Stuck Voice Injection in gsm call with Neofreerunner device

Al Johnson openmoko at
Fri Apr 30 22:22:37 CEST 2010

On Friday 30 April 2010, saravanan T wrote:
> Hello,
> I would like to find out whether voice injection in gsm call is possible in
> openmoko or not. I have read your FAQ's on the openmoko wiki, found out
> that we could play a file during gsm call. I also did find some posts in
> openmoko regarding this to be positive.
> My Questions are
> 1. I did not find any api(Java,Python) to inject the voice during call ?
> Where should I look ?

It isn't the sort of task that needs an API really, at least on the Openmoko 
handsets. You just need to set the mixer to route the output of the DAC into 
the GSM input and play the file. How to do this will vary slightly depending 
on what distro you are using, and what sort of interface you want. Give us 
more details and we can give more hints. Timo's method of setting up the mixer 
is much more long winded than it needs to be though! For some background on 
the mixer see the wiki:

> 2. It said that the hardware is capable of doing so? Do I have have to
> reprogram or mod the kernel or os ?

No mods required. Once the mixer state file is modified it's _very_ simple.

> 3.Why does android does not support this kind of mechanism? (They say
> android is open-source) Is it the Hardware problem or software one?

On the Openmoko handsets it's a software issue as we know the hardware can do 
it. If the Android audio API can't cope with it then I guess Google didn't 
think it was important. I know the linphone guys are complaining that Android 
is incapable of doing low-latency audio.

> I dont know how to proceed in this one with the device(neofreerunner).
> Please do me help me regarding the above. Thanks

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