[linux-dvb] Re: VDR suggestion - record to TS?

[Dave Chapman <dave@dchapman.com>]

On Wednesday 02 May 2001  2:44 pm, Klaus Schmidinger wrote:
> My idea would be to have a TS that contains the packets from the video,
> audio and AC3 PIDs and store these in a multiplexed PES file. That file
> would then contain 0xE0 (video), 0xC0 (audio) and 0xC1 (AC3) sections. When
> replaying, VDR could send the 0xE0 and 0xC0 sections to the DVB hardware,
> while sending the 0xC1 sections to whatever program is necessary to replay
> AC3.
>
> Is this something that would make sense? Is it at all possible?
>
> Klaus

Klaus,

Sorry for not replying earlier - I was hoping that someone else would confirm 
this.

Yesterday I tested this out on Pro-7, and successfully recorded all 3 streams 
into the same TS file - PIDs 255 (video), 256 (mpeg audio) and 257 (ac3 
audio).

Using the command:

ts2pes 0 257 < recording.ts | ac3dec

I got perfect audio through my (stereo) soundcard.  I used the latest CVS 
version of "ac3dec", available from linuxvideo.org.  "ts2pes" is part of the 
mpegtools distributed with the driver.

The problem I think you will have if you try and playback the ac3 stream 
"live" is syncronisation - the video will probably always be ahead of the 
audio..  You may only be able to solve this by using one DVB card to receive 
the channel, and another to decode it (i.e. VDR's "transfer mode").

Maybe the best format for recording would be as a Program Stream (PS/VOB) 
file.  This way, users can use any of the available DVD players (including 
the dvdplayer that uses the DVB-S card?) to replay the recorded files.  I 
don't know the details of PS files, so I can't help with the conversion.  

I know PS files are designed to have multiple audio streams - I don't know 
anything about the way you suggest for PES files.

Dave.


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