection signal is described in the user data area. Then, the encoding device generates encoded data that has been compression-encoded using the VLC table selected by the encoding selection signal. Next, decoding of the encoded data generated as described above will be described.
[0114]
FIG. 7 shows the configuration of the image signal decoding apparatus according to the second embodiment equipped with the decoding method of the encoded data, and will be described below with reference to the drawings.
The image signal decoding device 20a shown in FIG. 1 includes an MPEG decoder 22a, a VLC table selector 23, a standard VLC table 24, and a special VLC table 25. The MPEG decoder 22a includes a VLC decoder 221 and a user data decoder 222. In the figure, blocks having the same functions as those in the first embodiment are denoted by the same reference numerals. Also in the figures shown after this figure, the same reference numerals denote blocks having the same functions unless otherwise specified.
[0115]
Next, the operation of the image signal decoding apparatus 20a configured as described above will be described.
First, the encoded data that has been compression-encoded by the image signal encoding device 10a is supplied to the MPEG decoder 22a. Here, a signal compression-encoded by the MPEG method is decoded using a value of a VLC table temporarily stored in the VLC decoder 221.
[0116]
The user data described by the user data description unit 122 shown in FIG. 3 is decoded by the user data decoder 222 to obtain an encoding selection signal, and the encoding selection signal is used. Thus, the decoding operation of the encoded data is performed.
[0117]
That is, the encoding selection signal obtained by the user data decoder 222 is supplied to the VLC table selector 23. The VLC table selector 23 selects the value of one of the VLC tables stored in the standard VLC table 24 and the special VLC table 25 based on the encoding selection signal supplied from the CPU 16a. The selected VLC table is supplied to the VLC decoder 221 and temporarily stored therein.
[0118]
Using the VLC table temporarily stored in the VLC table 221, the MPEG decoder 22a decodes the supplied encoded data. As described above, the image signal obtained by decoding is decoded using the same VLC table as the VLC table temporarily stored in the VLC unit 121 of the MPEG encoder 12a described above, so that quality degradation does not occur. It can be obtained as a decoded image signal.
[0119]
As described above, the image signal encoding device 10a and the image signal decoding device 20a in the second embodiment are based on the encoding selection signal described in the user data description area defined in the MPEG standard, for example. Since the VLC table selected as described above is used for compression encoding and compression encoding, high-quality image signals are encoded and decoded.
[0120]
The configurations of the image signal encoding device and the image signal decoding device according to the second embodiment that describe and transmit the encoding selection signal in the user data description area and the operation of these devices have been described above.
Next, a description will be given of a third embodiment in which the encoding selection signal is transmitted using digital watermark data embedded using, for example, a quantization value defined by the MPEG standard.
[0121]
<Third embodiment>
FIG. 8 shows the configuration of an image signal encoding apparatus according to a third embodiment in which the image signal encoding method is mounted, and will be described with reference to the drawings.
An image signal encoding device 10b shown in FIG. 1 includes an MPEG encoder 12b, a VLC table selector 13, a standard VLC table 14, a special VLC table 15, and a CPU 16b. The MPEG encoder 12b includes a VLC unit 121 and a quantized digital watermark information description unit 123.
[0122]
Next, regarding the operation of the image signal encoding device 10b, the operation performed differently from the first embodiment will be mainly described.
First, the encoding selection signal supplied from the CPU 16b is supplied to the quantized value digital watermark information description device 123 of the MPEG encoder 12b. In this case, information related to the encoding selection signal is described as a quantization value of an input image obtained by DCT conversion as digital watermark information.
[0123]
A VLC table is selected from the VLC table selector 13 based on the encoding selection signal supplied from the CPU 16 b, and the selected VLC table is supplied to the VLC unit 121. Then, the input image data in which the encoding selection signal is described and embedded by the quantized value digital watermark information description unit 123 is subjected to variable length encoding using the VLC table stored in the VLC unit 121. The encoded data thus compression-encoded is output from the image signal encoding device 10b.
[0124]
Next, the operation of a digital watermark described as embedded by the quantized digital watermark information description unit 123 will be described.
FIG. 9 shows an example in which digital watermark information is described in a quantized value obtained by DCT transformation.
[0125]
In the figure, the entire image is shown by a large square. The small squares shown therein indicate macroblocks each having 16 pixels vertically and horizontally. The numbers shown therein are examples of quantized values used when quantizing the macroblock data.
[0126]
Here, for example, when the value of the quantization scale set for one macroblock defined by the MPEG standard is an odd number, the information is “1”, and when the value is an even number, the information is “0”. Embed digital watermark information. That is, data of “0” and “1” can be embedded as data corresponding to the number of macroblocks depending on odd and even numbers of macroblock quantization values.
[0127]
It is defined by the MPEG standard that the quantization value of the macroblock is expressed by a value of 1 to 31 (5 bits). Even when compression encoding is performed using a value different from the value at the time of optimal encoding by intentionally setting a predetermined quantized value that is odd or even, the encoded data It has been experimentally confirmed that a decoded image obtained by decoding can be visually inferior in image quality degradation.
[0128]
In this way, by using the information embedded by the quantized value digital watermark information description unit 123, an encoding selection signal that can be transmitted in one bit is transmitted using only one macroblock transmitted first. You may make it do. Furthermore, the same data may be transmitted by using one macroblock of a specific address or repeatedly using a plurality of macroblocks.
[0129]
As described above, the configuration and operation of the image signal encoding apparatus according to the third embodiment that performs encoding by embedding the encoding selection signal by the quantized value digital watermark information description unit 123 have been described.
Next, decoding of the encoded data generated as described above will be described.
[0130]
FIG. 10 shows a configuration example of an image signal decoding apparatus according to the third embodiment that decodes encoded data encoded by the image signal encoding apparatus according to the third embodiment. explain.
The image signal decoding apparatus 20b shown in FIG. 1 includes an MPEG decoder 22b, a VLC table selector 23, a standard VLC table 24, and a special VLC table 25. The MPEG decoder 22b includes a VLC decoder 221 and a quantized value digital watermark information detector 223.
[0131]
Next, with respect to the operation of the image signal decoding device 20b configured as described above, the operation performed differently from the decoding device 20 of the first embodiment will be mainly described.
First, the encoded data that has been compression-encoded by the image signal encoding apparatus 10b is supplied to the MPEG decoder 22b. Therefore, a signal that has been compression-encoded by the MPEG method is decoded using the value of the VLC table temporarily stored in the VLC decoder 221.
[0132]
Then, a part of the quantized value information obtained by decoding there is inversely quantized and inverse DCT transformed to obtain image data. The other part is supplied to the quantized digital watermark information detector 223. There, an encoding selection signal is obtained by detecting information described by the quantized value digital watermark information description unit 123.
[0133]
The obtained encoding selection signal is supplied to the VLC table selector 23. In the VLC table selector 23, the VLC table stored in the standard VLC table 24 or the special VLC table 25 based on the supplied encoding selection signal, that is, the encoding selection signal output from the CPU 16b. The value of is selected. The selected VLC table value is supplied to the VLC decoder 221, and the VLC table value is temporarily stored in the VLC decoder 221.
[0134]
As described above, the image signal coding apparatus according to the third embodiment for transmitting the coding selection signal by setting the quantization value for each macroblock to an odd number and an even number, and the coded data transmitted by the apparatus. The configuration of the image signal decoding apparatus that decodes the above and the operation of these apparatuses have been described.
[0135]
<Fourth embodiment>
Next, a description will be given of a fourth embodiment in which an encoding selection signal is embedded in a vector value of a motion vector defined by the MPEG standard as an electronic watermark data and transmitted.
[0136]
FIG. 11 shows the configuration of an image signal encoding apparatus according to the fourth embodiment equipped with the image signal encoding method, which will be described below with reference to the drawings.
An image signal encoding device 10c shown in FIG. 1 includes an MPEG encoder 12c, a VLC table selector 13, a standard VLC table 14, a special VLC table 15, and a CPU 16c. The MPEG encoder 12c includes a VLC unit 121 and a motion vector digital watermark information description unit 124.
[0137]
Next, the operation of the image signal encoding device 10c configured in this manner will be mainly described as different from the operation according to the first embodiment.
That is, in the image signal encoding device 10c, the encoding selection signal supplied from the CPU 16c is supplied to the motion vector digital watermark information description unit 124 of the MPEG encoder 12c. Then, information related to the encoding selection signal is described as a motion vector value in motion prediction encoding as digital watermark information.
[0138]
The VLC table selector 13 selects a VLC table based on the encoding selection signal supplied from the CPU 16 c and supplies the VLC table to the VLC unit 121. The motion vector digital watermark information description unit 124 generates a motion vector signal in which an encoding selection signal is described and embedded. Then, the quantized value of the input recorded image data subjected to DCT conversion is subjected to variable length coding by a VLC table stored in the VLC unit 121, and encoded data is generated. The motion vector signal and the encoded data thus generated are output from the image signal encoding device 10c.
[0139]
Next, the operation of a digital watermark described as embedded by the motion vector digital watermark information description unit 124 will be described.
FIG. 12 shows an example in which digital watermark information is described in a motion vector obtained by motion prediction detection.
[0140]
In the figure, the entire image is shown by a large square. The small squares shown therein are macroblocks each having 16 pixels vertically and horizontally, and the numbers shown therein are the motion compensation vector values in the horizontal direction of the macroblock data, which are motion vector values in units of pixels.
[0141]
Here, for example, when the motion vector value set for each macroblock defined by the MPEG standard is an odd number, embedded information of “1” is set, and when it is an even number, “0” is set. , 0 and 1 information are embedded. That is, electronic watermark information is described by embedding data of “0” and “1” as data corresponding to the number of macroblocks according to the odd and even numbers of motion vector values of the macroblock.
[0142]
For example, the MPEG standard stipulates that the motion vector value of the macroblock is expressed with a value of ± 16 (VLC) basically with an accuracy of 0.5 pixels. Even in such a case where a vector value is intentionally set to an odd or even number, that is, even when compression encoding is performed using a different value for a predetermined motion vector value, the vector value is Based on experiments, it has been confirmed that a decoded image obtained by decoding encoded data on the basis of it can be obtained with visually comparable image quality.
[0143]
In this way, by using the information embedded by the motion vector digital watermark information description unit 124, an encoding selection signal that can be transmitted in one bit is transmitted using only one macroblock transmitted first. You may do it. Furthermore, the same data may be transmitted by using one macroblock of a specific address or repeatedly using a plurality of macroblocks.
[0144]
The configuration and operation of the image signal encoding apparatus according to the fourth embodiment that performs encoding by embedding the encoding selection signal using the motion vector digital watermark information description unit have been described above.
Next, decoding of the encoded data generated as described above will be described.
[0145]
FIG. 13 shows a configuration example of an image signal decoding apparatus according to the fourth embodiment that decodes encoded data encoded by the image signal encoding apparatus according to the fourth embodiment. To do.
The image signal decoding device 20c shown in FIG. 1 includes an MPEG decoder 22c, a VLC table selector 23, a standard VLC table 24, and a special VLC table 25. The MPEG decoder 22c includes a VLC decoder 221 and a motion vector digital watermark information detector 224.
[0146]
Next, the operation of the image signal decoding apparatus will be described.
First, encoded data including motion vector information compression-encoded by the image signal encoding apparatus 10c is supplied to the MPEG decoder 22c.
[0147]
Then, the motion vector information is supplied to the motion vector digital watermark information detector 224, and an encoding selection signal embedded in the motion vector is detected. The detected encoding selection signal is supplied to the VLC table selector 23, and the signal compressed and encoded by the MPEG method using the transmitted motion vector information is decoded to obtain an image signal. The obtained output image is output from the image signal decoding device 20c.
[0148]
As described above, as described with reference to the first to fourth embodiments, the encoding selection signal is embedded in the image signal data as digital watermark information, described in a predetermined user data description area, and quantized value electrons. Transmission is possible by a method of embedding as watermark information or a method of embedding as motion vector digital watermark information.
[0149]
Among the above four methods, there are a transmission method using one method, a simultaneous transmission method using a plurality of methods, and the like. Furthermore, for example, a method may be used in which information in which encoded selection signal information is transmitted by user data is described and transmitted, and the value of the encoded selection signal is transmitted by digital watermark information.
