JP2947581B2 - Recording / playback method of DCT compressed video data - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DCT compressed moving image data recording / reproducing apparatus used as an interactive moving image recording / reproducing system for education or entertainment.

(Prior Art) Currently, interactive video recording / playback systems for education and entertainment are being developed. In this system, as in the case of a television signal, a series of moving images is processed as a set of screens called frames that are discretely arranged at predetermined intervals on a time axis.

In such a moving image recording / reproducing system, highly efficient data compression is required to reduce the recording capacity.

Further, in order to enhance the convenience as an interactive reproduction system, a data format suitable for various special reproductions such as stationary and reverse rotation is required.

"Image compression recording system" related to the applicant's earlier application
According to Japanese Patent Application No. 62-108350, there is disclosed a compression recording technique which achieves high data compression efficiency and easy reverse reproduction by a combination of interframe / intraframe predictive coding and quantization. .

(Problem to be Solved by the Invention) In the image compression recording system according to the above-mentioned prior application, a considerable degree of data compression is realized by a combination of inter-frame / intra-frame predictive coding and quantization. Is not yet enough in terms of

Further, in the image compression recording system according to the prior application, special reproduction such as reverse reproduction is realized, but it is necessary to further enhance the convenience as an interactive system by realizing a wider variety of special reproduction.

(Means for Solving the Problems) According to the recording / reproducing method of DCT compressed moving image data according to the present invention, a predetermined number of pixel data arranged in a row and a column direction in each of a plurality of continuous frames constituting a moving image A prediction error signal in a block is created by equally dividing into a plurality of blocks including a group and performing inter-frame prediction coding or intra-frame prediction coding for each block, and a discrete cosine transform is performed on the prediction error signal in each block. Performing quantization and variable-length coding to create a variable-length quantized transform coefficient, and adding a control code that indicates the compression method applied at the time of this compression to the optical disc as DCT-compressed moving image data while adding variable-length coding to the control code Compression / recording means for recording, and inverse variable length coding, inverse quantization, and variable length quantization transform coefficients included in DCT compressed moving image data read from the optical disc. By providing a reproducing means for reproducing while performing inverse discrete cosine transform and inverse predictive coding, and a display means, further data compression can be performed as compared with the conventional method using only predictive coding, quantization, and variable length coding. It is configured to be realized.

Further, the reproducing means reproduces an all-zero transform coefficient instead of an actual transform coefficient, or reproduces a pseudo control code instead of an actual control code such as type information indicating a type of predictive coding or a motion vector. Or freezes from interactive devices,
It is configured to implement a wide variety of special playback functions in accordance with commands such as fade-out, mosaic playback, and scroll-out.

 Hereinafter, the operation of the present invention will be described in detail with examples.

(Embodiment) FIG. 1 is a block diagram showing a configuration of a compression / recording system to which a recording / reproducing method of DCT compressed moving image data according to an embodiment of the present invention is applied. IN denotes a moving image to be compressed / recorded. A data input terminal, 11 is a predictive coding unit, 12 is a discrete cosine transform (DCT) unit, 13 is a scalar quantization (SQ) unit, 14 is a variable length coding (VLC) unit, 15 is a buffer memory, and 16 is a buffer memory. A recording data assembling unit 17 is an optical disk recording unit.

Each frame constituting the moving image data supplied from the input terminal IN to the predictive encoding unit 11 is equally divided into a plurality of blocks. That is, as shown in FIG. 2, mn blocks from B11 to Bmn are generated by equally dividing each frame into 1 / m and 1 / n in the row and column directions, respectively. Each block is composed of 8.times.8 pixel data arranged in the row and column directions.

Next, data compression by inter-frame prediction coding or intra-frame prediction coding is performed for each block. Inter-frame prediction coding is performed by calculating a difference from corresponding pixel data in a preceding frame to generate an inter-frame prediction error signal.Intra-frame prediction coding calculates a difference from a preceding pixel in a frame. This is done by calculating and generating an intra-frame prediction error signal. This predictive coding mainly performs inter-frame predictive coding. In order to prevent image quality deterioration due to accumulation of error signals between the compression / recording system and the reproducing system, the intra-frame predictive coding is performed at an appropriate frequency. A change (refresh) is made to the system. Further, when the correlation between the frames is extremely reduced due to the switching of the scene, the change to the intra-frame predictive coding is performed adaptively.

