JP4432284B2 - Recording apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording apparatus and method for recording a data stream on a recording medium with the same length in a predetermined unit.
[0002]
[Prior art]
As represented by a digital VTR (Video Tape Recorder), a data recording / reproducing apparatus for recording a digital video signal and a digital audio signal on a recording medium and reproducing from the recording medium is known. Since a digital video signal has an enormous data capacity, it is generally compressed and encoded by a predetermined method and recorded on a recording medium. In recent years, MPEG2 (Moving Picture Experts Group 2) system is known as a standard system for compression coding.
[0003]
In the above-described image compression technology such as MPEG2, the data compression rate is increased by using a variable length code. Therefore, the code amount after compression of data per screen, for example, one frame or one field varies depending on the complexity of the image to be compressed.
[0004]
In the MPEG2 system described above, the slice layer is a variable length coding unit in data having a hierarchical structure from the lower layer to the upper layer in the order of the macroblock layer, slice layer, picture layer, GOP layer, and sequence layer. The macroblock layer further includes a plurality of DCT (Discrete Cosine Transform) blocks. A header portion for storing header information is provided at the head of each layer. For example, in the slice layer, the delimiter position of the variable length code is detected by detecting this header portion. The decoder that decodes the variable-length code decodes the variable-length code based on the detected delimiter position.
[0005]
For example, in MPEG2, the data arrangement defined by the standard is referred to as syntax.
[0006]
On the other hand, various image data formats are conceivable depending on the combination of the image size and the frame frequency, the scanning method, and the like. In video equipment for broadcasting or production, a predetermined restriction is generally given to the format of image data to be handled. The above-mentioned MPEG2 standard is considered to be able to flexibly cope with such various image formats.
[0007]
By the way, when a video signal input as a baseband signal is encoded as described above and recorded on a recording medium such as a magnetic tape, a stream is set in a predetermined unit, for example, a frame unit by an encoder of the device. Is isometric. The unit of equal length varies depending on the configuration of the recording apparatus. In addition to this, for example, one field and a plurality of frames can be set as the equal length unit. Hereinafter, it is assumed that equalization is performed in units of frames. The recording area on the recording medium is divided into a size corresponding to the length of the equal length, and the equal length stream is sequentially recorded in this area.
[0008]
In this way, by processing the variable-length encoded stream to the same length and recording it on the recording medium, it becomes possible to easily perform processing in units of frames for the video signal.
[0009]
Further, by recording the stream on the recording medium in equal length units, the recording medium is consumed in proportion to the recording time in which the equal length units are recorded. Therefore, it is possible to easily obtain an accurate value of the total recording amount (recording time) and the remaining amount of the recording medium, and to easily find a head by a high-speed search. Furthermore, there is an advantage that stabilization can be achieved by keeping the magnetic tape that is dynamically driven at a constant speed, such as when the recording medium is a magnetic tape.
[0010]
[Problems to be solved by the invention]
However, when the input stream is recorded with the same length, there is no guarantee that the equal length unit, that is, the code amount for each frame is within the upper limit of the length of the equal length. If this recording device records the stream for each frame in the order of input, the limit of the code amount (equalization amount) specified for equalization of the encoding amount of a certain frame. In the case of exceeding the frame length, only the equal length capacity is recorded in the stream of the frame, and the subsequent codes are divided.
[0011]
If the frame stream is divided in this way, there is a problem in that the lower end of the screen is lost in the reproduced image of the frame. Further, if the frame stream is divided and the frame does not end normally, a syntax error may occur at the boundary with the next frame during reproduction. There is a problem that syntax errors may cause runaway or hang-up of a decoder to which the stream is input.
[0012]
Furthermore, a recording device with low error tolerance designed on the assumption that the input stream is made to be the same length can fail at the stage of recording a stream that exceeds the upper limit of the length. There is sex. That is, there is a problem in that a code overflowing from the equalized amount enters the area of the next frame, and the capacity and recording position of the next frame are compressed by the overflowing code. As a result, the meaning of equalizing the area on the recording medium is lost.
[0013]
Furthermore, if the situation where the next frame in which the capacity and the recording position are compressed further compresses the next frame is repeated, there is a possibility that the recording system memory may eventually overflow. It was.
[0014]
Therefore, an object of the present invention is not to record a stream in which the code amount of the equal length unit exceeds the upper limit of the equal length when the variable length coded stream is recorded in a predetermined equal length unit. It is an object of the present invention to provide a recording apparatus and method.
[0015]
[Means for Solving the Problems]
  In order to solve the above-described problem, the present invention provides a recording apparatus for recording a stream encoded using a variable length code on a recording medium in a predetermined equal length unit.
  Input means for receiving a stream encoded using a variable-length code;
  The stream input to the input means is recorded on a recording medium in a predetermined equal length unit.FirstRecording means;
  Measuring means for measuring the code amount of a predetermined equal length unit of the stream input to the input means;
  Based on the measurement result of the measuring means, the code amount of the predetermined equal length unit of the input stream exceeds the total code amount defined for the predetermined equal length unit.The stream within the total code amount specified for the predetermined equalization unit and the total code amount specified for the predetermined equalization unit.streamWhenTheA stream that exceeds the total code amount defined for the first equalization unit and the predetermined equalization unit is read out separately and recorded in the second recording means, and is defined for the predetermined equalization unit. A second packing process that reads a stream that is smaller than the total code amount and that exceeds the total code amount defined for a predetermined equal-length unit in an area in which a free space has occurred; When reading is performed, reading is temporarily interrupted, parity of the outer code is generated, and write-back processing is performed to write back the second packed data and the parity of the outer code to the first recording unit.Control means and
It is a recording device characterized by having.
[0016]
  Further, the present invention provides a recording method for recording a stream encoded using a variable length code on a recording medium in a predetermined equal length unit.
  An input step in which a stream encoded using a variable length code is input;
  A measurement step for measuring a code amount of a predetermined equal length unit of the stream input in the input step;
  If the code amount of a predetermined equal length unit of the input stream exceeds the total code amount specified for the predetermined equal length unit, the code specified for the predetermined equal length unit A first packing step of separately recording a stream in the total amount and a stream exceeding a total code amount defined for a predetermined equal length unit in a recording unit;
  A stream that exceeds the total code amount specified for the predetermined equalization unit is read, and the predetermined code is added to the area where the free space area is smaller than the total code amount specified for the predetermined equalization unit. A second packing step for reading a stream that exceeds the total code amount defined for the lengthening unit;
  When a stream of a block of a predetermined unit is read, the reading is temporarily interrupted, the parity of the outer code is generated, and the second packed data and the parity of the outer code are written back to the recording means. Step back and
It is a recording method characterized by having.
[0017]
  As described above, the present invention records a stream encoded using an input variable length code on a recording medium in a predetermined equal length unit,If the code amount of a predetermined equal length unit of the input stream exceeds the total code amount specified for the predetermined equal length unit, the code specified for the predetermined equal length unit The stream within the total amount and the stream exceeding the total code amount specified for the predetermined equal length unit are separately recorded on the recording means, and the total code amount specified for the predetermined equal length unit is recorded. The excess stream is read, and is smaller than the total code amount specified for the predetermined equalization unit, and exceeds the total code amount specified for the predetermined equalization unit in the area where the free space is generated. When the stream is read and the stream of a predetermined unit block is read, the reading is temporarily interrupted, the parity of the outer code is generated, and the second packed data and the parity of the outer code are recorded. Write on ToTherefore, when a stream having a bit rate exceeding a specified value is input, unauthorized recording on the recording medium can be prevented.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The concept of the present invention will be described below with reference to FIGS. FIG. 1 shows a basic configuration of a digital VTR (Video Tape Recorder) that records and reproduces a baseband signal using a magnetic tape as a recording medium. At the time of recording, a baseband signal that is an uncompressed digital video signal is input from a terminal 500. The baseband signal is supplied to an ECC (Error Correction Coding) encoder 511. The baseband signal supplied to the ECC encoder 501 is subjected to shuffling and error correction encoding processing, is recorded and encoded by the recording amplifier 502, is supplied to a rotating head (not shown), and is recorded on the magnetic tape 503 by the rotating head. The
[0019]
At the time of reproduction, a reproduction signal reproduced from the magnetic tape 503 by the rotary head is supplied to the reproduction amplifier 504 and decoded into a digital signal. The output of the reproduction amplifier 504 is supplied to the ECC decoder 505, where the error correction code is decoded and error corrected and deshuffled. The baseband signal output from the ECC decoder 505 is derived to the terminal 506.
[0020]
FIG. 2 shows a basic configuration of a digital VTR that records and reproduces a stream in which a video signal is encoded by the MPEG2 system. At the time of recording, a baseband signal is input from the terminal 510 and supplied to the MPEG encoder 511. The MPEG encoder 511 encodes the supplied baseband signal in a predetermined MPEG2 format and outputs it as a stream. The stream output from the MPEG encoder 511 is supplied to one input terminal of the selector 513. In addition, a stream encoded in advance in the MPEG2 system is input from a terminal 512. This stream is supplied to the other input terminal of the selector 513.
[0021]
In the selector 513, a stream supplied to one and the other input terminals is selected in advance and supplied to the ECC encoder 514. The stream is subjected to predetermined shuffling and error correction encoding processing by the ECC encoder 514, recording encoded by the recording amplifier 515, supplied to a rotating head (not shown), and recorded on the magnetic tape 516.
[0022]
At the time of reproduction, a reproduction signal reproduced from the magnetic tape 516 by the rotary head is supplied to the reproduction amplifier 517 and decoded into a digital signal. The output of the reproduction amplifier 517 is supplied to the ECC decoder 518, where the error correction code is decoded and error-corrected and deshuffled to obtain an MPEG2 stream. The stream output from the ECC decoder 518 is also supplied to the MPEG decoder 520. The stream supplied to the MPEG decoder 520 is decoded into a baseband signal and led to the terminal 521.
[0023]
In this way, if the video signal between devices can be transmitted as a stream, the same number of images can be transmitted with a smaller amount of information than the baseband signal. In contrast to the baseband connection that repeatedly deteriorates and compresses data every time data is transmitted and causes deterioration in image quality, image information can be transmitted without deterioration in image quality if stream connection is used. If the image is not processed, it can be said that the stream connection is more advantageous than the baseband connection.
[0024]
FIG. 3 shows a basic configuration of a VTR according to the present invention. In FIG. 3, the same reference numerals are given to portions corresponding to the configuration of FIG. 2 described above, and detailed description thereof is omitted. In FIG. 3, a code amount measuring device 530 for measuring the code amount of equal length units in the input stream and a memory 531 are added to the configuration of FIG. The stream input from the terminal 512 is also supplied to the memory 531 and the code amount measuring device 530, and the code amount measuring device 530 measures the code amount of an equal length unit, for example, one frame.
