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

Georg Chini georg at chini.tk
Mon Feb 9 02:42:15 PST 2015

On 09.02.2015 11:19, Arun Raghavan wrote:
> On 9 February 2015 at 15:44, Georg Chini <georg at chini.tk> wrote:
>> On 09.02.2015 10:55, Arun Raghavan wrote:
>>> On 9 February 2015 at 14:54, Georg Chini <georg at chini.tk> wrote:
>>>> On 09.02.2015 10:16, Arun Raghavan wrote:
>>>>> On 9 February 2015 at 14:29, Georg Chini <georg at chini.tk> wrote:
>>>>>> On 09.02.2015 09:28, Arun Raghavan wrote:
>>> [...]
>>>>> If you mean that we need to do AT command handling, we now already do
>>>>> a bit of that in PA (we couldn't really agree upon any other place for
>>>>> that once BlueZ dropped it). Is there much we need to support other
>>>>> than volume commands?
>>>>> Assuming it's not too much more complex than the HSP support, we
>>>>> should be able to manage that just fine by extending the native
>>>>> backend.
>>>> For audio you probably won't need much more. But if you do not
>>>> support the telephony functions, you are in the same situation as
>>>> ofono is with the AG role. Here ofono supports the AT commands,
>>>> but no audio, and what use is a headset without audio?
>>>> And if you support audio for a phone but not the telephony functions,
>>>> what is phone audio good for where you can't make or receive a call?
>>> You can receive a call (you don't need the headset functions to accept
>>> one), so we've had users using their computer, their Raspberry Pi, or
>>> other devices for such use cases.
>> Really? Without using ofono? I wonder how this worked. I did already
>> use ofono with bluez4 and it would not have worked without. Who
>> sends the AT command to accept the call to the phone? Or do I have
>> to pick up manually then?
> Since we didn't have a mechanism to answer the phone call, probably
> was manual. Do note that this mode would be useful for more than
> telephony calls (i.e. voip calls too).
Sorry that I can't stop ...
First, I can't think of a case were you need a bluetooth HF profile for 
How should that work?
The main difference between the implementation in Bluez4 and Bluez5
is, that the connection management is no longer done by the Bluez
stack but either by ofono or pulseaudio.
With Bluez 4 you could "share" the connection, meaning let Bluez
manage the connection and then use audio from pulse and AT commands
from ofono.
Now the situation is different: Either ofono or pulse has to implement
connection management and then pass on the unused part to the
other application. If you don't do that you will break the other 
(See AG implementation in ofono)

The best would be to implement the AG role in pulse (because a headset
is mostly audio) and pass on AT handling to ofono while implementing
the HF role in ofono (because it's mostly telephony) and pass on the
audio to pulse. But that would imply that the developers talk to each
other and resolve the overlap which apparently has not been the case
until now.

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