JP2772518B2 - Digital signal encoding / decoding device, digital signal encoding device, digital signal decoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal encoding / decoding apparatus for compressing and encoding digitized video and audio signals, and expanding and decoding the compressed digitally encoded signal. .

[0002]

2. Description of the Related Art Conventionally, a digital signal encoding apparatus for compressing and encoding a digitized video signal and audio signal is recorded on a recording medium such as a magnetic tape, a magnetic disk, and an optical disk, and recorded on a recording medium. 2. Description of the Related Art A digital signal recording / reproducing apparatus for reproducing using a digital signal decoding apparatus for decompressing and decoding encoded data is known.
FIG. 13 is a block diagram showing the configuration of such a digital signal recording / reproducing apparatus described in the broadcasting technology, 1988, July 1988.

In FIG. 13, reference numerals 1 and 2 are a video A / D converter and an audio A / D converter for converting an input analog video signal and a 4-channel analog audio signal into a digital signal. The video signal digitized by the video A / D converter 1 is output to the C2 encoder 3. The C2 encoder 3 derives C2 parity in the error correction coding of the video signal, adds it to the video signal, and outputs the video signal with the C2 parity added to the interleave 4. The interleave 4 shuffles the input video signal. The audio signal digitized by the audio A / D converter 2 is output to the audio error correction encoder 5. The audio error correction encoder 5 performs error correction encoding on the digitized audio signal. The video signal shuffled by the interleave 4 and the audio signal error-correction-coded by the audio error-correction encoder 5 are combined by an adder and then output to the C1 encoder 6. The C1 encoder 6 derives the C1 parity from the combined data, adds it, and outputs the data with the C1 parity added to the modulator 7. The modulator 7 records and codes the error-correction-coded data. The record-encoded data is
The data is recorded on the magnetic tape 8 by the magnetic head 10 mounted on the rotating drum 9.

[0004] Reference numerals 11 to 19 denote components of a reproduction system.
Reference numeral 11 denotes a demodulator for recording and decoding reproduced data, and the recorded and decoded data is output to the C1 decoder 12. C1
The decoder 12 corrects the error based on the C1 parity word and outputs the corrected reproduction data to the A / V separation circuit 13. The A / V separation circuit 13 separates the reproduced data into a video signal and an audio signal, outputs the video signal to the deinterleave 14, and outputs the audio signal to the audio error correction decoder 18. The deinterleave 14 deshuffles the input video signal and converts the deshuffled video signal into a C2 decoder 15.
Output to The C2 decoder 15 corrects an error based on the C2 parity word, and outputs the corrected video signal to an interpolation circuit 16.
Output to When error correction is impossible, the interpolation circuit 16 performs interpolation processing of the video signal, and outputs the processed video signal to the video D / A converter 17. The video D / A converter 17
A digital video signal is converted into an analog signal and output. The audio error correction decoder 18 corrects the error of the input audio signal, and outputs the corrected audio signal to the audio D / A converter 19. The audio D / A converter 19 converts a digital audio signal into an analog signal and outputs it.

Next, the operation will be described.

The input analog video signal is a video A / D
The signal is converted into a digital signal by the converter 1 and output to the C2 encoder 3. Here, the video signal to which the C2 parity for error correction is added is subjected to predetermined shuffling in interleave 4, and then output to the adder.
On the other hand, the input analog audio signal is digitized by the audio A / D converter 2, subjected to error correction encoding by the audio error correction encoder 5, and output to the adder.
The two signals are combined by the adder, and the combined data is C1
The C1 parity is supplied to the encoder 6 and added.
The data subjected to the error correction encoding and the shuffling process is recorded and encoded by the modulator 7 and then recorded on the magnetic tape 8 by the magnetic head 10. FIG. 14 shows a signal recording format recorded on the magnetic tape 8. The video signal and the four-channel audio signal are recorded at different locations on the same track, and the audio signal is recorded at both ends of the video signal.

In the reproducing system, digital data reproduced by the magnetic head 10 is recorded and decoded by the demodulator 11 and then corrected by the C1 decoder 12 based on the C1 parity word. The output of the C1 decoder 12 is separated by an A / V separation circuit 13 into a video signal and an audio signal.
The audio signal is processed by the audio error correction decoder 18 and then reproduced by the audio D / A converter 19 as a 4-channel analog audio signal. On the other hand, the video signal is subjected to deshuffling for returning to the original arrangement in the deinterleave 14, and then the error is corrected by the C2 decoder 15 based on the C2 parity word. After the primary or secondary signal interpolation processing is performed at 16, an analog video signal is reproduced through the video D / A converter 17.

[0008]

Since the conventional digital recording / reproducing apparatus is configured as described above, if the size of the recording medium is reduced in order to reduce the size of the digital apparatus,
There is a problem that the recording time is shortened by that much. On the other hand, if the compression ratio is increased to solve this problem, there is a conflicting problem that the signal quality at the time of reproduction is deteriorated.

The present invention has been made in view of such circumstances, and provides a digital signal encoding / decoding apparatus capable of simultaneously increasing a signal compression rate while minimizing deterioration of signal quality during reproduction. The purpose is to gain.

[0010]

A digital signal encoding / decoding apparatus according to the present invention compresses and encodes a plurality of types of digital signals, and decodes and decompresses the encoded types of digital signals. a digital signal encoding and decoding apparatus for an encoding means variable compression rate for encoding to compress the double <br/> several digital signal input to the unit time, among the plurality of types of digital signal of
A first control unit that controls the compression ratio of each of the plurality of types of digital signals in the encoding unit so that the sum of the information amounts falls within a predetermined amount while making the ratio of the information amount after encoding variable .
Control means, and a decompression rate variable decoding means for decompressing and decoding the plurality of types of encoded digital signals,
Second control means for controlling the decompression rate of each of the plurality of types of digital signals in the decoding means in accordance with the compression rate of each of the plurality of types of coded digital signals , wherein the first control means Are the plurality of types of digital
The information amount of each signal is compared with a predetermined reference information amount,
Based on the amount of free information obtained as the difference from each reference information amount
The plurality of types of digital signals in the encoding means.
The compression ratio of each signal is controlled .