[0025]
If the code amount measured by the code amount measuring device 530 exceeds a predetermined value specified for the equal length unit, the code amount measuring device 530 sends the stream to the magnetic tape 516. A control signal for controlling recording is output. In the example of FIG. 3, this control signal is supplied to the recording amplifier 515 ', and the output of the recording RF signal is stopped. Furthermore, the recording operation itself may be stopped by supplying a control signal to a servo circuit (not shown).
[0026]
In this way, by measuring the code amount of the equal length unit of the input stream on the input side and controlling the recording based on the measurement result, the stream whose code amount of the equal length unit is equal to or greater than the specified amount Is prevented from being recorded on the recording medium.
[0027]
The memory 531 is provided to prevent the input stream from being recorded on the magnetic tape 516 before the measurement result by the code amount measuring device 530 is obtained. For example, the memory 531 is not necessary if a sufficient delay can be obtained by the processing in the ECC encoder 514.
[0028]
Next, an example in which the first embodiment is applied to a digital VTR will be described. This digital VTR is suitable for use in a broadcast station environment, and enables recording / reproduction of video signals of a plurality of different formats.
[0029]
Note that the application example of the first embodiment described below can be similarly applied to the second to fifth examples described later.
[0030]
In the first embodiment, for example, the MPEG2 system is adopted as the compression system. MPEG2 is a combination of motion compensation predictive coding and compression coding by DCT. The data structure of MPEG2 has a hierarchical structure. FIG. 4 schematically shows a hierarchical structure of a general MPEG2 data stream. As shown in FIG. 4, the data structure includes, from the bottom, the macroblock layer (FIG. 4E), the slice layer (FIG. 4D), the picture layer (FIG. 4C), the GOP layer (FIG. 4B), and the sequence layer (FIG. 4A). It has become.
[0031]
As shown in FIG. 4E, the macroblock layer is composed of DCT blocks that are units for performing DCT. The macroblock layer is composed of a macroblock header and a plurality of DCT blocks. As shown in FIG. 4D, the slice layer includes a slice header part and one or more macroblocks. As shown in FIG. 4C, the picture layer is composed of a picture header part and one or more slices. A picture corresponds to one screen. As shown in FIG. 4B, the GOP layer includes a GOP header part, an I picture that is a picture based on intra-frame coding, and a P and B picture that are pictures based on predictive coding.
[0032]
An I picture (Intra-coded picture) uses information that is closed only in one picture when it is encoded. Therefore, at the time of decoding, it can be decoded only with the information of the I picture itself. A P picture (Predictive-coded picture: a forward predictive coded picture) uses a previously decoded I picture or P picture that is temporally previous as a predicted picture (a picture that serves as a reference for obtaining a difference). . Whether the difference from the motion compensated predicted image is encoded or encoded without taking the difference is selected in units of macroblocks. A B picture (Bidirectionally predictive-coded picture) is a previously decoded I picture or P picture that is temporally previous, as a predicted picture (a reference image for obtaining a difference). Three types of I pictures or P pictures that have already been decoded and interpolated pictures made from both are used. Among the three types of motion-compensated difference encoding and intra-encoding, the most efficient one is selected for each macroblock.
[0033]
Therefore, the macroblock types include intra-frame (Intra) macroblocks, forward (Forward) inter-frame prediction macroblocks that predict the future from the past, and backward (Backward) frames that predict the past from the future. There are prediction macroblocks and bidirectional macroblocks that predict from both the front and rear directions. All macroblocks in an I picture are intraframe coded macroblocks. Further, the P picture includes an intra-frame encoded macro block and a forward inter-frame prediction macro block. The B picture includes all the four types of macroblocks described above.
[0034]
A GOP includes at least one I picture, and P and B pictures are allowed even if they do not exist. As shown in FIG. 4A, the uppermost sequence layer includes a sequence header portion and a plurality of GOPs.
[0035]
In the MPEG format, a slice is one variable length code sequence. A variable-length code sequence is a sequence in which a data boundary cannot be detected unless the variable-length code is correctly decoded.
[0036]
In addition, a start code having a predetermined bit pattern arranged in units of bytes is arranged at the heads of the sequence layer, the GOP layer, the picture layer, and the slice layer. The start code arranged at the head of each layer is referred to as a sequence header code in the sequence layer and a start code in other layers, and the bit pattern is [00 00 01 xx] (hexadecimal notation). Two digits are shown, and [xx] indicates that a different bit pattern is arranged in each layer.
[0037]
That is, the start code and the sequence header code are 4 bytes (= 32 bits), and the type of information that follows can be identified based on the value of the 4th byte. Since these start code and sequence header code are arranged in units of bytes, they can be captured only by performing 4-byte pattern matching.
[0038]
Further, the upper 4 bits of 1 byte following the start code is an identifier of the contents of the extended data area described later. Based on the value of this identifier, the contents of the extension data can be determined.
[0039]
Note that such identification codes having a predetermined bit pattern arranged in units of bytes are not arranged in the macroblock layer and the DCT blocks in the macroblock.
[0040]
The header part of each layer will be described in more detail. In the sequence layer shown in FIG. 4A, a sequence header 2 is arranged at the head, followed by a sequence extension 3, an extension, and user data 4. A sequence header code 1 is arranged at the head of the sequence header 2. Although not shown, predetermined start codes are also arranged at the beginning of the sequence extension 3 and the user data 4, respectively. The sequence header 2 to the extension and user data 4 are used as the header portion of the sequence layer.
[0041]
In the sequence header 2, as shown in FIG. 5, the contents of each parameter and the assigned bits, the encoded image size, aspect ratio, frame rate, bit, consisting of the sequence header code 1, the number of horizontal pixels and the number of vertical lines Information set in units of sequences, such as a rate, a VBV (Video Buffering Verifier) buffer size, a quantization matrix, and the like are each assigned a predetermined number of bits and stored.
[0042]
In FIG. 5 and FIGS. 15 to 15 described later, some parameters are omitted in order to avoid complexity.
[0043]
In sequence extension 3 after the extension start code following the sequence header, as shown in FIG. 6, additional data such as a profile, level, color difference format, progressive sequence, and the like used in MPEG2 are designated. As shown in FIG. 7, the extension and user data 4 can store information on the RGB conversion characteristics and display image size of the original signal by the sequence display (), and the scalability mode and the scalability by the sequence scalable extension (). Layer specification can be performed.
[0044]
A GOP is arranged after the header portion of the sequence layer. As shown in FIG. 4B, a GOP header 6 and user data 7 are arranged at the head of the GOP. The GOP header 6 and user data 7 are used as the header part of the GOP. As shown in FIG. 8, the GOP header 6 stores a GOP start code 5, a time code, and a flag indicating GOP independence and validity, each assigned a predetermined number of bits. As shown in FIG. 9, the user data 7 includes extended data and user data. Although not shown, predetermined start codes are arranged at the heads of the extension data and the user data, respectively.
[0045]
Pictures are arranged following the header of the GOP layer. As shown in FIG. 4C, a picture header 9, a picture encoding extension 10, and an extension and user data 11 are arranged at the head of the picture. A picture start code 8 is arranged at the head of the picture header 9. Further, predetermined start codes are arranged at the heads of the picture coding extension 10 and the extension and user data 11, respectively. The picture header 9 to the extension and user data 11 are used as a picture header.
[0046]
As shown in FIG. 10, the picture header 9 is provided with a picture start code 8 and an encoding condition for the screen. In the picture encoding extension 10, as shown in FIG. 11, the range of motion vectors in the front-rear direction and the horizontal / vertical direction and the picture structure are designated. In the picture encoding extension 10, DC coefficient accuracy of an intra macroblock, selection of a VLC type, selection of a linear / non-linear quantization scale, selection of a scanning method in DCT, and the like are performed.
[0047]
In the extension and user data 11, setting of a quantization matrix, setting of a spatial scalable parameter, and the like are performed as shown in FIG. These settings are possible for each picture, and encoding according to the characteristics of each screen can be performed. In addition, in the extension and user data 11, a picture display area can be set. Furthermore, copyright information can be set in the extension and user data 11.
[0048]
A slice is arranged following the header portion of the picture layer. As shown in FIG. 4D, a slice header 13 is arranged at the head of the slice, and a slice start code 12 is arranged at the head of the slice head 13. As shown in FIG. 13, the slice start code 12 includes position information of the slice in the vertical direction. The slice header 13 further stores extended slice vertical position information, quantization scale information, and the like.
[0049]
Subsequent to the header part of the slice layer, a macroblock is arranged (FIG. 4E). In the macro block, a plurality of DCT blocks are arranged following the macro block header 14. As described above, the start code is not arranged in the macroblock header 14. As shown in FIG. 14, the macroblock header 14 stores relative position information of macroblocks, and instructs setting of motion compensation modes, detailed settings regarding DCT encoding, and the like.
[0050]
Following the macroblock header 14, a DCT block is arranged. As shown in FIG. 15, the DCT block stores variable length coded DCT coefficients and data relating to the DCT coefficients.
[0051]
In FIG. 4, a solid line break in each layer indicates that the data is aligned in byte units, and a dotted line break indicates that the data is not aligned in byte units. That is, up to the picture layer, as shown in FIG. 16A, the code boundary is delimited in bytes, whereas in the slice layer, only the slice start code 12 is delimited in bytes. Each macroblock can be divided in bit units as shown in FIG. 16B. Similarly, in the macroblock layer, each DCT block can be divided in bit units.
[0052]
On the other hand, in order to avoid signal degradation due to decoding and encoding, it is desirable to edit on the encoded data. At this time, the P picture and the B picture require the temporally previous picture or the previous and subsequent pictures for decoding. For this reason, the editing unit cannot be set to one frame unit. In consideration of this point, in the first embodiment, one GOP is made up of one I picture.
[0053]
Further, for example, a recording area in which recording data for one frame is recorded is a predetermined one. Since MPEG2 uses variable length coding, the amount of data generated for one frame is controlled so that data generated in one frame period can be recorded in a predetermined recording area. Furthermore, in this first embodiment, one slice is composed of one macroblock so as to be suitable for recording on a magnetic tape, and one macroblock is applied to a fixed frame of a predetermined length.
[0054]
FIG. 17 specifically shows the header of the MPEG stream according to the first embodiment. As can be seen from FIG. 4, the header portions of the sequence layer, the GOP layer, the picture layer, the slice layer, and the macroblock layer appear continuously from the top of the sequence layer. FIG. 17 shows an example of a data array continuous from the sequence header portion.
[0055]
From the top, a sequence header 2 having a length of 12 bytes is arranged, and subsequently, a sequence extension 3 having a length of 10 bytes is arranged. Following the sequence extension 3, extension and user data 4 are arranged. A user data start code for 4 bytes is arranged at the head of the extension and user data 4, and information based on the SMPTE standard is stored in the following user data area.
