JP3550651B2 - Method and apparatus for speeding up transcoding - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to transcoding, and in particular, to high-speed transcoding for recompressing coded audio and video that can be applied to or incorporated in electronic devices such as video disk recorders, set-top boxes, and video servers. The present invention relates to a conversion method and an apparatus.
[0002]
[Prior art]
The transcoding device includes a decoding device and an encoding device, and is used for the purpose of increasing the free space of a storage device by recompressing a recorded program file. By using the transcoding device, it becomes possible to store another program file using the free space.
[0003]
[Problems to be solved by the invention]
However, in a normal transcoding device, the time required for processing is the same as the time required for reproducing the program file. Therefore, even when transcoding is performed without reproducing the program file to create free space in the storage device, it takes the same time as when reproducing the program file, and there is a problem in terms of efficiency. For this reason, a method of performing parallel processing using a plurality of transcoding devices (Japanese Patent Application Laid-Open Nos. 7-123270 and 11-155128) can be considered. It is difficult to divide a file (code stream) to be supplied to the apparatus and to perform synchronization processing between transcoding apparatuses.
[0004]
(Purpose)
The present invention has been made to solve such a problem, and an object of the present invention is to provide a transcoding speed-up method and apparatus capable of speeding up file division for a plurality of transcoding devices. It is in.
[0005]
It is another object of the present invention to provide a code stream dividing apparatus suitable for parallel processing of transcoding.
[0006]
[Means for Solving the Problems]
The transcoding speed-up method according to the present invention is a transcoding speed-up method for reading a code stream from a storage device in which a code stream in GOP units is stored as a file and performing re-encoding for code compression. A temporary division length (approximately 1 / N of all files: N is a positive integer of 2 or more) which is a temporary division length related to the length (the code length of one GOP unit or more ) is set, and (n−1) of the temporary division length is set. ) The code streams are read from the storage locations corresponding to the multiple (n is a positive integer equal to or less than N) , the position of the first GOP of each read code stream is detected, and the storage position of each detected GOP is detected. , The code streams in the divided range are read independently from each other, and re-encoding is performed in parallel by different transcoding devices. Further, the detection of the position of the GOP from the storage position corresponding to (n-1) times the provisional division length is performed in chronological order from the beginning of the file.
[0007]
The high-speed transcoding device according to the present invention is a high-speed transcoding device that reads a code stream from a storage device in which a code stream in GOP units is stored as a file and performs re-encoding for code compression. Is set as a temporary division length (approximately 1 / N of all files: N is a positive integer of 2 or more) with respect to the temporary division length (n or more). Is a positive integer equal to or less than N) , a code stream reading unit that reads a code stream from a storage position corresponding to each of them, a GOP detecting unit that detects the position of the first GOP from each read code stream, An actual division position storage unit for storing the storage position of the GOP, and a file for reading the code stream of the division range from the storage position of the stored GOP. A code reading unit, a plurality of transcoding devices for re-encoding each read code stream, and a file writing unit for storing each re-encoded code stream as one code stream in a storage device. Features. Further, the code stream reading unit detects a GOP position from a storage position corresponding to (n-1) times the provisional division length in a time-series manner from the beginning of a file.
[0008]
A code stream dividing apparatus for parallel processing of transcode according to the present invention is a code stream dividing apparatus that reads a code stream from a storage device in which a code stream in GOP units is stored as a file and performs re-encoding for code compression. , A provisional division length (approximately 1 / N of all files: N is a positive integer of 2 or more), which is a provisional division length related to the division length of the file (the code length in units of 1 GOP ), is set. (N-1) times (n is a positive integer less than or equal to N) , a code stream reading unit that reads a code stream from each storage position, and detects the position of the first GOP from each read code stream. A GOP detection unit, an actual division position storage unit for storing the storage position of each detected GOP, and a code indicating a division range from the storage position of the stored GOP. And having a file reading part for reading the stream. Further, the code stream reading unit detects a GOP position from a storage position corresponding to (n-1) times the provisional division length in a time-series manner from the beginning of a file.
[0009]
(Action)
Using a plurality of transcoding devices, a file is divided at GOP (Group of Picture) boundaries, and transcoding is performed in units of code streams in a division range of about a specified size. A tentative division length related to a division length equal to or longer than the code length of 1 GOP is used for dividing the code stream, and the position is (n-1) times (n = 1 , 2 ,...), That is, the position of the first G0P, after the provisional division length. , The code stream is divided at the position of the first GOP after the double provisional division length,..., And parallel processing of encoding is performed by the number of transcoders corresponding to the number of divisions. Since the detection of the position of the GOP only reads the code stream from the temporary division length × (n−1) times (n = 1 , 2 ,...) Position until the first GOP is detected from the storage device, it is exceptional. No processing time is required.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method and an apparatus for increasing the speed of a transcoding device according to the present invention will be described in detail.
