[mythtv-users] Audio starts before video on some recordings

[Jean-Yves Avenard]

On 25 July 2014 14:16, Jesse Hughes <jesse at phiwumbda.org> wrote:
> Hello.
>
> I have two HD-PVRs and I'm having an odd effect with recordings from one of
> the two.
>
> On some, but not all, recordings, I hear the audio begin about half a second
> or more before the video.  The video often starts in a kind of slow motion
> when this happens.  As a result, the audio is far ahead of the video during
> playback.
>
> This occurs in both HD and SD recordings.  However, and this is the kicker,
> the problem is not in the recording itself!  If I play back the recording
> using mplayer, the audio and video are synced.

What video profile are you using?

if software decoding, this is likely related to how FFmpeg h264
decoder works when multi-threaded decoding is enabled.

It will only start to output frames once all threads have decoded a
frame, and with the HD-PVR having rather large spaced reference frame,
this can take a short while...

Shouldn't lead to bad A/V sync however.
Which version of mythtv are you using?

if 0.27, try the devel/027candidates as it contains some changes on
the matter (A/V Sync)
or Master which has much better handling of HD-PVR files, including
much faster seeking