Experimental technique for testing call audio quality?

Neil Jerram neiljerram at googlemail.com
Fri Jan 22 23:48:35 CET 2010

2010/1/22 Helge Hafting <helge.hafting at hist.no>:

> To test the quality of analog components (mic, amplifier, speaker):
> * Record voice (or test tones) to a file. Transfer the file to a
>   computer with a good soundcard, to check quality.
> * Get a sound file of known quality, transfer it to the FR.
>   Play it (alsaplayer or some other audio player)
>   and check the quality.
> With this, you should get an idea of what sound the FR is
> capable of. Tweak relevant volume settings; too little
> is hard to hear, too much may clip and distort.

Many thanks.  I have indeed - but very slowly - been following this
kind of approach.

I figured that it made sense to look at the ringtone volume problem
first, as that should be easier, and because in-call quality is not so
important if one is missing the calls anyway.

So FWIW I've been trying to understand all the available information
about the Wolfson codec, and the *.state files.

I've nothing really to report yet, just one hunch, namely that the
structure of the alsa state management - i.e. saving and restoring all
of the settings when the "scenario" changes - makes this audio
situation harder to understand and to improve.  I'm wondering about an
alternative approach where the deltas between the state files are
grouped into a number of independent operations, like 'enable GSM
input', 'set PCM volume to X' etc.

One specific thing I noticed is that gsmhandset.state has control.90
"DAPM Headset Mic Switch" set to true.  I wonder if that could be a
source of extra noise (when using the handset)?

> Calls will surely not be better than what you can get this
> way. Ideally, you should be able to get calls up to
> the same quality as this, by tweaking volume settings. Calls are digital
>  and shouldn't have sound distortion of its own. At least not worse
> than other phones.
> The current default call volumes in SHR-U are quite bad, which may be
> the reason for many recent reports of audio problem. Anyone installing
> SHR-U should call themselves (on some other phone) and adjust both
> mic volume and speaker volume.  (And then reboot the phone,
> so the settings are saved.)


> If the FR sound quality is too bad, consider a BT headset. Sound quality
> should then depend on the BT headset only. The FR's problems with buzz,
> bad bass, and possibly other analog issues shouldn't matter at all.

I guess so - but I really hope and believe that handset audio quality
is a soluble problem.


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