As shown in FIG. 3, the prediction error signal e (i, j) generated by the inter-frame / intra-frame predictive encoding is divided into eight rows and eight columns in each block, similarly to the pixel data before encoding. Are arranged. This prediction error signal e (i, j)
Is subjected to a discrete cosine transform in a discrete cosine transform unit (DCT) 12 at the next stage, and as shown in FIG.
A transform coefficient group E (u, v) arranged in 8 rows and 8 columns in the v space is generated. The scalar quantization (SQ) unit 13 at the next stage performs scalar quantization on the transform coefficient group E (u, v). The term scalar quantization (SQ) is used to distinguish a set of transform coefficients from vector quantization, which quantizes two-dimensionally based on a distribution pattern in the (u, v) space. In the quantization, quantization is performed in a predetermined quantization step for each transform coefficient as in the case of normal quantization.

The quantized transform coefficient group is subjected to variable length coding in a variable length coding (VLC) unit 14 at the next stage, in which shorter codes are assigned as the frequency of appearance increases, and the variable length coding It is stored in the buffer memory 15.

The recording data assembling unit 16 reads the variable-length quantized transform coefficients from the buffer memory 15 and supplies them to the optical disc recording unit 17 as DCT compressed moving image data of a predetermined format while adding a predetermined index, header, and the like thereto. In this header, various information on the compression method applied at the time of compression (type information indicating which predictive coding is applied between frames or within a frame, quantization characteristics including a quantization step width, etc.) are included. The variable-length encoded data is included as a control code.

DCT compressed video data recorded on this optical disc is
As shown in the data format of FIG. 5, the data format is composed of a plurality of scenes each having an index added to the head thereof.
Each scene is composed of a plurality of shots, and each shot is composed of a plurality of frames and a null code. This shot is a 2K byte physical recording unit of the optical disk.
The number is set to an integral multiple of a CD frame (referred to as such in order to be distinguished from a frame meaning one screen). Due to the variable length coding, the data length of each frame fluctuates, and accordingly, at the end of the shot, an empty portion having a length shorter than the data length of the subsequent one frame is generated. A null code that is treated as invalid data is inserted into this empty portion. One frame of data is composed of a plurality of block data,
Each block data includes a block header added to the head, compressed pixel data following the block header, and an end of block (EOB) which is an end code indicating the end of the block.

As shown in FIG. 6, the index added to the head portion of the DCT compressed moving image data includes the data length, title, number of scenes of the entire DCT compressed moving image data, and a set of scene information on each scene. Each scene information includes a scene number, a scene title, the number of shots, and the like, and a set of shot information related to each shot. Each piece of shot information includes a shot number, a storage start address, an image file name, an image title name, the number of frames, and a spare area for extension. The picture header added to the head of each frame data includes a frame data length, frame type information indicating a format of predictive coding in frame units, quantization characteristics, a global motion vector indicating a motion vector in frame units, parity, It consists of a spare area.
Further, a block header added to the head of each block data is obtained from block attributes such as a block address, block type information indicating a format of predictive coding in block units, a scan class, and a differential motion vector indicating a motion vector of a block terminal. Be composed.

FIG. 7 shows the recording and recording of DCT compressed moving image data of the above embodiment.
It is a block diagram showing a configuration of a reproducing apparatus to which a reproducing method is applied, 21 is an optical disk reproducing unit, 22 is a buffer memory, 23
Is an inverse variable length encoding unit (VLD), 24 is an inverse quantization (Q ^-1 ) unit,
25 is an inverse discrete cosine transform (DCT ^-1 ) unit, 26 is an inverse prediction encoding unit, 27 is a display unit, 28 is a main control unit, and 29 is a dialogue device.

When the user issues a playback start command from the interactive device 29, the main control unit 28 that has received the command causes the optical disc playback unit 21 to start a playback operation. The compressed moving image data reproduced by the optical disk reproducing unit 21 is transferred to the SCSI interface unit 35 and the bus 3
6. The data is written into the buffer memory 22 under the control of the write controller 31 via the SCSI interface 37 and the common bus 38. The compressed image data read from the buffer memory 22 under the control of the read control unit 32 is supplied to the inverse variable-length coding unit 23 via the switch 39, where the fixed-length quantization transform coefficient and the control code Is decrypted.

