Re: #12498 HIGH 13.1.0: [CL4] Scratch can not record audio normally, and show “Block cannot return”.

Zarro Boogs per Child bugtracker at
Thu Feb 28 14:38:43 EST 2013

#12498: [CL4] Scratch can not record audio normally, and show “Block cannot
           Reporter:  tomyin        |       Owner:  dsd          
               Type:  defect        |      Status:  new          
           Priority:  high          |   Milestone:  13.1.0       
          Component:  not assigned  |     Version:  not specified
         Resolution:                |    Keywords:               
        Next_action:  never set     |    Verified:  0            
Deployment_affected:                |   Blockedby:               
           Blocking:                |  
Changes (by dsd):

 * cc: dsd (removed)
 * cc: saadia (added)
  * owner:  saadia => dsd
  * status:  assigned => new


 As of build 32 (with #12289 workaround: only support 48k sample rate for
 recording), if you open Scratch you can record a sound. We seem to have
 (temporarily?) hidden the "rate reduced to zero" problem described above.

 But if you try to record another, or play a sound first, you can't record
 again. The error comes up.

 The fundamental issue here is under these conditions, that Scratch tries
 to do playback (of silence) plus recording at the same time.

 Our hardware can only support simultaneous record/playback if both streams
 run at the same rate. This is because SSPA_AUD_CTRL0 encodes "the rate"
 (via clock division) and this rate applies to both playback and capture.
 Our driver does not currently enforce this restriction; it probably should
 (via ASoC "symmetric_rates" mechanism), but we probably want to fix #12289
 first. Scratch is trying to play back at 22050 and record at 48000 (since
 thats the only rate we made available).

 If we restrict both playback and record to 48k, Scratch works OK. But
 thats probably not the solution we want.

Ticket URL: <>
One Laptop Per Child <>
OLPC bug tracking system

More information about the Bugs mailing list