[0011] The compression rate of each of the plurality of types of digital signals in the first control means is controlled based on the information amount of other digital signals excluding the digital signal whose compression rate is controlled. I do.

The plurality of types of digital signals have a low correlation with each other as a first type digital signal and a second type digital signal, and the first control means compresses the first type digital signal. The rate is controlled based on the information amount of the second type digital signal, and the compression rate of the second type digital signal is controlled based on the information amount of the first type digital signal.

The encoding in the encoding means may be
The digital signal processing is performed individually for each of the plurality of types of digital signals.

Further, the information amount of each of the plurality of types of digital signals is obtained from a randomized digital signal by shuffling each type of digital signal.

The digital signal of the first type is a digital video signal, and the digital signal of the second type is a digital audio signal.

Further, the digital audio signal includes an audio signal of a plurality of channels, and audio signal selecting means for selecting an audio signal of a channel to be encoded is provided.

Further, the digital signal encoding apparatus according to the present invention is a digital signal encoding apparatus for compressing and encoding a plurality of types of digital signals , wherein
Compressing said inputted plurality of types of digital signal encoding means for variable compression rate encoded into the plurality of types of de
The ratio of the amount of encoded information between digital signals
One, as the information amount of the total sum falls within the predetermined amount, and a first control means for controlling the digital signal each compression rate of the plurality of types of the encoding means, said first control
Means for calculating the information amount of the plurality of types of digital signals.
Each is compared with the predetermined reference information amount, and the difference between each reference information amount
The encoding means based on the amount of free information obtained
The compression ratio of each of the digital signals
Characterized in that it.

Further, the compression ratio of each of the plurality of types of digital signals in the control means is controlled based on the information amount of other digital signals excluding the digital signal whose compression ratio is controlled.

Further, the plurality of types of digital signals have a low correlation with each other as a first type digital signal and a second type digital signal, and the first control means compresses the first type digital signal. The rate is controlled based on the information amount of the second type digital signal, and the compression rate of the second type digital signal is controlled based on the information amount of the first type digital signal.

Further, the encoding in the encoding means is as follows:
The digital signal processing is performed individually for each of the plurality of types of digital signals.

Further, the information amount of each of the plurality of types of digital signals can be obtained based on a randomized digital signal by shuffling each type of digital signal.

The digital signal of the first type may be a digitized video signal, and the digital signal of the second type may be a digitized audio signal.

Further, the digital audio signal includes an audio signal of a plurality of channels, and is provided with audio selecting means for selecting an audio signal of a channel to be encoded.

[0024]

Further, the digital signal decoding apparatus according to the present invention compares the information amounts of a plurality of types of digital signals input within a unit time with predetermined reference information amounts, respectively.
Based on the amount of vacant information obtained as the difference from the reference information amount
Controlling the compression ratio of each of the plurality of types of digital signals
After encoding between multiple types of digital signals,
A digital signal decoding apparatus for decoding a digital signal whose sum of information amounts is kept within a predetermined amount while making the ratio of the information amount variable , expands the plurality of types of compressed and encoded digital signals. Decoding means having a variable expansion rate for decoding by decoding, and control means for detecting the compression rate of each of the plurality of types of input digital signals and controlling the expansion rate of each of the plurality of types of digital signals in the decoding means. It is characterized by having.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

Embodiment 1 FIG. 1 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for explaining a digital signal encoding / decoding apparatus according to the present invention. In the drawing, members having the same reference numerals as those in FIG. The members are shown. In FIG. 1, reference numerals 1 and 2 denote a video A / D converter and an audio A / D converter for converting input analog video signals and analog audio signals into digital signals. The video signal digitized by the video A / D converter 1 is output to the video interleave 21. The video interleave 21 divides an input video signal into blocks for each of a plurality of pixels, and performs a shuffling process in block units. The video signal read from the video interleave 21 is output to the video efficient encoder 22. The video efficient encoder 22 performs a compression process on a block-by-block basis, and outputs the compressed video signal to the adder 32. On the other hand, the audio signal digitized by the audio A / D converter 2 is output to the audio interleave 23. The audio interleave 23 divides an input audio signal into blocks for each of a plurality of pixels, and performs a shuffling process for each block. The audio signal read from the audio interleave 23 is output to the high-efficiency audio encoder 24. The high-efficiency audio encoder 24 performs a compression process on a block-by-block basis, and outputs the compressed audio signal to the adder 32.
The adder 32 combines the coded video signal and the coded audio signal, and outputs the combined data to an error correction encoder.
Output to 25. The error correction encoder 25 performs error correction coding and outputs coded data to the modulator 7. The modulator 7 records and codes the error-correction-coded data.
The record-encoded data is recorded on a magnetic tape 8 by a magnetic head 10 mounted on a rotating drum 9.

A demodulator 11 in the reproducing system records and decodes the reproduced data reproduced from the magnetic tape 8. The demodulated data is output to the error correction decoder 26. The error correction decoder 26 corrects errors in the video signal and the audio signal, and outputs the corrected video signal and audio signal to the A / V separation circuit 13. The A / V separation circuit 13 separates the input signal into a video signal and an audio signal, outputs the video signal to the video efficient decoder 27, and converts the audio signal into an audio efficient decoder.
Output to 29. The video efficient decoder 27 decompresses the compressed video signal and outputs the decompressed video signal to the video deinterleave 28. Video deinterleave 28
Deshuffling processing is performed in block units. The video signal from the video deinterleave 28 is read out to the interpolation circuit 16. The interpolation circuit 16 performs an interpolation process on the video signal when error correction is impossible, and converts the processed video signal into a video D / A
Output to converter 17. The video D / A converter 17 converts a digital video signal into an analog signal and outputs it. The audio efficient decoder 29 expands the compressed audio signal and outputs the expanded audio signal to the audio deinterleave 30. The audio deinterleave 30 performs a deshuffling process on a block basis and converts the processed audio signal into an audio D
Output to the / A converter 19. The audio D / A converter 19 converts a digital audio signal into an analog signal and outputs it.

