[linux-dvb] API ioctls for Bypass and RAW Audio

Dr. Werner Fink werner at suse.de
Fri Oct 21 11:40:52 CEST 2005


On Fri, Oct 21, 2005 at 11:31:19AM +0200, Marcus Metzler wrote:
> >>>>> "Werner" == Werner Fink <Dr.> writes:
> 
>     Werner> You do not need such a driver. The AV7110 can handle not
>     Werner> only PES (aka AudioPES) but RAW audio data like Mpeg Audio
>     Werner> and PCM. And the next firmware release will support this
>     Werner> (AudioMp2 and AudioPCM).  The question is: How can I move
>     Werner> the RAW audio data through the DVB driver.
> 
> I know. The sound driver just put the PCM data into PES to get it
> through DEBI port to the card. Using some kind of container will always be
> necessary unless you switch off all other communication. The av7110
> needs to know what raw data is coming. The PCM PES did not have too
> much overhead and also contained the sample frequency, so that was the
> easiest way. 

The communications is simply to tell the firmware with
AUDIO_SET_ATTRIBUTES which stream type (e.g. PCM, AC3, DTS,
Mpeg Audio) is used for replaying.  For PCM the sampling
rate is also provided by the type audio_attributes_t.

The data is then put parts of 2048 bytes through the DEBI
port.  The rest is done by the new firmware part.


     Werner

-- 
AC3 loop through sound card http://bitstreamout.sourceforge.net/
Howto http://www.vdr-portal.de/board/thread.php?threadid=1958
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