Coding control method, coding control apparatus and storage medium containing coding control program

• US 6,389,073 B1
• Filed: 04/07/1999
• Issued: 05/14/2002
• Est. Priority Date: 04/07/1998
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kurobe, Akio, Masaki, Shoichi
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US09/287,337
• Time in Patent Office: 1,133 Days
• Field of Search: 375/240.03, 375/240.04, 375/240.05, 375/240.08
• US Class Current: 375/240.03
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• 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 19/196 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 19/61 in combination with predictive coding

Abstract

In a coding control apparatus deciding, when coding of motion picture data on the basis of a generated information amount Aig of coded data generated by coding one frame, a quantization characteristic to be used for coding a next frame, a threshold comparison part compares the generated information amount Aig with upper bound and lower bound thresholds Th_U and Th_L, and on the basis of the comparison result, a quantization characteristic decision part decides the quantization characteristic to be used for coding the next frame. In other words, the quantization characteristic decision part divides each frame of the motion picture data previously into a plurality of areas and classifies the plurality of areas in each frame into a first group and a second group, and sets, in response to the aforementioned comparison result, the same quantization characteristic for the first and second groups, or sets one of most approximate two different quantization characteristics for the first group and the other one for the second group respectively. Due to such a structure, a quantization state corresponding to the average quantization characteristic of most approximate two quantization characteristics q(s) and q(s+1) can be created, whereby precision of coding control improves.

Claims

1. A coding control apparatus for deciding, in coding data formed by a plurality of frames on the basis of a generated information amount being the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, a quantization characteristic employed for coding a next frame to said one frame, comprising:

comparison means for comparing said generated information amount or said occupied amount with a predetermined value; and

quantization characteristic decision means for dividing each frame of said plurality of frames previously into a plurality of areas while classifying said plurality of areas in said each frame into a first group and a second group for setting in response to a comparison result by said comparison means the same quantization characteristic for said first and second groups or setting one of most approximate two different quantization characteristics for said first group and the other one for said second group respectively.

2. The coding control apparatus in accordance with claim 1, wherein said plurality of areas are so classified that the amount of coded data obtained by coding said first group and the amount of coded data obtained by coding said second group balance with each other previously into said first and second groups.

3. The coding control apparatus in accordance with claim 2, wherein said areas belonging to said first group and said areas belonging to said second group are spatially alternately arranged.

4. The coding control apparatus in accordance with claim 2, further comprising time axis placement control means for outputting a signal instructing an operation of exchanging a quantization characteristic to be set for said first group and a quantization characteristic to be set for said second group every prescribed time as a time axis placement control signal, wherein

said quantization characteristic decision means sets in response to said time axis placement control signal quantization characteristics for said first and second groups.

5. The coding control apparatus in accordance with claim 2, wherein, in the case that forced updating by INTRA coding is performed on any one area among said plurality of areas when coding said data formed by said plurality of frames, said quantization characteristic decision means classifies, among said plurality of areas, an area to be subjected to forced updating to said first group, while classifying the remaining areas other than said area to be subjected to forced updating to said second group.

6. The coding control apparatus in accordance with claim 5, wherein said quantization characteristic decision means sets quantization characteristics for said first and second groups so that quantization precision for coding areas to be subjected to forced updating among said plurality of areas is higher or equal to quantization precision for coding the remaining areas other than said areas to be subjected to forced updating.

7. The coding control apparatus in accordance with claim 1, wherein said areas are groups of blocks.

8. The coding control apparatus in accordance with claim 1, further comprising:

transition step width control means for comparing previously set upper bound and lower bound transition step width control thresholds with said generated information amount;

wherein

quantization characteristic set means sets, on the basis of a comparison result by said transition step width control means,

said quantization characteristic employed for coding said next frame so that, when said generated information amount is less than said upper bound transition step width control threshold and greater than said lower bound transition step width control threshold, only a quantization characteristic having been set for one of said first and second groups is changed or quantization characteristics for said first and second groups are maintained, and

sets said quantization characteristic employed for coding said next frame so that, when said generated information amount is greater than said upper bound transition step width control threshold or less than said lower bound transition step width control threshold, both said quantization characteristics having been set for said first and second groups are changed.

