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Summary:ASTERISK-27851: app_confbridge: Opus participants have bad quality in confbridge audio conference with non-20ms mixing interval
Reporter:Aleksandr Salanov (havier163)Labels:pjsip
Date Opened:2018-05-11 07:21:49Date Closed:
Priority:MinorRegression?
Status:Open/NewComponents:Applications/app_confbridge Codecs/codec_opus
Versions:13.18.0 13.20.0 13.21.0 15.4.0 Frequency of
Occurrence
Constant
Related
Issues:
Environment:PowerEdge R630/2 x Intel Xeon E5-2667 v4 3.2GHz()/RAM 32Gb/Attachments:
Description:We caught some strange behavior of the Asterisk that works as the audio conference bridge.

We have a solution:
1) The Hardware server
2) OS version is Linux version 3.10.0-693.21.1.el7.x86_64 (mockbuild@x86-ol7-builder-02.us.oracle.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16)
3) Asterisk 13.18 with confbridge and chan_sip
4) Last version of opus codec 1.3.0
5) The confbridge has settings:
[default_bridge]
type=bridge
video_mode=none
mixing_interval=40
sound_join=en/beep
sound_only_person=en/beep
sound_leave=en/nc_custom/confbridge-leave

The scenario is:
1) More then one opus participants join to a the same conference bridge
2) Bad quality occur if one of them on mute (not server mute) or just silent. it affect only who on mute/silent.
3) The quality is good when both of them are speaking at the same time.

Testing other version of the Asterisk:
I tried pjsip with 13.18,13.20,13.21 and last 15.4 version. I got the same results.

Workaround is:
The issue has been resolved by changing mixing_interval to 20.
I read documentation and found that 40 ms should cover sample rates 8-96 kHz. So, opus has 48 kHz but by some reason it doesn’t work properly.

Is this the expected behavior or a bug?
Comments:By: Asterisk Team (asteriskteam) 2018-05-11 07:21:50.616-0500

Thanks for creating a report! The issue has entered the triage process. That means the issue will wait in this status until a Bug Marshal has an opportunity to review the issue. Once the issue has been reviewed you will receive comments regarding the next steps towards resolution.

A good first step is for you to review the [Asterisk Issue Guidelines|https://wiki.asterisk.org/wiki/display/AST/Asterisk+Issue+Guidelines] if you haven't already. The guidelines detail what is expected from an Asterisk issue report.

Then, if you are submitting a patch, please review the [Patch Contribution Process|https://wiki.asterisk.org/wiki/display/AST/Patch+Contribution+Process].

By: Aleksandr Salanov (havier163) 2018-06-22 15:14:20.238-0500

Hello Team,

Do you have any updates?

By: Richard Mudgett (rmudgett) 2018-06-22 15:27:47.955-0500

Your issue is in the queue. Your patience is appreciated as a developer may work the issue when time and resources become available.

Asterisk is an open source project and community members work the issues on a voluntary basis. You are welcome to develop your own patches and submit them to the project.[1]

If you are not a programmer and you are in a hurry to see a patch provided then you might try rallying support on the Asterisk users mailing list or forums.[2] Another alternative is offering a bug bounty on the asterisk-dev mailing list.[3] Often a little incentive can go a long way.

[1]: https://wiki.asterisk.org/wiki/display/AST/Patch+Contribution+Process
[2]: http://www.asterisk.org/community/discuss
[3]: https://wiki.asterisk.org/wiki/display/AST/Asterisk+Bug+Bounties

Any updates will get posted on this issue.