The quantized transform coefficient decoded by the inverse variable length encoding unit 23 is supplied to the inverse quantization unit 24. On the other hand, the control codes such as the quantization characteristics, frame type information, block type information, and motion vectors included in the picture header and the block attribute decoded to the fixed length are transmitted to the inverse quantization unit 24 and the inverse prediction encoding unit 26 in the subsequent stage. Supplied.

The inverse quantization unit 24 restores the fixed-length quantized transform coefficient supplied from the inverse variable length encoding unit 23 into a transform coefficient according to the quantization characteristic also supplied as a control code from the inverse variable length encoding unit 23. , To the inverse discrete cosine transform unit 25. The inverse discrete cosine transform unit 25 restores the transform coefficient supplied from the inverse quantization unit 24 into a prediction error signal in the real space and supplies the prediction error signal to the inverse prediction encoding unit 26. The inverse predictive encoding unit 26 performs frame encoding on the pixel data supplied from the inverse discrete cosine transform unit 25 according to type information indicating the format of predictive encoding supplied as part of the control code from the inverse variable length encoding unit 23. By performing inverse prediction coding between frames or within a frame, the pixel data group is restored to a pixel data group before compression and supplied to the display unit 27.

As shown in FIG. 8, the above-described inverse prediction encoding unit 26 includes an input terminal I1 for a prediction error signal and input terminals I2 and I2 for a control code.
3, an adder 51, a frame memory 52, a delay unit 53,
And a data output terminal O.

The prediction error signal output from the inverse discrete cosine transform unit 25 at the preceding stage is supplied from the data input terminal I1 to one input terminal of the adder 51. On the other hand, the input terminal 12 is supplied with a control code such as frame type information or block type information indicating whether the predictive coding is the inter-frame predictive coding or the intra-frame predictive coding. Is switched. If the prediction error signal supplied to one input terminal of the adder 51 is based on inter-frame predictive coding, the pixel data of the previous frame output from the frame memory 52 passes through the switch 54 and is output to the other end of the adder 51. The data is supplied to the input terminal, restored to the pixel data of the current frame by the addition of the two, and supplied to the display unit via the data output terminal O.
And supplied to. On the other hand, if the prediction error signal supplied to one input terminal of the adder 51 is based on intra-frame prediction coding, the preceding pixel data in the current frame output from the delay unit 53 is switched to the switch 54. Is supplied to the other input terminal of the adder 51, is restored to the pixel data in the current frame by the addition of the two, is supplied to the display unit via the data output terminal O, and the frame memory 52 and the delay unit 53 Supplied to

As shown in the block diagram of FIG. 9, the inverse variable length encoding unit 23 of FIG. 7 includes a data input terminal I4, an input terminal I5 of a special reproduction command from the main control unit 28, selectors 61 and 63, , Decryption R
OM62a to 62n, sequencer 64, data output terminal O1,
It consists of control code output terminals O2 and O3. Since variable length coding different for each quantization conversion coefficient and control code is applied during compression / recording, the decoding ROMs 62a to 62n
Is a selector 6 that is set for each quantization conversion coefficient and control code and that is switched in synchronization with the appearance of the data input terminal I4.
The corresponding decoding ROM is selected by 1,63.

That is, the variable-length quantized transform coefficient read from the buffer memory 22 in FIG. 7 and the variable-length control code such as a motion vector are supplied to the input terminal I4, and are switched by the selector 61 under the control of the sequencer 64. Compatible decryption RO
It is supplied to one of M62a to 62n, decoded into fixed-length data, and passed through a selector 63 that is switched in synchronization with the selector 61.An output terminal O1 for a quantized transform coefficient and an output terminal for a control code
It is supplied to one of O2 and O3.

The operation of the sequencer 64 in the inverse variable length coding unit 23 of FIG. 9 will be described with reference to the flowchart of FIG.

When the sequencer 64 starts operation, it waits for the appearance of a frame synchronization signal added to the beginning of the frame (step 71), and upon detecting the appearance, determines whether or not the next appearing block is the last block in the frame. A determination is made (step 72). If the block is not the last block, the block address (BA) added to the block is decoded and set as the jump block number (JB). This block address (BA) indicates the number of blocks to be skipped because the prediction error signal from the preceding frame is zero in inter-frame prediction coding at the time of compression and recording. It is added to the block immediately after. In the next step 74, it is determined whether or not JB is zero. If JB is zero, decoding to one block of quantized transform coefficients is performed in step 75, and return to step 72 is performed.