Reference numeral 31 denotes a controller for controlling the compression ratio in the video high-efficiency encoder 22 and the audio high-efficiency encoder 24. The controller 31 controls the compression rate of the video high-efficiency encoder 22 and the audio high-efficiency encoder 24. The estimated value of the amount of information is input to the controller 31. Based on the input value, the controller 31 uses the video high-efficiency encoder 22, the audio high-efficiency encoder 24, the video high-efficiency decoder 27, The control value is output to the efficiency decoder 29.

FIG. 2 is a schematic diagram showing the internal configuration of the video high efficiency encoder 22 (audio high efficiency encoder 24) of the recording system in FIG. The video high-efficiency encoding circuit 22 (audio high-efficiency encoding circuit 24) includes an orthogonal transformation circuit 41 that performs orthogonal transformation such as DCT (Discrete Cosine Transform) on the video signal (audio signal) in block units, An information amount estimating circuit 43 for estimating an information amount of a video signal (audio signal) based on a transform coefficient output from the orthogonal transform circuit 41; A variable-length encoding circuit 42 that adaptively quantizes and encodes the transform coefficient from the video signal (audio signal), and an information amount estimating circuit 43 A subtractor 44 for subtracting the estimated information amount of the video signal (audio signal) to obtain the free information amount of the video signal (audio signal).

FIG. 3 is a schematic diagram showing the internal configuration of the controller 31. The controller 31 includes a reference information amount setting device 45 for setting the reference information amount of the video signal and the audio signal, and a reference information amount setting device 45.
From the reference information amount of the video signal from the
A subtractor 46 for subtracting a feedback value indicating a vacant information amount of the audio recording information amount from the reference information amount, and outputting the subtracted value to the video high efficiency encoder 22; and a reference information of the audio signal from the reference information amount setting device 45. And a subtractor 47 for subtracting a feedback value indicating a vacant information amount of the video recording information amount from the video high efficiency encoder 22 from the set value of the amount, and outputting the subtracted value to the audio high efficiency encoder 24. ing.

Next, the operation will be described.

In the recording system, the video A
The video signal digitized by the / D converter 1 (about 10
0 Mbps) is divided into blocks in units of a plurality of pixels in the video interleave 21 and shuffling processing is performed in block units, and then compressed and encoded by the video high efficiency encoder 22 . In the high-efficiency video encoder 22, orthogonal transform is performed by the orthogonal transform circuit 41. In this case, the compression ratio is 8 pixels × 3
The video signal is divided into blocks of eight lines. The shuffling process in the video interleave 21 is performed in order to improve the estimation accuracy of the estimated information amount in the information amount estimation circuit 43 by randomizing the video signal. Since the amount of information becomes uniform by the shuffling process,
Estimation of the entire information amount is easy even with a small amount of information.
The video signal orthogonally transformed by the orthogonal transformation circuit 41 is a word of the number of quantization bits of the transform coefficient according to the estimated information amount from the information amount estimation circuit 43 so that the reference information amount set by the controller 31 is obtained. After being compressed by the variable length coding circuit 42 for controlling the length and the like, the compressed data is output to the adder 32. The information amount of the compressed video signal is, for example, about １ ／ of the original video signal. At this time, the free information amount of the video signal obtained by subtracting the estimated information amount from the information amount estimation circuit 43 from the reference information amount of the video signal set by the controller 31 is fed back to the controller 31. . On the other hand, the audio signal (approximately 4 Mbps) digitized by the audio A / D converter 2 is subjected to block processing and block shuffling processing in the audio interleave 23 similarly to the video signal. In the high-efficiency audio encoder 24, the same orthogonal transformation, information amount estimation, and variable-length encoding as the video signal are performed, the audio signal is compressed, and the compressed audio signal is output to the adder 32. Is done. At this time, similarly to the video signal, the vacant information amount of the audio signal obtained by subtracting the estimated information amount from the information amount estimation circuit 43 from the reference information amount of the audio signal set by the controller 31 is controlled. vessel
Feedback to 31. After the highly efficient coded video signal and audio signal are combined by the adder 32, error correction coding is performed by the error correction encoder 25, and after recording and coding by the modulator 7, Recording is performed on the magnetic tape 8 by the attached magnetic head 10.

Next, the control of the recording information amount by the setting unit 31 will be described. First, in the reference information amount setting unit 45, for example, in the case of four audio signals, the video signal is 100 Mbps.
A reference information amount of 24 Mbps and an audio signal of 4 Mbps → 1 Mbps is set, and the set reference information amount is applied to a subtractor 46 and an image efficient decoder 27 for a video signal, and to a subtractor 47 and an audio signal for an audio signal. Each is output to the high-efficiency decoder 29. By the way, it is known that the amount of information of a video signal after compression is considerably reduced as the image becomes closer to a still image.For example, in the above-described compression from 100 Mbps to 24 Mbps, it may be compressed to several Mbps depending on the type of image. is there. Also, the amount of information of the audio signal is significantly reduced in a silent part. In addition, since the video signal and the audio signal have no correlation, in this embodiment, when the information amount of the compressed video signal is smaller than the reference information amount (a predetermined compression ratio), the video signal is recorded. A space is generated in the area of the recording medium (magnetic tape 8) to be compressed, so that an audio signal with a reduced compression rate (increased amount of information) can be recorded in this empty area, and the information of the compressed audio signal is recorded. If the amount is smaller than the reference information amount (predetermined compression ratio), an empty space is created in the area of the recording medium (magnetic tape 8) for recording the audio signal. The video high efficiency encoder 22 and the audio high efficiency encoder are controlled so that the video signal (increased in amount) can be recorded so that the sum of the recorded information amounts of the video signal and the audio signal is always constant. 24 and control the compression ratio. More specifically, the subtractor 46 subtracts a feedback value indicating the free information amount of the audio recording from the high-efficiency audio encoder 24 from the reference information amount of the video signal set by the reference information amount setting device 45. , And the subtracted value is used as the video high-efficiency encoder 22.
To the video information efficient encoder based on the reference information amount of the audio signal set by the reference information amount setting unit 45.
The subtractor 47 subtracts the feedback value indicating the free information amount of the video recording from 22, and outputs the subtracted value to the high-efficiency audio encoder 24. In the present embodiment, since the compression ratio of the video signal and the audio signal is kept to the minimum, the quality deterioration of the video signal and the audio signal is minimized.

