[FFmpeg-user] confusion with "-vsync 1" / "-vsync cfr" and "-map" (to sync audio to video)

Carl Eugen Hoyos cehoyos at ag.or.at
Fri Jan 11 20:19:04 CET 2013

Tracey Jaquith <tracey <at> archive.org> writes:

> I am the developer of the TV Archive ( http://archive.org/tv )
> and have a question regarding A/V "sync" issues.
> We are finding that some of our "harder" channels are 
> requiring "-vsync 0" or "-vsync 1".  The problem with the 
> former is that our resulting .mp4 get A/V slip when 
> progressively downloaded through the flash plugin (only) but 
> are fine for html5 browsers.   So we want to go with "-vsync 1".
> I'd *like* to make the audio frames dropped/duped

I suspect this means that, instead of -vsync x, 
you want to use -async 1 (which is now also 
-af aresample=async iirc).

Generally, please do not post extracts of console but only 
complete, uncut console output (at least the first 50 and 
the last 50 lines).

(Did -vsync in your command line really make a difference? 
Hard to believe...)

Carl Eugen

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