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

Dr. Werner Fink werner at suse.de
Fri Oct 21 11:14:05 CEST 2005


On Thu, Oct 20, 2005 at 07:27:39PM +0200, Marcus Metzler wrote:
> >>>>> "Werner" == Werner Fink <Dr.> writes:
> 
>     Werner> Hi, is there really no one out here which want to be able
>     Werner> to use RAW Audio streams? That means replaying Audio
>     Werner> without the needs of a PES remuxer?  The hardware can do
>     Werner> it, the firmware will support it ... but the DVB API 3 and
>     Werner> DVB API 4 seems not be designed for this approach.
> 
>     Werner> How to extend the DVB API 3 for RAW Audio replay?  Do I
>     Werner> need a new ioctl or should I extend AUDIO_SELECT_SOURCE by
>     Werner> something like AUDIO_SOURCE_MEMORY_RAW or use the
>     Werner> AUDIO_SET_STREAMTYPE and define a type class
>     Werner> AUDIO_CAP_RAW_XXX.
> 
> I once wrote a rudimentary audio driver that made PES from raw audio
> and send it to the DVB driver, there were one or two lines in the
> av7110 driver and a couple of lines for the audio device. 
> I haven't used it in a while and it is probably not usable for newer
> kernels, but you should be able to see what was going on from the old
> drivers on http://www.metzlerbros.org/dvb/index.html. The last
> snapshot http://www.metzlerbros.org/dvb/DVB-20050311.tar.gz
> should contain the code.
> IN that case the audio was blocked from the DVB device when there was
> sound input to /dev/dspX (X usually =1). I used it with mpg321.

You do not need such a driver. The AV7110 can handle not only PES
(aka AudioPES) but RAW audio data like Mpeg Audio and PCM. And the
next firmware release will support this (AudioMp2 and AudioPCM).
The question is: How can I move the RAW audio data through the DVB
driver.


      Werner

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