[0150]
In this way, the encoding selection signal can be transmitted from the image signal encoding device to the image signal decoding device.
Next, a VLC table that is switched by the encoding selection signal will be described.
[0151]
FIG. 14 shows a standard VLC table defined by the MPEG standard.
In the figure, the relationship between the run length and level for the VLC code is shown. That is, this table is a variable length coding table for encoding and transmitting a data string indicated by a 6-bit number from “−31” to “+31”. In particular, when the data string includes a lot of “0” values, the number of consecutive “0” s is the run length, and the value transmitted following the consecutive “0” is the level. A VLC code is assigned according to the number of consecutive “0” and the value of the level transmitted subsequently.
[0152]
The table to which the VLC code is assigned in this manner is stored in a normal MPEG decoder, and the table is used for decoding a bit stream encoded by a normal MPEG system.
[0153]
By the way, the image signal encoding apparatus shown in the present embodiment is special in that the copyright holder reproduces it as a slightly deteriorated reproduction image with respect to a normal image signal decoding apparatus and is in a contractual relationship. A special VLC table is used for compression encoding so that a high-quality image without deterioration is reproduced for a simple image signal decoding apparatus.
[0154]
Next, the special VLC table will be described.
15 and 16 show examples of special VLC tables used in this embodiment.
The VLC tables in these drawings are obtained by dividing one special VLC table into two.
[0155]
That is, this table defines the run length indicating the continuous length of data “0” and the level that is the value of the data arranged after the continuous “0” for the VLC code to be defined. It is. The replacement address is shown in the right column.
[0156]
As replacement addresses, A1 to A38, B1 to B5, and C1 to C2 are described. When the table values shown there are used as they are, encoding using the standard VLC table is performed. Also, a special VLC table can be created by exchanging addresses at locations where the exchange address values are the same.
[0157]
Next, the address exchange operation will be described.
The groups A, B, and C shown in the replacement address column of the table indicate the VLC category, respectively. The categories are grouped based on run length values.
[0158]
In other words, A shows the categorization when the run length is 0, B the run length is 1, and C the run length is 2. Here, only a part of the VLC table is displayed, but the run lengths that are not displayed are also grouped in the same manner.
[0159]
Then, the replacement of the address value designating the VLC code in the special VLC table is performed by replacing the VLC code with the same category, that is, with the same run length value.
[0160]
The reason why the VLC codes having the same run length are replaced with each other is that compression is performed by variable-length coding the coefficient value data obtained by, for example, zigzag scanning the coefficient value obtained by orthogonal transformation like MPEG. In the coding system, it is important as a change to be made while keeping the number and arrangement of data constant.
[0161]
That is, the total run length of DCT coefficients in an MPEG DCT block must not exceed 63 for intra pictures and 64 for inter pictures. Therefore, even if the VLC conforms to the Huffman code system, if the number exceeds 63 or 64 due to rereading, an abrupt error will occur during decoding of the encoded signal, and decoding will not be possible. This is because the image is broken.
[0162]
Therefore, it is necessary to replace the VLCs to be replaced with the same category. In the example shown here, “run lengths are the same”, each of A, B, and C shown as the same category. Are replaced by the same symbol. For example, A2 and A3 can be replaced, but A2 and B2 cannot be replaced.
[0163]
As described above, a special VLC table based on the standard VLC table can be created by performing replacement within each group of replacement addresses A1 to A38, B1 to B5, and C1 to C2.
[0164]
When VLC codes with a combination of run lengths and level values that are often generated when encoding a normal image are replaced with ones having greatly different level values, a semi-disclosure image deteriorated by a predetermined degree is decoded. Is obtained. That is, the semi-disclosure image referred to here indicates an image displayed in a degraded manner so that it is reproduced with distortion when the image signal is recorded in analog.
[0165]
For example, when each of A1 and A4 and A2 and A3 is replaced, a moderately deteriorated semi-disclosure image is obtained. The same applies to B1 and B5, B2 and B4, and C1 and C2. Furthermore, such a combination relating to replacement is created as 32 to 64 different replacement rules, and the identification signal is used as the replacement rule so that it can be decoded with the desired semi-disclosure image quality. Is also possible.
[0166]
The method for replacing the VLC code based on the replacement address has been described above. The VLC code events having the same run length are defined by those set in the MPEG standard. Therefore, the special decoder equipped with the special VLC code performs an operation in which compatibility is ensured with the conventional standard decoder.
[0167]
Since the replacement of the VLC code is performed with a code having a different level value for the same run length, the standard decoder in which only the standard VLC table is installed with the encoded data encoded using the special VLC table. When decoding is performed by the above, an image whose resolution is changed due to a decrease or improvement in the high-frequency signal level of the image signal, a decrease or improvement in the low-frequency signal level, or the like is reproduced.
[0168]
Next, such a change in image resolution will be described.
FIG. 17 shows a conventional device using a conventional standard VLC table, a special VLC table, and a standard VLC table for the quality of an image signal obtained by decoding the encoded data compressed and encoded by the encoder. The relationship of the encoding and decoding between the special equipment which carries both of these is shown.
[0169]
In the figure, the quality of the reproduced image by each of the four combinations is shown. A circle indicates that a high quality image is reproduced, and a Δ mark indicates that the image is slightly degraded.
[0170]
In other words, an image signal with reduced image quality is output only when it is encoded with a special device and decoded with a conventional device, and when encoded with a special device and decoded with a special device, a high-quality image is reproduced. It is also shown that compatibility with other conventional encoders is ensured.
[0171]
In this way, it is possible to provide a difference in image quality that is reproduced within a range in which compatibility is ensured. Therefore, according to the intention of the copyright holder of the image signal, a special decoder and a special decoder are used. It is possible to provide image data with different image quality to a decoder of a type. Then, the generation of the encoding selection signal in the image signal encoding device for that purpose, the embedding of the encoding control signal into the encoded data, the acquisition of the encoding selection signal in the image signal decoding device, and the decoding of the encoded data are as follows: These operations are performed by calculation processing of signals by a computer and by control of circuit units by the computer.
[0172]
Next, a method for performing such signal processing by causing a computer to execute the program will be described.
FIG. 18 is a flowchart showing the flow of a computer program executed in connection with image signal encoding.
[0173]
In the figure, in step S11, it is checked whether or not to perform special processing of an image signal so that image data with different image quality is reproduced for a conventional decoder and a special decoder. When special processing is performed, an encoding control signal is generated from the computer in S12.
[0174]
The generated encoding control signal is supplied to the VLC table selector, and in S14, the VLC table selector obtains a special VLC table. Then, the special VLC table acquired in S15 is loaded into the VLC unit of the MPEG encoder, and a transmission coding control signal for transmitting the coding control signal to the image signal decoding device is generated in S16.
[0175]
The transmission coding control signal is embedded in image signal data as digital watermark information, described in a predetermined user data description area, embedded as quantized value digital watermark information, or embedded as motion vector digital watermark information. Is generated by
[0176]
The generated transmission encoding control signal is transmitted together with the encoded image data. Also, the MPEG encoder in which the VLC table for encoding the image data is a special VLC table is subjected to DCT conversion in S17 to obtain quantized number data. Next, the obtained quantization number data is subjected to variable length encoding using a special VLC table and is generated as encoded data.
[0177]
The generation of the transmission encoded signal and the encoding of the image data are repeatedly performed until the supply of the image data related to the encoding is finished.
[0178]
The encoded data obtained by encoding in this way is decoded by the image signal decoding device. Next, a computer program for operating the image signal decoding apparatus will be described.
[0179]
FIG. 19 is a flowchart showing the flow of a computer program executed in connection with image signal decoding.
In the figure, it is checked whether or not the information of the encoding control signal is transmitted to the encoded data supplied in S21. When the encoded control signal is attached and transmitted, it is embedded in the encoded data in S22. The encoded control signal transmitted in this manner is read out as being decoded.
[0180]
The read control signal is supplied to the VLC table selector, and a special VLC table is acquired in S23, and the acquired special VLC table is loaded into the VLC decoder of the MPEG decoder in S24.
[0181]
Then, the MPEG decoder performs variable length decoding based on the loaded VLC table and obtains image data obtained by decoding the supplied encoded data. The obtained image data is supplied as an output signal from the image signal decoding apparatus, and the operations in S25 and S26 are executed until the supply of the supplied encoded signal is completed.
[0182]
As described above in detail, on the encoding side of the image signal, when trying to supply reproduced video with different image quality between the decoding device having the standard VLC table and the decoding device having the special VLC table, A method of embedding information relating to the use of the special VLC table in image signal data as digital watermark information, describing it in a predetermined user data description area, embedding as quantized value digital watermark information, or embedding as dynamic vector digital watermark information Can be performed.
[0183]
The configuration and operation of the image signal encoding device and the image signal decoding device according to the first to fourth embodiments have been described above.
Next, an example in which these image signal encoding device and image signal decoding device are applied to a transmission device and a reception device will be described.
[0184]
<Fifth embodiment>
FIG. 20 shows the configuration of an image signal encoding / transmission (transmission) apparatus according to the fifth embodiment, which will be described below with reference to the drawings.
[0185]
Compared with the configuration of the image signal encoding apparatus according to the first embodiment shown in FIG. 1, the image signal encoding / transmission apparatus 10d shown in FIG. The difference is that it is arranged after the output of the encoder 12. The same reference numerals are assigned to blocks having the same function.
[0186]
Next, the operation of the image signal encoding / transmission apparatus 10d configured as described above will be described with respect to differences from the first embodiment.
That is, a coding selection signal that is a VLC table switching signal is embedded as digital watermark information, and a compression coded signal obtained by compression coding by the MPEG encoder 12 is supplied to the transmission path packet encoder 17.
[0187]
There, multiplexing processing is performed to packetize the compressed encoded signal, for example, a bit stream as defined by the MPEG system for each piece of information such as audio and video and supply the packet to the transmission path. The encoded packet data subjected to the multiplexing process is output from the image signal encoding / transmission apparatus 10d to the communication network via the transmission path interface 18. The transmitted multiplexed signal is received by the image signal decoding receiving device.
[0188]
FIG. 21 shows the configuration of an image signal decoding and receiving apparatus according to the fifth embodiment, which will be described below with reference to the drawings.
Compared with the image signal decoding apparatus according to the first embodiment shown in FIG. 2 described above, the image signal decoding / receiving apparatus 20d shown in the figure is a transmission path packet decoder between the input terminal and the MPEG decoder 22. 27 is different in that it is arranged. The same reference numerals are assigned to blocks having the same function.
[0189]
Next, the operation of the image signal decoding / receiving apparatus 20d configured as described above will be described with respect to differences from the first embodiment.
That is, a packetized compressed encoded signal (encoded packet data) received from the communication network via the transmission path interface 28 is supplied to the transmission path packet decoder 27.
[0190]
There, the packetization is performed by the transmission path packet encoder 17 described above, and complementary processing to the packetization transmitted is performed to obtain a compressed encoded signal. The compressed encoded signal is supplied to the MPEG decoder 22 and is decoded in the same manner as described above. Then, the decoded image signal is output as an output image.
[0191]
The configuration and operation of the image signal encoding / transmission device and the image signal decoding / reception device according to the fifth embodiment have been described above. These operations may be executed by being controlled by a computer program.
[0192]
FIG. 22 is a flowchart showing the flow of a computer program executed in connection with image signal encoded transmission according to the fifth embodiment.
In the figure, parts that perform the same operations as those in the flowchart shown in FIG. Next, an operation part different from that described in the fourth embodiment will be described.
[0193]
That is, the next operation for encoding the image data in S17 is a processing operation related to the packetization of the encoded data in S31, and then an operation for checking whether the packetization processing is completed is performed in S32. Is different.
[0194]
The packetization of the encoded data in S31 is, for example, an operation for generating an audio video multiplexed bit stream, which is performed by the transmission path packet encoder 17 in FIG. The generated bit stream is supplied to the communication network and transmitted. In addition, packetization processing unique to the transmission line is also performed in accordance with the transmission conditions defined in the transmission line for transmission through the transmission line as necessary.
[0195]
Then, the generation of the generated transmission encoded signal and the encoding of the image data are performed by repeating the operations of S16, S17, and S31 until the packetization of the image data encoded in S32 is completed.