Next, a specific example of such control of the compression ratio will be described with reference to FIG. FIG. 4A shows the basic compression (reference information amount) of a video signal and an audio signal. The video signal is 100 Mbps → 24 Mbps, and the audio signal is 4 Mbps → 1 Mb.
Each is compressed to ps. FIG. 4B shows a case where the information amount of the video signal is less than the reference information amount (for example, when the image signal is a still image and the video information is small).
The audio signal is compressed from 0 Mbps to 15 Mbps, and the audio signal is not compressed from 4 Mbps to 4 Mbps. Here, since the original video signal has less information, the image quality is the same even if the video signal is compressed from 100 Mbps to 24 Mbps. FIG. 4C shows a case where the information amount of the audio signal is less than the reference information amount (for example, when there is no sound information and there is no audio information).
Mbps and the audio signal is changed from 4 Mbps to 0 Mbps. As described above, the compression ratio is not increased as much as possible so that the image quality and the sound quality can be prevented from deteriorating so that there is no empty area in the total recordable information amount (25 Mbps) that can be recorded.
The compression ratio of the video signal in the video high efficiency encoder 22 and the compression ratio of the audio signal in the audio high efficiency encoder 24 are controlled.

Next, the operation of the reproducing system will be described. In the reproducing system, data reproduced from the magnetic tape 8 by the magnetic head 10 is recorded and decoded by the demodulator 11, and an error correction decoder 26 corrects a burst error or the like generated on the magnetic tape 8. If the data cannot be corrected, the data is transferred with an error flag. The video signal and the audio signal whose errors have been corrected are separated by the A / V separation circuit 13. Next, in the video efficient decoder 27, the compressed video signal is expanded in accordance with the reference information amount from the controller 31. The decompressed video signal is taken into the video deinterleave 28, subjected to deshuffling processing in block units, and returned to the original video block position. With respect to a video block to which error correction cannot be performed and an error flag is attached, a pixel interpolation process is performed by the interpolation circuit 16, and an analog reproduction video signal is obtained by the video D / A converter 17. Further, the audio signal separated by the A / V separation circuit 13 is subjected to expansion of the compressed audio signal in the audio efficient decoder 29 in accordance with the reference information amount from the controller 31. The decompressed audio signal is taken into the audio deinterleave 30, subjected to deshuffling processing in block units, returned to the original audio signal sequence, and the audio D / A converter 19 obtains an analog reproduced audio signal.

Embodiment 2 FIG. 5 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for explaining Embodiment 2 of the present invention. In the figure, members having the same reference numerals as those in FIG. Show. In the recording system, a video error correction encoder 33 inserted between the video high efficiency encoder 22 and the adder 32 performs error correction coding of a video signal. In addition, between the plurality of audio A / D converters 2 provided for each channel of the audio signal and the adder 32, the digitized audio signals of the plurality of channels (N channels) should be actually recorded. An audio selector 34 for selecting an audio channel and an audio error correction encoder 35 for performing error correction encoding of an audio signal are provided. A video error correction decoder 36 inserted between the A / V separation circuit 13 and the high-efficiency video decoder 27 in the reproduction system corrects an error in the video signal. Also, between the A / V separation circuit 13 and a plurality of audio D / A converters 19 provided for each channel of the audio signal, an audio error correction decoder 37 for correcting an error of the audio signal and a reproduced audio signal are provided. And an audio distributor 38 for distributing the audio signal to a predetermined output terminal (audio D / A converter 19). 31 is a video high efficiency encoder 2 according to the set number of audio signal channels.
2, audio selector 34, video efficient decoder 27, audio distributor 3
It is a controller that controls 8.

FIG. 6 is a schematic diagram showing the internal configuration of the video high efficiency encoding circuit 22 of the recording system in FIG. The video high-efficiency encoding circuit 22 estimates the amount of information of the video signal based on the orthogonal transform circuit 41 that performs orthogonal transform such as DCT on a block basis of the video signal and the transform coefficient output from the orthogonal transform circuit 41. An information amount estimating circuit 43 that outputs a control signal to the variable length coding circuit 42 so that the compression ratio given from the controller 31 is obtained.
And the transformation coefficient from the orthogonal transformation circuit 41 to the information amount estimation circuit 43
And a variable-length encoding circuit 42 for adaptively quantizing and encoding in accordance with the control signal from the CPU.

