ConfBridge Audio Issues

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We have a system where two calls are in a ConfBridge with recording. This is Asterisk 16.3.0

Channel A seems to work perfectly. Wireshark is showing the RTP to/from working fine and having no jitter/lag issues. This call hears everything from channel B.

Channel B we have more issues capturing a wireshark trace because their channel can be in the system for hours. When the two calls are in the ConfBridge, Channel B is the first to speak. Everything seems perfectly fine. Channel A hears it well and ConfBridge recording sounds good. Then, channel B replies. Audio from channel B seems fine in wireshark (no jitter/lag). However, the ConfBrdge recording and channel B indicate garbled audio.

This only happens for the first couple seconds channel B talks. After that, everything seems to be perfectly fine.

For each channel added to the ConfBridge, the user profile has… jitterbuffer = yes denoise = no dsp_drop_silence = yes dsp_silence_threshold = 2500
dsp_talking_threshold = 160

On the bridge profile. internal_sample_rate = 0
mixing_interval = 20
jitterbuffer is not being set. According to the wiki, this defaults to no binaural_active is not being set. According to the wiki, this defaults to no

One other possible coincidence in the samples I have received, channel B seems to always start talking roughly 2500 ms into the ConfBrdge. Could this static audio be occurring due to the dsp_drop_silence and the dsp_silence_threshold hitting at 2500 ms?

Does anyone have any suggestions?

Dan

2 thoughts on - ConfBridge Audio Issues

  • Um, did Channel A say something in the meantime?

    Or did you mean “Channel A replies”?

    In which case…

    So, which channel speaks first, which replies, and which has garbled audio in the recording?

    Antony.

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  • Sorry, for not being clearer.

    Channel A and B added to the ConfBridge. Same settings for both user profiles.
    Channel B starts speaking. Their audio makes it through ConfBridge to Channel A perfectly fine.

    Now, Channel A speaks to reply to question asked. Channel B’s audio is fine in Wireshark trace to Asterisk box.

    The ConfBridge recording has the garbled audio. Channel A hears the garbled audio as well.

    If it was network/jitter related, I would expect wireshark to indicate some jitter/lag issues in the audio from Channel B to Asterisk. That doesn’t seem to be the case.

    Since the ConfBridge recording contains the garbled audio, my thought is I’m doing something wrong with the settings. Not sure what setting would cause this.

    Could it be the jitterbuffer enabled on each ConfBridge user’s profile?
    Could it be the dsp_drop_silence?

    Oddly enough, this happened on Friday to several calls. Over the weekend, they had no issues. Also, today they have experienced no issues.

    Additional information. Channel A and B are using ulaw codec. The recording in the ConfBridge is being transcoded to gsm for the recording.

    Dan

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