[0196]
The encoded packet data obtained by encoding and packetizing in this way is sent from the image signal encoding and transmitting apparatus 10d to the communication network. The data is received and decoded by the image signal decoding / receiving device 20d.
Next, operations for receiving and decoding an image signal shown as the fifth embodiment will be described.
[0197]
FIG. 23 is a flowchart showing the operation of the computer program executed in connection with the image signal decoding reception according to the fifth embodiment.
In the figure, parts that perform the same operations as those in the flowchart shown in FIG. Next, different parts of the operation will be described.
[0198]
That is, the next operation after loading to the VLC unit in S24 is the packet decoding operation of the decoded data in S41, and the data obtained by the decoding is passed to the decoding of the encoded data in S25. Is different.
[0199]
That is, the packet decoding of the decoded data in S41 is an operation performed by the transmission path packet decoder 27 in FIG. 21 described above, in which the multiplexed bit stream is transmitted to the bit stream described above. The signal processing operation complementary to the transmission path packet encoder 17 in FIG.
[0200]
As such, the packet decoded signal is transferred to the decoding of the encoded data in S25, and the next processing is performed. Then, in these signal processing, the operations of S41, S25, S26, and S27 are repeatedly executed until it is determined as Yes depending on whether the image decoding of S27 is completed.
The operation executed under the control of the computer program of the image signal encoding / transmission apparatus and the image signal decoding / reception apparatus according to the fifth embodiment has been described above.
[0201]
As described in detail above, the decoding of the image signal encoded using the special VLC table on the side of the encoding transmission apparatus, the decoding reception apparatus having only the standard VLC table, and the standard VLC table and the special VLC table are provided. In addition, by using the decoding reception device that is switched and used, it is possible to realize a decoding reception device that can reproduce with different desired image quality.
[0202]
Then, information relating to the use of the special VLC table is embedded in the image signal data as digital watermark information, described in a predetermined user data description area, embedded as quantized value digital watermark information, or embedded as motion vector digital watermark information, etc. Transmit by the method.
[0203]
The compressed encoded signal transmitted in this way is decoded by detecting the transmitted VLC table control signal from the syntax defined by MPEG, which is a standard for transmitting the encoded signal, and detecting the detected VLC table control signal. The VLC table used for encoding is detected based on the VLC table control signal. Then, by decoding using the detected table, an image signal having a desired degree of degradation is obtained.
[0204]
In addition, the VLC code of the VLC table used by switching is configured by using a code existing in a VLC code system defined by, for example, an international standard and generally used MPEG standard, and uses a special VLC table. Thus, the interchangeability of the signal between the signal encoded using the standard VLC table and the signal encoded using the standard VLC table is maintained within a predetermined range. Thus, it is possible to ensure and configure signal exchange with an apparatus conforming to the MPEG standard that is widely used in a wide market.
[0205]
Furthermore, for the information on the use of the special VLC code, for example, user data defined in MPEG, digital watermark data mixed in an image, digital watermark data mixed using a quantized value, and a motion vector value are used. Since at least one of the digital watermark data embedded by the above method is transmitted using a plurality of data as necessary, a plurality of security levels are set for a desired content to be encoded. The encoding method of the image signal performed by setting can be realized.
[0206]
As described above, the MPEG2 video compression encoding method in which the encoding of the moving image signal is performed using the special VLC table instead of the standard VLC table has been described as an example.
Next, compression encoding of an acoustic signal performed using the same standard VLC table and special VLC table and decoding of encoded data supplied after being encoded will be described.
[0207]
First, encoding and decoding of an audio signal in the MPEG-2 AAC (Advanced Audio Coding) system, which is a typical compression encoding system for acoustic signals, will be described.
[0208]
<Sixth embodiment>
FIG. 24 shows the configuration of an audio signal encoding apparatus (hereinafter also simply referred to as an encoding apparatus) according to the sixth embodiment, which will be described below with reference to the drawings.
[0209]
The audio signal encoding device 430 shown in the figure includes an MPEG-2 AAC encoder 431, a Huffman codebook selector 432, a scale factor standard Huffman codebook 433, a scale factor special Huffman codebook 434, and a CPU 435. . The MPEG-2 AAC encoder 431 includes a variable length encoder 436 that performs variable length encoding using a Huffman codebook.
[0210]
The MPEG-2 AAC encoder 431 is configured in the same manner as the conventional one, but the variable length encoder 436 performs variable length encoding using a special VLC table in addition to the standard VLC table used conventionally. The difference is that a control signal for performing is input.
Here, the Huffman code encoding is an encoding method included in the VLC encoding, and the Huffman code book is an encoding table used for that purpose. Therefore, the concept of the Huffman code book is included in the VLC table in a broad sense.
[0211]
Next, the operation of the audio signal encoding device 430 configured as described above will be described.
First, an audio signal to be encoded is input to the MPEG-2 AAC encoder 431 and an external switching signal is input to the CPU 435. The CPU 435 generates an encoding selection signal for switching the Huffman codebook based on the supplied external switching signal.
[0212]
The encoding selection signal is generated as a cipher subjected to some cryptographic processing by using, for example, a pseudo-random number, with the external switching signal supplied by the CPU 435 as an initial value. Then, by decoding the generated external switching signal, an encoding selection signal which is a Huffman codebook switching signal is output.
[0213]
Then, an encoding selection signal that is a Huffman codebook switching signal is supplied from the CPU 435 to the Huffman codebook selector 432. For example, when the encoding selection signal supplied from the CPU 435 is “0”, the scale factor standard Huffman codebook is selected and encoded, and when it is “1”, the scale factor special Huffman codebook is selected. Encoding is set.
[0214]
That is, the Huffman codebook selector 432 selects the Huffman codebook selected by the encoding selection signal from the standard Huffman codebook 433 for scale factor and the special Huffman codebook 434 for scale factor. Is supplied to the variable length encoder 436.
[0215]
In the MPEG-2 AAC encoder 431, the supplied audio signal is subjected to variable length encoding based on the Huffman codebook temporarily stored in the variable length encoder 436.
Next, a scale factor Huffman codebook will be described.
[0216]
FIG. 25 shows an example of obtaining a scale factor in the scale factor band (Sfb).
In the figure, on the upper side, scale factors in N scale factor bands from 0 to (N−1) are shown. The lower side shows index values for these scale factor bands.
[0217]
In other words, the supplied audio signal has a scale factor calculated based on the result of auditory psychoanalysis by FFT and coefficient value data obtained by MDCT (Modified Discrete Cosine Transform) conversion. Then, the difference value of the scale factor is obtained. That is, the (k−1) th Sfb is subtracted from the kth Sfb to obtain a difference value. Next, using a value obtained by adding 60 to the offset value, variable length coding is performed such that a value (hereinafter referred to as an index) corresponding to the scale factor Huffman codebook is read.
[0218]
The Huffman codebook for the scale factor is created using the fact that when the index is 60, the difference value of the scale factor is 0, and the occurrence frequency decreases as the absolute value of the difference value increases. ing.
[0219]
FIG. 26 is a table showing a part of the Huffman codebook for scale factor used in the MPEG-2 AAC encoding system.
The scale factor Huffman code book shown in this table is used as the scale factor standard Huffman code book 433. Also, the scale factor special Huffman code book 434 is created by exchanging the indexes of the scale factor standard Huffman code book 433.
[0220]
FIG. 27 illustrates an index replacement method.
In the figure, the table on the left shows a part of the standard Huffman codebook and how to replace it. And the table on the right is a part of the special Huffman codebook created by switching.
[0221]
That is, the replacement is performed at locations where the codeword length is the same in an index larger than index 60 and an index smaller than that in the table. For example, a special Huffman codebook is obtained by replacing the indexes 56 and 55 and the indexes 64 and 65 each having a codeword length of 6.
[0222]
FIG. 28 shows an example of variable length coding of a scale factor using the above-mentioned Huffman codebook.
In the figure, (1) the scale factors from sfb0 to sfb4 are 10, 15, 19, 14, and 10, respectively. (2) When the overall quantization step is 30, difference values -20, 5, 4, -5, and -4 from adjacent sfb are obtained when variable length coding is performed.
[0223]
Next, (3) the offset value 60 is added, and each sfb is calculated as an index value of 40, 65, 64, 55, 56. Here, since there is no previous sfb for the first sfb0, a difference calculation is performed for the entire quantization step value 30.
[0224]
When a code word is obtained using the standard Huffman code book shown in FIG. 26, ff9, 3b, 39, 3a, and 38 are obtained. However, since the Huffman codebook used here is a special Huffman codebook in which codewords are replaced, codewords ff9, 3a, 38, 3b, and 39 shown in (4) are obtained. Then, a bit stream is generated using the obtained data.
[0225]
Next, the generated and transmitted bit stream is decoded. When the normal decoder has only the standard Huffman codebook of the MPEG-2 AAC encoding system, variable length decoding is performed, and (5) the indices of each sfb are 40, 55, 56, 65, 64. As obtained.
[0226]
Next, (6) the offset value 60 is subtracted from these data, and (7) the scale factor is obtained as 10, 5, 1, 6, 10. This value is different from the original scale factor.
[0227]
As such, different audio signals are reproduced when decoding the encoded bitstream using a different scale factor than the encoding. Therefore, scramble processing for generating a semi-disclosure audio signal can be performed using this method.
[0228]
Next, decoding of the bitstream generated by encoding in this way will be described.
FIG. 29 shows the configuration of an audio signal decoding apparatus (hereinafter also simply referred to as a decoding apparatus) according to the sixth embodiment, which will be described below with reference to the drawings.
[0229]
The audio signal decoding apparatus 440 shown in the figure includes an MPEG-2 AAC decoder 441, a Huffman codebook selector 442, a scale factor standard Huffman codebook 443, a scale factor special Huffman codebook 444, and a CPU 445. . The MPEG-2 AAC decoder 441 includes a variable length decoder 446 that performs variable length decoding using a Huffman codebook.
[0230]
The MPEG-2 AAC decoder 441 is configured in the same manner as in the prior art, but the variable length decoder 446 uses a special Huffman codebook in addition to the conventional standard Huffman codebook and performs variable length decoding. Is different.
[0231]
Next, the operation of the audio signal decoding apparatus 440 configured as described above will be described.
First, an external switching signal output from the audio signal encoding device 430 is supplied to the CPU 445.
[0232]
There, processing equivalent to the CPU 435 in the audio signal encoding device 430 is performed. That is, an encoding selection signal that is a Huffman codebook switching signal is generated, and the signal is supplied to the Huffman codebook selector 442.
[0233]
Next, the bit stream compressed and encoded by the audio signal encoding device 430 is supplied to the MPEG-2 AAC decoder 441. Here, the signal compressed and encoded by the MPEG-2 AAC system is decoded using the value of the Huffman codebook temporarily stored in the variable length decoder 446.
[0234]
The Huffman code book selector 442 stores the scale factor standard Huffman code book 443 or the scale factor special Huffman code book 444 based on the supplied coding selection signal, that is, the coding selection signal supplied from the CPU 445. The value of the Huffman codebook to be executed is selected and supplied to the variable length decoder 446. The value of the Huffman codebook is temporarily stored in the variable length decoder 446.
[0235]
The MPEG-2 AAC decoder 441 uses the Huffman codebook temporarily stored as described above to decode the supplied bit stream. The decoding is performed by using the same Huffman codebook as the Huffman codebook temporarily stored in the variable length encoder 436 of the MPEG-2 AAC encoder 431, so that the decoding is performed with high fidelity. Audio signal can be obtained.
[0236]
However, when the audio signal decoding apparatus does not have the special Huffman codebook for scale factor, the standard Huffman codebook for scale factor installed in the normal MPEG-2 AAC decoder is used to decode the bitstream. Therefore, the decoded audio signal is decoded as an audio signal including a distortion component based on the difference between the Huffman codebooks.
[0237]
The configurations and operations of the audio signal encoding device and the audio signal decoding device according to the sixth embodiment that perform variable length encoding of the scale factor using the standard Huffman codebook and the special Huffman codebook have been described above. .
[0238]
<Seventh embodiment>
Next, the configuration and operation of the audio signal encoding apparatus and audio signal decoding apparatus according to the seventh embodiment in which the standard Huffman codebook and the special Huffman codebook are used for variable-length encoding of a spectrum signal will be described.
FIG. 30 shows the configuration of an audio signal encoding apparatus according to the seventh embodiment, which will be described below with reference to the drawings.