[0011]
(Description of configuration)
FIG. 1 is a configuration diagram showing one embodiment of a transcoding device according to the present invention. A dividing circuit 105 to which one program file 101 is input, two transcoding devices 102a and 102b to which the program files divided by the dividing circuit 105 are input, and a transcoding device to which each output of the transcoding devices 102a and 102b is input. And a coupling circuit 106 for forming one coded program file 103.
[0012]
The division circuit 105 receives one program file 1 and outputs the program file 101 to the transcoding device 102a and the transcoding device 102b, for example, as two files separated into the first half and the second half of the file. The transcoding devices 102a and 102b perform transcoding of only the respective files, and output the transcoded files to the combining circuit 106, respectively. The combining circuit 106 combines the files from the transcoding device 102a and the transcoding device 102b, outputs the combined program file 103, and stores it in the storage device.
[0013]
For example, the transcoding devices 102a and 102b simultaneously perform the transcoding process on the first half and the second half of the file, respectively, in parallel, so that the processing time is reduced to about half and high-speed transcoding is realized.
[0014]
Next, a processing method of dividing one file and transcoding at the same time will be described in more detail. First, a method of dividing a program file will be described with reference to FIGS.
[0015]
FIG. 2 is a diagram showing a processing block for detecting a division position of a program file. A storage device 203 in which a program file is stored; a temporary division length instructing unit 201 in which a temporary division length corresponding to a division length for dividing the program file is stored; a file read out from the storage device 203; A code stream reading unit 202 that skips a file to a position (data address or the like) designated by 201 and outputs a subsequent code stream, and analyzes a code stream of a file output from the code stream reading unit 202 to perform GOP And a real division position storage unit 205 for recording the output of the GOP detection unit 204.
[0016]
(Description of operation)
FIG. 3 is a diagram showing a flowchart relating to the file dividing process in the block diagram shown in FIG. The procedure for detecting the actual storage position information of the GOP of the program file based on the temporary division length of the file division length from the temporary division length instructing unit 201 and storing it in the actual division position storage unit 205 is shown. . The position information stored in the actual division position storage unit 205 is used for dividing a program file to be supplied to each of a plurality of transcoder devices.
[0017]
First, an initial value of the file division is set to the control variable n, and 1 is substituted for n in order to detect the position information of the first GOP of the file (step S31). Subsequently, the code stream reading unit 202 opens the file in the storage device 203, and from the temporary division position instructing unit 201 to the position of the value obtained by multiplying the value of the temporary division length relating to the division length of the file by (n-1). The pointer (file pointer) is advanced (step S32).
[0018]
It is checked whether or not the position of the file pointer has reached the end position (final position) of the file (step S33). If the position has been reached, the entire process ends, and if not, the process proceeds to step S34. In step S34, the file is read from the position of the current file pointer, and the read code stream is sent to the GOP detection unit 204 to detect the head position of the first GOP of the code stream (step S35). It is checked whether or not the head position of the GOP has been detected (step S36), and if not, the process is terminated. If the head position of the GOP is detected, the head file position of the detected GOP (for example, the address of a storage device or data) is stored in the actual division position storage means 205 (step S37). Next, n + 1 is substituted for the control variable n (step S38), the process returns to step S32, and the same processing as above is repeated.
[0019]
By the above-described processing operation, the start position information serving as a GOP break of the file is stored in the actual division position storage unit 205. The length of the file divided by the head position information of this GOP is a value close to the provisional division length specified by the provisional division position designation unit 201. The provisional division length can be, for example, approximately half the length of all files. In this case, the length of the division file is divided by the GOP at substantially the center of all files. When the temporary division length is divided into a plurality of files of three or more, the temporary division length can be set to approximately 1 / M of all files (M is, for example, an integer of three or more).
[0020]
Next, a method of simultaneously transcoding a plurality of divided files will be described by way of an example in which a program file is divided into a first half and a second half. When the two transcoding devices shown in FIG. 1 are used, the dividing circuit 105 uses the first head position information of the GOP stored in the real division position storage unit 205 to transfer the program file of the storage device (not shown) to the first GOP. Is supplied to the transcoding device 102a, and the code stream read from the position of the GOP is supplied to the transcoding device 102b using the head position information of the GOP in the middle of the program file, Let's transcode each. The combining circuit 106 combines the coded output of the transcoding device. Also, a transcoded program is stored by storing the re-encoded output in the storage device (not shown) into one program file using the head position information of the GOP stored in the actual division position storage unit 205. A file is generated.
[0021]
In the process of dividing the program file in the above process, the file pointer skips near the position of a desired GOP in accordance with an instruction from the temporary division position instructing unit 201, and requires tracing of all files. Therefore, the processing can be executed in an extremely short time as compared with the total reproduction time of the program file or the transcoding operation time, and the processing itself does not cause a processing delay that affects the entire transcoding.
