[Linphone-users] Bad audio output - but only on one side.

[Nakonda]

Hello list,

I am new with Linphone and with this list and I am very happy to use this great software for some weeks now.
I managed to install Linphone on some devices within my family and we are testing several situations.

Here is one of our settings:

Me:
Hardware: Tablet Nexus 7 (2012)
OS: Cyanogenmod 11
Linphone: 2.3.2 (download from daily builds)
Local Connection: Wifi (1 Mbit/s)
Internet: ADSL (7 Mbit/s)


my partner
Hardware: Lenovo Tablet 10.1
OS: Android 4.?
Linphone: 2.3.2 (download from Google Play)
Local Connection: Wifi
Internet: ADSĹ

both:
no other apps active on the device during calls
encryption SRTP
input via tablet microphone
output via tablet loudspeaker
camera: built-in front camera
Audio codec: opus48
Video codec: VP8
Upload: 461/55 kbit/s
Download: 401/52 kbit/s
video resolution: 480x640/640x480


We have good video transmission in both directions but audio output is only good for my partner.

Audio output on MY side is bad and it is altering a lot: 1 second the sound is clear and loud and 1 second it goes muffled and volume is down. Sometimes there are interruptions or audio is completely gone for some seconds.
During this, upload and download rates keep stable. We tried it w and w/o video, with different audio codecs and encryption "off" and echo cancellation ON (calibrated) on both sides but the audio quality is always very bad on my side.

It seems to get little better, when echo cancellation is "off" on both sides!
The sound of audio changes (gets a little better) when we start video.
I also notice that ICE connection changes from "Relay Connection" (audio) to "Reflexive Connection" (audio+video).

Audio is instantly very good when I turn off my microphone, while my partner is speaking. But when I turn it back on, sounds alter very strongly.

Unfortunately with echo cancellation "off" we sometimes suffer from strong high frequency echo oscillation. And unfortunately I can not use a headphone during video connection, as Linphone only uses loudspeaker instead of phone jack for output.

On my partner's side, the audio output is good/very good all times.

So I wonder, if this problem is a sending issue from my partner or a receiving issue on my side or even something else.

Can someone give me a hint, how I could trace and hopefully solve this issue?

Thanks and regards.

Rai.
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