On the other hand, if it is determined in step 74 that JB is not zero, one block of WAIT
A timer for transition to the state is started, and at the same time, insertion of zero data in place of the quantized transform coefficient is started. Even in the WAIT state regarding the decoding into the quantized transform coefficients, the presence or absence of the appearance of the frame synchronization signal and the presence or absence of the timeout of the timer are detected in steps 77 and 78. If the timeout occurs before the appearance of the frame sync signal, the step
At 79, JB is decremented by one, the process returns to step 74, and the above operation is repeated.

As shown in FIG. 11, the quantized transform coefficient decoding ROM, which is one of the decoding ROMs 62a to 62n in the inverse variable length coding unit 23, includes a data input terminal I6 and a main control unit 28 (FIG. 7). ), Decoding ROMs 81, 82 and 83 for normal reproduction, fade-out and mosaic reproduction,
In-block counter 84 and zero data insertion register 85
, A selector 86 and a data output terminal O.

As shown in FIG. 12, the motion vector decoding ROM, which is one of the decoding ROMs 62a to 62n in the inverse variable length coding unit 23, has a data input terminal I8 and an address from the main control unit 28 (FIG. 7). And switching signal input terminals I19 and I10, a decoding ROM 91 for normal reproduction, a decoding ROM 92 for scroll-out, an in-block counter 93, a register 94 for inserting zero data, a selector 95, and a data output terminal O5. Have been. This motion vector is a control code indicating from which point in the preceding frame each point in the current frame has moved during inter-frame predictive encoding at the time of compression in the recording system.

 Hereinafter, the operation of the special reproduction will be described.

I. [Freeze] A. Freeze 1 Upon receiving a freeze command from the interactive device 29, the main control unit 28 instructs the data insertion unit 30 to insert a pseudo control code and a pseudo block address for the freeze operation. At the same time, it instructs the inverse variable length encoding unit 23 to start a freeze operation. The data insertion unit 30 receiving the above command replaces the control code indicating whether it is inter-frame or intra-frame predictive coding included in the frame type information of the picchair header in each frame by switching the switch 39. A pseudo control code indicating that the encoding is inter-frame predictive encoding is output uniformly, and a value equal to or more than the upper limit is inserted instead of the block address (BA) of the first block in each frame. Upon receiving a freeze command from the input terminal I5, the sequencer 64 of the inverse variable length encoding unit 23 (FIG. 9) switches the selector 95 of the motion vector decoding ROM (FIG. 12) to perform decoding for normal reproduction. The zero data being held is output to the zero data insertion register 94 in place of the output of the ROM 91.

As a result, as shown in the flowchart of FIG.
The sequencer 64 in the inverse variable-length encoded portion 23 outputs zero data instead of the quantized transform coefficients in all blocks for each frame, and a pseudo control code and zero data indicating that the encoding is inter-frame prediction encoding. Is output. As a result, the contents of the frame memory 52 shown in FIG. 8 are repeatedly output, and the display screen is frozen (stationary).

B. Freeze 2 When receiving a freeze command from the interactive device 29, the main control unit 28 instructs the data insertion unit 30 to insert a pseudo control code indicating inter-frame prediction coding, A freeze operation is instructed to the long encoding unit 23. The data insertion unit 30 receiving this command replaces the control code indicating which predictive coding is performed between frames included in the frame type information of the picture header in each frame by switching the switch 39. A pseudo control code indicating that the encoding is inter-frame prediction encoding is uniformly output. On the other hand, when a freeze command is received from the terminal I5, the sequencer 64 in the inverse variable length coding unit 23
By switching the selector 86 in the above, the output of the zero data insertion register 85 is output to the output terminal O4 instead of the output of the normal reproduction decoding ROM 81. At the same time, sequencer 64
Switches the selector 95 of the motion vector decoding ROM (FIG. 12) to output the zero data being held in the zero data insertion register 94 in place of the output of the normal reproduction decoding ROM 91.

As a result, the contents of the frame memory 52 in FIG. 8 are repeatedly output from the output terminal O to the subsequent display unit, and the display screen is frozen (stationary).