Next, the operation will be described. In the recording system, a video signal (approximately 100 Mbps) digitized by the video A / D converter 1 is divided into blocks each having a plurality of pixels by a video interleave 21 in the same manner as in the conventional example. After the shuffling process is performed, the image is compressed and coded by the video high efficiency coding circuit 22.
The video signal orthogonally transformed by the orthogonal transformation circuit 41 in the video high-efficiency encoding circuit 22 is a variable-length code that controls the word length and the like of the number of quantization bits of the transform coefficient according to the control signal from the information amount estimation circuit 43. The data is compressed by the conversion circuit 42, subjected to error correction coding by the video error correction encoder 33, and output to the adder 32. On the other hand, an audio selector selects a plurality of channels of audio signals digitized by each audio A / D converter 2.
The audio signal to be recorded by 34 is, for example, two channels,
4 channels, etc. are selected and the audio error correction encoder 35
After being subjected to error correction coding in, the data is output to the adder 32.
After the video signal and the audio signal are combined by the adder 32, they are recorded and encoded by the modulator 7 and recorded on the magnetic tape 8 by the magnetic head 10 attached to the rotating drum 9.

In this embodiment, the input video signal 10
A compression process is performed on 0 Mbps, and the data is recorded on the magnetic tape 8 at a recording information amount of 25 Mbps. The audio signal is recorded on the magnetic tape 8 without being subjected to compression processing. FIG. 7 shows an information amount when a video signal (100 Mbps) and an audio signal (in the case of 2 channels, in the case of 4 channels) are recorded at a fixed recording information amount of 25 Mbps. When the number of channels of the audio signal to be recorded increases (the amount of audio information increases), the compression ratio in the video high efficiency encoder 22 is increased. Conversely, when the number of channels of the audio signal to be recorded decreases (the amount of audio information decreases), the compression ratio in the video high efficiency encoder 22 decreases. In the case of two channels (case 1), the amount of audio information becomes 2 Mbps when the recording formatting is performed. Therefore, the video efficient encoder 22 compresses the 100 Mbps video signal to 23 Mbps. In the case of four channels (case 2), the amount of audio information becomes 4 Mbps when recording formatting is performed, so that a 100 Mbps video signal is compressed to 21 Mbps. When the number of channels of the audio signal further increases, the compression ratio of the video signal is increased accordingly. Such a change in the compression ratio in the video high efficiency encoder 22 is controlled by the controller 31. Thus, even if the number of channels of the audio signal changes, the compression ratio of the video signal is changed accordingly, so that the number of channels can be freely set. Further, even when the audio signal increases from channel 2 to channel 4, the compression ratio of the video signal only slightly changes from 23/100 to 21/100, so that the image quality hardly deteriorates.

FIG. 8 shows an example of a recording format on the magnetic tape 8 in case 1 and case 2 described above.
The ratio of the recording area of the audio signal to the entire recording area changes according to the number of channels of the audio signal. Further, since recording codes including error correction coding are separately performed on the video signal and the audio signal, it is also possible to perform after-recording in which only the audio signal is recorded.

Next, the operation of the reproducing system will be described. In the reproducing system, data reproduced from the magnetic tape 8 by the magnetic head 10 is recorded and decoded by the demodulator 11, and
The video signal and the audio signal are separated by the V separation circuit 13. From the separated video signal and audio signal, a burst error or the like generated on the magnetic tape 8 is corrected by a video error correction decoder 36 and an audio error correction decoder 37. If the data cannot be corrected, the data is transferred with an error flag. Next, the compressed video signal is expanded by the video efficient decoder 27. The decompressed video signal is taken into the video deinterleave 28, subjected to deshuffling processing in block units, and returned to the original video block position. With respect to a video block to which error correction cannot be performed and an error flag is attached, a pixel interpolation process is performed by the interpolation circuit 16, and an analog reproduction video signal is obtained by the video D / A converter 17. The audio signal after error correction is input to a predetermined audio D / A converter 19 by an audio distributor 38, and an analog reproduced audio signal is obtained.

Embodiment 3 FIG. 9 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for describing Embodiment 3 of the present invention. In the figure, members denoted by the same reference numerals as in FIGS. 1 and 5 are the same or similar. Fig. 4 shows constituent members. In the recording system, between a plurality of audio A / D converters 2 provided for each channel of the audio signal and the audio interleave 23, a digitalized audio signal of a plurality of channels (N channels) is actually recorded. An audio selector 34 for selecting an audio channel to be provided is provided. In the reproduction system, between the audio deinterleave 30 and a plurality of audio D / A converters 19 provided for each channel of the audio signal,
An audio distributor 38 for distributing the reproduced audio signal to a predetermined output terminal (audio D / A converter 19) is provided. Also, in the figure, 31 is a video high efficiency encoder 22, an audio high efficiency encoder 24,
Audio selector 34, audio distributor 38, video efficient decoder 27,
This is a controller that gives a control value to the audio efficient decoder 29 and feeds back an estimated value of the information amount from the video efficiency encoder 22 and the audio efficiency encoder 24.

The internal configuration of the high-efficiency video encoder 22 (high-efficiency audio encoder 24) is the same as that of the first embodiment shown in FIG. FIG. 10 is a schematic diagram showing the internal configuration of the controller 31 in the present embodiment. Except that the reference information amount setting unit 45 sets the set value of the reference information amount of the video signal and the audio signal according to the set number of channels of the audio signal,
This is the same as the internal configuration of the 31.

Next, the operation will be described. The operation for the video signal in the recording system is the same as that of the first embodiment, and the description is omitted. On the other hand, each audio A / D
From the audio signals of the plurality of channels digitized by the converter 2, an audio signal to be recorded is selected by the audio selector 34 into, for example, 2 channels, 4 channels, or the like.
After being subjected to block processing and shuffling processing in block units in the audio interleave 23, the audio signal is compressed in the audio high efficiency coding circuit 24, and the compressed audio signal is added to the adder.
Output to 32. It should be noted that, as in the first embodiment, the amount of free information of the video signal and the audio signal is
This is fed back from the high-efficiency audio encoder 24 to the controller 31. Thereafter, the video signal and the audio signal are recorded on the magnetic tape 8 as in the first embodiment.

