JP3775525B2 - Decoding device and decoding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a decoding apparatus and decoding how decompresses and decodes the compressed video signal.
[0002]
[Prior art]
A system such as a digital VTR (video tape recorder) or an AV (audio video) server that compresses and records a video signal and decompresses and outputs the compressed video signal during reproduction encodes and compresses the video signal. An image encoding device and a compressed image decoding device that decodes and expands a compressed video signal are included.
[0003]
Here, as a method for compressing a video signal, for example, there is a bidirectional predictive encoding method adopted in the MPEG (Moving Picture Experts Group) standard. In this bidirectional predictive encoding method, three types of encoding are performed: intra-frame encoding, inter-frame forward predictive encoding, and bidirectional predictive encoding. An image by each type of encoding is an I picture, It is called a P picture and a B picture. In this method, a screen group containing at least one I picture is defined as a GOP (group of pictures), and random access is enabled by accessing the GOP as a unit.
[0004]
[Problems to be solved by the invention]
By the way, when encoding and compressing an input video signal, the image encoding device outputs history information of the compression process together with the compressed video signal. The history information includes, for example, information indicating whether the image is a B picture, a P picture, or an I picture, and information indicating which frame in the GOP the image is.
[0005]
Also, in the image encoding device, when an input video signal is encoded and compressed based on, for example, a 4: 2: 2 studio profile, and there is a history of the input video signal compressed in the past, the image encoding device is in accordance with the history. It is desirable to adaptively perform the best compression processing, for example, the same compression processing as that performed in the past. Although there is a degree of image quality deterioration depending on the compression process, if there is a history of compression in the past, it is better to perform the same compression process as the past compression process. This is because image quality deterioration is reduced as compared with a case where a different compression process is performed. Therefore, in a system that records and reproduces a compressed video signal, the image encoding device outputs compression processing history information together with the compressed video signal, and the compressed image decoding device outputs the compressed input video signal. When decoding and decompressing, the history information of the compression process is output together with the decompressed video signal. Further, when the decompressed video signal is compressed again by the image encoding device, the subsequent image encoding device Based on the history information of the compression process input together with the input video signal, it can be considered that the best compression process such as the same compression process as that performed in the past is adaptively performed.
[0006]
However, the compressed image decoding apparatus as described above, in addition to normal reproduction, jog reproduction (frame advance playback, slow playback) or variable speed playback (PLAY) or the like, normal shift of different playback speed and playback speed during playback When used in an image playback apparatus having a playback function, the history information of compression processing may become discontinuous (irregular) during variable speed playback. When the history information of the compression process becomes discontinuous in this way, when the video signal output from the compressed image decoding apparatus is compressed again and recorded by the subsequent image encoding apparatus, the subsequent image encoding apparatus However, there is a problem in that the adaptive compression processing based on the history information of the compression processing is disturbed and image quality deterioration occurs.
[0007]
The present invention has been made in view of the above problems, purpose of that, along with making it possible to perform adaptive compression processing based on the history information of the compression processing in the subsequent stage of the encoder, the variable speed reproduction Sometimes, the history information of the compression process becomes discontinuous and the adaptive compression process based on the history information of the compression process is prevented from being disturbed in the subsequent encoding apparatus, thereby preventing image quality deterioration. An object of the present invention is to provide a decoding device and a decoding method .
[0008]
[Means for Solving the Problems]
Decrypted device of the present invention is for decoding the compressed video signal is a compressed video signal, input means for the history information of the compression processing has been made in the compressed video signal is input together with the compressed video signal And a decoding means for decoding the compressed video signal input by the input means, and a video signal obtained by the decoding means was subjected to variable speed playback at a playback speed different from the playback speed during normal playback. At this time, the history information input by the input means is updated by the history information updating means together with the video information obtained by the decoding means and the history information updating means for updating the history information so that the history information is not discontinuous. Output means for outputting the recorded history information .
Input Step decrypt method is for decoding the compressed video signal is a compressed video signal, the history information of the compression processing has been made in the compressed video signal is input together with the compressed video signal of the present invention And a decoding step for decoding the compressed video signal input in this input step, and the video signal obtained in this decoding step was subjected to variable speed playback at a playback speed different from the playback speed during normal playback. The history information input in the input step is updated in the history information update step together with the video signal obtained in the decoding step and the history information update step for updating the history information so that the history information is not discontinuous. And an output step for outputting the recorded history information .