II.``Fade-out '' The main control unit 28, when receiving a fade-out command from the interactive device 29, instructs the data insertion unit 30 to insert a pseudo control code indicating that it is inter-frame predictive coding,
The fade-out operation is commanded to the inverse variable length coding unit 23.
Upon receiving this instruction, the data insertion unit 30 outputs a pseudo control code indicating that it is inter-frame predictive coding in place of the control code included in the frame type information of the picture header in each frame by switching the switch 39. . On the other hand, when a freeze command is received from the terminal I5, the sequencer 64 in the inverse variable length coding unit 23
By switching the selector 86 in (FIG. 11), the output of the fade-out decoding ROM 82 is output to the output terminal O4 instead of the output of the normal reproduction decoding ROM 81.

As shown in FIG. 13, the fade-out decoding ROM 82 decodes only the DC component (u = v = 0) out of the transform coefficients obtained by the discrete cosine transform into “−1”, and all other frequency components. Is set to “0”. As a result, only the DC value of each block of the frame memory 52 in FIG. 8 is decreased by one in the frame cycle, and a fade-out is performed in which the brightness of the display screen monotonously decreases.

III. “Mosaic Playback” Upon receiving the mosaic playback command from the interactive device 29, the main control unit 28 commands the inverse variable length encoding unit 23 to perform a mosaic playback operation. When the sequencer 64 in the inverse variable length encoding unit 23 receives a mosaic reproduction command from the input terminal I5, the sequencer 64 switches the selector 86 in the quantized transform coefficient decoding ROM (FIG. 11) to change the The output of the mosaic reproduction decoding ROM 83 is passed to the output terminal instead of the output.

As shown in FIG. 14 (A), only the DC component (u = v = 0) of the spatial frequency in the transform coefficients obtained by the discrete cosine transform is stored in the decoding ROM 83 for mosaic reproduction at the time of normal reproduction (at a magnification of 1). ), And all other frequency components are set to “0” (at a magnification of 0). As a result, a mosaiced screen including only the DC component of the spatial frequency is displayed.

FIG. 14B is a conceptual diagram showing another example of the mosaic reproduction decoding ROM 83. In this example, the DC component of the spatial frequency (u = v =
0) is decoded as it is at the time of normal reproduction, and the next lower frequency component is set at a magnification of 1/2 for normal reproduction, and a value to be decoded to “0” is set for all higher frequency components. ing. As a result, a mosaiced screen including only the low frequency components of the spatial frequency is displayed.

FIG. 14 (C) is a conceptual diagram showing still another example of the decoding ROM 83 for mosaic reproduction. In this example, the DC component of the spatial frequency (u =
v = 0) as it is, and the next lower frequency component is multiplied by 1/2 for normal reproduction, the next lower frequency component is multiplied by 1/4, and all higher frequency components Is set to a value to be decoded to “0”. As a result, a mosaiced screen including only the low frequency components of the spatial frequency is displayed.

IV. “Scroll out” This scroll out is performed using a motion vector which is one of the control codes.

Upon receiving the scroll-out instruction from the interactive device 29, the main control unit 28 instructs the data insertion unit 30 to insert a pseudo control code indicating that the encoding is inter-frame predictive encoding, and the inverse variable length encoding unit 23 Command a scroll-out operation. Upon receiving this instruction, the data insertion unit 30 sets the switch 39
, A pseudo control code indicating that the encoding is inter-frame predictive encoding is output instead of the control code included in the frame type information of the picture header in each frame.

On the other hand, the sequencer in the variable-length compressed image data decoding unit 23
64 receives a scroll-out command from terminal I5,
By switching the selector 86 in the quantized transform coefficient decoding ROM (FIG. 11), the zero data held in the zero data insertion register 85 is output to the output terminal O4 instead of the output of the normal reproduction decoding ROM 81. At the same time, the sequencer
64 is a selector 95 in the motion vector decoding ROM (FIG. 12).
Is switched, the output of the scroll-out decoding ROM 92 is passed to the output terminal O5 instead of the output of the normal reproduction decoding ROM 91.

That is, as exemplified in FIG. 15 (A), at the time of normal reproduction, the motion vector is a value (Vx, Vy) corresponding to the motion in the display screen, and the quantized transform coefficient corresponds to the prediction error signal between frames. Are the values Q1, Q2, Q3,... On the other hand, at the time of scrolling out, as illustrated in FIG. 3B, the motion vector is a value indicating the direction of scrolling out (Vx in this example) regardless of the actual movement in the display screen.
= 0, Vy = -1), and the quantized transform coefficients are all zero. In this example, the display screen moves downward (−Y direction),
It moves at a frame period and at a predetermined speed corresponding to the absolute value 1 of the motion vector, and scrolls downward. The direction and speed of this scroll-out are specified by the combination of the polarity and the absolute value of the motion vector to be replaced with (Vx, Vy) at the time of scroll-out.
Is specified by a part of the address supplied to the ROM 92 for scroll-out.

