Opened 3 years ago

Last modified 3 years ago

#2174 new defect

mencoder reports malformed audio position of tv recording when no audio

Reported by: jarekczek@… Owned by:
Priority: low Component: mencoder
Version: HEAD Severity: trivial
Keywords: Cc:
Blocked By: Blocking:
Reproduced by developer: no Analyzed by developer: no


Mencoder reports negative audio position. This kills mencoder's ability to sync audio and video.

Command line of mencoder r36960:
mencoder -o /m/test.avi tv:// -endpos 0.1 -ovc raw -v

VPos: 0.1s APos:-9223372036854775808.0s 3f ( 0%) 0fps Trem: 0min

My kernel is 3.12.8-1 on Debian. Not reproducible with kernel 3.2. I guess the problem lies in kernel video driver, which started to use monotonic timestamps somewhere about 3.9 version. These are the related kernel commits: introduced monotonic timestamps, flags for timestamps types, commits of this author. The changes are from 2012-12-21.

Mencoder needs to be changed to work with both kind of timestamps (old and new kernels). When time permits I will provide a patch.

Change History (2)

comment:1 Changed 3 years ago by jarekczek@…

Mencoder reports negative audio position, because it does not process audio at all. The command line needs adding "-tv immediatemode=0:forceaudio -oac copy". So it is not at all about kernel changes. Please remove "(monotonic timestamps)" from the bug summary, if possible.

I'll prepare a separate bug report for the kernel timestamps problem, which actually manifests in a different way. I joined these 2 erratic behaviours by mistake.

I'll provide a patch for this problem (negative APos reported). Mencoder should neither read nor print audio muxer time, if the audio muxer is not initialized (mux_a == 0).

comment:2 Changed 3 years ago by jarekczek@…

  • Component changed from streaming to mencoder
  • Priority changed from normal to low
  • Severity changed from major to trivial
  • Summary changed from mencoder reports malformed audio position of tv recording (monotonic timestamps) to mencoder reports malformed audio position of tv recording when no audio
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