[0056]
Next to the header portion of the sequence layer is the header portion of the GOP layer. A GOP header 6 having a length of 8 bytes is arranged, followed by extension and user data 7. A 4-byte user data start code is arranged at the head of the extension and user data 7, and information for compatibility with other existing video formats is stored in the subsequent user data area.
[0057]
Next to the header part of the GOP layer is the header part of the picture layer. A picture header 9 having a length of 9 bytes is arranged, followed by a picture coding extension 10 having a length of 9 bytes. After the picture encoding extension 10, the extension and user data 11 are arranged. The extension and user data are stored in the first 133 bytes of the extension and user data 11, followed by a user data start code 15 having a length of 4 bytes. Subsequent to the user data start code 15, information for compatibility with other existing video formats is stored. Further, a user data start code 16 is arranged, and following the user data start code 16, data based on the SMPTE standard is stored. Next to the header portion of the picture layer is a slice.
[0058]
The macro block will be described in more detail. The macroblock included in the slice layer is a set of a plurality of DCT blocks, and the coded sequence of the DCT block is a sequence of quantized DCT coefficients, the number of consecutive 0 coefficients (run), and the non-zero sequence immediately thereafter. (Level) is variable length encoded as one unit. Identification codes arranged in byte units are not added to the macroblock and the DCT block in the macroblock.
[0059]
The macro block is obtained by dividing a screen (picture) into a grid of 16 pixels × 16 lines. The slice is formed by, for example, connecting the macro blocks in the horizontal direction. The last macroblock of the previous slice and the first macroblock of the next slice are continuous, and it is not allowed to form macroblock overlap between slices. When the screen size is determined, the number of macro blocks per screen is uniquely determined.
[0060]
The numbers of vertical and horizontal macroblocks on the screen are referred to as mb_height and mb_width, respectively. The coordinates of the macroblock on the screen are expressed as mb_row, where the vertical position number of the macroblock is counted from 0 with respect to the upper end, and mb_column, where the horizontal position number of the macroblock is counted from 0 with respect to the left end. It is stipulated in. In order to represent the position of the macro block on the screen with one variable, macroblock_address is set as follows:
macroblock_address = mb_row × mb_width + mb_column
Define it like this.
[0061]
It is defined that the order of slices and macroblocks on the stream must be in the order of macroblock_address. That is, the stream is transmitted from the top to the bottom of the screen and from the left to the right.
[0062]
In MPEG, one slice is usually composed of one stripe (16 lines), and variable length coding starts from the left end of the screen and ends at the right end. Therefore, when the MPEG elementary stream is recorded as it is by the VTR, the reproducible part concentrates on the left end of the screen during high speed reproduction and cannot be uniformly updated. Further, since the arrangement of data on the tape cannot be predicted, uniform screen updating cannot be performed if the tape pattern is traced at a constant interval. Furthermore, if an error occurs even at one location, it affects the right edge of the screen and cannot be restored until the next slice header is detected. For this purpose, one slice is composed of one macroblock.
[0063]
FIG. 18 shows an example of the configuration of the recording side of the recording / reproducing apparatus applicable to the first embodiment. At the time of recording, a digital signal input from the terminal 100 is supplied to an SDI (Serial Data Interface) receiving unit 101. SDI is an interface defined by SMPTE for transmitting (4: 2: 2) component video signals, digital audio signals and additional data. The SDI receiver 101 extracts a digital video signal and a digital audio signal from the input digital signal, the digital video signal is supplied to the MPEG encoder 102, and the digital audio signal is sent to the ECC encoder 109 via the delay 103. To be supplied. The delay 103 is for eliminating the time difference between the digital audio signal and the digital video signal.
[0064]
Further, the SDI receiving unit 101 extracts a synchronization signal from the input digital signal and supplies the extracted synchronization signal to the timing generator 104. An external synchronization signal can also be input from the terminal 105 to the timing generator 104. The timing generator 104 generates a timing pulse based on a specified signal among these input synchronization signals and a synchronization signal supplied from an SDTI receiving unit 108 described later. The generated timing pulse is supplied to each part of the recording / reproducing apparatus.
[0065]
The input video signal is subjected to DCT (Discrete Cosine Transform) processing in the MPEG encoder 102, converted into coefficient data, and the coefficient data is variable-length encoded. The variable length coding (VLC) data from the MPEG encoder 102 is an elementary stream (ES) compliant with MPEG2. This output is supplied to one input terminal of a multi-format converter (hereinafter referred to as MFC) 106 on the recording side.
[0066]
On the other hand, SDTI (Serial Data Transport Interface) format data is input through the input terminal 107. This signal is synchronously detected by the SDTI receiving unit 108 and temporarily stored in the frame memory 170. The synchronization signal obtained by the synchronization detection is supplied to the timing generator 104 described above. The signal stored in the frame memory 170 is read according to a request signal RQ supplied from the recording side MFC 106 described later, an elementary stream is extracted, and is output from the SDTI receiving unit 108. At this time, the SDTI receiving unit 108 outputs an enable signal EN indicating the valid period of the output elementary stream.
[0067]
The elementary stream output from the SDTI receiving unit 108 according to the request signal RQ of the recording side MFC 106 is supplied to the code amount measuring unit 560 and temporarily stored in the memory 531 as described above with reference to FIG. The measuring device 530 measures the code amount of the equal length unit. The equal length unit is, for example, one frame of a video signal.
[0068]
In the first embodiment, when the code amount of the equal length unit exceeds the total code amount defined for the equal length unit based on the measurement result of the code amount, A control signal for stopping recording is output from the code amount control unit 560. This control signal is supplied to, for example, an equalizer 110 (to be described later). When the code amount of the equal length unit exceeds the total code amount defined for the equal length unit, the recording RF signal from the equalizer 110 is output. The output is stopped based on the control of this control signal. Recording may be stopped by providing a switch circuit between the equalizer 110 and a magnetic head attached to the rotary drum 111 described later, and controlling the open / close state of the switch circuit by a control signal. Details of the processing by the code amount measuring unit 560 will be described later.
[0069]
When this configuration is applied to second to fifth embodiments described later, the control signal output from the code amount measuring unit 560 and the control of the equalizer 110 and the like by the control signal are not necessary.
[0070]
The MPEG ES whose code amount is measured by the code amount measuring unit 56 is supplied to the other input end of the recording side MFC 106.
[0071]
In the present invention, for example, an SDTI (Serial Data Transport Interface) -CP (Content Package) is used to transmit MPEG ES (MPEG Elementary Stream). This ES is a component of 4: 2: 2, and as described above, all ES streams are I-picture streams and have a relationship of 1 GOP = 1 picture. In the SDTI-CP format, MPEG ES is separated into access units and packed into packets in frame units. In SDTI-CP, a sufficient transmission band (a clock rate of 27 MHz or 36 MHz and a stream bit rate of 270 Mbps or 360 Mbps) is used, and ES can be sent in bursts in one frame period.
[0072]
That is, system data, a video stream, an audio stream, and AUX data are arranged between SAV after one frame period and EAV. There is no data in one frame period, and there is data in bursts for a predetermined period from the beginning. An SDTI-CP stream (video and audio) can be switched in a stream state at the frame boundary. SDTI-CP has a mechanism for establishing synchronization between audio and video in the case of content using SMPTE time code as a clock reference. Furthermore, the format is determined so that SDTI-CP and SDI can coexist.
[0073]
The interface using SDTI-CP described above does not require the encoder and decoder to pass through the VBV (Video Buffer Verifier) buffer and TBs (Transport Buffers) as in the case of transferring TS (Transport Stream), and delay is reduced. it can. Further, the fact that SDTI-CP itself can transfer at extremely high speed further reduces the delay. Therefore, it is effective to use the SDTI-CP in an environment where there is synchronization that manages the entire broadcasting station.
[0074]
The SDTI receiving unit 108 further extracts a digital audio signal from the input SDTI-CP stream. The extracted digital audio signal is supplied to the ECC encoder 109.
[0075]
The recording side MFC 106 includes a selector and a stream converter. Further, the code amount measuring unit 560 described above can be incorporated in the recording side MFC 106. The recording side MFC 106 is configured in one integrated circuit, for example. Processing performed in the recording side MFC 106 will be described. One of the MPEG ESs supplied from the MPEG encoder 102 and the SDTI receiving unit 108 is selected by the selector and supplied to the stream converter.
[0076]
The stream converter has a simple decoder that only performs decoding of a variable-length code, for example. The MPEG ES supplied to the stream converter is simply decoded, and the DCT coefficients arranged for each DCT block based on the MPEG2 regulations are grouped for each frequency component through a plurality of DCT blocks constituting one macro block. The collected frequency components are rearranged. In addition, when one slice of an elementary stream has one stripe, the stream converter converts one slice to one macro block. Further, the maximum length of variable length data generated in one macro block is limited to a predetermined length by the stream converter. This can be done by setting the higher order DCT coefficients to zero. The rearranged conversion elementary stream is supplied to the ECC encoder 109.
[0077]
The ECC encoder 109 is connected to a large-capacity main memory (not shown), and includes a packing and shuffling unit, an audio outer code encoder, a video outer code encoder, an inner code encoder, an audio shuffling unit, and a video shuffling. Built-in parts. The ECC encoder 109 includes a circuit for adding an ID in sync block units and a circuit for adding a synchronization signal. The ECC encoder 109 is constituted by, for example, one integrated circuit.
[0078]
In the first embodiment, a product code is used as an error correction code for video data and audio data. In the product code, the outer code is encoded in the vertical direction of the two-dimensional array of video data or audio data, the inner code is encoded in the horizontal direction, and the data symbols are encoded doubly. As the outer code and the inner code, a Reed-Solomon code can be used.
[0079]
Processing in the ECC encoder 109 will be described. Since the video data of the elementary stream is variable-length encoded, the data lengths of the macroblocks are not uniform. In the packing and shuffling unit, the macroblock is packed in a fixed frame. At this time, the overflow portion that protrudes from the fixed frame is sequentially packed into an empty area with respect to the size of the fixed frame.
[0080]
Further, system data having information such as an image format and a shuffling pattern version is supplied from a syscon 121 described later and input from an input terminal (not shown). System data is supplied to the packing and shuffling unit, and is subjected to recording processing in the same manner as picture data. Further, shuffling is performed in which the macroblocks of one frame generated in the scanning order are rearranged to distribute the recording positions of the macroblocks on the tape. By shuffling, the image update rate can be improved even when data is reproduced piecewise during variable speed reproduction.
