[Trac #1110] audio problems with telephony applications

[Zarro Boogs per Child]

#1110: audio problems with telephony applications
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 Reporter:  ywwg    |       Owner:  marcelo  
     Type:  defect  |      Status:  new      
 Priority:  low     |   Milestone:  Untriaged
Component:  kernel  |    Keywords:           
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 It has been mentioned that the XO laptops will be used for tele- or even
 video-conferencing eventually.  To test this, I tried installing and
 running Skype and Gizmo in [http://ywwg.com/wiki/index.php/OLPC_Work
 Classic mode].  Obviously the final software will be neither of these
 packages, but I observed a problem which could be an issue with full-
 duplex mode audio.

 To install Skype, I used the static-qt version from their website and
 installed mesa-libGL and compat-libstdc++-33 to satisfy dependencies.  For
 Gizmo, the redhat rpm on their website was adequete.

 Both applications started up, were able to log in, and successfully made
 connections.  I did some testing with Skype's echo123 service, but I also
 tested with my thinkpad (using a headset) and the olpc (using headphones
 and the builtin mic).  Once the call was completed there were severe audio
 artifacts and distortion.  Here are my observations:

  * In Skype, the "I am dialling now!" sound played perfectly, as did the
 "hanging up" sound.  Only telephony sound was distorted.
  * In both apps, I would occasionally hear a snippet (1-2 seconds) of good
 sound.
  * more often I would hear pulsing samples of audio separated by silence
  * I also heard a lot of pulsing sound that could not have come from the
 microphone.
  * Switching from Alsa to OSS improved the situation but did not come
 close to solving the problem
  * Neither application was pegging the CPU according to top.  Both hovered
 between 30 and 60 percent CPU.

 I would normally guess cpu issues for this type of problem, but it doesn't
 look like this is the case.  I am thinking perhaps there is something
 wrong with the audio driver that is causing these problems.

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Ticket URL: <http://dev.laptop.org/ticket/1110>
One Laptop Per Child <http://laptop.org/>