[mythtv-commits] Ticket #12004: Short seeks intolerably slow with HDPVR and vdpau

[MythTV]

#12004: Short seeks intolerably slow with HDPVR and vdpau
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 Reporter:  mythtv@…                 |          Owner:  stichnot
     Type:  Bug Report - General     |         Status:  accepted
 Priority:  minor                    |      Milestone:  unknown
Component:  MythTV - Video Decoding  |        Version:  0.27-fixes
 Severity:  medium                   |     Resolution:
 Keywords:                           |  Ticket locked:  0
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Comment (by mythtv@…):

 I did a quick test measuring the frame-by-frame seek time on a decent
 ffmpeg decoded frontend (i7-3520M) with an hdpvr h264 stream, and came up
 with 648 ms to seek 95 frame, about 7 ms per frame.  At that speed it
 still doesn't make sense to me to spend 100ms decoding frames just to skip
 over 14 out of 95 frames after the keyframe.

 The advantage of your idea is that it is adaptive - on slow decoders you
 get something like keyframe seeking, on fast decoders you get exact
 seeking, but I think 100 ms is going to be too short to be useful, and a
 higher time would negatively impact seek times on slow decoders.  I've
 attached a patch that tries to predict the longer decoding time after the
 first 5 frames and then short-circuit the rest of the decoding.  Its still
 set to limit to an expected 100 ms, but it could be increased to 500 ms
 without causing effectively all of my seeks to take 500 ms.

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Ticket URL: <http://code.mythtv.org/trac/ticket/12004#comment:3>
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