[0081]
Video data and system data from the packing and shuffling unit (hereinafter referred to simply as video data including system data unless otherwise required) is a video in which video data is encoded by outer coding. An outer code parity is added to the outer code encoder. The output of the outer code encoder is shuffled by the video shuffling unit, in which the order is changed in units of sync blocks over a plurality of ECC blocks. Shuffling in sync block units prevents errors from concentrating on a specific ECC block. The shuffling performed by the shuffling unit may be referred to as interleaving. The output of the video shuffling unit is written into the main memory.
[0082]
On the other hand, as described above, the digital audio signal output from the SDTI receiving unit 108 or the delay 103 is supplied to the ECC encoder 109. In the first embodiment, an uncompressed digital audio signal is handled. The digital audio signal is not limited thereto, and can be input via an audio interface. Audio AUX is supplied from an input terminal (not shown). The audio AUX is auxiliary data, and is data having information related to audio data such as a sampling frequency of the audio data. The audio AUX is added to the audio data and is handled in the same way as the audio data.
[0083]
Audio data to which audio AUX is added (hereinafter referred to simply as audio data even when AUX is included unless otherwise required) is supplied to an audio outer code encoder that encodes the outer code of the audio data. Is done. The output of the audio outer code encoder is supplied to the audio shuffling unit and subjected to a shuffling process. As audio shuffling, shuffling in sync blocks and shuffling in channels are performed.
[0084]
The output of the audio shuffling unit is written into the main memory. As described above, the output of the video shuffling unit is also written in the main memory. In the main memory, the audio data and the video data are mixed into one channel data.
[0085]
Data is read from the main memory, an ID including information indicating a sync block number is added, and the data is supplied to the inner code encoder. The inner code encoder encodes the supplied data with the inner code. A sync signal for each sync block is added to the output of the inner code encoder, and recording data in which the sync block is continuous is configured.
[0086]
The recording data output from the ECC encoder 109 is supplied to an equalizer 110 including a recording amplifier and converted into a recording RF signal. The recording RF signal is supplied to a rotating drum 111 provided with a rotating head and recorded on the magnetic tape 112. Actually, a plurality of magnetic heads having different azimuths of heads forming adjacent tracks are attached to the rotating drum 111.
[0087]
As described above, in the equalizer 110, the output of the recording RF signal is controlled based on the control signal supplied from the code amount measuring unit 560. However, the present invention is not limited thereto, and a switch circuit whose opening / closing is controlled by a control signal supplied from the code amount measuring unit 560 may be provided between the equalizer 110 and the rotary drum 111.
[0088]
You may perform a scramble process with respect to recording data as needed. Also, digital modulation may be performed during recording, and partial response class 4 and Viterbi code may be used. The equalizer 110 includes both a recording side configuration and a playback side configuration.
[0089]
FIG. 19 shows an example of a track format formed on the magnetic tape by the rotary head described above. In this example, video and audio data per frame are recorded in four tracks. One segment is composed of two tracks of different azimuths. That is, 4 tracks are composed of 4 segments. A track number [0] and a track number [1] corresponding to azimuth are assigned to a set of tracks constituting a segment. In each of the tracks, a video sector in which video data is recorded is disposed on both ends, and an audio sector in which audio data is recorded is disposed between the video sectors. FIG. 19 shows the arrangement of sectors on the tape.
[0090]
In this example, four channels of audio data can be handled. A1 to A4 indicate 1 to 4 channels of audio data, respectively. Audio data is recorded by changing the arrangement in segment units. In this example, video data is interleaved with four error correction blocks for one track, and is divided into upper side and lower side sectors and recorded.
[0091]
The lower side video sector is provided with a system area (SYS) in which system data is recorded at a predetermined position. The system area is provided alternately for each track, for example, at the head side and the tail side of the lower side video sector.
[0092]
In FIG. 19, SAT is an area where a servo lock signal is recorded. A gap having a predetermined size is provided between the recording areas.
[0093]
FIG. 19 shows an example in which data per frame is recorded in 4 tracks. However, depending on the format of data to be recorded and reproduced, data per frame can be recorded in 8 tracks, 6 tracks, and the like.
[0094]
As shown in FIG. 19B, the data recorded on the tape is made up of a plurality of blocks called “sink blocks” divided at equal intervals. FIG. 19C schematically shows the configuration of a sync block. The sync block includes a SYNC pattern for detecting synchronization, an ID for identifying each sync block, a DID indicating the content of subsequent data, a data packet, and an inner code parity for error correction. Data is handled as a packet in sync block units. That is, the smallest data unit to be recorded or reproduced is one sync block. A large number of sync blocks are arranged (FIG. 19B) to form, for example, a video sector.
[0095]
FIG. 19D shows an exemplary data structure of the system area SYS. In the data area in the sync block shown in FIG. 19C, 5 bytes are allocated to the system data, 2 bytes to the MPEG header, 10 bytes to the picture information, and 92 bytes to the user data from the top.
[0096]
The system data includes the presence and location of switching points, the video format (frame frequency, interleaving method, aspect ratio, etc.), shuffling version information, and the like. In the system data, the appropriate level of the recorded MPEG ES syntax is recorded using 6 bits.
[0097]
In the MPEG header, MPEG header information necessary for shuttle playback is recorded. Information for maintaining compatibility with other digital VTRs is recorded in the picture information. Furthermore, the date of recording, the cassette number, and the like are recorded in the user data.
[0098]
Returning to the description of FIG. 18, at the time of reproduction, a reproduction signal reproduced from the magnetic tape 112 on the rotary drum 111 is supplied to the reproduction side configuration of the equalizer 110 including a reproduction amplifier and the like. The equalizer 110 performs equalization, waveform shaping, and the like on the reproduction signal. Further, demodulation of digital modulation, Viterbi decoding, and the like are performed as necessary. The output of the equalizer 110 is supplied to the ECC decoder 113.
[0099]
The ECC decoder 113 performs processing reverse to the ECC encoder 109 described above, and includes a large-capacity main memory, an inner code decoder, audio and video deshuffling units, and an outer code decoder. Further, the ECC decoder 113 includes a deshuffling and depacking unit and a data interpolation unit for video. Similarly, for audio, an audio AUX separation unit and a data interpolation unit are included. The ECC decoder 113 is composed of, for example, one integrated circuit.
[0100]
Processing in the ECC decoder 113 will be described. First, the ECC decoder 113 detects synchronization, detects a synchronization signal added to the head of the sync block, and cuts out the sync block. The reproduced data is supplied to the inner code encoder for each sync block, and error correction of the inner code is performed. An ID interpolation process is performed on the output of the inner code encoder, and the ID of the sync block, for example, the sync block number, which is an error due to the inner code, is interpolated. The reproduction data in which the ID is interpolated is separated into video data and audio data.
[0101]
As described above, the video data means DCT coefficient data and system data generated by MPEG intra coding, and the audio data means PCM (Pulse Code Modulation) data and audio AUX.
[0102]
The separated audio data is supplied to the audio deshuffling unit, and the reverse processing to the shuffling performed by the recording side shuffling unit is performed. The output of the deshuffling unit is supplied to an outer code decoder for audio, and error correction using the outer code is performed. Audio-corrected audio data is output from the audio outer code decoder. For data with errors that cannot be corrected, an error flag is set.
[0103]
The audio AUX separation unit separates the audio AUX from the output of the audio outer code decoder, and the separated audio AUX is output from the ECC decoder 113 (the path is omitted). The audio AUX is supplied to, for example, a syscon 121 described later. The audio data is supplied to the data interpolation unit. In the data interpolation unit, the sample having an error is interpolated. As an interpolation method, average value interpolation for interpolating with the average value of correct data before and after time, pre-value hold for holding the value of the previous correct sample, and the like can be used.
[0104]
The output of the data interpolation unit is the output of audio data from the ECC decoder 113, and the audio data output from the ECC decoder 113 is supplied to the delay 117 and the SDTI output unit 115. The delay 117 is provided to absorb a delay caused by the video data processing in the MPEG decoder 116 described later. The audio data supplied to the delay 117 is given a predetermined delay and supplied to the SDI output unit 118.
[0105]
The separated video data is supplied to the deshuffling unit, and the reverse processing to the shuffling on the recording side is performed. The deshuffling unit performs processing for restoring the shuffling in units of sync blocks performed by the recording side shuffling unit. The output of the deshuffling unit is supplied to the outer code decoder, and error correction by the outer code is performed. When an error that cannot be corrected occurs, an error flag indicating the presence or absence of an error indicates that there is an error.
[0106]
The output of the outer code decoder is supplied to the deshuffling and depacking unit. The deshuffling and depacking unit performs processing for returning the macroblock unit shuffling performed by the packing and shuffling unit on the recording side. The deshuffling and depacking unit disassembles the packing applied at the time of recording. That is, the original variable length code is restored by returning the data length in units of macroblocks. Further, in the deshuffling and depacking unit, the system data is separated, output from the ECC decoder 113, and supplied to the syscon 121 described later.
[0107]
The output of the deshuffling and depacking unit is supplied to the data interpolation unit, and the data with the error flag set (that is, with an error) is corrected. That is, if there is an error in the middle of the macroblock data before conversion, the DCT coefficient of the frequency component after the error location cannot be restored. Therefore, for example, the data at the error location is replaced with a block end code (EOB), and the DCT coefficients of the frequency components thereafter are set to zero. Similarly, during high-speed reproduction, only DCT coefficients up to the length corresponding to the sync block length are restored, and the subsequent coefficients are replaced with zero data. Further, in the data interpolation unit, when the header added to the head of the video data is an error, the header (sequence header, GOP header, picture header, user data, etc.) is also recovered.
[0108]
Since the DCT coefficients are arranged from the DC component and the low-frequency component to the high-frequency component across the DCT block, a macroblock is configured even if the DCT coefficient is ignored from a certain point in this way. For each DCT block, DCT coefficients from DC and low frequency components can be distributed evenly.
[0109]
The video data output from the data interpolation unit is the output of the ECC decoder 113, and the output of the ECC decoder 113 is supplied to a playback-side multi-format converter (hereinafter referred to as playback-side MFC) 114. The reproduction side MFC 114 performs processing reverse to that of the recording side MFC 106 described above, and includes a stream converter. The reproduction side MFC 114 is configured by, for example, one integrated circuit.
[0110]
In the stream converter, the reverse process of the stream converter on the recording side is performed. That is, the DCT coefficients arranged for each frequency component across DCT blocks are rearranged for each DCT block. As a result, the reproduction signal is converted into an elementary stream compliant with MPEG2.
[0111]
As for the input / output of the stream converter, a sufficient transfer rate (bandwidth) is secured in accordance with the maximum length of the macroblock, as in the recording side. When the length of the macroblock (slice) is not limited, it is preferable to secure a bandwidth that is three times the pixel rate.
