Video data compression apparatus and method of same

• US 6,337,879 B1
• Filed: 08/11/1997
• Issued: 01/08/2002
• Est. Priority Date: 08/14/1996
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kitamura, Takuya, Suzuki, Takao, Mihara, Kanji
• Primary Examiner(s): Kelley, Chris
• Assistant Examiner(s): PHILIPPE, GIMS S
• Application Number:
  US08/909,448
• Time in Patent Office: 1,611 Days
• Field of Search: 348/400, 348/402, 348/405, 348/384, 348/407, 348/413, 348/419, 348/415, 348/700, 348/672, 348/416, 348/390.1, 382/232, 382/235, 382/236, 382/239, 382/242, 375/240
• US Class Current: 375/240
• CPC Class Codes: H04N 19/114 Adapting the group of pictures [GOP] structure, e.g. number of B-frames between two anchor frames H04N19/107 takes precedence
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/177 the unit being a group of pictures [GOP]
• CPC Class Codes: H04N 19/194 involving only two passes
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/198 including smoothing of a sequence of encoding parameters, e.g. by averaging, by choice of the maximum, minimum or median value
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A video data compression apparatus with which compressed video data of suitable amounts of data can be produced and in addition the time required for processing is short. An encoder control unit performs a preprocessing for compression and coding and, at the same time, produces a flatness and an intra AC as parameters indicating the difficulty of the pattern of pictures to be compressed to I pictures. A motion detector calculates a predictive error amount (ME residual) of the motion prediction. An FIFO memory delays each picture of the input video data. A host computer approximates a real difficulty data D_j indicating the difficulty of the pattern of each picture by the ME residual, flatness, and intra AC and further calculates the target amount of data T_j of the compressed video data from the approximated real difficulty data D_j. The encoder performs the compression and coding so that the amount of data of the compressed video data becomes substantially the target amount of data T_j.

Claims

1. A video data compression apparatus, comprising:

indicator data calculating means for calculating indicator data indicating a complexity of video data for every picture from non-compressed video data;

target value calculating means for calculating a target value of an amount of data after compression of said video data for every picture based on said calculated indicator data; and

compressing means for compressing said non-compressed video data so that the amount of data after compression becomes said calculated target value, wherein

said compressing means compresses said non-compressed video data to a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture, or a combination of them) in a predetermined order,

said indicator data calculating means calculates ME residual data as said indicator data of pictures to be compressed to a P picture and B picture and calculates flatness data and intra AC data or one of the same as said indicator data of a picture to be compressed to an I picture, and

said target value calculating means calculates difficulty data corresponding to the amount of data after compression based on said calculated indicator data and further calculates said target value based on the calculated difficulty data.

2. A video data compression apparatus according to claim 1, wherein:

said indicator data calculating means calculates an activity as the indicator data for compressing said video data to an I picture.

3. A video data compression apparatus according to claim 1 further comprising:

delaying means for delaying said video data for a predetermined time and then outputting same;

wherein

said target value calculating means calculates said target value with respect to an output picture outputted by said delaying means based on said indicator data calculated during a period where said delaying means delays said video data, and

said compressing means compresses pictures outputted by said delaying means so that the amount of data after compression becomes said calculated target value.

4. A video data compression method, comprising the steps of:

calculating indicator data indicating a complexity of video data for every picture from non-compressed video data;

calculating a target value of an amount of data after compression of said video data for every picture based on said calculated indicator data; and

compressing said non-compressed video data by a predetermined compression method so that the amount of data after compression becomes said calculated target value, wherein

said compressing step compresses said non-compressed video data to a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture, or a combination of the same) in a predetermined order,

said indicator data calculating step calculates ME residual data as said indicator data of pictures to be compressed to a P picture and B picture and calculates flatness data and intra AC data or one of the same as said indicator data of a picture to be compressed to an I picture,

said data amount target value calculating step further has a step for calculating difficulty data corresponding to the amount of data after compression based on said calculated indicator data, and

said target value is calculated based on the calculated difficulty data.

