[vdr] Re: A/V synchronisation

[Andreas Schultz <aschultz+vdr@warp10.net>]

joachim.koenig@gmx.net wrote:

[...]

> 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.

You are right, that should work ok. It's probably best to discuss that 
with the driver/firmware developers, they should now more details.

> 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).

Replay and transfer modes use ringbuffers anyway. You only have to split 
it into video and audio buffers. The play thread the needs to be smart 
about fetching from the right buffer depending on timestamp +/- delay. I 
did that in an old version of the DVD patch. It worked ok and the logic 
behind it is not that complex.

> 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.

We'll see about that one. I think Klaus is working on the AC3 stuff and 
he has not yet said wether he will support LiveAC3overDVB or not. 
Anyway, we will also need the soundcard option as AC3overDVB does not 
work with all receivers.

Have fun

    Andreas



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