#11334 NORM 11.3.0: XO-1.75 audio sounds terrible in some configurations

Zarro Boogs per Child bugtracker at laptop.org
Thu Oct 13 09:25:33 EDT 2011

#11334: XO-1.75 audio sounds terrible in some configurations
 Reporter:  dsd     |                 Owner:  saadia       
     Type:  defect  |                Status:  new          
 Priority:  normal  |             Milestone:  11.3.0       
Component:  kernel  |               Version:  not specified
 Keywords:          |           Next_action:  never set    
 Verified:  0       |   Deployment_affected:               
Blockedby:          |              Blocking:               
 Mitch suggested " the codec does not have digital antialiasing, so, while
 it can play at numerous rates, anything lower than 48000 will be subject
 to "stairstepping", which results in analog domain aliasing that sounds

 However, after we made that change, so that the driver would only offer
 48k and so that alsa-lib would be forced to resample anything that came in
 at other rates, we found that sounds (like those which come in Scratch)
 now sound bad. They are 11025Hz, and sound fine if sent to the hardware
 like that, but sound terrible when resampled by ALSA.

 With a kernel that advertises the full set of rates, the horrible audio
 (which is presumably the analog domain aliasing referred to by mitch) can
 be reproduced with:

 gst-launch audiotestsrc ! audio/x-raw-int,rate=44100,channels=1

 but interestingly, if you run it with 2 channels, it sounds fine. I
 confirmed that the parameters being sent to the hardware do not differ in
 anything but the obvious in these 2 cases - with 2 channels a larger
 buffer is used, and it is configured as 2 channels, but the rest is fine.

 I've experimented with the full range of rate and channels values, results

 ||88200||WRONG TONE||BAD||

 "BAD" means that the sound was crackly. "WRONG TONE" means that the sound
 was not crackly but the test produced a different audible tone from the

Ticket URL: <http://dev.laptop.org/ticket/11334>
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