Next, the control of the recording information amount by the controller 31 will be described. The number of channels of the audio signal set in the reference information amount setting unit 45 of the controller 31 in FIG. 10 is input. Then, according to the number of channels of the audio signal, the compression ratio in the video high efficiency encoder 22 and the audio high efficiency encoder 24 is controlled. When the number of audio signal channels increases (when the amount of audio information increases), these compression ratios are increased, and when the number of audio signal channels decreases (when the amount of audio information decreases), these compression ratios decrease. For example, if the number of channels is two, the video signal 100 Mbps → 24.5
Mbps, audio signal 2 Mbps → 0.5 Mbps, if the number of channels is 4, video signal 100 Mbps → 24 Mbps
s, the reference information amount at the time of compressing the video signal and the audio signal from 4 Mbps to 1 Mbps of the audio signal is set. Depending on the type of video and audio, the amount of information may be significantly reduced after compression and may be smaller than the reference information amount. In such a case, as in the first embodiment, in order to keep the compression ratio of the video signal and the audio signal to a minimum, the video signal is controlled so that the sum of the recording information amounts of the video signal and the audio signal is always constant. High efficiency encoder
The compression ratio in the high-efficiency encoder 22 and the high-efficiency audio encoder 24 is controlled. The operation at this time is the same as that of the first embodiment (see FIG. 4), and the description thereof is omitted.

Next, the operation of the reproducing system will be described. The audio signal expanded by the audio efficient decoder 29 is taken into an audio deinterleave 30 and subjected to deshuffling processing in block units to return to the original audio signal sequence. The signal is input to a predetermined audio D / A converter 19, and an analog reproduced audio signal is obtained. Note that other operations are the same as those in the first embodiment, and a description thereof will not be repeated.

In the first, second, and third embodiments,
Although a magnetic tape is used as a recording medium, the present invention can be applied to all recording media such as a magnetic disk, an optical disk, and a semiconductor memory if the recording format is the same and the amount of recorded information is constant.

Embodiment 4 FIG. 11 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus according to Embodiment 4 of the present invention. In the figure, members denoted by the same reference numerals as those in FIG. 1 indicate the same components. In the coding system, between the adder 32 and the error correction encoder 25, a data array memory 39 for arranging the video signal and the audio signal in accordance with the frequency is provided. In the decoding system, between the error correction decoder 26 and the A / V separation circuit 13, a data reverse array memory 40 for rearranging the arrangement of the video signal and the audio signal to the original arrangement is provided.

Next, the operation will be described. In this embodiment, the high frequency components of the video signal and the audio signal are
This is an example in which recording is performed at the end of a recording track.
The following description focuses on the operation in this case. The video signal and the audio signal that have been subjected to the high-efficiency encoding are combined by an adder 32 and input to a data array memory 39. In the data array memory 39, the high-efficiency-coded video signal is rearranged in the order of high-frequency components to low-frequency components, and the high-efficiency-coded audio signal is reversed in the order of low-frequency components to high-frequency components. Can be rearranged. These rearranged signals are subjected to error correction encoding by the error correction encoder 25,
The data is recorded on the magnetic tape 8 by the magnetic head 10 via the modulator 7.

FIG. 12 shows a recording track pattern on the magnetic tape 8, and arrows in the figure indicate the helical scanning direction of the rotary head 10. The rotary head 10 performs a helical scan on the magnetic tape 8 in the direction of the arrow (from the lower end to the upper end of the magnetic tape 8) and records the video signal and the audio signal in this order. The high frequency component of the audio signal is recorded at the rear end of the component.

The video signal and the audio signal whose errors have been corrected by the error correction decoder 26 are decompressed by the data reverse array memory 40 so that they can be decompressed by the video high efficiency decoder 27 and the audio high efficiency decoder 29. The data array is returned in the original order,
The signal is separated by an A / V separation circuit 13. Thereafter, analog reproduced video signals and reproduced audio signals are obtained in the same manner as in the first embodiment. The high-frequency component of the video signal mainly indicates an edge component such as a fine image portion or an outline.
Therefore, even if an error remains in the high-frequency component of the video signal recorded at the front end of the recording track and all errors cannot be completely corrected by the error correction decoder 26, the reproduced image obtained is Only an error (bleeding) or the like occurs in the outline or the like, and the error does not become conspicuous in the entire image. Also, since the high-frequency component of the audio signal indicates a high-pitched tone, even if an error remains in the high-frequency component of the audio signal recorded at the rear end of the recording track, the level of the high-pitched tone is slightly reduced in the obtained reproduced audio. , But no error is noticeable in the entire voice.

In this embodiment, both the video signal and the audio signal are encoded with high efficiency according to the first embodiment, but either the video signal or the audio signal is encoded with high efficiency. However, if the high-frequency component of the video signal (audio signal) after high-efficiency encoding is recorded at the end of the recording track, the same effect can be obtained for the video signal (audio signal). Of course.

[0054]

As described above, according to the digital signal encoding / decoding apparatus of the present invention, a plurality of types of digital signals are compressed and encoded, and the encoded plurality of types of digital signals are encoded. In a digital signal encoding / decoding device that decodes and expands ,
Encoding means for variable compression rate for encoding to compress the plurality of kinds of digital signal power, while the ratio of the amount of information after encoding between the plurality of types of digital signal is variable,
First control means for controlling a compression rate of each of the plurality of types of digital signals in the coding means so that the total amount of information falls within a predetermined amount; and decompression of the plurality of types of encoded digital signals. A decoding means having a variable decompression rate for decoding, and controlling a decompression rate of each of the plurality of types of digital signals in the decoding means in accordance with a compression rate of each of the plurality of encoded digital signals. , The signal compression can be performed with high efficiency while keeping the quality of the reproduced signal within a predetermined range. And sign based on the amount of free information obtained
Control the compression ratio of each of multiple digital signals
Control allows fine-grained compression control. Ie empty
If there is enough information, lower the compression ratio to avoid quality degradation.
If the amount of free information is small, increase the compression
It is possible to avoid a coding error or recording failure.

