[mythtv-commits] Ticket #760: Transcode doesn't set keyframes properly

[MythTV]

#760: Transcode doesn't set keyframes properly
----------------------+-----------------------------------------------------
 Reporter:  wseltzer  |       Owner:  ijr
     Type:  defect    |      Status:  new
 Priority:  minor     |   Milestone:     
Component:  mythtv    |     Version:     
 Severity:  medium    |  
----------------------+-----------------------------------------------------
 Problem starts sometime between 7738 and 7780, and continues through
 current (8220).  If necessary, I can test further to find the precise rev
 where this was introduced.

 Recording from WinTV BT878 to MPEG4, cut and transcode to MPEG4.  After
 transcoding, keyframes do not appear to be set properly.  Watching a
 recording still works, but on skip forward or back, the image is blocky
 and then fills in.  Recordings are transcoded correctly if I revert to
 7738.

 mythfrontend -v playback on a brokenly transcoded file, jumping forward:
 2005-11-30 03:11:43.411 TV: ProcessKeypress()
 2005-11-30 03:11:43.411 TV: handled(0) actions[0](SEEKFFWD)
 2005-11-30 03:11:43.412 TV: handled(0) actions[1](RIGHT)
 2005-11-30 03:11:43.472 DecorderBase::DoFastForward(3425, do flush)
 2005-11-30 03:11:43.472 NVP: ClearAfterSeek()
 2005-11-30 03:11:43.473 VideoOutputXv: ClearAfterSeek()
 2005-11-30 03:11:43.473 VideoBuffers::DiscardFrames():
 UUAUUUUUUUUUUUUUUUUUUUUUUUUUUUU
 2005-11-30 03:11:43.473 VideoBuffers::DiscardFrames():
 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA -- done()
 2005-11-30 03:11:43.502 waiting for prebuffer... 0
 [mpeg4 @ 0xb75fd110]warning: first frame is no keyframe
 'video_output' mean = '34784.09', std. dev. = '14630.15', fps = '28.75'
 2005-11-30 03:11:48.012 TV: ProcessKeypress()
 2005-11-30 03:11:48.012 TV: handled(0) actions[0](SEEKFFWD)
 2005-11-30 03:11:48.013 TV: handled(0) actions[1](RIGHT)
 2005-11-30 03:11:48.060 DecorderBase::DoFastForward(6851, do flush)
 2005-11-30 03:11:48.060 NVP: ClearAfterSeek()
 2005-11-30 03:11:48.060 VideoOutputXv: ClearAfterSeek()
 2005-11-30 03:11:48.060 VideoBuffers::DiscardFrames():
 UUUUUUUUUUAUUUUUUUUUUUUUUUUUUUU
 2005-11-30 03:11:48.061 VideoBuffers::DiscardFrames():
 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA -- done()
 2005-11-30 03:11:48.100 waiting for prebuffer... 0
 [mpeg4 @ 0xb75fd110]warning: first frame is no keyframe
 'video_output' mean = '34918.18', std. dev. = '15315.23', fps = '28.64'
 'video_output' mean = '33330.83', std. dev. = '11012.46', fps = '30.00'

 Re-running commercial flagging on a broken recording gives a series of:
 [mpeg4 @ 0xb7663110]warning: first frame is no keyframe

 mplayer exits from the same files with "seek failed" on a ffwd (although
 testing with older files suggests it can't seek on those either).

 Let me know if more info would help.  I'll attach a snippet of a broken
 file to the ticket.

 --Wendy

-- 
Ticket URL: <http://cvs.mythtv.org/trac/ticket/760>
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