[0022]
(Other embodiments)
Next, another embodiment of the transcoding speed-up method and apparatus according to the present invention will be described with reference to FIGS.
[0023]
FIG. 4 is a configuration diagram showing the transcoding device according to the present embodiment. In this embodiment, a storage device 403 in which a file is stored, file reading units 411, 412, and 413 for reading files from the storage device 403, respectively, and a transcoding unit 421 for compressing the read encoded information again. , 422, 423, and transcoding for instructing the file writing units 431, 432, 433 and the transcoding units 421, 422, 423 to write the re-encoded data to the storage device 403, respectively. It comprises a control unit 404 and an actual division position storage unit 405.
[0024]
The transcode control unit 404 reads the head position information of the GOP from the real division position storage unit 405, and instructs the file reading unit 411 and the transcode unit 421 to perform transcoding. The file reading unit 411 reads the file in the storage device 403 from the position of the corresponding GOP and sends the file to the transcoding unit 421. The transcoding unit 421 sequentially recompresses the transmitted file and sends the file to the file writing unit 431. The file writing unit 431 writes the recompressed data to the storage device 403 based on the position of the GOP. The same operation as described above is performed simultaneously for the transcode units 422 and 423, and the recompressed data is stored in the storage device 403.
[0025]
In the above embodiment, the transcoding control unit 44 may notify the transcoding units 421 to 423 of the recompression ratio as a recompression ratio (for example, 0.8). The compression ratio may be configured to be stored in advance in each of the transcode units 421 to 423.
[0026]
For processing of the recompressed data, the data may be temporarily written to a temporary file and replaced with the original file after transcoding, but the data once recompressed is smaller than the data amount of the original file. Therefore, the file at the time of reading may be overwritten. In this case, the files are merged when all the transcoding is completed, and a transcoded file is created.
[0027]
FIG. 5 is a configuration diagram showing a transcoding device according to an embodiment using N transcoding devices. In this embodiment, the program files 501 to the N transcoding devices 502a to 502n are input by dividing one program file 501 into N files. The outputs of the N transcoding devices 502a to 502n are output as one program file 503 by the combining circuit 105. The transcoding processing speeds up according to the number of transcoding devices.
[0028]
FIG. 6 is a diagram showing an overall processing block diagram in the case where a program file is divided into N files and transcoding processing is performed. A storage device 603, a code stream reading unit 602 including a temporary division position instructing unit 601 and operation units 606 and 607, a GOP detection unit 604, a real division position storage unit 605, a transcode control unit 608, and a parallel transformer. And a code processing unit 609.
[0029]
The temporary division position instructing unit 601 sets the value a of the division length, the computing unit 606 computes a × (n−1) = 0 with n = 1, and sets the file start position as the file pointer related to the address of the storage device 603. To start reading from the position of the file pointer in the storage device 603 and output a code stream. Upon detecting the first GOP from the code stream, the GOP detection unit 604 notifies the storage location information of the GOP to the real division position storage unit 605 and instructs the calculation unit 607 to calculate GOP detection for the next file division. . The real division position storage unit 605 stores the storage position information, the calculation unit 607 calculates n = n + 1 = 1, and the calculation unit 606 points to the file pointer a × 1, and repeats the same processing as described above. By repeating the above processing, the actual division position storage unit 605 stores the position information of the first GOP to be divided.
[0030]
The transcode control unit 608 controls the storage device 603 and the parallel transcode processing unit 609 based on the position information of the GOP stored in the real division position storage unit 605 by the above processing, and the N transcoding devices control the storage device 603. The program files are read out in parallel and encoded, and are stored again in the storage device 603 as code-compressed program files.
[0031]
FIG. 7 is a diagram showing another embodiment for acquiring the position information of the first GOP for dividing the program file into N files. A storage device 703, a code stream reading unit 702 including a division position instruction unit 701 and GOP detection units 704-1 to 704-N, an actual division position storage unit 705, and arithmetic units 708-1 to 708-N Be composed.
[0032]
In the present embodiment, N file pointers 0, a × 1,... A × (n−1) are converted into N operation units 707-1 to 707 based on the temporary division length a from the temporary division position designating unit 701. −N, the code stream is output in parallel from each file pointer position, and the N GOP detectors 704-1 to 704-N respectively detect the position information of the first GOP and store it in the real division position storage unit 705. It is configured to store the information, and the detection of the position information to be divided is further speeded up by the parallel processing.
[0033]
【The invention's effect】
According to the present invention, the division of the program file for performing the transcoding parallel processing can be performed at high speed and reliably, so that the processing time of the entire transcoding can be sufficiently reduced. In addition, since the reading position from the storage device for the transcoding process is clearly demarcated by the GOP position information, the synchronization operation between the plurality of transcoding devices is facilitated.
