What's it going to take to get basic A2DP support into -HEAD?

Adrian Chadd adrian at freebsd.org
Sun Jun 9 06:55:14 UTC 2013

On 8 June 2013 23:48, Iain Hibbert <plunky at ogmig.net> wrote:
> On Sat, 8 Jun 2013, Adrian Chadd wrote:
>> So, given that these headphones pair, what would it take to write up a
>> basic A2DP profile with the minimum-supported codec, and then route
>> audio to it?
> it is probably a couple of weeks work; the specification document is not
> that thick..

Yeah, I see that. And lots of the codec types are optional, right?

>> Would it be something done in-kernel? Or would we just expose the
>> audio to userland and do the (re) encoding there?
> imo this is likely the best approach
> NetBSD has a simple "pseudo audio device" driver[1], which is like a pty
> but for audio devices.. I would use that (or something like, since I don't
> know how similar the FreeBSD kernel audio interface is to the NetBSD one)
> and provide a userland program to just route the audio back into a RFCOMM
> socket after conversion.
>> What about supporting data sources that will happily supply a
>> supported bitrate/encoding type? (eg, if a player wants to spit out
>> MPEG encoded audio; why decode and re-encode it?)
> your Bluetooth interface can be whatever you need, and you can transcode
> or feed whatever the kernel will accept (PCM in the case of pad(4) on
> NetBSD)
>> I'm happy to hack on code. I just don't know anything about the
>> bluetooth stack here. :-)
> just deal with an RFCOMM socket, is my advice..  (in part, because I am a
> NetBSD developer.. and our Bluetooth stack is somewhat different, but the
> socket interface is compatible :)

It's not a bad idea to begin with. I just have no idea where to begin
there. I'll keep on reading, see if I can muster the energy to write
some bluetooth socket code.



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