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

[Georg Chini]

On 09.02.2015 09:28, Arun Raghavan wrote:
> On 4 February 2015 at 14:10, David Henningsson
> <david.henningsson at canonical.com> 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...
>>
>> 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...?
>>
>> 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.
>>
>> 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?
> The reason I was against a "both" mode is that it seems odd to me from
> a system integration perspective. The current situation seems to be
> either you have oFono as a part of your system and you're using it for
> modem management, some amount of BT audio management, and so forth.
> Else, you're using PulseAudio for the BT audio management (the stuff
> that BlueZ used to do but dropped in 5.x).

That is not really correct. Even if you use ofono, you still need pulseaudio
for the BT audio, otherwise it just won't work. ofono will only manage
the connection for you.

>
> It seems odd to me to have a "both" mode -- I'd like to add back the
> features we supported before the BlueZ 5.x migration caused us to
> regress. Once Wim's HSP work is out, that basically leaves the HF role
> (PA on your acting as a headset). If I understand correctly, that will
> overlap with oFono (if oFono wasn't bringing a telephony stack along
> with it, I wouldn't be objecting to just using it as our external dep
> that provides these features)..

But that is the point of the HF role. If pulseaudio was going to support
the HF role, it would also need to implement an (external) handler for
RFCOMM. So you would need to duplicate the ofono functionality in
some way or do the integration the other way round.

>
> So to my mind, having a both mode does not seem too useful from a
> system integration point of view -- either we have oFono provide these
> and other services, system-wide, or we're having PA manage whatever
> (sub?)set of features we want to.

I think the idea of having ofono manage the HF role and using pulseaudio
for the AG is from the practical (user) perspective at the moment as near
as you can get to the bluez4 situation. With both backends I finally can
connect my mobile and my headset which was not possible for bluez5
before.

>
> Cheers,
> Arun