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Summary:ASTERISK-27405: Audio distortion after 3f7d0b63
Reporter:Joshua Elson (joshelson)Labels:
Date Opened:2017-11-08 07:44:42.000-0600Date Closed:2020-01-14 11:14:04.000-0600
Priority:MinorRegression?Yes
Status:Closed/CompleteComponents:Formats/General
Versions:13.19.0 Frequency of
Occurrence
Related
Issues:
Environment:Attachments:
Description:From IRC:

{quote}
This change, https://gerrit.asterisk.org/#/c/6406/, caused some interesting side effects on about 1/4 of our SIP carriers. Now, when waiting for a record prompt to run (say for voicemail), we get substantial audio distortions audible only to the external participant. Anything that might have caused that? Reverting this patch fixes. Not all carriers, but definitely more than one.
{quote}
Comments:By: Sean Bright (seanbright) 2017-11-08 07:46:28.957-0600

[~joshelson], please provide reproducing steps, codec configuration, version of Asterisk affected. And please report bugs here, not on IRC.
By: Joshua Elson (joshelson) 2017-11-09 14:40:15.229-0600

Apologies Sean. Was just going to chat briefly before submitting a formal defect.

Here's a better description of the issue:

When a call comes into Asterisk, an audio issue occurs when hitting an extension's voicemail box.
After the "beep" audio file if played, static (instead of silence) is heard during the recording period.
When the # key is pressed and the "thank you" audio file is played, static is also heard after this until the call is disconnected.
If a VM recording is made through the initial static and the VM is listened to afterwards, the voicemail recording audio sounds broken-up.
Static is not heard in the recording.

* Since we have multiple formats of audio files for prompts (other than the gsm files in the distribution) beep.ulaw and thank-you.ulaw are being used. If using a clean distribution of sounds (just the gsm files), the issue does not occur on said gsm files.
 The issue also occurs when using the beep file in alaw/wav formats, but does not occur if the system is forced to use GSM sounds and transcode them.
* The issue has been tracked down to commit a5b49ff388d7c6d5ed8742384c8671c398d1dd55 (14.7 branch), in which from formats/format_pcm.c file
 was changed, specifically in the change of the check of the fread() function return value. When reverted, the issue does not occur.
 BAD:         if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
 GOOD:        if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {

I can supply PCAPs separately if those are helpful.
By: Benjamin Keith Ford (bford) 2017-12-05 12:37:49.808-0600

Hey [~joshelson], I just tested this but am unable to reproduce the issue. Could you supply relevant config files in case there is something different between your setup and mine?
By: Asterisk Team (asteriskteam) 2017-12-20 12:00:01.706-0600

Suspended due to lack of activity. This issue will be automatically re-opened if the reporter posts a comment. If you are not the reporter and would like this re-opened please create a new issue instead. If the new issue is related to this one a link will be created during the triage process. Further information on issue tracker usage can be found in the Asterisk Issue Guidlines [1].

[1] https://wiki.asterisk.org/wiki/display/AST/Asterisk+Issue+Guidelines