9. A coding control apparatus deciding, in coding motion picture data formed by a plurality of frames on the basis of a generated information amount being the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, a quantization characteristic employed for coding a next frame to said one frame, comprising:

detection means for detecting, on the basis of a motion quantity of an object expressed by said motion picture, data either one or both of a motion start state of said object and a motion end state of said object; and

quantization control means for deciding, on the basis of said generated information amount or said occupied amount and a detection result by said detection means, said quantization characteristic employed for coding said next frame.

10. The coding control apparatus in accordance with claim 9, wherein said quantization control means suppresses on the basis of said detection result by said detection means change of a quantization characteristic employed for frame coding in said motion start state of said object in a direction improving the picture quality.

11. The coding control apparatus in accordance with claim 9, wherein said quantization control means suppresses, on the basis of said detection result by said detection means, change of a quantization characteristic employed for frame coding in said motion end state of said object in a direction deteriorating the picture quality.

12. The coding control apparatus in accordance with claim 9, wherein said quantization control means changes, in the case of changing said quantization characteristic in a direction deteriorating the picture quality, when said motion start state of said object is detected by said detection means, said quantization characteristic more largely than that when said motion start state of said object is not detected.

13. The coding control apparatus in accordance with claim 9, wherein said quantization control means changes, in the case of changing said quantization characteristic in a direction improving the picture quality, when said motion end state of said object is detected by said detection means, said quantization characteristic more largely than that when said motion end state of said object is not detected.

14. The coding control apparatus in accordance with claim 9, further comprising:

storage means for storing an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

threshold set means for setting, on the basis of said detection result by said detection means, said upper bound threshold in a period of said motion start state of said object at a value lower than said upper bound threshold in a period other than said period of said motion start state of said object, wherein

said quantization control means changes said quantization characteristic in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and changes said quantization characteristic in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold.

15. The coding control apparatus in accordance with claim 9, further comprising:

storage means for storing an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

threshold set means for setting on the basis of said detection result by said detection means said lower bound threshold in a period of said motion start state of said object at a value lower than said lower bound threshold in a period other than said period of said motion start state of said object, wherein

said quantization control means changes said quantization characteristic in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and changes said quantization characteristic in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold.

16. The coding control apparatus in accordance with claim 9, further comprising:

storage means for storing an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

threshold set means for setting on the basis of said detection result by said detection means said upper bound threshold in a period of said motion end state of said object at a value higher than said upper bound threshold in a period other than said period of said motion end state of said object, wherein

said quantization control means changes said quantization characteristic in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and changes said quantization characteristic in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold.

17. The coding control apparatus in accordance with claim 9, further comprising:

storage means for storing an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

threshold set means for setting, on the basis of said detection result by said detection means, said lower bound threshold in a period of said motion end state of said object at a value higher than said lower bound threshold in a period other than said period of said motion end state of said object, wherein

said quantization control means changes said quantization characteristic in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and changes said quantization characteristic in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold.

18. The coding control apparatus in accordance with claim 9, wherein said detection means detects such a state that a motion quantity of said object is greater than a previously set threshold and said motion quantity of said object continuously increases as said motion start state of said object.

19. The coding control apparatus in accordance with claim 9, wherein said detection means detects such a state that a motion quantity of said object is greater than a previously set threshold and said motion quantity of said object continuously reduces as said motion end state of said object.

20. The coding control apparatus in accordance with claim 9, wherein said motion quantity is the sum of absolute values of motion vectors being coded data when performing motion prediction inter-frame differential coding.