The motion vector output from the motion vector decoding ROM shown in FIG. 12 is supplied to the frame memory 52 via the control code input terminal I3 in the inverse prediction encoding unit 26 shown in FIG. In the frame memory 52, the pixel data of the preceding frame is read out at a timing shifted in the X and Y directions by a time corresponding to the direction and the size of the motion vector, and the preceding frame is displayed in the display screen of the current frame. The pixels that have moved from the frame are displayed.

As described above, the decoding ROM for the special reproduction is installed in the inverse variable length encoding unit, and the decoding RO for the normal reproduction is performed according to the special reproduction command.
The configuration for switching to M has been exemplified.

However, in a special reproduction operation that generates a zero prediction error signal, a decoding ROM that outputs this zero data is used.
May be installed in an inverse quantization unit or an inverse discrete cosine transform unit, and switched to the special reproduction decoding ROM in accordance with a special reproduction command.

Also, a configuration in which a data insertion unit for inserting a pseudo control code is provided at a stage preceding the inverse variable length coding unit has been illustrated.
However, instead of providing the data insertion unit, a configuration may be adopted in which a decoding ROM for outputting the pseudo control code is provided in the inverse variable length coding unit.

As described in detail above, according to the recording / reproducing method of DCT compressed moving image data according to the present invention, DCT is further added to the conventional compression method using predictive coding, quantization, and variable length coding.
Since the hybrid compression is performed by combining the compression methods, further data compression can be realized.

Further, according to the recording / reproducing method of the present invention, freeze / freezing is performed by utilizing the features of the inter-frame predictive coding and the DCT compression method.
Because it is a configuration that realizes various special playback functions such as fade out, mosaic playback, scroll out,
The convenience of the interactive playback device is greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a compression / recording system to which a recording / reproducing method of DCT compressed moving image data according to an embodiment of the present invention is applied, and FIG. 2 explains a block division method by the compression / recording system. FIG. 3 is a conceptual diagram illustrating an example of an array of prediction error signals in a block, and FIG. 4 is an illustration of an array in a frequency space of transform coefficients obtained by performing discrete cosine transform of the prediction error signal in the block. FIG. 5 is a conceptual diagram illustrating a data format of DCT compressed moving image data recorded on an optical disc, and FIG. 6 is a conceptual diagram illustrating a configuration of an index, a picture header, and a block header of FIG. FIG. 7 is a block diagram showing the configuration of a DCT compressed moving image data reproducing system according to the above embodiment, FIG. 8 is a block diagram showing an example of the configuration of the inverse prediction encoding unit (26) in FIG. Fig. 1 Variable length coding (VLD) section (2
FIG. 10 is a block diagram illustrating the configuration of 3), FIG. 10 is a flowchart for explaining the operation of the sequencer (64) in FIG. 9, and FIG. 11 is quantization of the decoding ROM (62a to 62n) in FIG. FIG. 12 is a block diagram showing the configuration of a transform coefficient decoding ROM, and FIG. 12 shows a motion vector decoding R of the decoding ROM (62a to 62n) in FIG.
FIG. 13 is a block diagram showing the configuration of the OM, FIG. 13 is a conceptual diagram for explaining the configuration of the fade-out decoding ROM 82 of FIG. 11, and FIG.
4 is a conceptual diagram for explaining the configuration of the mosaic reproduction decoding ROM 83 in FIG. 11, and FIG. 15 is a data format diagram for explaining a scroll-out operation using a motion vector. 11: predictive coding unit, 12: discrete cosine transform (DCT)
Section 13 Scalar quantization (SQ) section 14 Variable length coding (VLC) section 15 Buffer memory 16 Recording data assembling section 17 Optical disc recording section 21 Optical disc Reproduction unit, 22: buffer memory, 23: inverse variable length coding (VLD) unit, 24: inverse quantization (Q- ¹ ) unit, 25: inverse discrete cosine transform (DCT- ¹ ) unit, 26 …… Inverse prediction coding unit, 27
…… Display unit, 51 …… Adder, 52 …… Frame memory, 53
... 1-pixel delay device, 62a-62b... Variable-length code decoding
ROM, 64: Sequencer, 81: Quantized transform coefficient decoding ROM for normal playback, 82: Quantized transform coefficient decoding ROM for fade-out, 83: Quantized transform coefficient decoding ROM for mosaic playback, 85 ... Zero data Insertion register, 91 ... Motion vector decoding ROM for normal reproduction, 92 ... Motion vector decoding ROM for scroll-out, 94 ... Zero data insertion register.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Komatsu Matsushima 3-5-24 Miyahara, Yodogawa-ku, Osaka-shi, Osaka Within NEC Home Electronics Co., Ltd. (56) References JP-A-63-311888 (JP, A) JP-A-63-274277 (JP, A) JP-A-63-274274 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 5/91-5/956 H04N 7/24 -7/68

