Summary:ASTERISK-17519: Recorded calls corrupted (GSM?)
Reporter:David D. R. Palmer (palmerv0r)Labels:
Date Opened:2011-03-07 05:11:21.000-0600Date Closed:2011-03-08 11:53:03.000-0600
Versions:1.8.4 Frequency of
Description:We are using Asterisk 1.4.11 with several back-ported patches.  Our customers sometimes report clicking noises and distortion with the Monitor() application.  On inspecting the GSM .wav files which are produced, the waveform goes through periods of being offset, with the majority of the waveform appearing belong the centre line.


We believe we have the same issue as this poster:
And applied this patch accordingly:
However, it has not resolved the problem.  The same customers report the issue, however, we cannot reproduce it on demand.
Comments:By: David Woolley (davidw) 2011-03-07 06:26:06.000-0600

GSM doesn't encode a waveform; it encodes a model of the configuration of the human vocal tract.  There may be some information related to the original waverform, but it is not at all clear that it would cause the DC offsets you describe.  My expectation for damaged GSM is that the decoding codec would interpolate any seriously damaged parts.

By: Leif Madsen (lmadsen) 2011-03-08 11:53:02.000-0600

Your version of Asterisk is significantly old and you're using backported patches. This is not something we can support. Please re-test with a vanilla, recent version of Asterisk.