Voice quality on FreeRunner A7 ?

Al Johnson openmoko at mazikeen.demon.co.uk
Sun Feb 21 19:36:58 CET 2010

On Sunday 21 February 2010, Gand' wrote:
> i have a very annoying buzzing sound with the latest SHR for the caller on
> my openmoko A7
> i hear everything pretty well and clear, but the other side is hearing a
> mettalic buzz ...

The default setting for control 12 is 7, the maximum, which is too high for 
many people. The signal overloads the amp and gets distorted, giving what is 
often described as a buzz when you are speaking. In 
/etc/freesmartphone/alsa/default/gsmhandset you can drop it to 6 or 5. The 
distortion can also stop the echo cancellation working correctly.

> i think this is the "awful" here ...
> can you share your tweaked volume settings ?

As the other reply demonstrates, everyone has different needs. The important 
thing isn't my settings, but knowing how to get a sensible combination of the 
three controls so that you get the right volume level without distortion. Last 
time I looked the wiki had what I think is a good description of one way to do 
this. I didn't write it, and it may only seem like a good explanation to me 
because I already understand it. If you find any of it confusing then ask 
about it, and we can work on a better explanation.

I put another method in code as fso-simplemixer.py (also mentioned in the 
wiki) which may be worth a try. I think it may need a small fix for save to 
work with recent fso versions, and there are a few bugs that i never managed 
to fix. Please back up your alsa settings before using it as some once 
reported a corrupted alsa state, though we were never able to repeat it.

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