[0112]
The output of the stream converter is the output of the playback side MFC 114, and the output of the playback side MFC 114 is supplied to the SDTI output unit 115 and the MPEG decoder 116.
[0113]
The MPEG decoder 116 decodes the elementary stream and outputs video data. That is, the MPEG decoder 142 performs an inverse quantization process and an inverse DCT process. The decoded video data is supplied to the SDI output unit 118. As described above, the audio data separated from the video data by the ECC decoder 113 is supplied to the SDI output unit 118 via the delay 117. The SDI output unit 118 maps the supplied video data and audio data to an SDI format, and converts the data into a stream having an SDI format data structure. A stream from the SDI output unit 118 is output from the output terminal 120 to the outside.
[0114]
On the other hand, as described above, the audio data separated from the video data by the ECC decoder 113 is supplied to the SDTI output unit 115. In the SDTI output unit 115, the supplied video data and audio data as elementary streams are mapped to the SDTI format and converted into a stream having a data structure of the SDTI format. The converted stream is output from the output terminal 119 to the outside.
[0115]
In FIG. 18, a syscon 121 is composed of, for example, a microcomputer and controls the overall operation of the recording / reproducing apparatus. When switches provided on a control panel (not shown) are operated, a control signal corresponding to the operation is supplied to the syscon 121. Based on this control signal, operations such as recording and reproduction in the recording / reproducing apparatus are controlled by the syscon 121. As an example, an operation of recording a video signal input from the input terminal 100 or the input terminal 107 on the magnetic tape 112 is started by operating a recording switch 551 provided on the control panel.
[0116]
Furthermore, the control panel can be provided with a display unit such as an LCD (Liquid Crystal Display) (not shown). Based on the display control signal generated in the syscon 121, a predetermined display is made on the display unit. Each state of the recording / reproducing apparatus is displayed on the display unit.
[0117]
The servo 122 performs traveling control of the magnetic tape 112 and drive control of the rotary drum 111 while communicating with the syscon 121. Further, the servo 122 detects the acceleration state of the rotary drum 111. The acceleration state is detected, for example, by examining the time change of the FG pulse or PG pulse interval of the rotating drum 111. The detection result is supplied to the syscon 121 as a drum acceleration detection signal.
[0118]
FIG. 20A shows the order of DCT coefficients in the video data output from the DCT circuit of the MPEG encoder 102. The same applies to MPEG ES output from the SDTI receiving unit 108. Hereinafter, the output of the MPEG encoder 102 will be described as an example. Starting from the upper left DC component in the DCT block, DCT coefficients are output in a zigzag scan in the direction of increasing horizontal and vertical spatial frequencies. As a result, as shown in FIG. 20B, a total of 64 (8 pixels × 8 lines) DCT coefficients are arranged in order of frequency components.
[0119]
This DCT coefficient is variable length encoded by the VLC part of the MPEG encoder. That is, the first coefficient is fixed as a DC component, and a code is assigned from the next component (AC component) corresponding to a zero run and a subsequent level. Therefore, the variable length coding output for the coefficient data of the AC component is changed from the low (low order) coefficient of the frequency component to the high (high order) coefficient.₁, AC₂, AC_Three, ... are arranged. The elementary stream includes variable length encoded DCT coefficients.
[0120]
In the recording-side stream converter incorporated in the recording-side MFC 106 described above, the DCT coefficients of the supplied signal are rearranged. That is, in each macroblock, the DCT coefficients arranged in the order of frequency components for each DCT block by zigzag scanning are rearranged in the order of frequency components over each DCT block constituting the macroblock.
[0121]
FIG. 21 schematically shows the rearrangement of DCT coefficients in this recording-side stream converter. In the case of a (4: 2: 2) component signal, one macroblock includes four DCT blocks (Y₁, Y₂, Y_ThreeAnd Y_Four) And two DCT blocks (Cb) by chromaticity signals Cb and Cr, respectively.₁, Cb₂, Cr₁And Cr₂).
[0122]
As described above, in the MPEG encoder 102, zigzag scanning is performed in accordance with the provisions of MPEG2, and as shown in FIG. 21A, the DCT coefficient is changed from a DC component and a low frequency component to a high frequency component for each DCT block. Arranged in order of components. When the scan of one DCT block is completed, the next DCT block is scanned, and the DCT coefficients are arranged in the same manner.
[0123]
That is, in the macro block, the DCT block Y₁, Y₂, Y_ThreeAnd Y_Four, DCT block Cb₁, Cb₂, Cr₁And Cr₂DCT coefficients are arranged in order of frequency from the DC component and the low-frequency component to the high-frequency component. Then, a set consisting of a continuous run and the following level is divided into [DC, AC₁, AC₂, AC_Three,...], And variable length coding is performed so that codes are assigned.
[0124]
In the recording-side stream converter, the variable-length encoded and arranged DCT coefficients are once decoded by detecting the delimiter of each coefficient, and each frequency component straddling each DCT block constituting the macroblock. To summarize. This is shown in FIG. 21B. First, the DC components of the eight DCT blocks in the macroblock are gathered, then the AC coefficient components having the lowest frequency components of the eight DCT blocks are gathered, and then the AC coefficients of the same order are gathered in order. The coefficient data is rearranged across the DCT blocks.
[0125]
The rearranged coefficient data is DC (Y₁), DC (Y₂), DC (Y_Three), DC (Y_Four), DC (Cb₁), DC (Cb₂), DC (Cr₁), DC (Cr₂), AC₁(Y₁), AC₁(Y₂), AC₁(Y_Three), AC₁(Y_Four), AC₁(Cb₁), AC₁(Cb₂), AC₁(Cr₁), AC₁(Cr₂), ... Where DC, AC₁, AC₂,... Are each code of a variable length code assigned to a set consisting of a run and a subsequent level, as described with reference to FIG.
[0126]
The converted elementary stream in which the order of the coefficient data is rearranged by the recording-side stream converter is supplied to the packing and shuffling unit built in the ECC encoder 109. The data length of the macroblock is the same for the converted elementary stream and the elementary stream before conversion. Further, even if the MPEG encoder 102 has a fixed length in units of GOP (1 frame) by bit rate control, the length varies in units of macroblocks. In the packing and shuffling unit, the macroblock data is applied to the fixed frame.
[0127]
FIG. 22 schematically shows a macroblock packing process in the packing and shuffling unit. The macro block is applied to a fixed frame having a predetermined data length and packed. The data length of the fixed frame used at this time is made to coincide with the data length of the sync block which is the minimum unit of data at the time of recording and reproduction. This is because the shuffling and error correction coding processes are easily performed. In FIG. 22, it is assumed for simplicity that 8 macroblocks are included in one frame.
[0128]
As an example is shown in FIG. 22A by variable length coding, the lengths of 8 macroblocks are different from each other. In this example, the data of the macroblock # 1, the data of # 3, and the data of # 6 are longer than the length of the data area of one sync block, which is a fixed frame, respectively, and the data of the macroblock # 2, # 5 , # 7 data and # 8 data are short. Further, the data of the macro block # 4 has a length substantially equal to one sync block.
[0129]
By the packing process, macroblocks are packed into a fixed length frame having a length of one sync block. The reason why data can be packed without excess or deficiency is that the amount of data generated in one frame period is controlled to a fixed amount. As shown in an example in FIG. 22B, a macroblock that is longer than one sync block is divided at a position corresponding to the sync block length. Of the divided macroblocks, a portion (overflow portion) that protrudes from the sync block length is packed into an area that is vacant in order from the top, that is, after the macroblock whose length is less than the sync block length.
[0130]
In the example of FIG. 22B, the portion of the macro block # 1 that protrudes from the sync block length is first stuffed behind the macro block # 2, and when that reaches the length of the sync block, Stuffed into. Next, the portion of the macro block # 3 that protrudes from the sync block length is packed behind the macro block # 7. Further, the portion of the macro block # 6 that protrudes from the sync block length is packed behind the macro block # 7, and the portion that protrudes further is packed behind the macro block # 8. In this way, each macroblock is packed into a fixed frame having a sync block length.
[0131]
The length of the variable length data corresponding to each macroblock can be checked in advance in the recording side stream converter. As a result, the packing unit can know the end of the data of the macroblock without decoding the VLC data and checking the contents.
[0132]
FIG. 23 shows a more specific configuration of the ECC encoder 139 described above. In FIG. 23, reference numeral 164 denotes an interface of the main memory 160 externally attached to the IC. The main memory 160 is composed of SDRAM. The interface 164 arbitrates requests from the inside to the main memory 160 and performs write / read processing on the main memory 160. Also, the packing and shuffling unit 137 is configured by the packing unit 137a, the video shuffling unit 137b, and the packing unit 137c.
[0133]
FIG. 24 shows an example of the address configuration of the main memory 160. The main memory 160 is composed of, for example, a 64 Mbit SDRAM. The main memory 160 has a video area 250, an overflow area 251, and an audio area 252. The video area 250 includes four banks (vbank # 0, vbank # 1, vbank # 2, and vbank # 3). Each of the four banks can store a digital video signal in a unit of equal length. The equal length unit is a unit for controlling the amount of generated data to a substantially target value, and is, for example, one picture (I picture) of a video signal. A portion A in FIG. 24 indicates a data portion of one sync block of the video signal. In one sync block, data having a different number of bytes is inserted depending on the format. In order to support a plurality of formats, the number of bytes that is greater than the maximum number of bytes and is convenient for processing, for example, 256 bytes, is set as the data size of one sync block.
[0134]
Each bank of the video area is further divided into a packing area 250A and an output area 250B to the inner encoding encoder. The overflow area 251 is composed of four banks corresponding to the video area described above. Further, the main memory 160 has an audio data processing area 252.
[0135]
In the first embodiment, by referring to the data length indicator of each macroblock, the packing unit 137a separates the fixed frame length data and the overflow data that is a part exceeding the fixed frame into separate areas of the main memory 160. Memorize it separately. The fixed frame length data is data equal to or shorter than the length of the data area of the sync block, and is hereinafter referred to as block length data. The area for storing the block length data is the packing processing area 250A of each bank. When the data length is shorter than the block length, an empty area is generated in the corresponding area of the main memory 160. The video shuffling unit 137b performs shuffling by controlling the write address. Here, the video shuffling unit 137b shuffles only the block length data, and the overflow portion is written in the area allocated to the overflow data without being shuffled.
[0136]
Next, the packing unit 137c performs processing for packing the overflow portion into the memory to the outer code encoder 139 and reading it. That is, the block length data is read from the main memory 160 to the memory for one ECC block prepared in the outer code encoder 139, and if there is an empty area in the block length data, the overflow portion is added there. Read to block data in block length. When the data for one ECC block is read, the reading process is temporarily interrupted, and the outer code encoder 139 generates the parity of the outer code. The outer code parity is stored in the memory of the outer code encoder 139. When the processing of the outer code encoder 139 is completed for one ECC block, the data and outer code parity from the outer code encoder 139 are rearranged in the order in which the inner code is performed, and the packing processing area 250A of the main memory 160 and another output area 250B. Write back to The video shuffling unit 140 performs shuffling in units of sync blocks by controlling an address when the data whose outer code has been encoded is written back to the main memory 160.
