Method for reducing digital video frame frequency while maintaining temporal smoothness

• US 6,031,584 A
• Filed: 09/26/1997
• Issued: 02/29/2000
• Est. Priority Date: 09/26/1997
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Gray, Patricia Lee
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US08/938,776
• Time in Patent Office: 886 Days
• Field of Search: 348/845.2, 348/423, 348/439
• US Class Current: 375/240.28
• CPC Class Codes: G06T 9/004 Predictors, e.g. intraframe, interframe coding
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/440281 by altering the temporal resolution, e.g. by frame skipping television signal recording using magnetic recording on tape for reproducing at a rate different from the recording rate H04N5/783

Abstract

A method for reducing digital video frame frequency while maintaining temporal smoothness during processing of video frames for display is disclosed. The method predicts the number of video frames to be dropped prior to decoding of a video frame in response to a delay in the processing of video frames, adjusts the timestamp for each video frame surrounding the video frames to be dropped in response to the predicting and displays the video frames surrounding the video frames to be dropped according to the adjusted timestamp.

Claims

1. A method for maintaining temporal smoothness during processing of video frames comprising the steps of:

predicting the number of video frames to be dropped prior to decoding of a video frame in response to a delay in the processing of the video frames;

adjusting the timestamp of each video frame surrounding said video frames to be dropped in response to said step of predicting; and

displaying video frames surrounding said video frames to be dropped according to said adjusted timestamp.

2. The method of claim 1 wherein said step of adjusting further comprises the step of dividing the timestamp of said video frames to be dropped by a predetermined number of frames surrounding said video frames to be dropped to generate an adjustment value to be added to the timestamp of each said predetermined number of frames surrounding said video frame to be dropped.

3. The method of claim 1 wherein said step of predicting further comprises the step of determining an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames.

4. The method of claim 3 further comprising the step of generating an updated average decode time by adding the time elapsed of the last most recent video frame decoded.

5. The method of claim 4 further comprising the step of generating a targeted frame rate from the reciprocal of said average decode time, said targeted frame rate being the frame rate to be achieved during video processing.

6. The method of claim 5 further comprising the step of determining a time difference between a current time and a correct time at which a current video frame should be processing, said time difference being added to said average decode time and averaged to generate a new average decode time.

7. The method of claim 1 further comprising the step of detecting said delay in the processing of the video data.

8. The method of claim 7 further comprising the step of determining an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames.

9. The method of claim 8 further comprising the step of determining whether said average decode time is greater than a predetermined maximum time.

10. The method of claim 9 wherein said predetermined maximum time is an average of previous decode times.

11. The method of claim 10 wherein said predetermined maximum time is the reciprocal of an encoded frame rate, said encoded frame rate being the number of frames per second found in the video data being processed.

12. The method of claim 11 further comprising the step of determining the number of frames to drop by taking the difference between said encoded frame rate and said targeted frame rate, said encoded frame rate being the number of frames found in the video data being processed per second.

13. An apparatus comprising:

a decoder which decodes video information having,

a delay predictor which predicts the number of frames to be dropped,

a timestamp adjuster coupled to said delay predictor, said timestamp adjuster which determines a new timestamp for each video frame surrounding said video frames to be dropped; and

a video image renderer coupled to said decoder, said video image renderer displays said video frames surrounding said video frames to be dropped according to said new timestamps.

14. The apparatus of claim 13 wherein said delay predictor determines an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames, generates a targeted frame rate from the reciprocal of said average decode time, said targeted frame rate being the frame rate to be achieved during video processing, and determining the number of frames to drop by taking the difference between said encoded frame rate and said targeted frame rate, said encoded frame rate being the number of frames found in the video data being processed per second.

15. The apparatus of claim 13 wherein said timestamp adjuster divides the timestamp of said frames to be dropped by the number of a predetermined number of video frames surrounding said video frames to be dropped to generate an adjusted timestamp for each said predetermined number of video frames surrounding said video frames to be dropped.

16. An apparatus comprising:

means for decoding video information having,

means for predicting the number of video frames to be dropped,

means for adjusting coupled to said means for predicting, said means for adjusting adjusts new timestamp for each video frame surrounding said video frames to be dropped; and

means for rendering coupled to said means for decoding, said means for rendering renders video frames for display, displaying video frames surrounding said video frames to be dropped according to said new timestamps.

17. The apparatus of claim 16 wherein said means for predicting determines an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames, generates a targeted frame rate from the reciprocal of said average decode time, said targeted frame rate being the frame rate to be achieved during video processing, and determining the number of frames to drop by taking the difference between said encoded frame rate and said targeted frame rate, said encoded frame rate being the number of frames found in the video data being processed per second.

18. The apparatus of claim 16 wherein said means for adjusting divides the timestamp of said frames to be dropped by the number of a predetermined number of video frames surrounding said video frames to be dropped to generated an adjusted timestamp for each said predetermined number of video frames surrounding said video frames to be dropped.

19. A video decoding system comprising:

a storage medium having,

a decoder which decodes video frames, said decoder having,

a delay predictor which predicts the number of video frames to be dropped, and

a timestamp adjuster coupled to said delay predictor, said timestamp adjuster calculates a new timestamp for each video frame surrounding said video frames to be dropped, and

a video image renderer coupled to said decoder, said video image renderer displays video frames surrounding said video frames to be dropped according to said new timestamp; and

a central processing unit coupled to said storage medium, said central processing unit processes said delay predictor, said timestamp adjuster and said video image renderer.

20. The system of claim 19 wherein said delay predictor determines an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames, generates a targeted frame rate from the reciprocal of said average decode time, said targeted frame rate being the frame rate to be achieved during video processing, and determining the number of frames to drop by taking the difference between said encoded frame rate and said targeted frame rate, said encoded frame rate being the number of frames found in the video data being processed per second.

21. The system of claim 19 wherein said timestamp adjuster divides the timestamp of said frames to be dropped by the number of a predetermined number of video frames surrounding said video frames to be dropped to generated an adjusted timestamp for each said predetermined number of video frames surrounding said video frames to be dropped.

22. A video decoding system comprising:

a storage medium having,

means for decoding video frames, said means for decoding having,

means for predicting the number of video frames to be dropped,

means for adjusting coupled to said means for predicting, said means for adjusting adjusts a new timestamp for each frame surrounding said frames to be dropped, and

means for rendering coupled to said means for decoding, aid means for rendering renders video frames for display, displaying video frames surrounding said video frames to be dropped according to said new timestamp; and

means for processing coupled to said storage medium, said means for processing said means for predicting, said means for adjusting and said means for rendering.

23. The system of claim 22 wherein said means for predicting the number of video frames to drop determines an average decode time from the average time elapsed during decoding of a predetermined number of previous video frames, generates a targeted frame rate from the reciprocal of said average decode time, said targeted frame rate being the frame rate to be achieved during video processing, and determining the number of frames to drop by taking the difference between said encoded frame rate and said targeted frame rate, said encoded frame rate being the number of frames found in the video data being processed per second.

24. The system of claim 22 wherein said means for adjusting divides the timestamp of said frames to be dropped by the number of a predetermined number of video frames surrounding said video frames to be dropped to generated an adjusted timestamp for each said predetermined number of video frames surrounding said video frames to be dropped.