On Wednesday 08 August 2018 10:00:28 Luiz Augusto von Dentz wrote: > Hi Pali, > > On Sat, Jul 28, 2018 at 10:34 PM, Pali Rohár <pali.rohar at gmail.com> wrote: > > Hi! > > > > Some Bluetooth A2DP codecs like aptX Low Latency or FastStream provides > > "backchannel" support for voice data. And it really in A2DP profile. > > > > It can be very useful as there is no need to switch between A2DP and HSP > > modes. > > > > Now I was able to get FastStream codec (rebranded SBC) working in > > PulseAudio. And in "btmon" I see that my headset started sending > > backchannel voice data in SBC codec. I decoded that dump and it is > > really SBC codec, voice is in very good quality, better then in > > HSP profile. I hope that bluez can send them to pulseaudio via file > > descriptor. > > The fd sent to PA is a socket which is already bi-directional. Ok. > > Question is, how to handle this configuration in pulseaudio? Should it > > be a new profile for bluetooth devices which would provides both sink > > and source? Because now A2DP is one-direction profile, not > > bi-directional. > > While A2DP only configures a single direction we can assume > bi-directional depending on the endpoint, so in theory all you have to > do is register an endpoint for FastStream and create both sink and > source when it is connected. That said note that A2DP uses L2CAP on > top of ACL link which is asynchronous so it may not be as low latency > as SCO, but I guess being able to chat while listening to stereo audio > is quite convenient in some situations (e.g. when gaming). I mean how to export this configuration from pulseaudio. If it should be a new profile on pulseaudio card, or something different. After correct bluez endpoint registration I was able to send data to headset which correctly played it -- this is working. -- Pali Rohár pali.rohar at gmail.com
