[pulseaudio-discuss] bluetooth headset audio not supported by ofono

Georg Chini georg at chini.tk
Wed Feb 4 02:30:59 PST 2015

On 04.02.2015 09:40, David Henningsson wrote:
> On 2015-02-03 15:04, Tanu Kaskinen wrote:
>> On Mon, 2015-02-02 at 16:49 +0100, Georg Chini wrote:
>>> I think the release notes for 6.0 should be revised to account for
>>> that.
>> Indeed. Before I update the notes, though, I want to get a decision on
>> whether we will release with your patch to use both backends
>> side-by-side (probably implies another rc before final release), or will
>> we postpone that to the next release. Either is fine by me, but I'd vote
>> for releasing with your patch.
> Hmm. I'm not totally sure about the differences between HF and AG so 
> take this with a grain of salt, but...

The HF role is used when you connect a phone to the computer, in this 
case the phone is the
initiator of the connection, your microphone and speakers are on the 
computer side.
The AG role is used when you connect a headset to the computer, then the 
computer initiates the
audio connection and microphone and speaker are on the headset side.

> It seems to me that it's not extremely unlikely that either of us will 
> step into the other domain in the future, i e, bluez 5 might implement 
> AG audio or PulseAudio might implement a native support for HF.
> Also, if the AG plugin of Bluez 5 supports RFCOMM/AT commands then 
> we're already partially overlapping, because that's what we use to 
> set/get headset volume and mic gain. If we enable both backends, will 
> that then send AT commands from both backends when we try to set the 
> volume, or...?

No, this will not happen. Only on connection will take place. Usually 
the headset tries to connect to
UUID 0x111f (HFP profile) first, if that is not available it tries UUID 
0x1112 (HSP profile). Ofono
registers UUID 0x111f with bluetooth while pulse registers 0x1112. So 
normally when ofono is
running (and you have an active modem in your system) the headset will 
connect HFP to ofono and
pulse will only see the a2dp profile. You can disable the AG role in 
ofono though with a command
line switch if you prefer to have HSP connected to pulse.

> Hence, instead of removing all backend switching code, maybe we should 
> instead add a switching mode "both" which does what you say. Or 
> potentially replace "auto" with "both", if "auto" now makes no sense.

Fine for me, I can send another patch to implement it if you like.

> Finally, I remember Arun had a strong preference for not enabling the 
> ofono backend by default, so Arun, could you elaborate upon whether 
> that still makes sense given this new information?

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