[0009]
The decrypted device and decrypt the method of the present invention, history information of the compression process is entered with the compressed video signal, the compressed video signal is decoded. Further, when variable speed reproduction is performed on the obtained video signal, the input history information is updated so as not to be discontinuous, and the updated history information is output together with the video signal .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a compressed image decoding apparatus according to an embodiment of the present invention. The compressed image decoding apparatus is used for an image reproducing apparatus having a function of expanding and reproducing a compressed video signal and performing normal reproduction and variable speed reproduction at a reproduction speed different from the reproduction speed at the time of normal reproduction. It is. A compressed video signal is input to the compressed image decoding apparatus. The compressed video signal is compressed and recorded on a recording medium such as a hard disk or a video tape. The video signal is reproduced by a reproduction unit (not shown) and error-corrected by an ECC (error correction code) decoder. Here, it is a video signal, which is a video signal in accordance with a signal format called a serial digital data interface (hereinafter referred to as SDDI) format.
[0011]
The compressed image decoding apparatus shown in FIG. 1 inputs the SDDI format video signal 10 and decodes the SDDI decoder 11 and the output data of the SDDI decoder 11, and decodes and decompresses the video BRR ( Bit rate reduction) decoder 12 and the output data of this video BRR decoder 12 are input, and playback different from the normal playback speed, such as jog playback (frame-by-frame playback, slow playback), variable playback ( variable playback), etc. a jog memory controller 13 for controlling the speed of the variable speed reproduction, is connected to the jog memory controller 13, a video jog memory 14 is a memory that is used during variable speed reproduction, it receives the output data of the jog memory controller 13 , Video processor 1 that performs processing such as gain and color adjustment Then, the output data of the video processor 15 is input, the time code, which is time axis information, is inserted into an empty area in the vertical direction of the video signal, and the video signal 17 is output. VITC (vertical interval time code) The insertion unit 16 includes an SDDI decoder 11, a video BRR decoder 12, a jog memory controller 13, a video processor 15, and a system control unit 18 that controls the VITC insertion unit 16.
[0012]
In the compressed image decoding apparatus shown in FIG. 1, the video BRR decoder 12 outputs a control signal CFInfo12b to a subsequent stage together with, for example, an 8-bit expanded video signal 12a. The information included in the control signal CFInfo is included in the video signal 10 in the SDDI format. Similarly, the jog memory controller 13 and the video processor 15 also output control signals CFInfo 13b and 15b, for example, together with 8-bit video signals 13a and 15a to the subsequent stage.
[0013]
FIG. 3 is a timing chart showing the timing of the control signal CFInfo. As shown in this figure, the control signal CFInfo is a 1-bit serial signal, and is composed of 20 bits from the 0th bit to the 19th bit arranged in time series. The 0th bit of the control signal CFInfo starts at the falling timing of the horizontal synchronization signal HD.
[0014]
FIG. 4 is an explanatory diagram showing the contents of the control signal CFInfo. As shown in this figure, the 0th to 2nd bits are called CF2 (color frame 2), CF1 (color frame 1), and CF0 (color frame 0), respectively, and CF2 and CF1 are chroma signals. CF0 indicates the first field or the second field. The third bit indicates a composite signal when H (high) and a component signal when L (low). The fourth bit indicates that there is an error in the video index when H. The fifth bit indicates a line including a video index when H. The video index is control data inserted as data of a predetermined line during a vertical blanking period in a digital video signal. The sixth bit indicates that there is an error in the video ancillary data when H. The seventh bit indicates a line including video ancillary data when H. The video ancillary data is auxiliary data that can be inserted as data of a predetermined line during a vertical blanking period in a digital video signal. The 8th bit indicates that when H, the aspect ratio is 16: 9. The ninth bit is called recording enable, and when it is H, it indicates that it is a GOP to be recorded. The tenth bit is a flag called an image switch, and indicates a break when switching between a reproduction image and an input image when editing is performed in units of frames in an editing machine or the like. The eleventh bit is a flag called a frame delay, and indicates that an image one frame before the switch at the time of switching is output by one frame delay in simple switch editing. The 12th to 14th bits are called BPI [2] to [0], and these 3 bits indicate the type of compression processing, that is, the original image, B picture, P picture, or I picture. . The 15th to 19th bits are called GOP frame numbers [4] to [0], and the GOP frame number represented by these 5 bits indicates which frame in the GOP. Of the above control signal CFInfo, the 12th to 19th bits are history GOP information as history information of the compression process. The history GOP information is also transmitted by a video index in the digital video signal.
