[mythtv-commits] Ticket #13176: AVsync is broken at high playback speeds in some streams
MythTV
noreply at mythtv.org
Tue Nov 14 02:55:09 UTC 2017
#13176: AVsync is broken at high playback speeds in some streams
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Reporter: Brad Martin <mythtv@…> | Owner: jyavenard
Type: Patch - Bug Fix | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - Video Playback | Version: 0.28.1
Severity: medium | Keywords:
Ticket locked: 0 |
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At playback speeds of 1.5x or greater, I have found that the video can
often surge way ahead of the audio, by tens of seconds or more. This
often happens during a commercial break, where I was in sync prior to the
commercial, but completely lose sync upon the transition. It may
eventually sync again when the show comes back on. FWIW I have a frame-
doubling interlacer configured, which may be implicated as well.
I have tracked this down to a couple of causes:
* The VideoSync class is not being kept up to date with the frame
interval and frame-doubling state at any given time as the stream and
playback speed change.
* The VideoSync is attempting to clamp the maximum sync adjustment to a
small multiple of the wrong frame interval due to the above.
* The avsync_predictor is continually dropping frames, because it is
failing to account for extra time due to the repeat_pict setting on some
video frames, as well as any dynamically-applied sync delay.
Attached is a patch against the fixes/0.28 branch that improves these
issues for me.
--
Ticket URL: <https://code.mythtv.org/trac/ticket/13176>
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