Audio Buzz / Rattling Issue

Al Johnson openmoko at
Sun Feb 8 13:00:23 CET 2009

Before going any further I suggest you read this:
It tells you where the alsa state files are kept, what state files there are, 
what they do, and which alsamixer control does what. It links to a page that 
gives more detail of the underlying audio hardware, and to a volume control 

2008.x does not change the mixer state on headset jack insertion or removal, 
but the kernel does create an input event that would allow it to do so. FSO 
should switch from speaker to headset, but this isn't extensively tested and 
may be buggy.

The 'buzz' that most reports refer to is heard during phone calls by the 
person on the far end of the call, not on the FR itself. The buzz you hear 
seems like either a distortion from the media player or a mechanical issue in 
the speaker of your unit. 

On Sunday 08 February 2009, Kevin Day wrote:
> > I have never tested the headset, I did now and I have the same behavior
> > you are describing !!
> > The sound never goes to the headset it keeps on the FR.
> >
> > Does anyone else have this problem? I am using 2008.12 also.

> I would like to update with information I gained from further testing.
> I was able to get something close to normal audio output and even enable
> the external speakers.
> (however, the actual problem is still not _fixed_ at this time)
> I do not remember the exact order things were done in, so here are the
> rough steps:
> WARNING: these are done from a console, so you need to learn/know how to
> get console access first.
> first, I went to trac bug #1640, downloaded, and extracted this file:
> I then backed up my original asound.state file:
> # cp /etc/asound.state{,.orig}
> Of the extracted files (from scenarios.tgz), I took the stereoout.state
> file and replaced my existing asound.state file:
> # cp stereoout.state /etc/asound.state
> I then ran the alsactl tool to restore the sound settings from the brand
> new asound.state file:
> # alsactl restore
> The next thing to do was to play around with the alsamixer setting so
> see what does what..a royal pain in the ?undocumented? butt.
> # alsamixer
> Here are the important settings:
> PCM - thats your main audio
> Amp Spk - this seems to cause problems, when enabled it causes all
> stereo audio (right and left) to output only to one speaker. Disable
> this and suddenly you can get right+left through separate speakers.
> Amp Stat - not sure what this is for, but turning it off turns off all
> audio.
> DAPM Stereo Out - This seems to be your onboard speaker, turn it off to
> turn off your onboard speaker
> DAPM Handset Spk - This is your external headset; turn it on to turn on
> the external speakers!
> I set the above to the following:
> PCM - anything above ~60% produces audio; this does not seem to cause
> the buzz/rattle
> Amp Spk - OFF!!
> Amp Stat - On
> DAPM Stereo Out - off
> DAPM Handset Spk - On
> Now save your changes:
> # alsactl store
> The next step was to turn the music player's audio volume down to about
> 5-10%
> The volume bar is ~3 millimeters in length
> This is not the alsamixer volume, it is the media player's volume.
> The media players volume is quite difficult to get to, you will have to
> fight with the song seeking to get the volume to change.
> Not a very user-friendly design in my opinion..
> Once the music player is at 5-10% in volume, you will no longer have any
> easily noticeable buzzing or rattling.
> Of course, you won't be able to do any volume changes when not plugged
> into a computer.
> In addition, you will not be able to swap between internal and external
> speakers while not plugged into some desktop computer as well...
> The next problem is that, even though there seems to exist the boot
> script: /etc/init.d/alsa-state
> the sound settings are not restored when a reboot is made.
> So, every single time the device gets powered on, one will need console
> access to correct the audio settings with the command:
> # alsactl restore
> Unless one is willing to tug around an entire computer or notebook
> (laptop) in addition to the freerunner a person pretty much cannot
> change any of their audio settings.
> That is not good at all, particularly for a cell-phone.
> The problems at this time are as follows:
> - inability to manually mute/unmute the internal and external speakers
> via the freerunner user interface
> - inability to raise software controlled volume above ~10% without
> incurring audio buzz/rattling issues
> - inability to restore saved audio settings between boots...why?
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