Further, in the digital signal encoding / decoding device according to the present invention, the compression ratio of each of the plurality of types of digital signals in the first control means may be different from that of the digital signal whose compression ratio is controlled. Since the control is performed based on the information amount of the digital signal, it is possible to perform the signal compression with higher efficiency while keeping the quality degradation of the reproduction signal within a predetermined range.

Further, in the digital signal encoding / decoding apparatus according to the present invention, the plurality of types of digital signals are combined with a first type of digital signal having low correlation with the second type of digital signal.
And the compression rate of the first type of digital signal in the first control means is controlled based on the information amount of the second type of digital signal, and the compression rate of the second type of digital signal is controlled. Is controlled on the basis of the information amount of the first type of digital signal, so that more efficient signal compression can be performed while keeping the quality of the reproduced signal within a predetermined range.

Further, in the digital signal encoding / decoding apparatus according to the present invention, since the encoding in the encoding means is individually performed for each of the plurality of types of digital signals, the after-recording of each digital signal is performed. Can be easily performed.

Further, in the digital signal encoding / decoding apparatus according to the present invention, the information amount of each of the plurality of types of digital signals is obtained from the randomized digital signals by shuffling the individual types of digital signals. Therefore, the amount of information can be accurately estimated from a digital signal with a small amount.

In the digital signal encoding / decoding apparatus according to the present invention, the digital audio signal includes audio signals of a plurality of channels and includes audio selecting means for selecting an audio signal of a channel to be encoded. Accordingly, it is possible to appropriately compress the video signal and the audio signal in accordance with the number of channels of the audio signal to be encoded.

[0060] Furthermore, according to the digital signal encoding apparatus according to the present invention, a digital signal encoding apparatus for encoding to compress the plurality of kinds of digital signals, the unit
Encoding means for variable compression rate for encoding to compress the plurality of kinds of digital signal input in time, the more
Variable ratio of encoded information between digital signals
And first control means for controlling the compression ratio of each of the plurality of types of digital signals in the encoding means so that the total amount of information falls within a predetermined amount. Highly efficient signal compression can be performed while keeping deterioration within a predetermined range. And empty
Finer compression control is possible by using the amount of information
It is.

Also, in the digital signal encoding apparatus according to the present invention, the compression ratio of each of the plurality of types of digital signals in the first control means may be replaced with another digital signal other than the digital signal whose compression ratio is controlled. Therefore, the signal compression can be performed with higher efficiency while the signal quality degradation during reproduction is kept within a predetermined range.

Further, in the digital signal encoding apparatus according to the present invention, the plurality of types of digital signals are converted into a first type digital signal and a second type digital signal having low correlation with each other, and the first control First in the means
Is controlled based on the information amount of the second type digital signal, and the compression ratio of the second type digital signal is controlled based on the information amount of the first type digital signal. Therefore, it is possible to perform more efficient signal compression while keeping the signal quality degradation during reproduction within a predetermined range.

In the digital signal encoding apparatus according to the present invention, since the encoding by the encoding means is individually performed for each of the plurality of types of digital signals, after-recording of each digital signal can be easily performed. I can do it.

In the digital signal encoding apparatus according to the present invention, the information amount of each of the plurality of types of digital signals is obtained based on the randomized digital signals by shuffling the individual types of digital signals. Therefore, the amount of information can be accurately estimated from a digital signal with a small amount.

In the digital signal encoding apparatus according to the present invention, since the digital audio signal includes audio signals of a plurality of channels and includes audio selecting means for selecting an audio signal of a channel to be encoded, Video and audio signals can be appropriately compressed according to the number of channels of the audio signal to be transmitted.

[0066]

Further, according to the digital signal decoding apparatus of the present invention, the information amounts of a plurality of types of digital signals input within a unit time are compared with predetermined reference information amounts.
Based on the amount of vacant information obtained as the difference from each reference information amount.
Control the compression ratio of each of the digital signals.
By controlling the
In a digital signal decoding apparatus for decoding a digital signal in which the sum of the information amount is within a predetermined amount while making the ratio of the information amount after encoding variable, the plurality of types of compressed and encoded digital signals are A variable-decompression-ratio decoding means for decompressing and decoding, and a control for detecting the compression rate of each of the plurality of types of input digital signals and controlling the respective decompression rates of the plurality of types of digital signals in the decoding means Means, a digital signal transmitted while maintaining a high information compression rate can be reproduced easily and with high quality. Then, using the amount of free information,
Paddle compression control is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for describing Embodiment 1 of the present invention.

FIG. 2 is a schematic diagram showing an internal configuration of the high efficiency encoder in FIG.

FIG. 3 is a schematic diagram showing an internal configuration of a controller in FIG.

FIG. 4 is a conceptual diagram showing the amount of information when recording information is compressed by performing a high-efficiency encoding process on a video signal and an audio signal.

FIG. 5 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for describing Embodiment 2 of the present invention.

FIG. 6 is a schematic diagram showing an internal configuration of the video efficient encoder in FIG. 5;

FIG. 7 is a conceptual diagram showing an information amount when recording information is compressed by performing a high-efficiency encoding process on a video signal in the second embodiment.

FIG. 8 is a diagram showing a recording format on a magnetic tape according to the second embodiment.

FIG. 9 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for describing Embodiment 3 of the present invention.

FIG. 10 is a schematic diagram showing an internal configuration of a controller in FIG. 9;

FIG. 11 is a block diagram showing a configuration of a digital signal recording / reproducing apparatus for describing Embodiment 4 of the present invention.

FIG. 12 is a data pattern diagram showing an arrangement of a video signal and an audio signal on a recording track according to a fourth embodiment.

