[asterisk-bugs] [JIRA] (ASTERISK-27405) Audio distortion after 3f7d0b63

[Joshua Elson (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-27405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=239934#comment-239934 ] 

Joshua Elson commented on ASTERISK-27405:
-----------------------------------------

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.

> Audio distortion after 3f7d0b63
> -------------------------------
>
>                 Key: ASTERISK-27405
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27405
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Formats/General
>    Affects Versions: 13.19.0
>            Reporter: Sean Bright
>            Assignee: Joshua Elson
>            Severity: Minor
>
> 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}



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