[0015]
FIG. 2 is a block diagram showing a configuration of a main part of the jog memory controller 13 in FIG. The jog memory controller 13 receives the video signal 12 a and the control signal CFInfo 12 b from the video BRR decoder 12, processes these data into, for example, 8-bit data, writes the data into the video jog memory 14, and writes the data into the video jog memory 14. A data processor 21 is provided that reads out the written data, processes it into a video signal 21a and a control signal CFInfo 21b, and outputs the processed signal. The data write / read address for the video jog memory 14 in the data processor 21 is controlled by the system control unit 18 in accordance with the playback speed requested by the user, whereby normal playback and variable speed playback are performed. It has come to be realized.
[0016]
The jog memory controller 13 further includes a switch 22 that selectively outputs one of the video signal 12a from the video BRR decoder 12 and the video signal 21a from the data processor 21, a control signal CFInfo 12b from the video BRR decoder 12, and a data processor. And a switch 23 that selectively outputs one of the control signals CFInfo21b from the control signal CFInfo21b. The jog memory controller 13 further receives the control signal CFInfo output from the switch 23, detects the GOP frame number, generates a reset pulse at the timing when the GOP frame number is “0”, and outputs the reset pulse from the reset pulse output terminal. A GOP frame number detection / reset pulse generator 24 to be output, a counter 25 reset by a reset pulse input to a reset pulse input terminal, and a numerical value used as a GOP frame number as a count value, and a GOP frame A switch 26 provided between the reset pulse output terminal of the number detection / reset pulse generator 24 and the reset pulse input terminal of the counter 25, which connects and disconnects both ends, a control signal CFInfo output from the switch 23, and the counter 25 With the output of The history GOP information processing unit 27 for generating history GOP information and processing the history GOP information part in the control signal CFInfo, and the video signal output from the switch 22 by the history GOP information processing unit 27 A history GOP information insertion unit 28 for inserting newly created history GOP information is provided.
[0017]
The switches 22 and 23 are switched in synchronization by the system control unit 18 and selectively output the video signal 12a and the control signal CFInfo12b from the video BRR decoder 12, or the video signal 21a and the control signal CFInfo21b from the data processor 21. It is supposed to be. The switch 26 is switched by the system control unit 18 so that it is turned on during normal reproduction and turned off during variable speed reproduction. In the counter 25, the maximum value of the count value is set by the system control 18 corresponding to the number of frames constituting the GOP. The history GOP information processing unit 27 sends the newly created history GOP information to the history GOP information insertion unit 28 and outputs a control signal CFInfo 13b to be sent to the video processor 15. In addition, the history GOP information processing unit 27 can be switched by the system control unit 18 to use newly created history GOP information. The history GOP information insertion unit 28 outputs a video signal 13 a to be sent to the video processor 15. The history GOP information insertion unit 28 switches whether the system control unit 18 inserts history GOP information newly created by the history GOP information processing unit 27 into the video signal output from the switch 22. In addition, when inserting, the history GOP information in the video index is rewritten, and the newly created history GOP information is inserted into the video signal.
[0018]
Next, the operation of the compressed image decoding apparatus according to this embodiment will be described. In the compressed image decoding apparatus shown in FIG. 1, an SDDI format video signal 10 is decoded by an SDDI decoder 11, and the output data of the SDDI decoder 11 is decoded and expanded by a video BRR decoder 12 to obtain a video signal. 12 a and the control signal CFInfo 12 b are output, and the video signal 12 a and the control signal CFInfo 12 b are input to the jog memory controller 13. Note that the video BRR decoder 12 performs an input data expansion process according to the history GOP information included in the input data. The video signal 13a and the control signal CFInfo 13b which are output after being processed by the jog memory controller 13 are subjected to processing such as gain and color adjustment by the video processor 15, and the VITC is inserted as the video signal 15a and the control signal CFInfo 15b. Input to the unit 16. The VITC insertion unit 16 inserts a time code into the video signal 15 a and outputs it as a video signal 17.
