[pulseaudio-discuss] Bluetooth HSP and HFP support in pulseaudio

[Georg Chini]

On 28.04.20 21:06, Pali Rohár wrote:
> On Tuesday 28 April 2020 20:50:33 Georg Chini wrote:
>> Personally I don't see a problem to remove the AG role support from
>> the ofono backend because nobody uses it. What I proposed earlier
>> - allow hsphfpd to disable the HFP HS role and keep a "legacy" ofono
>> backend for the HFP HS role - should not be that hard to implement
>> compared to all the time and work you already invested and it would
>> help us to keep users happy.
> As I said, I have no problems with allowing to disable particular
> profile from hsphpfd. But the way how ofono has it implemented, when it
> is not possible to unregister specific profile and it always register
> master SCO listening socket, it means that you cannot have two
> applications which would implement or register HSP or HFP profile for
> audio, independently of the role.
>
> So you cannot use ofono's HFP AG role for connecting mobile phone and
> other application (e.g. hsphpfd) for using HFP HS role for connecting
> headset.
Sorry, forgive my ignorance. You can switch off ofonos AG role,
in that case it will only register the HS role with bluetoothd and
only react to connection attempts with the specific UUID.
Is it not possible that ofono registers one role and hsphfpd the
other?

And even if it is not possible and you can't use both at the same
time (which would be a pity), we still have to respect if a user
thinks that for him a working implementation for his mobile is
more important than good headset support and therefore prefers
the ofono backend over any other backend.
>
> So what you want is currently impossible. You have to first fix ofono
> daemon, design and export API for it and then implement other side to
> use that API.
>
> And I'm explaining again that this is reason why to have one central
> daemon which would implement HSP and HFP profiles and proxies needed
> support / sockets to target applications.
>
> If one application is stealing listening sockets and cannot be
> configured to not do it, other applications are just out of luck.
>
> It is same as if two UDP or TCP applications wants to listen on port
> 1234 and both want to accept new connections. Without full cooperative
> environment it does not work. hsphfpd daemon is there to accept new
> connections from both RFCOMM and SCO sockets and do all needed stuff
> with it (pass to other application, or process data on it directly).
>
The point is, that the applications that support the new hsphfpd
not yet exist, so we have at least to support the status quo until
there is some alternative.