[0239]
The audio signal encoding device 450 shown in the figure includes an MPEG-2 AAC encoder 451, a Huffman codebook selector 452, a spectrum standard Huffman codebook 453, a spectrum special Huffman codebook 454, and a CPU 455. The MPEG-2 AAC encoder 451 includes a variable length encoder 456 that performs variable length encoding using a Huffman codebook.
[0240]
The audio signal encoding apparatus 450 configured as described above uses a standard scale factor Huffman codebook as compared with the audio signal encoding apparatus according to the sixth embodiment shown in FIG. However, it is different in that a standard Huffman codebook for spectrum and a special Huffman codebook for spectrum are used for variable length coding of an audio signal obtained by MDCT.
[0241]
Next, the operation of the audio signal encoding device 450 configured as described above will be described.
First, an audio signal to be encoded is supplied to the MPEG-2 AAC encoder 451, and at the same time, an external switching signal is input to the CPU 455. On the other hand, the external switching signal is supplied to an audio signal decoding device 460 (described later) that performs a decoding operation complementarily to the audio signal encoding device 450.
[0242]
An external switching signal is supplied to the CPU 455, and an encoding selection signal which is a Huffman codebook switching signal is generated based on the signal. For example, when the CPU 455 generates a pseudo-random number with the external switching signal as an initial value, or when the external switching signal is supplied as a cipher subjected to some cryptographic processing, the Huffman codebook switching is performed by decrypting the external switching signal. An encoding selection signal that is a signal is obtained.
[0243]
In this manner, the CPU 455 supplies an encoding selection signal that is a Huffman codebook switching signal to the Huffman codebook selector 452. For example, when the encoding selection signal supplied from the CPU 455 is “0”, the standard Huffman codebook for spectrum is selected and encoded, and when it is “1”, the special Huffman codebook for spectrum is selected and encoded. Set to do.
[0244]
Next, the Huffman codebook selector 452 selects the Huffman codebook selected by the encoding selection signal from the standard Huffman codebook 453 for spectrum and the Huffman codebook supplied from the special Huffman codebook 454 for spectrum. The variable length encoder 456 is supplied.
[0245]
The MPEG-2 AAC encoder 451 performs variable-length coding on the spectrum signal of the MDCT audio input signal based on the Huffman codebook temporarily stored in the variable-length encoder 456.
Here, the Huffman codebook for the spectrum will be described.
[0246]
When variable length coding is performed on the quantized value of the spectrum, a code corresponding to the Huffman codebook for the spectrum from the index based on the quantized value of the spectrum calculated in units of two or four in sfb. Read a word. There are eleven types of spectrum Huffman codebooks, and combinations are selected from among them, which are generated by encoding and minimize the code amount of the entire code.
[0247]
FIG. 31 shows a part of the spectrum standard Huffman codebook in a table.
The spectrum standard Huffman codebook shown in the figure is a part of the codebook used in the MPEG-2 AAC coding system, and here, the codebook is used as the spectrum standard Huffman codebook 453. The special Huffman code book 454 is obtained by replacing the indexes of the spectrum standard Huffman code book 453.
[0248]
FIG. 32 shows an example of creating a special Huffman code book by replacing the code words of the standard Huffman code book.
The spectrum Huffman codebook shown here is part of the second one defined in the AAC standard.
[0249]
There are a plurality of codebooks having the same codeword length across the index 40. Therefore, for example, the index 36 to 39 and the index 44 to 41 are exchanged to create a new Huffman codebook, which is used as the special Huffman codebook.
[0250]
FIG. 33 shows an example of variable-length coding of spectral quantization values using the above Huffman codebook.
Each of the four quantized values in the figure is 0, 0, −1, 1. Next, conversion to an index in that case will be described.
[0251]
That is, when using the Huffman codebook No. 2, the following equation (1) is used as a conversion equation to the index (IDX) for the four spectra Q0 to Q3.
IDX = 27 × Q0 + 9 × Q1 + 3 × Q2 + Q3 + 40 (1)
The above 0, 0, -1, 1 is substituted for each of Q0 to Q3.
[0252]
The index value of the spectrum shown as (a) in the figure is
IDX = 27 × 0 + 9 × 0 + 3 × (−1) + 1 + 40 = 38
Thus, the code word corresponding to the Huffman code book No. 2 that has been replaced based on the value is read out.
[0253]
That is, the value in the special Huffman codebook with an index value of 38 is 1d, and that value is read out. Then, a bit stream obtained by encoding the audio signal based on the read value is generated and output from the audio signal encoding device 450.
[0254]
Next, the bit stream is input to an audio signal decoding device and decoded.
FIG. 34 shows the configuration of an audio signal decoding apparatus according to the seventh embodiment, which will be described below with reference to the drawings.
[0255]
The audio signal decoding apparatus 460 shown in the figure includes an MPEG-2 AAC decoder 461, a Huffman codebook selector 462, a spectrum standard Huffman codebook 463, a spectrum special Huffman codebook 464, and a CPU 465. The MPEG-2 AAC decoder 461 includes a variable length decoder 466 for performing variable length decoding using a Huffman codebook.
[0256]
The audio signal decoding apparatus 460 configured as described above uses a standard scale factor Huffman codebook as compared with the audio signal decoding apparatus according to the sixth embodiment shown in FIG. However, it differs in that a standard Huffman codebook and a special Huffman codebook are used for variable-length decoding for spectrum.
[0257]
Next, the operation of the audio signal decoding device 460 configured as described above will be described.
First, the bit stream compressed and encoded by the audio signal encoding device 450 is supplied to the MPEG-2 AAC decoder 461.
[0258]
Then, the external switching signal transmitted from the audio signal encoding device 450 is supplied to the CPU 465. The CPU 465 processes the supplied signal in the same manner as the CPU 455 in the audio signal encoding device 450. Next, an encoding selection signal which is a Huffman codebook switching signal is generated, and the signal is supplied to the Huffman codebook selector 462.
[0259]
In the Huffman code book selector 462, one of the spectrum standard Huffman code book 463 and the spectrum special Huffman code book 464 is selected based on the supplied coding selection signal, that is, the coding selection signal supplied from the CPU 465. The value of the Huffman codebook stored on one side is selected and supplied to the variable length decoder 466. The value of the Huffman codebook is temporarily stored in the variable length decoder 466.
[0260]
The MPEG-2 AAC decoder 461 decodes the supplied bit stream using the Huffman codebook temporarily stored in the variable length decoder 466 as described above.
[0261]
The decoding performed in such a manner is performed using the same Huffman codebook as the Huffman codebook temporarily stored in the variable length encoder 456 of the MPEG-2 AAC encoder 451, so that high-quality decoding is performed. An audio signal can be obtained.
[0262]
However, if the audio signal decoding apparatus does not have the spectrum special Huffman codebook information, the standard Huffman codebook installed in the normal MPEG-2 AAC decoder is used to decode the bitstream. Therefore, the decoded audio signal is decoded as an audio signal including a distortion component corresponding to the difference between the Huffman codebooks.
[0263]
For example, the index value for each of the above four quantized values 0, 0, -1, 1 was calculated as 38. When it is variable length encoded using a special Huffman codebook and variable length decoded using a standard Huffman codebook, an index value 42 is obtained.
[0264]
Decoding is shown in FIG. 33 (b). Here, the index value 42 is calculated as Q0 = 0, Q1 = 0, Q2 = 1, and Q3 = -1. That is, since the four quantized values are obtained as 0, 0, 1, and -1, respectively, values different from the quantization of the original spectrum are obtained.
[0265]
If the quantized value thus obtained is inversely quantized and an IMDCT (Inverse Modified Discrete Cosine Transform) is performed to decode the audio signal, the original signal cannot be reproduced. That is, the audio signal reproduced in this way is reproduced as a signal subjected to pseudo audio scramble.
[0266]
As described above, the configurations of the audio signal encoding device and the audio signal decoding device according to the seventh embodiment for performing variable length encoding of the spectrum of the audio signal obtained by MDCT using the standard Huffman codebook and the special Huffman codebook, The operation was described.
[0267]
In this embodiment, the case where the spectrum Huffman codebook No. 2 is used has been described as an example. Furthermore, since there are 11 types of Huffman codebooks for spectrum, special Huffman codebooks are created for each, and variable-length coding is performed, or special Huffman codebooks only for some of the Huffman codebooks. There are cases where encoding is performed using a code book, and any of them may be used.
[0268]
Also, from 1 to 10 of the Huffman codebook, 1 and 2, 3 and 4, 5 and 6, 7 and 8, and 9 and 10 are created as a pair, and the same among these pairs Has a number of codewords. Therefore, by using the same conversion formula to the same index, the pair of each other is used as a standard and special Huffman codebook so that the special Huffman codebook of the first Huffman codebook is second. In this way, encoding can be performed, and such a method may also be realized.
[0269]
The configuration of the apparatus for switching and encoding the standard and special Huffman codebooks by the external switching signal and the operation thereof have been described above. In addition, it is also necessary to scramble the audio signal to the external switching signal transmitted from the audio signal encoding apparatus of the present embodiment to the audio signal decoding apparatus so that the user cannot freely operate it. . That is, in order to reliably execute the scramble, it is necessary to encrypt the external switching signal generated by the audio signal encoding device.
[0270]
The encrypted signal generated by the audio signal encoding device is decrypted and obtained by the CPU in the audio signal decoding device, and the variable length decryption is performed using the obtained external switching signal. To do.
[0271]
Further, an external switching signal is embedded as digital watermark information in the MPEG-2 AAC bit stream in the audio signal encoding device, and the digital watermark information is extracted from the MPEG-2 AAC bit stream supplied to the audio signal decoding device, There is also a method of generating a Huffman codebook switching signal based on the information.
[0272]
Further, as a method of not transmitting the external switching signal separately from the bit stream, the digital watermarking method used in the image signal encoding / decoding device described above is used, for example, the scale factor or the spectrum value is rounded to an even value. A method of embedding watermark data by rounding it to a numerical value or the like and transmitting it may be used.
[0273]
The method uses, for example, a digital watermark technique to embed an encoding selection signal as a signal following an external switching signal in an audio signal at the first position for each predetermined interval, and compress the encoded signal by an MPEG2 AAC encoder. This is a method for generating a standardized MPEG-2 AAC bitstream.
[0274]
Then, the decoding of the signal encoded by the method is performed by detecting a coding selection signal embedded as digital watermark information and selecting an appropriate Huffman codebook from the detected coding selection signal. A switching signal may be obtained.
[0275]
In the foregoing, the method of transmitting as an encoded selection signal encrypted by using the digital watermark technique has been described. As a method that does not rely on digital watermarking, for example, there is a method in which data based on an external switching signal is described in data_stream_element defined by the MPEG-2 AAC encoding method and transmitted.
[0276]
This is a method of decoding data_stream_element on the audio signal decoding apparatus side to obtain decoded information, and generating a Huffman codebook switching signal based on the obtained information.
[0277]
Further, in the case of this method, the data related to the external switching signal described in the data_stream_element only needs to be consistent on the encoding side and the decoding side, and an appropriate encryption is required on the encoding side and the decoding side. The transmission and reception may be performed by setting the encryption method.
[0278]
As described above, for each of the image signal and the audio signal, when the coefficient value signal obtained by performing the orthogonal transform is variable length encoded and transmitted, by using the standard variable length table and the special variable length table, a little A variable-length data encoding method and a decoding method thereof that enable reproduction as an image signal with distortion and an audio signal have been described. The distortion can be individually set by using a standard or special variable length table for either or both of the image signal and the audio signal.
[0279]
Next, using such a variable-length data encoding method and its decoding method, an image is encoded for a preferred embodiment of a business model that can be used in broadcasting, communication, or information recording media. Is mainly described.
[0280]
<Eighth embodiment>
FIG. 35 shows a variable length encoded data transmitting apparatus (hereinafter simply referred to as a transmitting apparatus) according to the eighth embodiment, which is equipped with a variable length data encoding method for semi-disclosure used for broadcasting or communication. ) And will be described with reference to the drawings.