42. The coding control apparatus in accordance with claim 9, wherein said motion quantity is the sum of the macroblocks whose absolute values of motion vectors being coded data at the time of motion prediction inter-frame differential coding performed to the respective macroblocks exceed a previously set threshold.

21. A coding control method employed in coding data formed by a plurality of frames on the basis of a generated information amount being the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, for deciding a quantization characteristic employed for coding a next frame to said one frame, comprising:

a comparison step of comparing said generated information amount or said occupied amount with a predetermined value; and

a quantization characteristic decision step of dividing each frame of said plurality of frames previously into a plurality of areas while classifying said plurality of areas in said each frame into a first group and a second group for in response to a comparison result by said comparison step setting the same quantization characteristic for said first and second groups or setting one of most approximate two different quantization characteristics for said first group and the other one for said second group respectively.

22. The coding control method in accordance with claim 21, wherein said plurality of areas are classified previously into said first and second groups so that the amount of coded data obtained by coding said first group and the amount of coded data obtained by coding said second group can balance with each other.

23. The coding control method in accordance with claim 22, wherein said areas belonging to said first group and areas belonging to said second group are spatially alternately arranged.

24. The coding control method in accordance with claim 22, wherein a quantization characteristic to be set for said first group and a quantization characteristic to be set for said second group are exchanged every prescribed time in said quantization characteristic decision steps.

25. The coding control method in accordance with claim 22, wherein, in case that forced updating by INTRA coding is performed on any one area among said plurality of areas when coding said data formed by said plurality of frames, an area to be subjected to forced updating among said plurality of areas is classified to said first group, while the remaining areas other than said area to be subjected to forced updating is classified to said second group in said quantization characteristic decision steps.

26. The coding control method in accordance with claim 21, wherein said areas are groups of blocks.

27. The coding control method in accordance with claim 21, comprising:

a second comparison step of comparing previously set upper bound and lower bound transition step width control thresholds with said generated information amount;

wherein

in quantization characteristic decision, on the basis of a comparison result by said second comparison step,

said quantization characteristic employed for coding said next frame is set so that, when said generated information amount is less than said upper bound transition step width control threshold and greater than said lower bound transition step width control threshold, only a quantization characteristic having been set for one of said first and second groups is changed or quantization characteristics for said first and second groups are maintained, and

said quantization characteristic employed for coding said next frame is set so that, when said generated information amount is greater than said upper bound transition step width control threshold or less than said lower bound transition step width control threshold, both said quantization characteristics having been set for said first and second groups are changed.

28. A coding control method for deciding, in coding motion picture data formed by a plurality of frames, on the basis of a generated information amount being the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, a quantization characteristic employed for coding a next frame to said one frame, comprising:

a detection step of detecting, on the basis of a motion quantity of an object expressed by said motion picture data, either one or both of a motion start state of said object and a motion end state of said object; and

quantization control step of deciding, on the basis of said generated information amount or said occupied amount and a detection result by said detection step, said quantization characteristic employed for coding said next frame.

29. The coding control method in accordance with claim 28, wherein, on the basis of said detection result by said detection step, change of a quantization characteristic employed for frame coding in said motion start state of said object in a direction improving the picture quality is suppressed in said quantization control step.

30. The coding control method in accordance with claim 28, wherein, on the basis of said detection result by said detection step, change of a quantization characteristic employed for frame coding in said motion end state of said object in a direction deteriorating the picture quality is suppressed in said quantization control step.

31. The coding control method in accordance with claim 28, wherein, in the case of changing said quantization characteristic in a direction deteriorating the picture quality, when said motion start state of said object is detected by said detection step, said quantization characteristic is changed more largely than that when said motion start state of said object is not detected in said quantization control step.

32. The coding control method in accordance with claim 28, wherein, in the case of changing said quantization characteristic in a direction improving the picture quality, when said motion end state of said object is detected by said detection step, said quantization characteristic is changed more largely than that when said motion end state of said object is not detected in said quantization control step.