5. A video data compression method according to claim 4, wherein:

said indicator data calculating step calculates an activity as the indicator data for compressing said video data to an I picture.

6. A video data compression method according to claim 4, further comprising the step of delaying said video data by a predetermined time and outputting same, wherein

said data amount target value calculating step calculates said target value with respect to an output picture delayed and outputted based on said indicator data calculated during a period where said video data is delayed, and

said compression step compresses the output picture so that the amount of data after compression becomes said calculated target value.

7. A video data compression apparatus, comprising:

indicator data calculating means for calculating indicator data indicating a complexity of video data for every picture from non-compressed video data;

difficulty data calculating means for performing a predetermined computation processing for multiplying a coefficient with said calculated indicator data to calculate difficulty data corresponding to an amount of data after compression of said video data for every picture;

target value calculating means for calculating a target value of the amount of data after compression of said video data for every picture based on said calculated difficulty data;

compressing means for compressing each of the pictures of said non-compressed video data by a predetermined compression method so that the amount of data after compression becomes said calculated target value so as to generate compressed video data; and

coefficient updating means for updating said coefficient based on the amount of data of the generated compressed video data, wherein

said compressing means compresses said non-compressed video data to a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture, or a combination of the same) in a predetermined order; and

said indicator data calculating means calculates ME residual data as said indicator data of pictures to be compressed to a P picture and B picture and calculates flatness data, intra AC data, and activity or a combination of the same as said indicator data of a picture to be compressed to an I picture.

8. A video data compression apparatus according to claim 7, wherein:

said compressing means has

quantizing means for quantizing said video data by a quantization value set from an external unit so as to generate said compressed video data and

quantization value adjusting and setting means for successively adjusting said quantization value based on said calculated target value and setting the same in said quantizing means; and

said coefficient updating means updates said coefficient based on an average value of said quantization values set in said quantizing means of said compressing means, an amount of data of said generated compressed video data, and said calculated indicator data.

9. A video data compression apparatus according to claim 8, wherein

said coefficient updating means has:

global complexity calculating means for calculating a global complexity based on the average value of said quantization values set in said quantizing means of said compressing means and the amount of data of said generated compressed video data and

coefficient calculating means for calculating said coefficient based on said calculated global complexity and said indicator data.

10. A video data compression apparatus according to claim 9, wherein:

said coefficient calculating means divides the global complexity of a picture which becomes an I picture after compression by said generated flatness, intra AC, or activity to calculate said coefficient for an I picture and divides the global complexity of a picture which become a P picture or a B picture after compression by said generated HE residual to calculate said coefficient for a P picture and said coefficient for a B picture.

11. A video data compression apparatus according to claim 10, wherein:

said coefficient calculating means adds or subtracts a predetermined offset value with respect to said global complexity and divides the result by said generated flatness, intra AC, or activity to calculate said coefficient for an I picture and divides the global complexity of a picture which becomes a P picture or a B picture after compression by said generated HE residual to calculate said coefficient for a P picture and said coefficient for a B picture.

12. A video data compression method, comprising the steps of:

calculating indicator data indicating a complexity of video data for every picture from non-compressed video data;

performing predetermined computation processing for multiplying a coefficient with said calculated indicator data to calculate difficulty data corresponding to an amount of data after compression of said video data for every picture;

calculating a target value of the amount of data after compression of said video data for every picture based on said calculated difficulty data;

compressing each of the pictures of said non-compressed video data by a predetermined compression method so that the amount of data after compression becomes said calculated target value so as to generate compressed video data; and

updating said coefficient based on the amount of data of the generated compressed video data, wherein

said compressing step compresses said non-compressed video data to a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture, or a combination of the same) in a predetermined order; and

said indicator data calculating step calculates ME residual data as said indicator data of pictures to be compressed to a P picture and B picture and calculates flatness data, intra AC data, and activity or a combination of the same as said indicator data of a picture to be compressed to an I picture.