[0281]
The variable-length encoded data transmission apparatus 510 shown in FIG. 1 includes an image data converter 511, an encryption unit 512, an encryption method setting unit 513, an encryption key setting unit 514, a CPU 515, an MPEG encoder 516, and a VLC table selection unit 517. , A standard VLC table 518, a special VLC table 519, a transmission path packet encoder 521, and an encryption information transmitter 522. The MPEG encoder 516 includes a VLC unit 531.
[0282]
Next, the operation of the variable length encoded data transmission apparatus 510 configured as described above will be described.
First, an input image signal is supplied to an image data converter 511, where an identification signal is embedded as digital watermark information in the image signal by the method described above.
[0283]
The image signal in which the digital watermark information is embedded is supplied to the MPEG encoder 516, where a VLC table temporarily stored in the VLC unit 531 is used to generate a compression encoded signal by performing variable length encoding or the like. Is done.
[0284]
Next, the compressed and encoded signal is multiplexed with an audio signal (not shown) and other auxiliary signals in accordance with the MPEG system standard by the transmission path packet encoder 521. The packetized signal is output from the variable length encoded data transmission apparatus 510 as a transmission signal.
[0285]
At this time, the CPU 515 uses the identification signal for identifying whether the VLC table selector 517 selects the standard VLC table or the special VLC table based on the encoding selection signal supplied to the VLC table selector 517. Then, an encryption method related to the identification signal and encryption information related to an encryption key for decrypting the encryption are generated.
[0286]
The VLC table selector 517 selects either the standard VLC table or the special VLC table based on the encoding selection signal supplied from the CPU 515, and the selected VLC table is the VLC table of the MPEG encoder 516. 531.
[0287]
Also, in the encryption device 512, the identification information relating to the VLC table selected by the VLC table selection device 517 supplied via the CPU 515, the encryption method and the encryption set by the encryption method setting device 513 Information related to the encryption key set by the key setter 514 is encrypted, and the encrypted information is supplied to the image data converter 511.
[0288]
Further, the CPU 515 encrypts information indicating that encryption has been performed as encryption information, information related to the encryption method set by the encryption method setting device, and information related to the encryption key set by the encryption key setting device. Is supplied to the encrypted information transmitter 522 and output as an encrypted information signal therefrom.
[0289]
As such, the MPEG encoder 516 is supplied with the encrypted identification signal as an image signal embedded with a digital watermark. The image signal is compressed and encoded using the VLC table specified by the encoding selection signal corresponding to the embedded identification signal.
[0290]
For example, when the encoding selection signal supplied from the CPU 515 to the VLC table selector 517 is “0”, a standard VLC table is selected and obtained from the VLC table selector 517, and the standard VLC table is obtained by the VLC table of the MPEG encoder 516. Is supplied to the device 531 and temporarily stored therein.
[0291]
At this time, the CPU 515 supplies a 64-bit bit string “0101... 0101” indicating that the standard VLC table has been selected to the encryptor 512 as identification information. In the encryptor 512, the DES (Data Encryption Standard) encryption set by the encryption method setting unit 513 and the DES encryption encryption key 64 set by the encryption key setting unit 514 are provided. Bits (8 of which are parity bits) are used to encrypt the identification information.
[0292]
Next, the encrypted identification information is embedded as digital watermark information in the input image signal and supplied to the MPEG encoder 516. There, the supplied signal is compressed and encoded using a standard VLC table temporarily stored in the VLC unit 531.
[0293]
When the encoding selection signal is “1”, a special VLC table is obtained from the VLC table selector 517, and the table is supplied to the VLC unit 531 of the MPEG encoder 516 and temporarily stored therein. At this time, the CPU 515 supplies a 64-bit bit string “1010... 1010” indicating that the special VLC table has been selected to the encryptor 512 as identification information.
[0294]
The encryption unit 512 uses the DES encryption set by the encryption method setting unit 513 and the 64-bit DES encryption key set by the encryption key setting unit 514 to encrypt the identification information. The The identification information obtained by encryption is embedded as digital watermark information in the input image, and is encoded using a special VLC table temporarily stored in the VLC unit 531.
[0295]
At this time, the encryption information is “0” when the identification information is not encrypted, and is “1” when the identification information is encrypted. When the encryption method can be selected from, for example, four methods, the DES cipher is set to “00”, and the other three ciphers are set to “01”, “10”, and “11”, respectively. Further, encryption keys each having 64 bits such as Key A, Key B, Key C, and Key D, which are preset keys, are determined and used.
[0296]
It is assumed that Key A is “00”, Key B is “01”, Key C is “10”, and Key D is “11”. Accordingly, the encrypted information when the identification information is encrypted using DES encryption and Key C is represented by a 5-bit bit string of “1 00 10”.
[0297]
The configuration and operation of the variable-length encoded data transmission device according to the eighth embodiment have been described above.
Here, the encryption information may be encrypted and transmitted by including information on the encryption mode, information on the key length of the encryption key, and the like.
[0298]
Next, a variable-length encoded data receiving apparatus (hereinafter, simply referred to as a receiving apparatus) that receives and decodes the encoded data generated and transmitted in this way will be described.
FIG. 36 shows the configuration of a variable length encoded data receiving apparatus according to the eighth embodiment, which will be described with reference to FIG.
[0299]
The variable-length encoded data receiving apparatus 550 shown in the figure includes a transmission path packet decoder 551, an encryption information receiver 552, an MPEG decoder 561, a VLC table selector 562, a standard VLC table 563, a special VLC table 564, and a CPU 565. , A digital watermark detector 566, a decryptor 567, a decryption method selector 568, and a decryption key selector 569. The MPEG decoder 561 includes a VLC decoder 571.
[0300]
Next, the operation of the variable length encoded data receiving apparatus 550 configured as described above will be described.
First, the encoded packet data that has been multiplexed is packet-decoded by the transmission-line packet decoder 551 in a complementary manner to the transmission-line packetization encoder 521, and a compressed code obtained by decoding the packet-encoded data. The converted image data is supplied to the MPEG decoder 561.
[0301]
In this case, the value of the VLC table temporarily stored in the VLC decoder 571 is used for the signal compressed and encoded by the MPEG method, and is decoded by a method complementary to that performed by the MPEG encoder 516. The image signal obtained by decoding is supplied to the digital watermark detector 566.
[0302]
In the digital watermark detector 566, an identification signal that is embedded as digital watermark information by the image data converter 511 in FIG. 35 described above and is encrypted is detected by the digital watermark detector 566 and supplied to the decoder 567. .
[0303]
If the CPU 565 determines that the detected digital watermark information is encrypted based on the encryption information received by the encryption information receiver 552, the information related to the encryption method is the decryption method selector 568. In addition, information on the encryption key is supplied to the decryption key selector 569, respectively.
[0304]
The decryption method selector 568 selects a decryption method based on information related to the encryption method, and the decryption key selector 569 selects an encryption key based on information related to the encryption key. Using the selected decryption method and decryption key information, the decryption device 567 decrypts the encrypted identification information, and the decrypted signal is supplied to the CPU 565. In the CPU 565, an encoding selection signal corresponding to the decoded identification information is generated, and the signal is supplied to the VLC table selector 562.
[0305]
In the VLC table selector 562, either the standard VLC table or the special VLC table is selected based on the supplied encoding selection signal and supplied to the VLC decoder 571. The VLC table is the VLC table. Temporarily stored in the decoder 571.
[0306]
For example, when the encrypted information is obtained as a 5-bit bit string “1 00 10”, the variable-length encoded data receiving device 550 first uses the digital watermark detector 566 to generate a 64-bit bit string “b”. 63 b 62 b 61 ... b 1 b 0 ”Is detected, and the signal of the detected bit string is supplied to the decoder 567.
[0307]
Next, the CPU 565 determines that the identification information is encrypted based on the most significant bit “1” of the 5-bit encrypted information “1 00 10” received by the encrypted information receiver 552. Then, from the lower 4 bits “00 10” of the encryption information, the DES encryption is selected by the decryption method selector, and Key C is selected by the decryption key selector 569 and supplied to the decryptor 567.
[0308]
The decryptor 567 uses the key Key C in the DES encryption to generate a 64-bit bit string “b”. 63 b 62 b 61 ... b 1 b 0 "Is decoded, and data of" 0101 ... 0101 "or" 1010 ... 1010 "is obtained.
[0309]
The CPU 565 generates “0” for the decoding result “0101... 0101” and “1” for “1010... 1010” as the encoding selection signal. This is supplied to the VLC table selector 562. The VLC table selector supplies the standard VLC table to the VLC decoder 571 when the encoding selection signal is “0” and the special VLC table when the encoding selection signal is “1”.
[0310]
In this way, the VLC table temporarily stored in the VLC decoder 571 is used, and the MPEG decoder 561 decodes the supplied encoded data. The decoding is performed using the same VLC table as the VLC table temporarily stored in the VLC unit 531 of the MPEG encoder 516 in FIG. 35 described above, so that an image signal without deterioration is decoded. .
[0311]
As described above, the variable length encoded data transmitting apparatus 510 and the variable length encoded data receiving apparatus 550 in the eighth embodiment transmit the encrypted identification signal embedded in the image data as a digital watermark, and the transmitted A method for receiving signals is described.
[0312]
Heretofore, the method for embedding the encrypted identification signal in the image signal has been described. The embedding of the identification signal is not limited to the image signal, and a method of embedding it as digital watermark data in the audio signal using the above-described method may be used. Furthermore, there is a method in which image data and audio data are embedded as independent identification data and transmitted.
[0313]
Next, a variable-length encoded data receiving apparatus in the case where the signal transmitted by the variable-length encoded data transmitting apparatus 510 according to the eighth embodiment is received after being charged is described.
[0314]
<Ninth embodiment>
FIG. 37 shows the configuration of a variable length encoded data receiving apparatus according to the ninth embodiment, which will be described with reference to FIG.
The variable-length encoded data receiving device 550a shown in the figure is different from the variable-length encoded data receiving device 550 described above in that a large number of IC card reader / writers 572 are arranged.
[0315]
Parts having the same functions as those shown in FIG. 36 are given the same reference numerals. The IC card reader / writer 572 is connected to the CPU 565, and an IC card 601 is inserted there.
[0316]
Next, operations performed in the variable length encoded data receiving apparatus 550a configured as described above, which are different from the above-described variable length encoded data receiving apparatus 550, will be described.
First, an encrypted identification signal embedded as digital watermark information by the image data converter 511 of the variable length encoded data transmission apparatus 510 is detected by the digital watermark detector 566 and supplied to the decoder 567.
[0317]
When the CPU 565 determines that the detected watermark information is encrypted based on the encrypted information received by the encrypted information receiver 552, the information related to the encryption method is selected as the decryption method. Information on the encryption key is supplied to the decryption key selector 569 to the device 568, respectively.
[0318]
At this time, the CPU 565 determines whether or not to perform decryption based on the amount information recorded on the IC card via the IC card reader / writer 572 and the charging information at the time of reproduction. Based on the result, an encoding selection signal corresponding to the identification information obtained from the decoder 567 is supplied to the VLC table selector 562, or an encoding selection signal not corresponding to the identification information is supplied to the VLC table selector 562. To be supplied.
[0319]
For example, it is assumed that the IC card is prepaid and has amount information of 6000 yen recorded in advance. When the transmitted information is decrypted, for example, at a rate of 1 yen per minute, every time the decryptor 567 decrypts the encrypted information by the CPU 565 for 1 minute, The amount information is reduced by 1 yen.
[0320]
When the amount information of the IC card 601 becomes 0 yen, when the encoding selection signal corresponding to the identification information obtained from the decryption unit 567 by the decryption unit 567 is “0”, “ When “1” is “1”, “0” is supplied to the VLC table selector 562.
[0321]
The VLC table selector 562 selects a standard VLC table or a special VLC table based on the supplied encoding selection signal, and supplies the selected table to the VLC decoder 571. In this way, when the amount information in the IC card becomes 0 yen, a VLC table different from that at the time of encoding is thereafter supplied to the VLC decoder 571, and high quality images are not reproduced.
[0322]
Further, as information recorded on the IC card 601, information for identifying the user is recorded in addition to the amount information, and the CPU 565 outputs a correct encoding selection signal only for a specific user to the VLC table. It is made to supply to a selector.
[0323]
Further, by recording information on various reproduction conditions preferred by the user on the IC card 601, the CPU 565 can send a correct encoding selection signal to the VLC table selector only when the reproduction conditions from the IC card 601 are satisfied. It may be supplied.
