Voice call audio routing

Voice call audio routing

[Nicola Mfb]

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While testing an e169 huawei card I was able to make voice calls and
hear something with aplay and /dev/ttyUSB1.
On the openmoko/freerunner is a matter of HW switches, on the n900
IIRC is done with pulseaudio.
I guess that voice call audio routing is not in oFono plans, if I'm
correct is there a reference project (may be not depending deeply on
meego) that abstracts that task in an extensible/pluggable way?

Regards

     Niko

Re: Voice call audio routing

[Neil Jerram]

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Nicola Mfb <nicola.mfb@gmail.com> writes:

> While testing an e169 huawei card I was able to make voice calls and
> hear something with aplay and /dev/ttyUSB1.
> On the openmoko/freerunner is a matter of HW switches, on the n900
> IIRC is done with pulseaudio.
> I guess that voice call audio routing is not in oFono plans, if I'm
> correct is there a reference project (may be not depending deeply on
> meego) that abstracts that task in an extensible/pluggable way?

Have you read "design.txt" in telepathy-ring's repository?  I think it
touches on this subject.  From my limited (so far) understanding of that
file, I think you are right that ofono does not manage the audio routing
itself.

Regards,
          Neil

Re: Voice call audio routing

[Marcel Holtmann]

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Hi Niko,

> While testing an e169 huawei card I was able to make voice calls and
> hear something with aplay and /dev/ttyUSB1.
> On the openmoko/freerunner is a matter of HW switches, on the n900
> IIRC is done with pulseaudio.
> I guess that voice call audio routing is not in oFono plans, if I'm
> correct is there a reference project (may be not depending deeply on
> meego) that abstracts that task in an extensible/pluggable way?

check tools/huawei-audio.c for a really simple example of the audio
processing.

Regards

Marcel

RE: Voice call audio routing

[Kai.Vehmanen]

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Hi,

On 16 Dec 2010, Nicola Mfb wrote:
> While testing an e169 huawei card I was able to make voice calls and
> hear something with aplay and /dev/ttyUSB1.
> On the openmoko/freerunner is a matter of HW switches, on the n900
> IIRC is done with pulseaudio.
> I guess that voice call audio routing is not in oFono plans, if I'm
> correct is there a reference project (may be not depending deeply on
> meego) that abstracts that task in an extensible/pluggable way?

not really I'm afraid, no reference project yet. The MeeGo stack 
for N900 is the closest thing at the moment:
http://wiki.meego.com/ARM/N900/Features/CallAudio

There's nothing inherently specific to MeeGo in the above, but of 
course some parts of it are very specific to N900 and its modem. 
Fortunately these are mostly isolated into a separate PA modules (so 
the rest of the stuff could be shared with other modems). More
generally, the speech interface to modems is currently not at all 
standard, and the differences are fairly big among the current modems 
that supports this (the low-level hw interfaces are different, 
the protocols are different, the kernel drivers are different and 
so forth).

E.g. USB might be used as the interface in dongles for laptops, but
it is not really suitable as the primary interface when building
a phone (it might be used as a secondary channel to record calls,
but that's different). USB audio can still be supported of course,
but just as an example why not all modems will have an interface
such as the e169 has.

But e.g. if you got the e169 working with aplay, then in theory
it fits quite nicely to the N900 stack mentioned above. The same
pipeline (on N900) is already used for CS (with the device modem) and 
VoIP calls (with gstreamer/farsight), so architecture is in that sense 
ready to support other network source/destinations for voice streams.
The integration to oFono AudioSettings interface is also there
(so that the audio pipeline is automatically set up when there is 
a call).

br,
-- 
Kai Vehmanen