[vdr] Re: A/V synchronisation

[joachim.koenig@gmx.net]

> 
> I'm not sure that this would work. The DVB card has only very limited
> audio and video buffers. Adding an addional 240ms delay to 
> audio packets
> that are already aprox. 380ms late would most certainly overflow those
> buffers.
> It could be done using a soundcard. Then you are able to 
> delay audio as
> much as you like. However the new problem then will be 
> keeping the delay
> constant and audio/video in sync.

So when I patch the audio pts by lets say -250 ms I also have to delay 
the transfer of that packet to the card by 250 ms. Otherwise I risk that the
firmware has a problem with buffering the data until it can be played.
But this would then be a static issue and I would not need to take care
of the fine adjustment because this would still be done by the card
firmware.

Am I correct with this assumption? This would of course invent a delay
buffer
for audio into vdr (and to make it flexible we would need to do it for video
also).

As we are able to send AC3 now via the cards SPDIF I would not like to 
use a soundcard. Also I assume when we have transfer mode as standard with
one card
(so we can stop the programm with a single key) we will have live AC3 via
the internal SPDIF as well.

 
> What you are describing will hit us anyway once somebody creates a
> framebuffer device plugin and/or with AC3 playback through soundcards.
> 
> The only plugin that deals with manual a/v syncing is 
> currently the dxr3
> plugin. The syncing code in there is not from me, but i 
> believe that it
> could be modified to introduce almost any audio/video delay.

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