FIG. 13 is a block diagram showing a configuration of a conventional digital signal recording / reproducing apparatus.

FIG. 14 is a signal recording format diagram of a conventional digital signal recording / reproducing apparatus.

[Explanation of symbols]

8 magnetic tape, 10 magnetic head, 22 video high efficiency encoder, 24 audio high efficiency encoder, 27 video high efficiency decoder, 29 audio high efficiency decoder, 31 controller, 34 audio selector, 38 Voice distributor, 39 data array memory, 40 data reverse array memory

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H04N 7/24 H04N 7/13 Z (72) Inventor Yukari Ono 1 Baba Zoshosho, Nagaokakyo-shi, Kyoto Mitsubishi Electric Co., Ltd. (56) References JP-A-4-104683 (JP, A) JP-A-4-307679 (JP, A) JP-A-4-238164 (JP, A) (58) Fields studied (Int. Cl ^6, DB name) H04N 5/91 -. 5/956 G11B 20/12 H03M 7/30 H04N 7/24 - 7/68 G11B 20/10 341

Claims (15)

(57) [Claims] 1. A coded to compress the plurality of kinds of digital signals, a digital signal encoding and decoding apparatus for decompressing and decoding the plurality of types of digital signals encoded, the input in a unit time encoding means for variable compression rate of encoded <br/> compressing a plurality of types of digital signal, the information amount after encoding between the plurality of types of digital signal
First control means for controlling the compression ratio of each of the plurality of types of digital signals in the coding means so that the sum of the information amounts falls within a predetermined amount while making the ratio variable; and A variable expansion rate decoding means for expanding and decoding the digital signal of the above, and an expansion of each of the plurality of types of digital signals in the decoding means according to a compression rate of each of the plurality of types of encoded digital signals. And second control means for controlling the rate.
Wherein the first control means, the plurality of types of digital signal
Is compared with a predetermined reference information amount.
Based on the amount of free information obtained as the difference from the amount of information,
The plurality of types of digital signals individually in encoding means;
A digital signal encoding / decoding device characterized by controlling a compression ratio of a digital signal. 2. The compression ratio of each of the plurality of types of digital signals in the first control means is controlled based on the information amount of other digital signals excluding the digital signal whose compression ratio is controlled. The digital signal encoding / decoding device according to claim 1, wherein 3. The digital signal of the first type comprising a first type of digital signal and a second type of digital signal having low correlation with each other. Is controlled based on the information amount of the second type digital signal, and the compression ratio of the second type digital signal is controlled based on the information amount of the first type digital signal. The digital signal encoding / decoding device according to claim 1. 4. The digital signal encoding apparatus according to claim 1, wherein the encoding in said encoding means is individually performed for each of said plurality of types of digital signals.
Decryption device. 5. The method according to claim 2, wherein the information amount of each of the plurality of types of digital signals is obtained from a randomized digital signal by shuffling the individual types of digital signals. A digital signal encoding / decoding device according to the above. 6. The digital signal encoding / decoding according to claim 3, wherein said first type of digital signal is a digital video signal, and said second type of digital signal is a digital audio signal. Device. 7. The digital signal encoding / decoding according to claim 6, wherein said digital audio signal includes audio signals of a plurality of channels, and further comprises audio selecting means for selecting an audio signal of a channel to be encoded. Device. 8. A digital signal encoding apparatus for compressing and encoding a plurality of types of digital signals, wherein a compression rate variable for compressing and encoding the plurality of types of digital signals input within a unit time. Encoding means, and the amount of information after encoding between the plurality of types of digital signals.
While the ratio is variable so that the information amount of the sum falls within the predetermined amount, Bei and first control means for controlling the digital signal each compression rate of the plurality of types of the encoding means
For example, the first control means, the plurality of types of digital signal
Is compared with a predetermined reference information amount.
Based on the amount of free information obtained as the difference from the amount of information,
The plurality of types of digital signals individually in encoding means;
A digital signal encoding device for controlling a compression ratio of the digital signal. 9. The compression rate of each of the plurality of types of digital signals in the first control means is controlled based on the information amount of other digital signals excluding the digital signal whose compression rate is controlled. The digital signal encoding device according to claim 8, wherein 10. The first kind of digital signal in the first control means, wherein the plurality of kinds of digital signals comprise a first kind of digital signal and a second kind of digital signal having low correlation with each other. Is controlled based on the information amount of the second type digital signal, and the compression ratio of the second type digital signal is controlled based on the information amount of the first type digital signal. The digital signal encoding device according to claim 8. 11. The digital signal encoding apparatus according to claim 8, wherein encoding in said encoding means is performed individually for each of said plurality of types of digital signals. 12. The information processing apparatus according to claim 9, wherein the information amount of each of the plurality of types of digital signals can be obtained based on digital signals randomized by shuffling the individual types of digital signals. 3. A digital signal encoding device according to claim 1. 13. The digital signal of claim 10, wherein the first type of digital signal is a digitized video signal, and the second type of digital signal is a digitized audio signal. Digital signal encoding device. 14. The digital signal encoding apparatus according to claim 13, wherein said digital audio signal includes audio signals of a plurality of channels, and further comprises audio selecting means for selecting an audio signal of a channel to be encoded. 15. A plurality of types of digital data input within a unit time.
Compares the information content of digital signals with a predetermined reference information volume
Based on the amount of vacant information obtained as the difference from each reference information amount.
Control the compression ratio of each of the digital signals.
By controlling the
While making the ratio of the information amount after decoding variable, the sum of the information amount
Decode a digital signal that is adjusted to fit in a predetermined amount
That the digital signal decrypted device, extending said plurality of types of digital signal compression-coded
Decompression means with variable decompression rate for decoding and detecting the compression rate of each of the input digital signals
The plurality of types of digital data in the decoding means.
Digital signal decoding apparatus characterized in that e Bei and control means for controlling the signal individual elongation.