[0019]
In the jog memory controller 13 shown in FIG. 2, the input video signal 12 a and control signal CFInfo 12 b are input to the switch 22 and the switch 23 and to the data processor 21, respectively. When the switches 22 and 23 select the video signal 12 a and the control signal CFInfo 12 b side under the control of the system control unit 18, the input video signal 12 a does not pass through the data processor 21 and enters the history GOP information insertion unit 28. The input control signal CFInfo 12 b is also input to the GOP frame number detection / reset pulse generator 24 and the history GOP information processor 27 without passing through the data processor 21. On the other hand, when the switches 22 and 23 select the video signal 21a and the control signal CFInfo 21b from the data processor 21, the video signal 21a from the data processor 21 is input to the history GOP information insertion unit 28, and the data processor A control signal CFInfo 21 b from the GOP frame number detection / reset pulse generation unit 24 and the history GOP information processing unit 27 is input. The data processor 21 processes the video signal 12a and the control signal CFInfo12b into, for example, 8-bit data and writes the data to the video jog memory 14, and reads the data written in the video jog memory 14 to the video signal 21a and the control signal CFInfo 21b. Process and output. Data write / read addresses in the video jog memory 14 in the data processor 21 are controlled by the system control unit 18 in accordance with the playback speed requested by the user, thereby realizing normal playback and variable speed playback.
[0020]
The GOP frame number detection / reset pulse generator 24 receives the control signal CFInfo output from the switch 23, detects the GOP frame number, and generates a reset pulse when the detected GOP frame number is “0”. To output from the reset pulse output terminal. For example, when the GOP is composed of two frames, the GOP frame number is a repetition of “0”, “1”, “0”, “1”,..., And the GOP frame number detection / reset pulse generator 24 The reset pulse is generated at the timing when the GOP frame number is “0”.
[0021]
During normal playback, the switch 26 is turned on by the control of the system control unit 18, and the counter 25 is reset by the reset pulse output from the GOP frame number detection / reset pulse generation unit 24, and the period of the frame is set. The count operation is performed in synchronization. Therefore, for example, when the GOP is composed of two frames, the count value of the counter 25 is “0”, “1”, similar to the GOP frame number detected by the GOP frame number detection / reset pulse generator 24. , “0”, “1”,...
[0022]
At the time of variable speed reproduction, the GOP frame number in the control signal CFInfo output from the switch 23 becomes discontinuous (irregular) and has no meaning. Therefore, at the time of variable speed reproduction, the switch 26 is turned off under the control of the system control unit 18. Since the maximum value of the count value is set in the counter 25 by the system control 18 corresponding to the number of frames constituting the GOP, the counter 25 detects the GOP frame number when the switch 26 is turned off. Regardless of the reset pulse output from the reset pulse generator 24, the count operation with the flywheel is continued so as to maintain the sequence when the switch 26 is on. For example, when the GOP is composed of two frames, the count value of the counter 25 is “0”, “1”, “0”, “1”,... Will be repeated. The count value output from the counter 25 corresponds to the frame number in the history GOP information newly created by the history GOP information processing unit 27.
[0023]
During normal playback, the history GOP information processing unit 27 does not use newly created history GOP information under the control of the system control unit 18. That is, the history GOP information processing unit 27 outputs the control signal CFInfo output from the switch 23 as it is as the control signal CFInfo13b. Further, during normal playback, the history GOP information insertion unit 28 inserts history GOP information newly created by the history GOP information processing unit 27 into the video signal output from the switch 22 under the control of the system control unit 18. Without output as a video signal 13a.
[0024]
On the other hand, at the time of variable speed reproduction, the history GOP information processing unit 27 creates new history GOP information by using the control signal CFInfo output from the switch 23 and the output of the counter 25 under the control of the system control unit 18, and performs control. The history GOP information portion in the signal CFInfo is processed to output the control signal CFInfo 13b, and the newly created history GOP information is sent to the history GOP information insertion unit 28. Specifically, the history GOP information processing unit 27 sets all the BPI [2] to [0] in FIG. 4 to “0” so as to indicate the original image, and GOP frame numbers [4] to [[ 0], the count value of the counter 25 is written. At the time of variable speed reproduction, the history GOP information insertion unit 28 controls the system control unit 18 to add a history GOP newly created by the history GOP information processing unit 27 to the video index in the video signal output from the switch 22. The information is rewritten and inserted, and the video signal 13a is output.