13. A video data compression method according to claim 12, wherein:

said compressing step further contains

a step of quantizing the video data subjected to said predetermined compression processing by a quantization value set from an external unit so as to generate said compressed video data and

a step of successively adjusting and setting said quantization value based on said calculated target value; and

said updating step updates said coefficient based on an average value of said adjusted and set quantization values, the amount of data of said generated compressed video data, and said calculated indicator data.

14. A video data compression method according to claim 13, wherein:

said updating step

calculates a global complexity based on the average value of said adjusted and set quantization values and the amount of data of said generated compressed video data and

calculates said coefficient based on said calculated global complexity and said indicator data.

15. A video data compression method according to claim 14, wherein:

said updating step divides the global complexity of a picture which becomes an I picture after compression by said generated flatness, intra AC, or activity to calculate a coefficient for the I picture and divides the global complexity of a picture which becomes a P picture or a B picture after compression by said generated ME residual to calculate said coefficient for a P picture and said coefficient for a B picture.

16. A video data compression method according to claim 15, wherein:

said updating step adds or subtracts a predetermined offset value with respect to said global complexity and divides the result by said generated flatness, intra AC, or activity to calculate said coefficient for an I picture and divides the global complexity of a picture which becomes a P picture or a B picture after compression by said generated ME residual to calculate said coefficient for a P picture and said coefficient for a B picture.

17. A video data compression apparatus for compressing a continuous plurality of video data to compressed video data of a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture) in a predetermined order, comprising:

rearranging means for rearranging pictures of said video data to an order adapted to the compression method so that each head picture of said video data becomes an I picture or a P picture;

indicator data calculating means for calculating indicator data indicating a complexity of said rearranged video data for every picture;

border detecting means for detecting a scene change of a continuous plurality of said video data;

changing means for changing said picture type sequence so that a picture of any of said video data are compressed without reference to a picture of other video data for every border of a detected scene change;

target value calculating means for calculating a target value of the amount of data after compression of said video data based on said calculated indicator data and said picture type sequence after change; and

compressing means for compressing said video data to compressed video data of said picture type sequence after change so that the amount of data after compression becomes substantially said calculated target value, wherein

said target value calculating means has

approximating means for performing predetermined computation processing for multiplying a coefficient with said calculated indicator data to calculate difficulty data corresponding to the amount of data after compression and

calculating means for calculating a target of the amount of data after compression of said video data for every picture based on said calculated difficulty data, and

said compressing means has

quantizing means for quantizing said video data by a quantization value set from an external unit so as to generate said compressed video data and

quantization value adjusting and setting means for successively adjusting said quantization values based on said calculated target value and setting the same in said quantizing means;

said video data compression apparatus further comprising

coefficient updating means for updating said coefficient based on the average value of said quantization values set in said quantizing means of said compressing means, the amount of data of said generated compressed video data, and said calculated indicator data.

18. A video data compression apparatus according to claim 17, wherein

said target value calculating means has:

predictive target amount calculating means for calculating said target value in accordance with the type of picture after compression by predicting that pictures contained in the predetermined compression unit are compressed as an order of said picture type sequence in advance before the change of said picture type sequence and

target amount correcting means for correcting said target value of a picture of said video data of a type of picture which after compression is changed in accordance with the type of the picture after the change in only a case where a change of said picture type sequence actually exists.

19. A video data compression apparatus according to claim 18, wherein:

said indicator data calculating means calculates the flatness, intra AC, and activity as indicator data of a picture which becomes an I picture after compression and the ME residual as indicator data of a picture which becomes a P picture or a B picture after compression;

said changing means changes said picture type sequence so that the picture of the head of said video data is compressed to an I picture when the picture of the head of said video data would be compressed to a P picture; and

said target amount correcting means corrects said target value of a picture of a type of picture after compression which changes from a P picture to an I picture, which is calculated in advance, to said target amount of a picture in a case where it becomes an I picture after compression and corrects said target value of a picture of a type of the picture after compression which changes from an I picture to a P picture, which is calculated in advance, to said target amount of a picture in a case where it becomes a P picture after compression.