[0324]
Alternatively, the IC card 601 can be used by recording information (seed) that is a base of a decryption key necessary for decrypting the encrypted identification information on the IC card 601 and information on the encryption algorithm. Only when the identification information is correctly decoded, the CPU 565 may supply the correct encoding selection signal.
[0325]
Furthermore, in addition to the IC card 601, a variable-length encoded data receiving device via the Internet using a modem or by a user's own operation input using an operation remote control button of the variable-length encoded data receiving device 550a. The amount information, the user information, or the reproduction condition information may be acquired from outside the 550a, and a correct encoding selection signal may be supplied to the VLC table selector 562 based on those conditions.
[0326]
As described above, according to the variable length encoded data receiving device 550a of the ninth embodiment, only when the predetermined condition is satisfied, the same VLC table as that at the time of encoding is supplied to the VLC decoder 571 in the MPEG decoder 561. It has been described that a high-quality image signal can be obtained from the receiving device in order to decode the encoded image data.
[0327]
If the receiving device does not have a function for detecting image digital watermark information, does not have a function for decoding watermark information, or does not have a special VLC table, a standard VLC table is used. Thus, the encoded data is decoded. Therefore, the decoded image signal at that time is decoded as an image signal including a distortion component based on the difference between the respective VLC tables.
[0328]
Even if it has a function to read digital watermark information, decode it by an appropriate method, and decode code data using a predetermined VLC table, it satisfies the set conditions such as billing. If not, the decoded image signal includes a distortion component based on the difference in the VLC table, for example, by supplying a VLC table different from that at the time of encoding.
[0329]
In this way, the copyright holder who owns the copyright of the content has a special receiving device that has a contract relationship with the content held, a general receiving device that does not have a contract relationship with a receiving device that satisfies a specific condition, or a specific condition When receiving image signals of different qualities to receiving devices that do not satisfy the above, the special receiving device is equipped with an image digital watermark detector, an identification information decoder, and a special VLC table for decoding. By having a control device that can supply a suitable VLC table to the decoder, it is possible to supply image signals of different quality to the general public and special persons.
[0330]
The configuration and operation of the variable length encoded data receiving apparatus according to the ninth embodiment have been described above.
<Tenth embodiment>
Next, a variable length encoded data transmitting apparatus and a variable length encoded data receiving apparatus according to the tenth embodiment will be described.
[0331]
FIG. 38 shows the configuration of a variable length encoded data transmitting apparatus according to the tenth embodiment, which will be described with reference to FIG.
The variable-length encoded data transmission device 510b shown in the figure is different from the above-described variable-length encoded data transmission device 510 according to the eighth embodiment shown in FIG. 35 in that a VLC table selector 517, a standard VLC table 518, The VLC table generator 523 is provided instead of the special VLC table 519.
[0332]
Components having the same function are denoted by the same reference numerals.
Next, the operation of the variable length encoded data transmission apparatus 510b configured as described above will be described.
[0333]
First, the input image signal is supplied to the image data converter 511, and the encrypted identification signal is embedded as digital watermark information and supplied to the MPEG encoder 516. Then, compression encoding based on the VLC table temporarily stored in the VLC unit 531 is performed, and the transmission path packet encoder 521 performs packetization specific to the transmission path and outputs the packet.
[0334]
The VLC table generator 523 generates a VLC table supplied to the VLC unit 531 of the MPEG encoder 516. The generated VLC table is encrypted by the encryption unit 512 using the encryption method set by the encryption method setting unit 514 and the encryption key set by the encryption key setting unit 513. The encrypted code table is supplied to the image data converter 511.
[0335]
Further, the CPU 515 receives information indicating that encryption has been performed as encryption information, information regarding the encryption method set by the encryption method setting unit 513, and information regarding the encryption key set by the encryption key setting unit 514. Information is supplied to the encrypted information transmitter 522. From there, it is output as an encrypted information signal.
[0336]
At this time, for example, as encryption information, “0” is set when the VLC table is not encrypted, and “1” is set when the VLC table is encrypted. If four encryption methods can be selected, the DES cipher is “00”, the other three ciphers are “01”, “10”, and “11”, respectively. Keys A, B, C, and D are set in advance.
[0337]
When Key A is “00”, Key B is “01”, Key C is “10”, and Key D is “11”, the VLC table information is encrypted using DES encryption and Key C. In this case, the encryption information is expressed by a 5-bit bit string of “1 00 10”.
[0338]
In this manner, the MPEG encoder 516 is supplied with the information related to the encrypted VLC table as an image signal embedded by the digital watermark method. The image signal is compressed and encoded using an embedded VLC table.
[0339]
Next, a variable-length encoded data receiving apparatus that receives and decodes encoded data generated and transmitted as described above will be described.
FIG. 39 shows the configuration of a variable length encoded data receiving apparatus 550b in the tenth embodiment, which will be described with reference to the drawing.
[0340]
The variable-length encoded data receiving device 550b shown in the figure is different from the variable-length encoded data receiving device 550 according to the eighth embodiment shown in FIG. 36 described above in comparison with the VLC table selector 562, the standard VLC table 563, And the special VLC table 564 is not arranged.
[0341]
Further, a VLC generation decoder 571a is arranged instead of the VLC decoder 571. In addition, the same code | symbol is attached | subjected about the same functional block.
Next, regarding the operation of the variable length encoded data receiving device 550b, the operation different from that of the eighth embodiment will be mainly described.
[0342]
First, digital watermark information detected by the digital watermark detector 566 is supplied to a decoder 567. If the CPU 565 determines that the detected digital watermark information is encrypted based on the encryption information received by the encryption information receiver 552, the information regarding the encryption method is the decryption method selector. In 568, information on the encryption key is supplied to the decryption key selector 569, respectively.
[0343]
The decryption method selector 568 selects a predetermined decryption method from the information regarding the encryption method, and the decryption key selector 569 selects a predetermined encryption key based on the information regarding the encryption key. The selected decryption method and decryption key information are supplied to the VLC generation / decryption device 571a via the CPU 565.
[0344]
Then, the VLC generation decoder 571a generates the same VLC table as that generated by the VLC table generator 523 based on the supplied information. The MPEG decoder 561 uses the VLC table generated by the VLC generator / decoder 571a to decode the encoded data.
[0345]
As described above, in the variable length encoded data transmitting apparatus 510b and the variable length encoded data receiving apparatus 550b according to the tenth embodiment, the information related to the encrypted VLC table is embedded in the image data as a digital watermark. Thus, transmission and reception are performed.
[0346]
Next, another variable length encoded data receiving apparatus that receives a signal transmitted by the variable length encoded data transmitting apparatus 510b according to the tenth embodiment will be described.
<Eleventh embodiment>
FIG. 40 shows the configuration of the variable length encoded data receiving apparatus according to the eleventh embodiment, and the operation thereof will be described with reference to the drawing.
[0347]
The variable length encoded data receiving device 550c shown in the figure is not provided with the VLC table selector 562 and the special VLC table 564, compared to the variable length encoded data receiving device 550 shown in FIG.
[0348]
In place of the VLC decoder 571, a VLC generation decoder 571a is arranged. Also, an IC card reader / writer 572 is disposed, and the IC card 601 is inserted therein. Parts having the same functions as those shown in FIG. 36 are given the same reference numerals.
[0349]
Next, operations of the variable length encoded data receiving apparatus 550c configured as described above will be mainly described in operations different from those of the eighth embodiment.
First, the digital watermark detector 566 detects the embedded digital watermark information and supplies it to the decoder 567. In the CPU 565, when the detected digital watermark information is encrypted, the information regarding the encryption method is supplied to the decryption method selector 568, and the information regarding the encryption key is supplied to the decryption key selector 569, respectively. Is done.
[0350]
At that time, the CPU 565 obtains the information on the amount of money of the IC card and the information regarding the reproduction conditions via the IC card reader / writer 572, determines whether or not to perform decryption based on the obtained information, and performs decryption. Sometimes the VLC table obtained by decrypting the cipher is supplied to the VLC decoder 571.
[0351]
The reproduction operation including the IC prepaid card at that time is performed in the same manner as in the ninth embodiment. Since the standard VLC table 563 is connected to the CPU 565, the table stored in the standard VLC table 563 is supplied to the VLC generator / decoder 571a during normal playback, and the compressed and encoded image data is decoded. Done.
[0352]
When decoding using the special VLC table is permitted, the VLC generation decoder 571a creates a special VLC table based on the input VLC table information, thereby decoding an image without quality degradation. Is made.
[0353]
The configuration and operation of the variable-length encoded data transmitting apparatus and variable-length encoded data receiving apparatus in the eleventh embodiment have been described above.
Next, the configuration and operation of a variable length encoded data reproducing apparatus for recording a signal generated by the variable length encoded data recording apparatus on a recording medium and reproducing it will be described.
[0354]
<Twelfth embodiment>
FIG. 41 shows the configuration of a variable length encoded data recording apparatus according to the twelfth embodiment, which will be described with reference to the drawings.
[0355]
The variable-length encoded data recording device 510d shown in the figure is compared with the variable-length encoded data transmission device according to the eighth embodiment shown in FIG. 35 described above, and the transmission path packet encoder 521 and the encrypted information transmission. The difference is that a modulator 581 and a recorder 582 are arranged instead of the device 522. A recording medium 610 is inserted in the variable length encoded data recording device 510d.
[0356]
The same functional parts are denoted by the same reference numerals.
Next, with respect to the operation of the variable length encoded data recording apparatus configured as described above (hereinafter sometimes simply referred to as a recording apparatus), the differences from the above-described eighth embodiment will be mainly described.
[0357]
First, the input image signal is input to the image data converter 511, and the encrypted identification signal is embedded as digital watermark information. Next, the image signal in which the digital watermark information is embedded is supplied to the MPEG encoder 516, and compression coding is performed based on the VLC table temporarily stored in the VLC unit 531. The encoded image data and the encryption information output from the CPU 515 are input to the modulator 581.
[0358]
There, digital modulation for recording image data and encryption information on the recording medium 610 is performed. Further, an error correction signal for error signal correction is added as necessary. The digitally modulated signal is supplied to a recorder 582 where a signal for recording on the recording medium 610 is generated by, for example, modulating the light intensity of a laser beam, and the signal is recorded on a recording medium 610 such as a DVD. Irradiated and recorded.
[0359]
As such, the recording medium 610 has an encryption method in which an identification signal for identifying whether the VLC table selector 517 selects the standard VLC table 518 or the special VLC table 519, and Encryption information related to the encryption key and compressed and encoded image data are recorded.
[0360]
The encryption information at this time may be recorded in a time-division multiplexed manner together with the encoded data of the modulated image signal, or those signals may be recorded in different areas on the recording medium. Furthermore, each may be recorded on a plurality of different recording media.
[0361]
Next, a variable length encoded data reproducing apparatus for reproducing and decoding the recording medium recorded as described above will be described.
FIG. 42 shows the configuration of a variable length encoded data reproducing apparatus according to the twelfth embodiment, which will be described with reference to the drawings.
[0362]
The variable-length encoded data reproducing apparatus 550d shown in the figure has a transmission path packet decoder 551 and an encrypted information reception compared to the variable-length encoded data receiving apparatus according to the eighth embodiment shown in FIG. The difference is that a regenerator 591 and a demodulator 592 are arranged instead of the regenerator 552. In addition, a recording medium 610 is inserted in the variable length encoded data reproducing device 550d.
[0363]
The same functional parts are denoted by the same reference numerals.
Next, with respect to the operation of the variable length encoded data reproducing apparatus (which may be simply referred to as a reproducing apparatus hereinafter) configured as described above, the differences from the eighth embodiment will be mainly described.
[0364]
First, the recording medium 610 recorded by the recording device 510d is loaded into a loading unit (not shown) of the reproducing device 560d. The recording medium 610 is irradiated with, for example, a laser beam by a regenerator 591 and the recorded signal is read out.
[0365]
The signal obtained by reading is supplied to a demodulator 592, where signal processing is performed in a complementary manner to the modulator 581 described above, and compression-coded image data and encryption information are demodulated and obtained.
[0366]
Next, the encryption information is supplied to the CPU 565, and the compressed and encoded image data is supplied to the MPEG decoder 561.
