[linux-dvb] Re: Using a low-budget card as a secondary card.

[Guido Fiala <gfiala@s.netic.de>]

>  > What would help here would be some "official" standard text
>  > that describes how exactly two separate video and audio streams
>  > are to be multiplexed. So far it appears to me like remultiplexing
>  > is some sort of "black magic"... ;-)
>  >
>  > Is there any document that I could consult regarding this?
>  >
>  > Klaus
>
> The only thing I found is the source code of mplex, i.e. the muxing
> part of bbmpeg, which I used for the mplex program in the mpegtools.
> As far as I can understand the code, they use a "faked" buffer that
> represents the buffer of the player. they "write" the PES data into
> the buffer according to the PTS and check if the PTS is less than the
> SCR which they also simulate. Then they use some coditions depending
> on buffer filling and PTS of audio and video to write into the buffer
> and read out of buffer, i.e. write to disk. They only rule you can
> make out of this is that you have to have the data out of the buffer
> before it needs to be displayed, i.e. PTS < SCR. The audio and video
> buffer size acts are the boundary conditions for that. I didn't have
> time to take all that stuff apart, so I just used it as is.
> Maybe theres is a scientific paper or maybe a some kind of thesis
> about that on the net.

That sounds not all that promising as mplex does not cover all problems in 
vdr-files so far - remuxed streams still have vanishing audio (and latency)
at the same point the original file has.



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