[vdr] vdr-1.6.0 and syncearly

Reinhard Nissl rnissl at gmx.de
Tue Apr 1 18:46:39 CEST 2008


Hi,

Dominique Simon schrieb:

>> I'd say it's suggested. At least it is part of my H.264 patches.
> 
> What does the sync early patch do?

Vanilla VDR waits for an I frame before it passes video (and 
audio) data on to output devices. Further more, audio data is 
still not passed on from that time, because VDR takes some time 
to decide which audio track shall get selected.

The sync early patch addresses these issues. Audio and video 
packets are passed on a soon as they make up a valid frame. The 
result is that you can already hear the audio track before the 
video appears on screen. This is because video decoding can only 
start with an I frame. Any frames before the I frame won't appear 
on screen.

But passing these frames to the output device has the benefit 
that PTS' (presentation time stamp) for these frames are passed 
on to the output device which needs this information to 
synchronize audio and video. As a result, audio and video will be 
in sync already when the first image appears on screen.

That's why the patch got called "sync early".

Bye.
-- 
Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de



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