[pulseaudio-discuss] How to use "sco_sink" and "sco_source" in the bluetooth device module?

[Luiz Augusto von Dentz]

On Sun, Jun 12, 2011 at 2:59 PM, Lin, Mengdong <mengdong.lin at intel.com> wrote:
> Could someone tell me how to use "sco_sink" and "sco_source" in the
> bluetooth device module?
>
>
>
> Because of hardware restriction, our bluetooth driver cannot handle HSP data
> transport. We want use an ALSA device’s sink and source for BT HSP
> transport. It seems that by passing parameters to initialize the Bluetooth
> discover and device module, a bluetooth device can use external “sco-sink”
> and “sco-source” for HSP data transport.
>
>
>
> My questions:
>
> -          I can set the ALSA sink & source as the “sco-sink” and
> “sco-source”, right? If yes, how can I set “sco-source” and “sco-sink” names
> as the parameter to load Bluetooth discover module in the default script for
> my platform?

First, the BlueZ audio.conf indicates audio routing to pcm? As for the
actual names afaik this depend on the platform, but I have never used
them myself because my system uses hci routing. Btw, have you tried to
hardcode the actual alsa device just to see what happens?
>
> -          Since “sco-sink” and “sco-source” are not dynamically created, so
> I cannot routing inputs/outputs to them by hook the “SINK-PUT” or
> “SOURCE-PUT” event, right?

Not sure what you are talking about so I will just skip and let
somebody else answer this.

>
> -          When can I move sink inputs or source outputs to the “sco-sink”
> and “sco-source”? Their state changes outside of the Bluetooth device. How
> are their state change synchronized with BT headset connection and
> disconnection? In BT device module,  I saw both “start_thread” and state
> change hook of “sco-sink” and “sco-source” call “sco_over_pcm_state_update”
> to setup data transport. So they can change to IDLE state at any time?

Yes, sco_over_pcm_state_update should synchronize and yes they can
change to IDLE which means we should disconnect SCO.

>
> -          Is there any extra work for the Bluetooth device or the device
> providing actual “sco-sink” and “sco-source” to do?

This is platform specific so we might need some kind of configuration support.

>
> -          Has the usage “sco-sink” and “sco-source” been verified on any
> platform?

Yes, both Nokia N900/fremantle and meego harmattan uses them, so we
might need to check with them how to configure them.

-- 
Luiz Augusto von Dentz
Computer Engineer