20. A video data compression apparatus according to claim 17, wherein

said coefficient updating means has

global complexity calculating means for calculating a global complexity based on an average value of said quantization values set in said quantizing means of said compressing means and the amount of data of said generated compressed video data and

coefficient calculating means for calculating a coefficient based on said calculated global complexity and said indicator data.

21. A video data compression apparatus according to claim 20, wherein:

said coefficient calculating means divides a global complexity of a picture which becomes an I picture after compression by said generated flatness, intra AC, or activity to calculate a coefficient for an I picture and divides a global complexity of a picture which becomes a P picture or a B picture after compression by said generated ME residual to calculate a coefficient for a P picture or a coefficient for a B picture.

22. A video data compression method for compressing a continuous plurality of video data to compressed video data of a picture type sequence containing a plurality of types of pictures (I picture, P picture, and B picture) in a predetermined order, comprising the steps of:

rearranging pictures of said video data to an order adapted to the compression method so that each head picture of said video data becomes an I picture or a P picture;

calculating indicator data indicating a complexity of said rearranged video data for every picture;

detecting a scene change of a continuous plurality of said video data;

changing said picture type sequence so that a picture of any of said video data is compressed without reference to a picture of other video data for every border of a detected scene change;

calculating a target value of the amount of data after compression of said video data based on said calculated indicator data and said picture type sequence after change; and

compressing said video data to compressed video data of said picture type sequence after change so that the amount of data after compression becomes substantially said calculated target value, wherein

said target value calculating step performs predetermined computation processing for multiplying a coefficient with said calculated indicator data so as to calculate difficulty data corresponding to the amount of data after compression and

calculates a target of the amount of data after compression of said video data for every picture based on said calculated difficulty data,

said compressing step quantizes video data subjected to said predetermined compression processing by a quantization value set from an external unit so as to generate said compressed video data and

successively adjusts said quantization value based on said calculated target value and sets the same, and

said predetermined coefficient is updated based on the average value of said set quantization values, the amount of data of said generated compressed video data, and said calculated indicator data.

23. A video data compression method according to claim 22, wherein

said target value calculating step calculates said target value in accordance with the type of picture after compression by predicting that pictures contained in said predetermined compression unit are compressed as an order of said picture type sequence in advance before the change of said picture type sequence and

corrects said target value of the picture of said noncompressed video data of a type of picture which after compression is changed in accordance with the type of the picture after the change in only a case where a change of said picture type sequence actually exists.

24. A video data compression method according to claim 23, wherein:

said indicator data calculating step calculates a flatness, intra AC, and activity as indicator data of a picture which becomes an I picture after compression and an ME residual as indicator data of a picture which becomes a P picture or a B picture after compression;

changes said picture type sequence so that the picture of the head of said video data is compressed to an I picture where the picture of the head of said video data would be compressed to a P picture; and

corrects said target value of a picture of a type of picture after compression which is changed from a P picture to an I picture, which is calculated in advance, to said target amount of a picture in the case where it becomes an I picture after compression and corrects said target value of a picture of a type of picture after compression which is changed from an I picture to a P picture, which is calculated in advance, to said target amount of a picture in the case where it becomes a P picture after compression.

25. A video data compression method according to claim 22, wherein

said coefficient updating step calculates a global complexity based on the average value of said quantization values to be set and the amount of data of said generated compressed video data and

calculates said coefficient based on said calculated global complexity and said indicator data.

26. A video data compression method according to claim 25, wherein:

said coefficient calculating step divides a global complexity of a picture which becomes an I picture after compression by said generated flatness, intra AC, or activity to calculate said coefficient for an I picture and divides a global complexity of a picture which becomes a P picture or a B picture after compression by said generated ME residual to calculate said coefficient for a P picture or said coefficient for a B picture.