[alsa-devel] alsa virtual sound card (with networked output)

[Metyl Methylius]

On Tue, Jan 11, 2011 at 5:33 PM, Jaroslav Kysela <perex at perex.cz> wrote:
> On Tue, 11 Jan 2011, Metyl Methylius wrote:
>
>> Hello everyone,
>>
>> I was wondering if its possible to just create a "virtual" sound card
>> using alsa which will just sent its audio stream to other computer
>> (using TCP/IP or UDP for example). On the other end there would be
>> some kind of server (or just nc -u -l -p 31337 | aplay ). I want to do
>> it on alsa layer because other aps using alsa will get immediate
>> support.
>>
>> It should be something like described in
>>
>> http://alsa.opensrc.org/index.php/Network
>>
>> but with transparent support for all alsa based applications. I dont
>> care about syncronization or transmission delay. Any pointers as how
>> this could be done in alsa ?
>
> I plan to add network support to the alsaloop utility (in the current
> repository of the alsa-utils package) using the snd-aloop loopback kernel
> module on the playback (producer) side. This solution would be 100%
> transparent for all current ALSA apps. But I don't have any estimate when I
> start the work on this. Any volunteer? I think that it would be best to use
> the RTP UDP streaming.
>

That sounds very interesting. Still there is minor problem with RTP as
I've found in rfc3551 that at least there defined RAW audio encodings - L8
and L16 - supports only 8 and 16-bit wide samples (how to support 24
or 32-bit audio ?).
Which RTP library do you plan to use unless you wanted to integrate
RTP code directly into alsaloop ?

metyl