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Asked: 2022-01-25 10:48:14 +0800 CST

bluetooth: call audio loop when paired with phone

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I have a phone connected to my Ubuntu 21.10 PC via bluetooth, sharing phone calls and media audio. I basically want to use the PC as a headset with access to two-way audio during calls.

Media from the phone is played on the laptop speakers as expected. Blueman shows that the High Fidelity Capture (A2DP Source) audio profile is selected.

During a call the profile switches to Headset Audio Gateway (HSP). I do get two-way audio:

  • Sounds played on the PC are heard on the call.
  • Speakers on the call can be recorded on the PC. HOWEVER: this input gets echoed back to the callers.

It seems like call input is treated just like media input: it's played back on whatever output channel is set up. How can I prevent this?

I did try Linux HFP from this answer, but the project is very old and getting it to compile and run on a modern system isn't easy.

sound

1 Answers

  1. Found a way to disable loopback manually during a call. From the PulseAudio wiki:

    When PulseAudio is acting as a headset... module-bluetooth-policy will also load module-loopback instances to loop the audio from bluetooth to the local speakers and microphone.

    So just unloading the module during a call gets rid of the loop effect:

    pactl unload-module module-loopback

    This needs to be done every time. It's possible to prevent it from loading in the first place by passing the hfgw argument to module-bluetooth-policy in /etc/pulse/default.pa:

    load-module module-bluetooth-policy hfgw=false

    Unfortunately this also disables playback of media audio. Is there a way to only do it for calls?

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