[0137]
In this way, block length data and overflow data are divided and data is written to the first area 250A of the main memory 160 (first packing processing), and overflow data is packed and read into the memory to the outer code encoder 139. Processing (second packing processing), outer code parity generation, data and outer code parity are written back to the second area 250B of the main memory 160 in units of one ECC block. Since the outer code encoder 139 includes a memory having an ECC block size, the frequency of access to the main memory 160 can be reduced.
[0138]
When the processing of a predetermined number of ECC blocks (for example, 32 ECC blocks) included in one picture is completed, the packing of one picture and the encoding of the outer code are completed. Then, the data read from the area 250B of the main memory 160 via the interface 164 is processed by the ID adding unit 148, the inner code encoder 147, and the synchronization adding unit 150, and the parallel / serial conversion unit 124 outputs the output data of the synchronization adding unit 150. Is converted into bit serial data. The output serial data is processed by the partial response class 4 precoder 125. This output is digitally modulated as necessary, and is supplied to the rotary head provided on the rotary drum 111 via the recording amplifier 110.
[0139]
A sync block called null sync in which no valid data is arranged is introduced in the ECC block so that the configuration of the ECC block is flexible with respect to the difference in the format of the recording video signal. The null sync is generated in the packing unit 137 a of the packing and shuffling block 137 and written in the main memory 160. Accordingly, since the null sync has a data recording area, it can be used as a recording sync for the overflow portion.
[0140]
In the case of audio data, even-numbered samples and odd-numbered samples of audio data in one field constitute separate ECC blocks. Since the ECC outer code sequence is composed of audio samples in the input order, the outer code encoder 136 generates an outer code parity each time an outer code sequence audio sample is input. The shuffling unit 137 performs shuffling (channel unit and sync block unit) by address control when the output of the outer code encoder 136 is written to the area 252 of the main memory 160.
[0141]
Further, a CPU interface indicated by 126 is provided to receive data from an external CPU 127 functioning as a system controller and to set parameters for the internal blocks. In order to support a plurality of formats, it is possible to set many parameters including a sync block length and a parity length.
[0142]
“Packing length data” as one of the parameters is sent to the packing units 137a and 137b, and the packing units 137a and 137b are shown as fixed frames (“sync block length” in FIG. 22A) determined based on this. VLC data is packed into (length).
[0143]
"Pack number data" as one of the parameters is sent to the packing unit 137b, and the packing unit 137b determines the number of packs per sync block based on this, and the data for the determined number of packs is an outer code. This is supplied to the encoder 139.
[0144]
The “video outer code parity number data” as one of the parameters is sent to the outer code encoder 139, and the outer code encoder 139 encodes the outer code of the video data from which the number of parity is uttered. Do.
[0145]
Each of “ID information” and “DID information” as one of the parameters is sent to the ID adding unit 148, and the ID adding unit 148 reads the ID information and DID information from the main memory 160 in the unit length. Append to the data column.
[0146]
Each of the “intra-video code parity number data” and the “audio intra-code parity number data” as one of the parameters is sent to the inner code encoder 149, and the inner code encoder 149 has a number of parityes based on them. Encode the inner code of the video data and the audio data. Note that “sync length data”, which is one of the parameters, is also sent to the inner code encoder 149, thereby restricting the unit length (sync length) of the inner encoded data.
[0147]
Further, shuffling table data as one of the parameters is stored in the video shuffling table (RAM) 128v and the audio shuffling table (RAM) 128a. The shuffling table 128v performs address conversion for shuffling of the video shuffling units 137b and 140. The shuffling table 128a performs address conversion for the audio shuffling 137.
[0148]
Next, processing in the code amount measuring unit 560 will be described. The code amount measuring device 530 can know the code amount of the input elementary stream by checking the data amount between start codes corresponding to the equal length unit break. In the first embodiment, since 1 GOP = 1 picture, it is possible to know the code amount of the equal length unit by examining the clock from the GOP header 6 to the next GOP header 6.
[0149]
As described above, when outputting the elementary stream, the SDTI receiving unit 108 outputs the enable signal EN corresponding to the effective period of the elementary stream. In the code amount measuring device 530, the code amount of the equal length unit is actually checked based on the length of the enable signal EN. For example, when the data width is 8 bits (1 byte), the code amount can be known by the number of bytes by examining the number of clocks in a state (“H” state) in which the enable signal EN represents an effective period.
[0150]
The code amount measurement using the enable signal EN will be described with reference to FIGS. 25 and 26. FIG. FIG. 25 schematically shows an interface between the SDTI receiving unit 108 and the recording-side MFC 106. FIG. 26 shows a time chart of an example of signals exchanged between the SDTI receiving unit 108 and the recording side MFC 106. In FIG. 25, it is assumed that the code amount measuring unit 560 is built in the recording-side MFC 106 for the sake of explanation.
[0151]
Between the SDTI receiving unit 108 and the recording side MFC 106, a request signal line for sending a request signal RQ from the recording side MFC 106 to the SDTI receiving unit 108, and an enable signal EN and a bit stream are sent from the SDTI receiving unit 108 to the SDTI receiving unit 108. It is connected with a bit stream line with an enable signal EN. The request signal RQ is a signal for requesting the SDTI receiving unit 108 to output MPEG ES in the “H” state and requesting output stop in the “L” state, for example.
[0152]
As described above, the MPEG ES and the enable signal EN are output from the SDTI receiving unit 108 based on the request signal RQ from the recording side MFC 106.
[0153]
First, a case where the stream input to the SDTI receiving unit 108 is separated for each frame and the frame boundary (frame length) can be determined by the SDTI receiving unit 108 will be described. The timing generator 104 generates a frame synchronization signal based on the synchronization signal extracted by the SDTI reception unit 108 from the MPEG ES input to the input terminal 107. This frame synchronization signal is supplied to the recording side MFC 106.
[0154]
Based on the frame synchronization signal, a request signal RQ is transmitted from the recording MFC 106 to the SDTI receiver 108. In the SDTI receiving unit 108, the enable signal EN is set to the “H” state with a delay of a predetermined clock (for example, 2 clocks) required for processing in the SDTI receiving unit 108 from the reception of the request signal RQ. Minute bit stream (MPEG ES) is output. The bit stream is stored in the buffer of the recording side MFC 106 and is simply decoded to detect the rear end of the frame.
[0155]
For example, in the first embodiment in which 1 picture = 1 GOP, the trailing edge of the frame is detected by checking the number of slices following the GOP header 6 and the number of macroblocks included in the last slice. can do. Alternatively, the number of macro blocks may be simply checked.
[0156]
When the end of the frame is detected, the request signal RQ sent from the recording side MFC 106 to the SDTI receiving unit 108 is canceled. In response to this, the output of the MPEG ES from the SDTI receiving unit 108 is stopped with a predetermined clock delay, and the enable signal EN is canceled and set to the “L” state. The code amount measuring unit 560 can know the code amount of one frame, that is, the equal length unit, by measuring the number of clocks during the period when the enable signal EN is in the “H” state.
[0157]
A case where the stream input to the SDTI receiving unit 108 is not separated for each frame will be described. In this case, since the SDTI receiving unit 108 cannot know the boundary of the frame, the MPEG ES is continuously output regardless of the frame and stored in the buffer of the recording side MFC 106. In the first frame, the recording side MFC 106 decodes the MPEG ES stored in the buffer, and when the rear end of the frame is detected, the request signal RQ is set to the “L” state for the SDTI receiver 108, and the MPEG ES output stop is requested.
[0158]
In response to this request, the SDTI receiving unit 108 stops the actual stream output with a predetermined clock delay, as described above. Therefore, the recording-side MFC 106 inputs the stream of the next frame before the processing of the stream stored in the buffer is completed and the stream is not swept out of the buffer.
[0159]
That is, when the recording end MFC 106 detects the rear end of the frame first stored in the buffer, the request signal RQ requesting the stop of the stream output is sent to the SDTI receiving unit 108, and the frame Stream is flushed from the buffer. The stream of the next frame supplied until the stream output is stopped by the sent request signal RQ is stored in the buffer.
[0160]
The recording side MFC 106 sends a request signal RQ to the SDTI receiving unit 108 based on the frame synchronization signal, and requests a stream of the next frame. In response to this request, a stream following the portion interrupted by the stream output stop by the previous request signal RQ is output from the SDTI receiving unit 108 and stored in the buffer of the recording side MFC 106. The recording MFC 106 processes the stream accumulated in the previous request and remaining in the buffer, and the stream accumulated in the buffer in the current request, and detects the trailing edge of the frame.
[0161]
When the rear end of the frame is detected, the request signal RQ requesting the stream output stop is sent from the recording MFC 106 to the SDTI receiving unit 108 in the same manner as described above. Similarly, the SDTI receiving unit 108 stops stream output after a predetermined clock delay, and the stream of the next frame is stored in the buffer of the recording side MFC 106 for a predetermined clock. This process is repeated until the input of the stream to the SDTI receiving unit 108 is completed.
[0162]
The enable signal EN is transmitted together with the bit stream and indicates the valid period of the bit stream. By repeating the processing as described above, the period of the enable signal EN in the “H” state is substantially equal to one frame period of the stream output from the SDTI receiving unit 108. Therefore, by measuring the length of the enable signal EN by the code amount measuring unit 560, it is possible to know the code amount of one frame, that is, the equal length unit.
[0163]
However, in this case, the first frame of the stream supplied to the SDTI receiving unit 108 has the enable signal EN longer than the one frame by a predetermined clock, and the last frame is shorter by the predetermined clock.
[0164]
Note that the method of measuring the code amount of the equalization unit is not limited to the method described above. For example, each header of MPEG ES may be detected and the length from sequence_header_code, group_of_pictures_start_code, or picture_start_code to sequence_end_code of the next frame may be measured. Similarly, from sequence_header_code, group_of_pictures_start_code or picture_start_code to the length of sequence_header_code, group_of_pictures_start_code or picture_length of the next frame. In these methods, since the header information is a unit arranged for each byte (see FIG. 16A), there is no need to decode the variable length code. There may be a pattern matching means for detecting each start_code and a counter for measuring a clock.
[0165]
Also, stuffing may be removed when a stream is input. In this case, only the effective recording information amount is extracted without measuring the deleted stuffing. That is, only the code amount to be recorded is measured.