[0025]
The history GOP information transmitted by the control signal CFInfo and the video index in the video signal is finally inserted into the video signal 17 output from the VITC insertion unit 16 and output to the subsequent stage. When the video signal 17 output from the compressed image decoding apparatus according to the present embodiment is compressed and recorded again by the subsequent image encoding apparatus, the subsequent image encoding apparatus uses the input video signal. Based on the history GOP information input together, the best compression processing such as the same compression processing as that performed in the past can be adaptively performed.
[0026]
As described above, according to the compressed image decoding apparatus according to the present embodiment, the jog memory controller 13 outputs the history GOP information inputted together with the video signal as it is during normal reproduction, and outputs the history GOP as it is during variable speed reproduction. Since the history GOP information is newly created and output so that the information does not become discontinuous, it is possible to perform adaptive compression processing based on the history GOP information in the subsequent image encoding apparatus. At the time of variable speed reproduction, it is possible to prevent the history GOP information from becoming discontinuous and to prevent the adaptive compression processing based on the history GOP information from being disturbed in the subsequent image encoding apparatus, and to prevent image quality deterioration.
[0027]
The present invention is not limited to the above embodiment. For example, in the above embodiment, the history GOP information as the history information of the compression process is transmitted by the control signal CFInfo and the video index in the video signal. However, the transmission method of the history information of the compression process is not limited to these, and can be designed as appropriate.
[0028]
【The invention's effect】
As described above, according to the decoding apparatus or decoding method of the present invention, at the time of variable speed reproduction, together with the video signal obtained by decoding, the history of compression processing updated so that the history information does not become discontinuous. Since the information is output, it is possible to perform adaptive compression processing based on the compression processing history information in the subsequent encoding apparatus, and the compression processing history information is discontinuous during variable speed reproduction. Thus, it is possible to prevent the adaptive compression processing based on the history information of the compression processing from being disturbed in the encoding device at the subsequent stage, and to prevent image quality deterioration .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a compressed image decoding apparatus according to an embodiment of the present invention.
2 is a block diagram showing a configuration of a main part of the jog memory controller in FIG. 1. FIG.
FIG. 3 is a timing chart showing timings of control signals in FIG. 1;
4 is an explanatory diagram showing the contents of a control signal in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... SDDI decoder, 12 ... Video BRR decoder, 13 ... Jog memory controller, 14 ... Video jog memory, 18 ... System control part, 21 ... Data processor, 24 ... GOP frame number detection and reset pulse generation part, 25 ... Counter, 26 ... switch, 27 ... history GOP information processing section, 28 ... history GOP information insertion section

Claims (5)

A decoding device for decoding a compressed video signal, which is a compressed video signal,
Input means for inputting history information of compression processing performed on the compressed video signal together with the compressed video signal;
Decoding means for decoding the compressed video signal input by the input means;
When the video signal obtained by the decoding means is subjected to variable speed playback at a playback speed different from the playback speed during normal playback, the history information input by the input means is indicated as discontinuous. History information updating means for updating without being
A decoding apparatus comprising: output means for outputting history information updated by the history information updating means together with the video signal obtained by the decoding means. The decoding apparatus according to claim 1, wherein the history information includes information (picture type) indicating a type of compression processing. The decoding apparatus according to claim 1, wherein the history information includes information indicating which screen is in a GOP (group of pictures) which is a screen group related to compression processing. The decoding apparatus according to claim 1, wherein the output means multiplexes the history information updated by the history information update means with the video signal obtained by the decoding means. A decoding method for decoding a compressed video signal, which is a compressed video signal,
An input step of inputting history information of compression processing performed on the compressed video signal together with the compressed video signal;
A decoding step of decoding the compressed video signal input in the input step;
When the video signal obtained in the decoding step is subjected to variable speed playback at a playback speed different from the playback speed during normal playback, the history information input in the input step is regarded as discontinuous. A history information update step for updating without being
An output step of outputting the history information updated in the history information update step together with the video signal obtained in the decoding step.

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