Bert Freudenberg bert at
Sun Nov 26 12:25:09 UTC 2006

On Nov 26, 2006, at 12:46 , Dominique Dutoit wrote:

> I think I have found the culprit.
> If you listen carefully to the recorded sound, you will notice that  
> frames are dropped at regular intervals. Since this pattern is  
> quite obvious and the VM doesn't seem to screw the sound data, it  
> should be something happening at the image level.
> Looking for a clue in a 3.9 alpha version, I found a change made by  
> "dgd" on April 4, 2006:
> 	"workaround for OSS emulation on top
> 	on ALSA (on Linux environments)"
> 	(Delay forMilliseconds: 20) wait.
> If the last line is commented out, the sound recorder just works as  
> expected. The same code is present in the OLPC and Squeakland  
> images and both work pretty well without this delay.
> CoreAudio records the audio input in real time but SoundRecorder  
> picks the data once in a while. The end result is that the sound  
> data is stored in a different time frame that the sampling rate and  
> the sound plays faster.
> Now I am not sure what can be done to have a cross-platform  
> solution, but as far I have seen the problem is not on the Mac VM  
> side.

Since there is now an ALSA plugin we don't really need the OSS  
emulation anymore. Maybe Diego could explain what this was about?

- Bert -

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