[0166]
Although it is conceivable to examine the bit_rate_value by extracting the parameter of the sequence header 2 from the stream, the bit_rate_value does not prescribe the code amount of the picture unit or the GOP unit, and the bit rate includes the above stuffing. This is not preferable.
[0167]
Next, a second embodiment of the present invention will be described. In the second embodiment, a frame in which the code amount of the equal length unit exceeds a specified amount is replaced with a frame with a small code amount, such as black display or gray display. At this time, the picture_coding_type in the picture header 9 is changed to a value indicating I picture, and the macroblock_type in the macroblock header 14 is changed to a value indicating “Intra”. Further, in all macroblocks of the frame, the DC component is set to a value representing black or gray, and the AC component is set to 0.
[0168]
In this way, by replacing a frame whose code amount exceeds the code amount specified in the equal length unit with another predetermined frame, avoiding syntax errors and complying with the tape format, Continuity can be maintained.
[0169]
The reason why the frames whose code amount exceeds the code amount defined in the equal length unit is replaced with a frame displaying black or gray because these are image patterns with the smallest code amount. That is, it is considered that a frame for displaying an achromatic single image having no color information has a small code amount. Other image patterns can be applied as long as the code amount of the equal length unit is smaller than the total code amount defined for the equal length unit.
[0170]
FIG. 27 shows a basic configuration of a VTR according to the second embodiment. Note that, in FIG. 27, the same reference numerals are given to portions common to FIG. 3 described above, and detailed description thereof is omitted. In the configuration of FIG. 27, a stream generator 532 and a switch circuit 533 are added to the code amount measuring unit 560 in addition to the configuration of FIG. 3 described above.
[0171]
The stream generator 532 generates and outputs a stream in which, for example, black is displayed. The switch circuit 533 switches the outputs of the memory 531 and the stream generator 532 based on the measurement result of the code amount measuring device 530 and supplies the same to the ECC encoder 514. The stream input from the terminal 512 is stored in the memory 531 and supplied to the code amount measuring device 530, and the code amount of the equal length unit is measured as in the first embodiment described above. The memory 531 is controlled so that the stream accumulated in the memory 531 is not output until the code amount measurement of the corresponding stream by the code amount measuring device 530 is completed.
[0172]
If the measured code amount does not exceed the specified value, the switch 531 selects the memory 531 side, and the stream stored in the memory 531 is read. The stream read from the memory 531 is supplied to the ECC encoder 514 via the switch circuit 533 and the switch circuit 513.
[0173]
On the other hand, if the code amount measured by the code amount measuring device 530 exceeds the specified value, the switch circuit 533 selects the stream generator 532 side, and the black or gray stream generated by the stream generator 532 is switched to the switch circuit. It is supplied to the ECC encoder 514 via the 533 and the switch circuit 513.
[0174]
The stream generator 532 includes, for example, a memory, in which data of a macro block or a DCT block representing black and each header information are stored in advance. By reading the data stored in the memory in order according to the clock, a stream representing black can be output from the stream generator 532. However, the present invention is not limited to this, and data may be sequentially output according to a predetermined procedure to output a stream representing black.
[0175]
Next explained is the third embodiment of the invention. In the third embodiment, a frame in which the code amount of the equal length unit exceeds a prescribed amount is replaced with a frame of a P picture that performs forward reference in MPEG2, for example. In a stream of frames in which the code amount of the equal length unit exceeds a prescribed amount, the picture_coding_type of the picture header 9 is changed to a P picture, and all macroblocks are forward-referenced difference = 0, that is, MC (Motion Compensation) = 0. , MV (Motion Vector) = 0, Not Coded.
[0176]
In this way, stream continuity can be avoided while avoiding syntax errors and complying with the tape format by replacing frames whose code amount exceeds the code amount specified in the equal length unit with frames that perform forward reference. Can be maintained. Furthermore, since the image formed by the replaced frame is formed by performing forward reference, it is not greatly different from the original image.
[0177]
In the third embodiment, the configuration of the second embodiment of FIG. 27 described above can be applied as it is. Here, the stream generator 532 has a memory, and in this memory, the picture_coding_type of the picture header 9 described above is set to a value indicating P picture, and all macroblocks are set to values indicating forward reference = 0. A stream of frames is stored in advance.
[0178]
The stream input from the terminal 512 is stored in the memory 531 and supplied to the code amount measuring device 530, and the code amount of the equal length unit is measured as in the first embodiment described above. The memory 531 is controlled so that the stream accumulated in the memory 531 is not output until the code amount measurement of the corresponding stream by the code amount measuring device 530 is completed.
[0179]
If the measured code amount does not exceed the prescribed value, the switch 531 selects the memory 531 side, the stream stored in the memory 531 is read out, and the ECC encoder 514 is passed through the switch circuit 533 and the switch circuit 513. To be supplied. On the other hand, if the code amount measured by the code amount measuring device 530 exceeds the prescribed value, the stream generator 532 side is selected by the switch circuit 533, and the P picture stream generated by the stream generator 532 is the switch circuit 533. And supplied to the ECC encoder 514 via the switch circuit 513.
[0180]
Note that the third embodiment is not applicable to a device that allows only I-pictures as picture_coding_type.
[0181]
Next explained is the fourth embodiment of the invention. In the fourth embodiment, a frame in which the code amount of the equal length unit exceeds the specified amount is already confirmed that the code amount of the equal length unit does not exceed the specified value. Is also replaced with the stream of the previous frame in time.
[0182]
FIG. 28 shows a basic configuration of a VTR according to the fourth embodiment. In FIG. 28, the same reference numerals are given to the portions common to FIG. 3 described above, and detailed description thereof is omitted. In the configuration in FIG. 28, a memory 540 and a switch circuit 541 are added in the code amount measuring unit 560 to the configuration in FIG. 3 described above.
[0183]
The stream input from the terminal 512 is stored in the memory 531 and supplied to the code amount measuring device 530, and the code amount of the equal length unit is measured as in the first embodiment described above. The memory 531 is controlled so that the stream accumulated in the memory 531 is not output until the code amount measurement of the corresponding stream by the code amount measuring device 530 is completed.
[0184]
As a result of the measurement by the code amount measuring device 530, if the code amount of the equal length unit does not exceed the specified value, the corresponding stream is read from the memory 531 and stored in the memory 540. At the same time, the switch circuit 541 selects the memory 531 side, and the stream read from the memory 531 is supplied to the ECC encoder 514 via the switch circuit 533 and the switch circuit 513.
[0185]
On the other hand, if the code amount measured by the code amount measuring device 530 exceeds the specified value, the switch circuit 533 selects the memory 540 side, and the stream of the past frame (previous frame) stored in the memory 540 is read. Then, it is supplied to the ECC encoder 514 via the switch circuit 540 and the switch circuit 513.
[0186]
According to the fourth embodiment, as a result of the measurement, the memory 540 is updated in units of frames in a stream in which the code amount in the equal length unit does not exceed the specified value. Then, the stream whose code amount exceeds the code amount defined in the equal length unit is replaced with the stream stored in the memory 540. By doing this, stream continuity can be maintained while avoiding syntax errors and complying with the tape format. Furthermore, since the frame of the stream whose code amount exceeds the code amount defined in the equal length unit is replaced with the nearest past frame, the formed image does not differ greatly from the original image.
[0187]
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, higher-order components of the DCT coefficient of each macroblock are deleted for a frame in which the code amount of the equalization unit exceeds a specified amount. Thereby, the code amount of the frame can be suppressed to a predetermined value or less of the equalization unit.
[0188]
FIG. 29 shows a basic configuration of a VTR according to the fifth embodiment. In FIG. 29, the same reference numerals are given to the portions common to FIG. 3 described above, and detailed description thereof is omitted. In the configuration of FIG. 29, a low-pass filter (LPF) 550 and a switch circuit 551 are added in the code amount measurement unit 560 to the configuration of FIG. 3 described above. The LPF 550 deletes a high-order component of the DCT coefficient in a predetermined manner.
[0189]
The stream input from the terminal 512 is stored in the memory 531 and supplied to the code amount measuring device 530, and the code amount of the equal length unit is measured as in the first embodiment described above. The memory 531 is controlled so that the stream accumulated in the memory 531 is not output until the code amount measurement of the corresponding stream by the code amount measuring device 530 is completed.
[0190]
As a result of the measurement by the code amount measuring device 530, if the code amount of the equal length unit does not exceed the specified value, the memory 531 side is selected by the switch circuit 551, and the stream read from the memory 531 is the switch circuit. 551 and the switch circuit 513 to be supplied to the ECC encoder 514.
[0191]
On the other hand, if the code amount measured by the code amount measuring device 530 exceeds the specified value, the switch circuit 551 selects the LPF 550 side. The MPEG ES read from the memory 531 is supplied to the LPF 550, the high-order component of the DCT coefficient is deleted in a predetermined manner, and the code amount of the equal length unit is suppressed to a predetermined value or less. The MPEG ES output from the LPF 550 is supplied to the ECC encoder 514 via the switch circuit 551 and the switch circuit 513.
[0192]
The following two methods are conceivable as the above-described method for deleting the high-order component of the DCT coefficient in the LPF 550.
(1) Delete all DCT coefficients of a predetermined order or more for all macroblocks in the frame. That is, frequency limitation is performed on the DCT coefficient.
(2) In principle, all the highest-order DCT coefficients are deleted from all macroblocks in the frame. At this time, DCT coefficients of a predetermined order or less are not deleted.
[0193]
The reason why the DCT coefficients of a predetermined order or less are protected by the method of deleting all the highest-order DCT coefficients in (2) above is to protect an image having a small frequency component such as a flat image.
[0194]
FIG. 30 shows an example of the configuration of the LPF 550. FIG. 30A shows an example configuration in which a variable-length code of an input stream is decoded and a high-order component of a DCT coefficient is deleted. In FIG. 30A, the variable length code of the input MPEG ES is decoded by the variable length code decoder 555, and the DCT coefficient is extracted. For the extracted DCT coefficients, the above-described process (1) of deleting all DCT coefficients of a predetermined order or higher, or (2) deleting all DCT coefficients of the highest order while leaving the coefficients of a predetermined order or less. The high-order component of the DCT coefficient is deleted. The stream from which the high-order component of the DCT coefficient has been deleted is supplied to the variable-length code encoder 556, subjected to variable-length encoding, converted into MPEG ES, and output.
[0195]
FIG. 30B shows an example configuration in which the variable-length code of the input stream is decomposed to remove higher-order components of the DCT coefficients. The input MPEG ES variable length code is decomposed into code words by the variable length code decomposer 557, and the code and the code length are output. Based on the code and the code length, the positions of DCT coefficients of a predetermined order or higher, or the DCT coefficients of the highest order and coefficients of a predetermined order or lower are determined and deleted. Then, (1) a DCT coefficient having a predetermined order or higher or (2) a stream in which the DCT coefficient having the highest order is deleted while a coefficient having a predetermined order or lower is left is supplied to the variable length code connector 558, and the variable length code is received. Reconnected and output as MPEG ES.