Thereafter, the same operation as that of the variable length encoded data receiving apparatus according to the ninth embodiment shown in FIG. 37 is performed.
[0367]
The configuration of the recording apparatus and the reproducing apparatus according to the twelfth embodiment and the operation thereof have been described above. Next, another embodiment of the reproducing apparatus will be described.
<Thirteenth embodiment>
FIG. 43 shows the structure of a reproducing apparatus according to the thirteenth embodiment used in combination with the recording apparatus according to the twelfth embodiment.
[0368]
Compared with the receiving apparatus 550b according to the tenth embodiment shown in FIG. 42, the variable-length encoded data receiving apparatus 550e shown in the figure has an IC card reader / writer 572 and an IC card 601 inserted therein. It differs in that it is arranged. The same functional blocks are denoted by the same reference numerals.
[0369]
Next, with respect to the operation of the playback device 550e configured as described above, the difference from the operation of the playback device 550d will be mainly described.
That is, the playback device 550e has a function added by the IC card reader / writer 572 described in the eleventh embodiment shown in FIG. 40 and the IC card 601 inserted therein.
[0370]
Therefore, when a predetermined chargeable amount is stored in the IC card 601 and a predetermined reproduction condition is satisfied, the VLC decoder 571 in the MPEG decoder 561 is encoded with the MPEG encoder 516 of the recording device 510d. The same VLC table is supplied. Using this, the input encoded image data is decoded, and at that time, a high-quality image signal can be obtained.
[0371]
Then, the copyright holder who has the copyright of the content such as image data has a special playback device that has a contract relationship with the content held or a playback device that satisfies a specific condition, a general playback device that does not have a contract relationship, and charging An image signal having a different quality can be supplied to a playback apparatus that does not satisfy a specific condition such as lack of information.
[0372]
In addition, the special playback device is equipped with an image digital watermark detector, an identification information decoder, and a special VLC table, and has a control device capable of supplying the decoder with a VLC table suitable for decoding. In addition, it is possible to supply a general medium and a special person with a recording medium on which different quality image signals are reproduced while being the same recording medium.
[0373]
The configuration and operation of the variable length encoded data receiving device 550e according to the thirteenth embodiment have been described above.
Next, a recording apparatus and a reproducing apparatus that switch VLC tables of MPEG encoders and MPEG decoders using VLC table information will be described.
[0374]
<14th embodiment>
FIG. 44 shows the configuration of a variable length encoded data recording apparatus according to the fourteenth embodiment, which will be described with reference to the drawing.
The variable-length encoded data recording device 510f shown in the figure replaces the transmission line packet encoder 521 and the encrypted information transmitter 522 as compared with the transmission device 510b according to the tenth embodiment shown in FIG. 1 in that a modulator 581 and a recorder 582 are arranged. A recording medium 610 is inserted in the variable length encoded data recording device 510f.
[0375]
The same functional parts are denoted by the same reference numerals.
Next, the operation of the variable length encoded data recording apparatus 510f configured as described above will be described mainly with respect to differences from the tenth embodiment.
[0376]
First, the input image signal is input to the image data converter 511, and the encrypted identification signal is embedded as digital watermark information. Then, the image signal in which the digital watermark information is embedded is supplied to the MPEG encoder 516, and compression coding is performed based on the VLC table temporarily stored in the VLC unit 531. Also, the encoded image data and the encryption information output from the CPU 515 are input to the modulator 581.
[0377]
The image data and encryption information input to the modulator 581 are recorded on the recording medium 610 in the same manner as in the twelfth embodiment shown in FIG. 41, and the same operation as described above is performed.
[0378]
Next, a variable length encoded data reproducing apparatus for reproducing and decoding the recording medium recorded as described above will be described.
FIG. 45 shows the configuration of a variable length encoded data reproducing apparatus according to the fourteenth embodiment, which will be described with reference to the drawings.
[0379]
The variable-length encoded data reproducing device 550f shown in the figure is compared with the variable-length encoded data receiving device 550b according to the tenth embodiment shown in FIG. 39 described above, and the transmission path packet decoder 551 and the encrypted information. The difference is that a regenerator 591 and a demodulator 592 are arranged instead of the receiver 552. In addition, a recording medium 610 is inserted into the variable length encoded data reproducing device 550f.
[0380]
The same functional parts are denoted by the same reference numerals.
Next, with respect to the operation of the variable length encoded data reproducing apparatus configured as described above, the differences from the tenth embodiment will be mainly described.
[0381]
First, the recording medium 610 recorded by the recording device 510f is loaded into a loading unit (not shown) of the reproducing device 550f. The recording medium 610 is reproduced by a reproducing device 591 and a demodulator 592 to obtain compression-coded image data and encrypted information.
[0382]
Next, the encryption information is supplied to the CPU 565, and the compressed and encoded image data is supplied to the MPEG decoder 561.
Thereafter, the same operation as that of the variable length encoded data receiving apparatus 550b according to the tenth embodiment shown in FIG. 39 is performed.
[0383]
The configuration of the recording apparatus and the reproducing apparatus according to the fourteenth embodiment and the operation thereof have been described above. Next, another embodiment of the reproducing apparatus will be described.
<Fifteenth embodiment>
FIG. 46 shows the configuration of a reproducing apparatus according to the fifteenth embodiment used in combination with the recording apparatus according to the fourteenth embodiment.
[0384]
The variable-length encoded data reproducing device 550g shown in the figure has an IC card reader / writer 572 and an IC card 601 inserted therein, as compared with the receiving device 550f according to the fourteenth embodiment shown in FIG. In addition, a VLC regenerative decoder 571a is arranged in place of the VLC decoder 571. The same functional blocks are denoted by the same reference numerals.
[0385]
Next, the operation of the playback device 550g configured as described above will be described mainly with respect to the differences from the operation of the playback device 550f.
That is, a function realized by the IC card reader / writer 572 and the IC card 601 inserted therein described in the thirteenth embodiment shown in FIG. 43 is added to the playback device 550g.
[0386]
Therefore, when a predetermined chargeable amount is recorded on the IC card 601 and a predetermined reproduction condition is satisfied, the VLC table information is supplied from the CPU 565 to the VLC reproduction decoder 571a.
[0387]
When decoding using the special VLC table is permitted, the VLC generation decoder 571a creates the special VLC table, and the MPEG decoder 561 decodes the image without quality degradation.
[0388]
The configuration and operation of the receiving apparatus in the fifteenth embodiment have been described above.
In this way, image signals of different quality can be supplied to a playback device that is not contracted with a playback device that is contracted by the copyright holder who has the copyright of the content.
[0389]
The copyright holder only supplies the content recorded on the same recording medium, and the content is reproduced as a recording medium that can be reproduced as an image signal of a different quality for the general public and a special person. Is possible.
[0390]
As described above, according to the first to fifteenth embodiments, the encoding method is performed by MPEG to obtain a coefficient value signal by orthogonally transforming an image signal and a sound signal, and perform the run length coding on the obtained coefficient value signal. Has described the configuration and operation of a decoding device that reproduces content information with high quality and a decoding device that reproduces semi-disclosed content that is reproduced with distortion.
[0390]
In order to reproduce such contents with different qualities, the present invention can be applied to a similar encoding method in which run-length encoding is performed on the coefficient value signal obtained by the orthogonal transformation.
[0392]
In other words, the content signal is converted so that the energy of the information is concentrated on the predetermined information, and compression encoding is performed by performing run-length encoding on the information where the energy of the numerical information obtained by the conversion is not concentrated. As long as it is a method to be performed, a method of encoding a run length related to a number other than “0” may be used.
[0393]
Furthermore, in the code table of the variable length code, as a rule for exchanging codes of the same code category, in the case of an image, the AC component run length and level, in the case of sound, it has been described as information including a scale factor and spectrum, As long as the parameters and syntax change the quality of the image and sound, the type of information handled by the run-length table generated by replacing the code information at the time of encoding may be used.
[0394]
In other words, the copyright holder who owns the copyright of the content holds the information even if the information includes the run length and level of the AC component in the case of an image and the information including the scale factor and spectrum in the case of a sound. Supplying different quality image signals to special playback devices that have a contractual relationship with content or playback devices that meet specific conditions, and general playback devices that do not have contractual relationships or playback devices that do not meet specific conditions Can do.
[0395]
Furthermore, a method has been described in which two or more code tables are provided, and one of them is selected to perform variable length coding. In addition to selecting and using a code table, the above operation can be performed by having only one code table and replacing part of the description contents of the table.
[0396]
The encoding selection signal for identifying the replacement of the code table can be implemented only by transmitting number information such as an algorithm number for specifying the replacement rule. Therefore, the method realized by switching the table is one of a plurality of means for realizing the above operation.
[0397]
Furthermore, the above-described run-length encoding accurately counts the number of numerical information when describing an event with a low probability of occurrence according to the establishment of numerical information, such as a Huffman code, by a method with reduced redundancy. As a numerical value described after the number information, any encoding method may be used as long as encoding is performed such that a correct value and an approximate value can be selected.
[0398]
Furthermore, although the present embodiment has been described mainly with respect to an example applied to variable length coding, the present invention can be similarly applied to coding using fixed length coding instead of variable length coding. That is, in the case of fixed-length encoding, although the improvement in encoding efficiency is small, the above-described method can be applied as a method for providing contents of different qualities.
[0399]
At that time, the reproduction apparatus designated as special by the copyright holder includes the image digital watermark detector, the identification information decoder, and the parameters and syntax encoded by the fixed length by a special rule. A function with an algorithm to convert will be installed.
[0400]
The same encoding is performed for general users and special users by having a control function for supplying the special decoder with parameters and syntax information for decoding the specially encoded signal. It is possible to provide image and audio signal services in which image signals and audio signals of different quality are reproduced while being data.
[0401]
As described above, content disclosure and semi-disclosure of content are performed for both cases of application to fixed-length encoding and application to variable-length encoding. That is, for example, in an image signal and audio signal decoder compliant with the MPEG standard, an absurd error due to a VLC error or the like does not occur and decoding is not broken. Enables encrypted transmission with semi-disclosure display and pronunciation effect.
[0402]
And, the content held by the copyright holder who has the copyright of the content including at least images or sound, the special playback device in the contract relationship or the playback device that satisfies the specific condition, and the general playback device not in the contract relationship or Content of different quality can be supplied to playback devices that do not satisfy specific conditions.
[0403]
Furthermore, the special playback apparatus is equipped with an image digital watermark detector, an identification information decoder, and a special VLC table, and has a control device capable of supplying the decoder with a VLC table suitable for decoding. It is possible to realize a content providing service for reproducing contents of different quality while having the same encoded data for general users and special users.
[0404]
In other words, using these devices, methods, and computer control programs, contents are distributed and transmitted in a semi-disclosure state, and the user is encouraged to promote the purchase effect. A table reproducible playback method is provided, where a business model capable of playing back high-quality content can be realized.
[0405]
As a recording medium capable of semi-disclosure reproduction of such content, a DVD recording medium has been mainly described. The recording medium is not limited to a DVD-ROM, DVD-RAM, DVD-RW, and DVD-R as long as it can record content information, and also a magneto-optical disk, a magnetic disk, a magnetic tape, and the like It can be applied to other digital recording media.
[0406]
In addition, the content signal encoding method obtains coefficient value data by quantizing transform data obtained by orthogonal transform of the content signal, and obtains time series data by arranging the obtained coefficient value data in a predetermined order. Said about the case. The encoding method is not limited to obtaining the coefficient value data by orthogonally transforming the content as in the MPEG method, for example, and also in the case of a conversion method including a technique other than the orthogonal transform as in the fractal encoding method. Functions similar to those described in the above can be realized.
[0407]
That is, when the content signal is encoded without dividing a single image into small blocks, such as wavelet conversion, for example, the content signal is compared with a method using orthogonal conversion in which block division is performed and DCT conversion is performed. However, there is an advantage that the block division portion does not occur as block distortion.
[0408]
The wavelet transform is a combination of subband coding, in which an image signal is divided in frequency, and each divided frequency band portion is sampled and encoded at different sampling frequencies, and the orthogonal transform described above. Encoding method.
[0409]
As another encoding method, there is also a vector quantization method in which an image is divided into small blocks, and each divided block is encoded by one vector value.
