[linux-dvb] full duplex?

[Ralph Metzler <rjkm@convergence.de>]

Hi Arpi,

Arpi writes:
 > Is it possible to record Sat TV program to disk (as TS or PES stream) and play
 > other mpeg file at the same time? (full duplex function)


Yes, but currently not without problems (lost packets, etc.).

 
 > At least I was able to record audio stream of tuned TV program and play
 > other mpeg video at the same time. It has no much sense, but it proves that
 > recording and playing at the same time is possible!
 > 
 > I also tried to record video (with fixed test_dvr.c) and play mpeg
 > video-only file, but the playback hangs.
 > 
 > I don't know the card's design/layout, but the problem can be the demuxer.
 > If it's possible, I can ignore demuxer at input, so save raw/TS stream to
 > the disk, without hardware demultiplexing. This way demuxers are free for
 > playback.

No, it is not possible to circumvent the demuxer at all.
The demuxer also cannot be used during playback.
Everything has to be done via the dual ported RAM and data has to be
shoveled around by the ARM7 core.

This is the major shortcoming of the design of this card.
If they would have used the firewire interface of the AV7110 all this
would be possible with minimal CPU usage. But this would take some
support logic for the AV7110 and of course a firewire chip/card for the PC
and would be a "little" more expensive ...


Ralph









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