GPU timeline with render-ahead queue

• US 7,817,900 B2
• Filed: 06/30/2005
• Issued: 10/19/2010
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Walker, Brian J.
• Primary Examiner(s): Tran; Thai
• Assistant Examiner(s): TOPGYAL, GELEK W
• Application Number:
  US11/170,930
• Publication Number:
  US 20070006060A1
• Time in Patent Office: 1,937 Days
• Field of Search: 386/46, 386/53, 386/125, 386/68
• US Class Current: 386/278
• CPC Class Codes: H04N 5/765 Interface circuits between an apparatus for recording and another apparatus
• CPC Class Codes: H04N 5/775 between a recording apparatus and a television receiver
• CPC Class Codes: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/783 Adaptations for reproducing at a rate different from the recording rate
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 5/907 using static stores, e.g. storage tubes or semiconductor memories H04N5/91 takes precedence
• CPC Class Codes: H04N 9/8042 involving data reduction
• CPC Class Codes: H04N 9/877 by assembling picture element blocks in an intermediate memory

Abstract

Video editing and video playback utilizing a render-ahead queue for storing rendered video frames. The render-ahead queue facilitates the smooth playback of video in forward and reverse timeline direction, avoiding video glitches that occur when video frames are rendered at a rate that is less than the timeline rate of the video file. Embodiments of the present invention also include the use of a graphics processing unit in conjunction with the render-ahead queue to further ensure smooth playback of video.

Claims

1. A computer-implemented method for displaying a plurality of video frames in a reverse order relative to a forward order, the method comprising:

decoding in a forward order video frames in a video timeline from a video file;

storing the decoded video frames into video memory;

rendering effects onto the stored video frames for playback at a playback rate;

queuing the rendered video frames in the forward order into a secondary queue;

removing the rendered video frames from the secondary queue in a reverse order relative to the forward order;

queuing said removed video frames into a render-ahead queue, wherein queuing video frames into the render-ahead queue occurs at a rate that exceeds the playback rate;

displaying the queued video frames from the render-ahead queue to a screen in the reverse order; and

deleting the displayed video frames from the render-ahead queue after said queued video frames have been displayed to the screen.

2. The method of claim 1, whereby a graphics processing unit renders the effects onto the video frames stored in video memory and queues the rendered video frames into the render-ahead queue.

3. The method of claim 1, whereby a central processing unit decodes the video frames and a graphics processing unit displays the rendered video frames to the screen.

4. The method of claim 1, further comprising retaining one or more video frames on the render-ahead queue after the video frames have been displayed to the screen.

5. The method of claim 1, whereby the render-ahead queue contains at least three video frames.

6. The method of claim 1, whereby the queue is comprised of memory buffers that store the rendered video frames, the method further comprising:

pausing allocation of additional rendered video frames to the render-ahead queue when all available memory buffers are full;

making the memory buffer available for allocation of video frames; and

resuming allocation of additional rendered video frames to the available buffers on the render-ahead queue.

7. The method of claim 1, wherein one or more computer-readable media have computer-executable instructions for performing the computer-executable method of claim 1.

8. A system for displaying video in a reverse order relative to a forward order, said system having a video file, video memory, a screen, a central processing unit, and a graphics processing unit, comprising:

a render-ahead queue comprising rendered video frames;

the central processing unit being configured to execute computer-executable instructions for;

decoding in a forward order a video file comprising a plurality of video frames in a video timeline into the video memory;

the graphics processing unit being configured to execute computer executable instructions for;

rendering effects onto two or more video frames in the video memory for playback at a playback rate;

queuing the rendered video frames in the forward order into a secondary queue;

removing the rendered video frames from the secondary queue in a reverse order relative to the forward order;

queuing the removed video frames in the reverse order into the render-ahead queue in the reverse order, wherein queuing video frames into the render-ahead queue occurs at a rate that exceeds the playback rate;

displaying the queued video frames from the render-ahead queue to a screen in the reverse order; and

deleting the displayed video frames from the render-ahead queue after said queued video frames have been displayed to the screen.

9. The system of claim 8, wherein said graphics processing unit is further configured to execute computer executable instructions for retaining the video frame on the render-ahead queue after it has been displayed to the screen.

10. The system of claim 8, wherein the render-ahead queue contains at least three video frames.

11. The system of claim 8, wherein the queue is comprised of memory buffers that store the rendered video frames, said graphics processing unit is further configured to execute computer executable instructions for:

pausing allocation of additional rendered video frames to the render-ahead queue when all available memory buffers are full;

making the memory buffer available to allocation of video frames; and

resuming allocation of additional rendered video frames to the available buffers on the render-ahead queue.

12. One or more non-transitory computer-readable storage media having computer-executable instructions stored thereon for performing the following steps:

rendering effects onto two or more video frames in a video timeline for playback at a playback rate;

queuing the rendered video frames in a forward order into a secondary queue;

queuing the rendered video frames from the secondary queue into a render-ahead queue in a reverse order relative to the forward order, wherein queuing video frames into the render-ahead queue occurs at a rate that exceeds the playback rate;

displaying the queued video frames from the render-ahead queue to a screen in the reverse order; and

deleting the displayed video frames from the render-ahead queue after said queued video frames have been displayed to the screen.

13. The non-transitory computer-readable storage media of claim 12, wherein the queue is comprised of memory buffers that store the rendered video frames, the computer-readable storage media further comprising computer-executable instructions for:

pausing allocation of additional rendered video frames to the render-ahead queue when all available memory buffers are full;

making the buffer available for allocation of video frames; and

resuming allocation of additional rendered video frames to available buffers on the render-ahead queue.