Rockbox

  • Status Unconfirmed
  • Percent Complete
    0%
  • Task Type Bugs
  • Category Recording
  • Assigned To No-one
  • Operating System Sansa AMSv2
  • Severity Low
  • Priority Very Low
  • Reported Version Release 3.11
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: Rockbox
Opened by dockjkox - 2012-06-11

FS#12692 - Recording - positive clipping wraps around to negative or zero values

On my Sansa Clip+ 4GB, with Rockbox v3.11.2

Recording a wav file through internal microphone. If the audio signal clips at the positive limit, bad things happen:
1) Most of the time the recorded signal wraps around to a full scale negative value, which makes it sound terrible.
2) Sometimes the recorded signal wraps around to a near zero value, which still makes it sound terrible but the distortion is not so loud

3) Clipping at the negative end of the range is as you would expect - a flat line which sounds like normal digital distortion, as you would expect

See attached picture of the recorded waveform showing each of the 3 situations described above.

   ClippingWrapAround.GIF (132.5 KiB)
MikeS commented on 2012-06-12 02:44

As far as I can say about AMS and its limited recording hardware is that this is a hardware issue. It's not unique to AMSv2 but the same happens with e200v1 with the AS3514.

dockjkox commented on 2012-06-12 11:48

Interesting.

I did see somewhere that this issue happened with some Sansa player at some time in the past, and it was fixed with a firmware update. But I can't find the link now.

I can say that this problem doesn't happen on my Clip+ with the latest Sansa Clip+ Original Firmware. The Original Firmware seems to be happy to clip pretty heavily without any apparent way to alter the sensitivity, but crucially without the wrap-around problem. See attached waveform recorded with the OF.

   ClippingNoWrapAroundWithOrigi... (88.8 KiB)

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