[0196]
Here, the deletion of the DCT coefficient can be performed using a memory. For example, taking the configuration of FIG. 30A as an example, the output decoded by the variable-length code decoder 555 is developed on a memory. Then, when data is read from the memory by the variable length code encoder 556, DCT coefficients other than the order to be deleted are read by performing predetermined address control. The read DCT coefficient is supplied to the variable length code encoder 556, and is variable length encoded into MPEG ES. This processing using the memory can be similarly applied to the configuration of FIG. 30B.
[0197]
Note that the configuration and operation of the LPF 550 described with reference to FIGS. 30A and 30B can be realized by controlling the recording-side MFC 106.
[0198]
According to the fifth embodiment, it is necessary to decode and decompose a variable length code and re-encode or connect it. However, since information is uniformly omitted from the entire screen, There is no distortion at a specific location.
[0199]
In the above description, the case where the present invention is applied to a stream compressed and encoded by the MPEG system has been described. However, the present invention is not limited to this example. For example, the present invention can be widely applied to devices such as JPEG (Joint Photographic Experts Group) to which a stream compression-encoded by another method is input.
[0200]
In the above description, the present invention has been described as applied to a recording / reproducing apparatus that records MPEG ES on a recording medium. However, the present invention is not limited to this example. The present invention can be widely applied not only to recording / reproducing apparatuses but also to video and audio equipment that handles compression-encoded streams.
[0201]
Further, in the above description, the recording medium is described as being a magnetic tape, but this is not limited to this example. For example, the present invention can be applied to a disk-shaped recording medium such as an MO (Magneto-Optical) disk. The present invention is not limited to this, and any recording device that records a stream encoded with a variable-length code on a recording medium with a code amount defined in an equal-length unit, for example, a disk recorder or a RAM (Random Access Memory) recorder The present invention can also be applied to a recording device using other recording media.
[0202]
Furthermore, in the above description, the case where the present invention is applied to a recording / reproducing apparatus that handles a stream obtained by compressing and encoding a video signal has been described, but this is not limited to this example. For example, the principle of the present invention is applied to an acoustic recording apparatus using audio compression technology such as AC-3 (Audio Code Number 3), AAC (Advanced Audio Coding), dts (Digital Theater Systems), and ATRAC (Adaptive Transform Acoustic Coding). It is possible to apply.
[0203]
In the above description, when the code amount of the equal length unit exceeds the specified value in the input MPEG ES, the recording is stopped, the stream is replaced, or the DCT coefficient is deleted. It is not limited to this example. For example, even if the code length of the equal length unit exceeds the specified value in the input MPEG ES, it is recorded as it is on the recording medium, and at that time, this is recorded in a predetermined area of the recording medium, for example, the system area. It may be recorded. In this case, when reproducing the recording medium, a predetermined process is performed on the stream of the equal length unit whose code amount exceeds the specified value on the reproducing device side.
[0204]
Furthermore, when the encoder cannot perform equal length when encoding a baseband signal, the present invention can be applied to relieve the encoder's insufficiency.
[0205]
【The invention's effect】
As described above, according to the present invention, when a stream encoded using a variable length code is equalized in a predetermined unit and recorded on a recording medium, the code amount of the equalized unit of the input stream is set. It is possible to cope with the case where the measured code amount is equal to or greater than a predetermined amount. Therefore, even when a stream exceeding the specified bit rate is input, the recording circuit fails, the recording medium fails, that is, the recording format on the recording medium breaks, the image is seriously disturbed in the reproduced image, and the illegal recording medium is created. It is effective in preventing troubles such as.
[0206]
In addition, when the encoder cannot perform equal length when encoding the baseband signal, the present invention can be applied to relieve the lack of encoder capability.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of a VTR that records and reproduces baseband signals using a magnetic tape as a recording medium.
FIG. 2 is a block diagram showing a basic configuration of a VTR that records and reproduces a stream in which a video signal is encoded by MPEG2.
FIG. 3 is a block diagram showing a basic configuration of a VTR according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram schematically showing a hierarchical structure of MPEG2 data.
FIG. 5 is a schematic diagram showing data contents and bit allocation arranged in an MPEG2 stream.
FIG. 6 is a schematic diagram showing data contents and bit allocation arranged in an MPEG2 stream.
FIG. 7 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 8 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 9 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 10 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 11 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 12 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 13 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 14 is a schematic diagram illustrating data contents and bit allocation arranged in an MPEG2 stream.
FIG. 15 is a schematic diagram showing data contents and bit allocation arranged in an MPEG2 stream;
FIG. 16 is a diagram for explaining alignment of data in units of bytes.
FIG. 17 is a schematic diagram specifically showing a header of an MPEG stream.
FIG. 18 is a block diagram showing an example of the configuration of a recording / reproducing apparatus applicable to the present invention.
FIG. 19 is a schematic diagram illustrating an example of a track format formed on a magnetic tape.
FIG. 20 is a schematic diagram for explaining a video encoder output method and variable-length coding.
FIG. 21 is a schematic diagram for explaining rearrangement of the output order of the video encoder;
FIG. 22 is a schematic diagram for explaining a process of packing the rearranged data into a sync block;
FIG. 23 is a block diagram showing a more specific configuration of an ECC encoder.
FIG. 24 is a schematic diagram illustrating an example of an address configuration of a main memory.
FIG. 25 is a block diagram schematically showing an interface between an SDTI receiving unit and a recording-side MFC.
FIG. 26 shows a time chart of an example of signals exchanged between the SDTI receiving unit and the recording side MFC.
FIG. 27 is a block diagram showing a basic configuration of a VTR according to second and third embodiments of the present invention.
FIG. 28 is a block diagram showing a basic configuration of a VTR according to a fourth embodiment of the present invention.
FIG. 29 is a block diagram showing a basic configuration of a VTR according to a fifth embodiment of the present invention.
FIG. 30 is a block diagram illustrating an example of a configuration of an LPF.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sequence header code, 2 ... Sequence header, 3 ... Sequence extension, 4 ... Extension and user data, 5 ... GOP start code, 6 ... GOP header, 7 ... User data, 8 ... picture start code, 9 ... picture header, 10 ... picture coding extension, 11 ... extension and user data, 12 ... slice start code, 13 ... slice header , 14 ... Macroblock header, 101 ... SDI receiver, 102 ... MPEG encoder, 106 ... Recording side multi-format converter (MFC), 108 ... SDTI receiver, 109 ... ECC Encoder, 112 ... magnetic tape, 113 ... ECC decoder, 114 ... playback MFC, 115 ... S TI output unit 116... MPEG decoder 118 118 SDI output unit 137 a 137 c packing unit 137 b video shuffling unit 139 outer code encoder 140 video Shuffling, 149 ... inner code encoder, 530 ... code quantity measuring device, 531, 540 ... memory, 532 ... stream generator, 550 ... LPF, 560 ... code quantity measuring unit

Claims (9)

In a recording apparatus for recording a stream encoded using a variable length code on a recording medium in a predetermined equal length unit,
Input means for receiving a stream encoded using a variable-length code;
First recording means for recording the stream input to the input means on a recording medium in a predetermined equal length unit;
Measuring means for measuring a code amount of the predetermined equal length unit of the stream input to the input means;
When the code amount of the predetermined equal length unit of the input stream exceeds the total code amount defined for the predetermined equal length unit based on the measurement result of the measurement means , and stream in the code amount that has been defined for the predetermined equal length unit, the second recording means separately and stream exceeds the code amount that has been defined for the predetermined equal length units The first packing process to be recorded and a stream that exceeds the total code amount defined for the predetermined equal length unit are read out, and the stream is larger than the total code amount defined for the predetermined equal length unit. A second packing process for reading a stream that exceeds the total code amount defined for the predetermined equal length unit in an area where a small empty area has occurred, and when the stream for the predetermined unit block is read In , Suspends the reading, it generates a parity of outer code, and the second packing processing data, and a control means for the of the outer code parity performs processing written back is written back to the first recording means A recording apparatus comprising: The recording apparatus according to claim 1,
The recording apparatus according to claim 1, wherein the control unit controls the recording unit to stop the recording. The recording apparatus according to claim 1,
The control means defines the stream of the predetermined equal length unit that exceeds the specified total code amount with respect to the predetermined equal length unit, and the code amount of the predetermined equal length unit is the predetermined. The recording apparatus is controlled so as to be replaced with another stream within the total code amount. The recording apparatus according to claim 3,
Stream output means for outputting a stream of the predetermined equal length unit for displaying a single achromatic screen;
The recording apparatus according to claim 1, wherein the other stream is a stream of the predetermined equal length unit output from the stream output means. The recording apparatus according to claim 3,
Based on the measurement result of the measuring means, when the input stream is recorded on the recording medium, the predetermined equal length not exceeding the specified total code amount with respect to the predetermined equal length unit. A storage means for storing the unit stream;
The recording apparatus according to claim 1, wherein the other stream is a stream of the predetermined equal length unit stored in the storage unit. The recording apparatus according to claim 1,
The control means, for a stream of the predetermined equal length unit exceeding the specified total code amount of the predetermined predetermined length unit, sets a high DCT coefficient for each macroblock of the stream. A recording apparatus that controls to delete a next component. The recording apparatus according to claim 6, wherein
The recording apparatus according to claim 1, wherein the DCT coefficients of a predetermined order or more of each macroblock are deleted. The recording apparatus according to claim 6, wherein
A recording apparatus, wherein all the DCT coefficients not exceeding a predetermined order and having the highest order are deleted from each macroblock. In a recording method for recording a stream encoded using a variable length code on a recording medium in a predetermined equal length unit,
An input step in which a stream encoded using a variable length code is input;
A measurement step of measuring a code amount of the predetermined equal length unit of the stream input to the input step;
When the code amount of the predetermined equal length unit of the input stream exceeds the total code amount defined for the predetermined equal length unit, the code amount for the predetermined equal length unit A first packing step of separately recording a stream within a specified code total amount and a stream exceeding a code total amount specified for the predetermined equal length unit to the recording means;
A stream that exceeds the total code amount defined for the predetermined equal length unit is read, and the stream is smaller than the total code amount defined for the predetermined equal length unit and has an empty area. A second packing step of reading a stream that exceeds the total code amount defined for the predetermined equalization unit;
When the stream for a predetermined unit of block is read, the reading is temporarily interrupted to generate the parity of the outer code, and the second packing processed data and the parity of the outer code are stored in the recording means. And a write back step for writing back to the recording method.

Images