[0034]
Further, according to the code stream dividing device for parallel processing of transcode of the present invention, a provisional division length equal to or longer than the code length of 1 GOP is used as the division length of the code stream, and is (n-1) times (n = 1). 1 , 2,...), Ie, the first GOP position, the position of the first GOP after the provisional division length, the position of the first GOP after the provisional division length × 2,. Simply reads the code stream from the temporary division length × (n−1) (n = 1 , 2,...) Position until the GOP is detected from the storage device. Even if the number of divisions increases, it is possible to ignore the transcoding processing time.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing one embodiment of a transcoding speed-up method and apparatus according to the present invention.
FIG. 2 is a configuration diagram of file division position detection according to the present embodiment.
FIG. 3 is a flowchart showing a file dividing process according to the embodiment.
FIG. 4 is a diagram showing another embodiment of a transcoding speed-up method and apparatus according to the present invention.
FIG. 5 is a block diagram illustrating an operation of dividing a file into N files and performing a transcoding process.
6 is a diagram showing an overall processing block diagram when the transcoding process shown in FIG. 5 is performed.
FIG. 7 is a diagram showing another embodiment for acquiring position information of a GOP.
[Explanation of symbols]
101, 501 Program files 102a, 102b, 102c, 502a, 502b, 502n Transcoding device 103, 503 Transcoded program file 105, 505 Dividing circuit 106, 506 Coupling circuits 201, 601, 701 Temporary division position instructing section 202, 602, 702 Code stream reading units 203, 503, 603, 703 Storage devices 204, 604, 704-1, 704-2, 704-N GOP detection units 205, 405, 605, 705 Real division position storage units 411, 412, 413 File read unit 404, 608 Transcode control unit 421, 422, 423 Transcode unit 431, 432, 433 File write unit 606, 607, 707-1, 707-2, 707-N Operation unit 609 Parallel transcode processing Department

Claims (6)

In a transcoding speed-up method for reading a code stream from a storage device in which a code stream in GOP units is stored as a file and performing re-encoding of code compression,
A provisional division length (approximately 1 / N of all files: N is a positive integer of 2 or more) is set as a provisional division length related to the division length of the file ( the code length of one GOP unit or more) , and ( n-1) times (n is a positive integer equal to or less than N) , reading out the code streams from the storage locations, detecting the position of the first GOP of each read code stream, and detecting each of the detected GOPs. A code stream in a divided range is read out independently from the storage position of the above, and re-encoding is performed in parallel by different trans-coding devices, respectively. 2. The transcoding speed-up method according to claim 1, wherein the detection of the position of the GOP from the storage position corresponding to (n-1) times the provisional division length is performed in chronological order from the beginning of the file. In a high-speed transcoding device that reads a code stream from a storage device in which a code stream in GOP units is stored as a file and performs re-encoding of code compression,
A provisional division length (approximately 1 / N of all files: N is a positive integer of 2 or more) is set as a provisional division length related to the division length of the file ( the code length of one GOP unit or more) , and ( a code stream reading unit that reads a code stream from a storage position corresponding to (n-1) times (n is a positive integer equal to or less than N) , and a GOP detection that detects a position of a first GOP from each read code stream Unit, an actual division position storage unit for storing the storage position of each detected GOP, a file reading unit for reading a code stream of a division range from the storage position of the stored GOP, and a readout unit for reading each code stream. A plurality of transcoding devices for re-encoding; and a file writing unit for storing each re-encoded code stream as one code stream in a storage device. Fast transcoding apparatus which is characterized in that. 4. The high-speed apparatus according to claim 3, wherein the code stream reading unit detects a GOP position from a storage position corresponding to (n-1) times the provisional division length in a time-series manner from the beginning of the file. Transcoding device. In a code stream splitting apparatus for transcoding parallel processing for reading a code stream from a storage device in which a code stream in GOP units is stored as a file and performing re-encoding for code compression,
A provisional division length (approximately 1 / N of all files: N is a positive integer of 2 or more) is set as a provisional division length related to the division length of the file ( the code length of one GOP unit or more) , and ( a code stream reading unit that reads a code stream from a storage position corresponding to (n-1) times (n is a positive integer equal to or less than N) , and a GOP detection that detects a position of a first GOP from each read code stream And a file reading unit for reading a code stream of a division range from the storage position of the stored GOP and a real division position storage unit for storing a storage position of each detected GOP. A code stream division device for parallel processing. 6. The code according to claim 5, wherein the code stream reading unit detects a GOP position from a storage position corresponding to (n-1) times the provisional division length in a time series from the head of the file. Stream splitting device.

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