[0410]
Then, when the image data is converted by any of the above methods to obtain time-series data, and the time-series data can be generated as a compressed encoded signal in which the amount of information is compressed by performing variable-length encoding, how The image data may be converted into time series data by any method.
[0411]
That is, when information contained in a content content signal such as an image signal and an audio signal is converted by a predetermined method, and the energy (entropy) of the converted content is concentrated in a predetermined area, the energy is concentrated and expressed. It is possible to perform variable-length coding that describes the time-series data to be described by the number of numerical values of the data and the numerical value level that follows.
[0412]
And even if it is a case by which any encoding system is expressed as a semi-disclosure content signal that can be obtained by recording / reproducing content with an analog consumer device using the above-described plurality of variable length coding tables, Alternatively, it is possible to realize content encoding and decoding techniques that can be expressed with high fidelity.
[0413]
【The invention's effect】
According to the variable length data encoding method and the variable length data encoding device of the present invention, the variable length encoding is performed using either one of the variable length encoding table and the exchange variable length encoding table. Since the encoding selection signal that specifies whether to perform is generated, and the variable length encoding of the time-series data is performed using the specified encoding table, the compressed encoded signal is generated. When encoding is performed using the exchange variable length table, the decoding apparatus having the function of detecting the encoding selection signal is allowed to reproduce the high-quality content, and the decoding does not have the detection function. It is possible to cause the reproduction apparatus to reproduce the content by reducing the reproduction quality (can reproduce the content including the distortion component). Therefore, by using the variable length data encoding method and variable length data encoding device of the present invention, it is possible to ensure that the decoding device can decode the content while ensuring a predetermined security level.
[0414]
Furthermore, in the variable-length data encoding method and variable-length data encoding device of the present invention, the exchange variable for causing the content to be encoded to be decoded with a predetermined security level secured to the desired content to be encoded. While variable-length coding using a long coding table prevents deterioration of coding efficiency and prevents generation of an error signal due to an absurd operation during decoding, the variable-length coding table is standard. Therefore, it is possible to provide a configuration of a variable length data encoding method and a variable length data encoding apparatus having good consistency in the market.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image signal encoding device according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of an image signal decoding apparatus according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of an image signal encoding device according to a second embodiment of the present invention.
FIG. 4 shows a sequence header syntax according to a second embodiment of the present invention.
FIG. 5 shows a GOP layer syntax according to a second embodiment of the present invention;
FIG. 6 shows a syntax of a picture layer according to a second embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of an image signal decoding apparatus according to a second embodiment of the present invention.
FIG. 8 is a block diagram showing a configuration of an image signal encoding device according to a third embodiment of the present invention.
FIG. 9 is a diagram showing a digital watermark on a macroblock quantized value according to a third embodiment of the present invention.
FIG. 10 is a block diagram showing a configuration of an image signal decoding apparatus according to a third embodiment of the present invention.
FIG. 11 is a block diagram showing a configuration of an image signal encoding device according to a fourth embodiment of the present invention.
FIG. 12 is a diagram showing a digital watermark to a macroblock motion vector value according to the fourth embodiment of the present invention.
FIG. 13 is a block diagram showing a configuration of an image signal decoding apparatus according to a fourth embodiment of the present invention.
FIG. 14 shows a variable-length coding table used in the MPEG coding method.
FIG. 15 shows the first half of a variable length coding table used for coding according to a fourth embodiment of the present invention.
FIG. 16 shows the latter half of the variable length coding table used for coding according to the fourth embodiment of the present invention.
FIG. 17 is a diagram illustrating the relationship between image quality according to the fourth embodiment of the present invention and the combination of the encoder and the decoder according to the present invention.
FIG. 18 is a flowchart showing an image encoding operation according to the fourth embodiment of the present invention.
FIG. 19 is a flowchart showing an image decoding operation according to the fourth embodiment of the present invention.
FIG. 20 is a block diagram showing a configuration of an image signal encoding device according to a fifth embodiment of the present invention.
FIG. 21 is a block diagram showing a configuration of an image signal decoding apparatus according to a fifth embodiment of the present invention.
FIG. 22 is a flowchart showing an image encoding operation according to the fifth embodiment of the present invention.
FIG. 23 is a flowchart showing an image decoding operation according to the fifth embodiment of the present invention.
FIG. 24 is a block diagram showing a configuration of an audio signal encoding device according to a sixth example of the present invention.
FIG. 25 is a diagram showing a relationship between a scale factor band and a scale factor according to the sixth embodiment of the present invention.
FIG. 26 shows a part of a Huffman codebook used in the MPEG AAC encoding method.
FIG. 27 is a diagram showing a method for replacing indexes of a Huffman codebook according to a sixth embodiment of the present invention.
FIG. 28 is a diagram illustrating an example of scale factor variable length encoding and decoding according to the sixth exemplary embodiment of the present invention;
FIG. 29 is a block diagram showing the configuration of an audio signal decoding apparatus according to a sixth embodiment of the present invention.
FIG. 30 is a block diagram showing a configuration of an audio signal encoding device according to a seventh example of the present invention.
FIG. 31 shows a part of a spectrum Huffman codebook used in the MPEG AAC encoding method.
FIG. 32 is a diagram showing replacement of code words in a spectrum Huffman code book according to a seventh embodiment of the present invention.
FIG. 33 is a diagram for explaining codeword replacement according to the seventh embodiment of the present invention;
FIG. 34 is a block diagram showing the configuration of an audio signal decoding apparatus according to a seventh embodiment of the present invention.
FIG. 35 is a block diagram showing a configuration of an image signal encoding device according to an eighth embodiment of the present invention.
FIG. 36 is a block diagram showing a configuration of an image signal decoding apparatus according to an eighth embodiment of the present invention.
FIG. 37 is a block diagram showing a configuration of an image signal decoding apparatus according to a ninth embodiment of the present invention.
FIG. 38 is a block diagram illustrating a configuration of an image signal encoding device according to a tenth embodiment of the present invention.
FIG. 39 is a block diagram showing a configuration of an image signal decoding apparatus according to a tenth embodiment of the present invention.
FIG. 40 is a block diagram showing a configuration of an image signal decoding apparatus according to an eleventh embodiment of the present invention.
FIG. 41 is a block diagram showing a configuration of an image signal recording apparatus according to a twelfth embodiment of the present invention.
FIG. 42 is a block diagram showing a configuration of an image signal reproduction device according to a twelfth embodiment of the present invention.
FIG. 43 is a block diagram showing a configuration of an image signal reproduction device according to a thirteenth embodiment of the present invention.
FIG. 44 is a block diagram showing a configuration of an image signal recording apparatus according to a fourteenth embodiment of the present invention.
FIG. 45 is a block diagram showing a configuration of an image signal reproduction device according to a fourteenth embodiment of the present invention.
FIG. 46 is a block diagram showing a configuration of an image signal reproduction device according to a fifteenth embodiment of the present invention.
FIG. 47 is a block diagram showing a configuration of a conventional MPEG encoder.
FIG. 48 is a block diagram showing a configuration of a conventional MPEG decoder.
FIG. 49 is a block diagram showing a configuration of a conventional MPEG AAC encoder.
FIG. 50 shows a table of a Huffman codebook used in the conventional MPEG AAC system.
FIG. 51 is a block diagram showing a configuration of a conventional MPEG AAC decoder.
[Explanation of symbols]
10, 10a, 10b, 10c Image signal encoding device
10d image signal encoding and transmitting apparatus
11 Image data converter
12, 12a, 12b, 12c MPEG encoder
13 VLC table selector
14 Standard VLC table
15 Special VLC table
16, 16a, 16b, 16c CPU
17 Transmission path packet encoder
18 Transmission line interface
20, 20a, 20b, 20c Image signal decoding apparatus
20d image signal decoding receiver
22, 22a, 22b, 22c MPEG decoder
23 VLC table selector
24 Standard VLC table
25 Special VLC table
26 Image watermark detector
27 Transmission path packet decoder
28 Transmission path interface
50 MPEG encoder
51 Input terminal
52 Adder
53 DCT unit
54 Quantizer
55 VLC device
56 buffers
57 Conversion code amount controller
61 Inverse quantizer
62 Inverse DCT device
63 Adder
64 image memory
65 Motion Compensated Predictor
70 MPEG decoder
71 Encoded data input terminal
72 buffers
73 VLD device
74 Inverse Quantizer
75 Inverse DCT device
76 Adder
77 Image memory
78 Motion Compensated Predictor
121 VLC unit
122 User data descriptor
123 Quantized Value Watermark Information Descriptor
124 Motion vector digital watermark information description device
221 VLC decoder
222 User data decoder
223 Quantized value watermark information detector
224 Motion vector digital watermark information detector
400 Audio signal encoding device
401 Auditory psychological analyzer
402 MDCT device
403 Scale factor calculator
404 Quantizer
405 Codebook selector
406 Variable length encoder
407 Minimum code amount detector
408 Code amount determination unit
409 bitstream generator
420 Audio signal decoding apparatus
421 Bitstream Analyzer
422 Variable length decoder
423 Inverse Quantizer
424 IMDCT device
430 Audio signal encoding apparatus
431 MPEG-2 AAC Encoder
432 Huffman codebook selector
433 Standard Huffman Codebook
434 Special Huffman Codebook
435 CPU
436 Variable Length Encoder
440 Audio signal decoding apparatus
441 MPEG-2 AAC decoder
442 Huffman codebook selector
443 Standard Huffman Codebook for Scale Factor
444 Special Huffman Codebook for Scale Factor
445 CPU
446 Variable length decoder
450, 460 Audio signal decoding apparatus
451, 461 MPEG-2 AAC decoder
452, 462 Huffman codebook selector
Standard Huffman codebook for 453 and 463 spectra
Special Huffman codebook for 454, 464 spectrum
455, 465 CPU
456 Variable length decoder
510, 510b Variable length encoded data transmission apparatus
510d, 510f Variable length encoded data recording apparatus
511 Image data converter
512 encryptor
513 Encryption method setter
514 Encryption key setter
515 CPU
516 MPEG encoder
517 VLC table selector
518 Standard VLC table
519 Special VLC table
521 Transmission path packet encoder
522 Encrypted information transmitter
523 VLC table generator
531 VLC unit
550, 550a, 550b, 550c variable length encoded data receiver
550d, 550e, 550f, 550g variable length encoded data reproduction device
551 Transmission path packet decoder
552 Encrypted information receiver
561 MPEG decoder
562 VLC table selector
563 Standard VLC table
564 Special VLC table
565 CPU
566 Digital Watermark Detector
567 Decoder
568 decoding method selector
569 Decryption key selector
571 VLC decoder
571a VLC generator decoder
572 IC card reader / writer
581 modulator
582 recorder
591 Regenerator
592 Demodulator
601 IC card
610 recording medium

Claims (2)

  1. Time series data is obtained by performing data conversion, quantization, and arrangement on a content signal including at least one of an image signal and an audio signal by a predetermined method. In a variable length data encoding method for encoding sequence data to obtain a compressed encoded signal,
    A first step of obtaining a variable-length coding table describing a predetermined code word assigned to a plurality of data values of the time-series data;
    Among the code words described in the variable length coding table, the number of the time-series data is allocated as the same number, and different code words are exchanged to create an exchange variable length coding table. A second step;
    A third step of generating an encoding selection signal that specifies which encoding table of the variable length encoding table and the exchange variable length encoding table is used to perform the variable length encoding;
    A fourth step of performing variable-length encoding of the time-series data using the specified encoding table and generating the compressed encoded signal;
    A variable length data encoding method characterized by comprising:
  2. Time series data is obtained by performing data conversion, quantization, and arrangement on a content signal including at least one of an image signal and an audio signal by a predetermined method. In a variable length data encoding device that encodes sequence data to generate a compressed encoded signal,
    Variable-length coding table obtaining means for obtaining a variable-length coding table described by assigning a predetermined code word to a plurality of data values of the time-series data;
    Among the code words described in the variable length coding table, the number of the time-series data is allocated as the same number, and different code words are exchanged to create an exchange variable length coding table. Exchange variable length coding table creation means;
    Coding selection signal generating means for generating a coding selection signal that specifies which one of the variable length coding table and the exchange variable length coding table is used to perform the variable length coding. When,
    Variable length encoding means for performing variable length encoding of the time-series data using the specified encoding table and generating the compressed encoded signal;
    A variable length data encoding apparatus comprising:
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