[pulseaudio-discuss] Setting Bluetooth headset connection to *both* A2DP _AND_ HSP at the same time?

[Johan Hedberg]

Hi Alexander,

On Fri, Sep 09, 2011, Alexander Skwar wrote:
> As mentioned in another thread, I've got an Arctic P311 bluetooth
> headset[1] and a Hama Nano-Bluetooth-USB-Adapter Version 3.0+EDR
> Class1 dongle[2].
> 
> In the KDE 4.6.0 multimedia Phonon settings, I noticed, that I cannot
> select the P311 as a recording device. I noticed that this is because
> I've set the connection to be using the a2dp protocol/profile (ie. in stereo
> for music), like so:
> 
>   card_profile=a2dp
>   pacmd "set-card-profile bluez_card.$headset $card_profile"
> 
> When I change this to hsp, I can select the device as a recording
> device.
> 
> Well, if you think about it, it kinda makes sense that this is so - in
> a2dp mode, there's no recording capability. hsp mode, however, sounds
> awful for music.
> 
> Q: Is it possible to make PulseAudio use BOTH profiles _at_ _the_
> _same_ _time_?
> Or is this actually not a PA question, but rather something for bluez?

Firstly, you should be a bit more precise: I assume you're talking about
having audio streams active to both profiles at the same time, and not
about them being connected (but having an audio stream inactive) at the
same time.

The default BlueZ behavior when connecting a headset, and also something
recommended in Bluetooth white papers, is to always have both profiles
connected. However, the audio stream will be active only to one profile
at a time. The SCO link of HFP/HSP is always full-duplex so you'd get
undefined behavior if you tried to have that open at the same time as an
A2DP stream. You could of course experiment and see how headsets behave
with that, but I'm quite sure that they'd either refuse the second
stream or behave erratically (reset themselves, lock up, etc.).

Johan