Claims (5)

(57) [Claims] 1. A plurality of continuous frames constituting a moving image are equally divided into a plurality of blocks including a predetermined number of pixel data groups arranged in rows and columns, and each block has a corresponding block in a preceding frame. By calculating the difference with the pixel data to obtain the inter-frame prediction error signal to obtain the inter-frame prediction error signal or calculating the difference with the preceding pixel in the frame to perform the intra-frame prediction encoding to obtain the intra-frame prediction error signal A prediction error signal in a block is created, a discrete cosine transform is performed on the prediction error signal in each block to obtain a transform coefficient, and this is quantized to obtain a quantized transform coefficient. Creates a quantized transform coefficient and performs variable-length coding on the control code indicating the compression method applied during this compression to obtain a variable-length control code, which is added to the variable-length quantized transform coefficient Compression / recording means for recording on the optical disc as DCT-compressed moving image data, and inverse-variable-length coding of the variable-length quantizing transform coefficient included in the DCT-compressed moving image data read from the optical disc to obtain a quantized transform coefficient. To obtain a transform coefficient by performing inverse quantization on the data, obtain a prediction error signal by performing an inverse discrete cosine transform, obtain a prediction error signal, and perform inverse prediction coding on the obtained signal to reproduce a pixel data group, and display the reproduced pixel data group. Display means, and the reproduction means outputs a prediction error signal of zero instead of the prediction error signal in accordance with a freeze command instructing to freeze the display screen input from the interactive device, and replaces the control code. DCT-compressed moving image data recording, characterized in that it comprises a freeze special reproducing means for outputting a pseudo control code indicating that inter-frame predictive coding is being performed.
Playback method. 2. A block in which the inter-frame prediction error signal is zero during the compression / recording is skipped from a subsequent compression / recording target, and the continuous number of the skipped blocks is used as a block address for a block immediately after the end of the skip. For the continuous number of blocks included in the control code and displayed at the block address at the time of the reproduction, a zero inter-frame prediction error signal is reproduced, and the freeze special reproduction means performs the freeze instruction in accordance with the freeze instruction. 2. The apparatus according to claim 1, wherein means for inserting a value equal to or more than the upper limit value as pseudo data in place of the block address is provided at a stage preceding said means for outputting said zero inter-frame prediction error signal. DCT compressed video data recording and playback method. 3. The reproduction means according to claim 1, wherein only the DC component has a predetermined negative polarity value and the AC component has a negative value instead of the conversion coefficient in each of said blocks in accordance with a fade-out command for fading out a display screen input from the interactive device. 3. The recording / reproducing method of DCT compressed moving image data according to claim 1, further comprising a fade-out special reproducing means for outputting a zero conversion coefficient. 4. The reproduction means outputs a transform coefficient in which the AC component is suppressed in place of the transform coefficient in each of the blocks in accordance with a mosaicing command inputting a mosaicing of a display screen input from the interactive device. 4. The recording / reproducing method of a DCT compressed moving image DCT according to claim 1, further comprising a special reproduction unit for mosaic reproduction. 5. The compression / recording means includes in the control code a motion vector indicating from which point in the preceding frame each point in the current frame has moved during inter-frame predictive encoding, The inverse predictive encoding is performed using the vector, and the reproducing unit reproduces a pseudo motion vector indicating a motion in a predetermined direction instead of the motion vector according to a scroll-out command of the display screen input from the interactive device. 5. The DCT compressed moving image according to claim 1, further comprising a scroll-out special reproduction unit that reproduces a zero inter-frame prediction error signal instead of the inter-frame prediction error signal. DCT recording / playback method.