33. The coding control method in accordance with claim 28, further comprising:

a first set step of setting an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

a second set step of setting, on the basis of said detection result by said detection steps, said upper bound threshold in a period of said motion start state of said object at a value lower than said upper bound threshold in a period other than said period of said motion start state of said object, wherein

said quantization characteristic is changed in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and said quantization characteristic is changed in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold in said quantization control step.

34. The coding control method in accordance with claim 28, further comprising:

a first set step of setting an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

a second set step of setting again, on the basis of said detection result by said detection step, said lower bound threshold in a period of said motion start state of said object at a value lower than said lower bound threshold in a period other than said period of said motion start state of said object, wherein

said quantization characteristic is changed in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and said quantization characteristic is changed in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold in said quantization control step.

35. The coding control method in accordance with claim 28, further comprising:

a first set step of setting an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

a third set step of setting again, on the basis of said detection result by said detection step, said upper bound threshold in a period of said motion end state of said object at a value higher than said upper bound threshold in a period other than said period of said motion end state of said object, wherein

said quantization characteristic is changed in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and said quantization characteristic is changed in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold in said quantization control step.

36. The coding control method in accordance with claim 28, further comprising:

a first set step of setting an upper bound threshold and a lower bound threshold for said generated information amount or said occupied amount; and

a third set step of setting, on the basis of said detection result by said detection step, said lower bound threshold in a period of said motion end state of said object at a value higher than said lower bound threshold in a period other than said period of said motion end state of said object, wherein

said quantization characteristic is changed in a direction deteriorating the picture quality when said generated information amount or said occupied amount exceeds said upper bound threshold and said quantization characteristic is changed in a direction improving the picture quality when said generated information amount or said occupied amount falls below said lower bound threshold in said quantization control step.

37. The coding control method in accordance with claim 28, wherein such a state that a motion quantity of said object is greater than a previously set threshold and said motion quantity of said object continuously increases is detected as said motion start state of said object in said detection step.

38. The coding control method in accordance with claim 28, wherein such a state that a motion quantity of said object is greater than a previously set threshold and said motion quantity of said object continuously reduces is detected as said motion end state of said object in said detection steps.

39. The coding control method in accordance with claim 28, wherein said motion quantity is the sum of absolute values of motion vectors being coded data when performing motion prediction inter-frame differential coding.

43. The coding control method in accordance with claim 28, wherein said motion quantity is the sum of the macroblocks whose absolute values of motion vectors being coded data at the time of motion prediction inter-frame differential coding performed to the respective macroblocks exceed a previously set threshold.

40. A storage medium containing a coding control program deciding, in coding data formed by a plurality of frames on the basis of a generated information amount which is the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, a quantization characteristic employed in coding of a next frame to the one frame as a program executed in a computer unit, wherein said coding control program implementing on the computer unit an operating environment which includes:

comparison step of comparing the generated information amount or the occupied amount with a predetermined value, and

quantization characteristic decision step of dividing each frame of the plurality of frames previously into a plurality of areas while classifying the plurality of areas in each frame into a first group and a second group for setting in response to a comparison result by the comparison steps the same quantization characteristic for the first and second groups or setting one of most approximate two different quantization characteristics for the first group and the other one for the second group respectively.

41. A storage medium containing a coding control program deciding, in coding motion picture data formed by a plurality of frames on the basis of a generated information amount which is the amount of coded data generated by coding one frame or an occupied amount in a smoothing buffer used for transmission of data after coding, a quantization characteristic employed in coding of a next frame to the one frame as a program executed in a computer unit, wherein said coding control program implementing on the computer unit an operating environment which includes:

a detection step of detecting, on the basis of a motion quantity of an object expressed by the motion picture data, either one or both of a motion start state of the object and a motion end state of the object, and

a quantization control step of deciding, on the basis of the generated information amount or the occupied amount and a detection result by said detection step, the quantization characteristic employed in coding of the next frame.