Thread: mplayer vdpau
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Old 09-25-09, 09:37 AM   #1190
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Join Date: May 2007
Posts: 72
Default Blu-ray audio desync in 28900+ mplayer SVNs

Hi *

Wrt post #1175 in this thread, I finally found direction where issue starts:

Issue is caused by refresh rate change. Namely:
-If TV refresh-rate is 50Hz - my BD rip having 23.976 plays OK (but of course with judder)
-When I automatically switch via XrandR refresh rate to 24Hz - no judder, but slow AV desync start to be present.

It looks like after approx mplayer SVN28900-29000 and nv newer than 180.60, we start to have different behavior regarding A/V synchronization.

Well - indeed it is interesting topic.

My logic says me that audio & video channel should be slaves to fps/bitrate of content - if we want to avoid judder/sleeps in video/audio.
But my issue - where I have refresh v.close to fps, but not equal - shows that mplayer video speed fps follows TV refresh rate. Pls notice: 50Hz refresh gives perfect A/V sync.

Now, if we assume that A/V sync in mplayer is implementation where - for avoiding judder - video playback fps is following display refresh rate, but audio is going with content fps speed - we should have delay approx 1s for 16 minutes (23.976/24.000). This is delay which I approx observe, so probably above theory works.

Now question is: how can I change fps synchronization direction: from TV->mplayer to mplayer->TV ?

Of course another solution is to free run mplayer & TV with exact the same fps. I already tried try force TV refresh rate to 23.976 via custom modes - but unfortunately such modes are not available via XrandR (they are reported in pool of XrandR available modes in Xorg.log, but not in XrandR tool).
I'm using perl script for auto refresh change - so use XrandR as toll for TV refresh rate change is essential for me.

Thx in advance for any help !
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