Bluetooth HFP phone call loopback problem

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It seems like you’re experiencing an echo and latency issue when making phone calls using Bluetooth HFP (Hands-Free Profile) on your Apalis iMX8QM module with the Ixora carrier board. Here are a few steps and considerations to help you troubleshoot and potentially resolve the issue:

1. Echo Cancellation:

   • Echo is a common issue in audio systems, especially in hands-free communication. PulseAudio has a module for echo cancellation that you can try to load. Add the following line to your /etc/pulse/default.pa:

     load-module module-echo-cancel
     

   • This module can help reduce or eliminate the echo by processing the audio streams.

2. Latency Adjustment:

   • The latency might be due to buffer sizes or the way audio streams are handled. You can try adjusting the buffer sizes in PulseAudio. Add or modify the following lines in your /etc/pulse/daemon.conf:

     default-fragments = 2
     default-fragment-size-msec = 10
     

   • These settings can help reduce the latency by adjusting the audio buffer sizes.

3. Bluetooth Profile Configuration:

   • Ensure that the correct Bluetooth profiles are being used. In your /etc/bluetooth/main.conf, you have:

     Enable = Source,Sink,Media,Socket,Headset
     

   • Make sure that the Headset profile is correctly configured and that your device supports HFP.

4. PulseAudio Loopback Configuration:

   • The loopback module you are using might be causing the echo. You can try to adjust or remove the loopback module to see if it helps. In your /etc/pulse/default.pa, you have:

     load-module module-loopback source=alsa_input.hw_0_0 sink=alsa_output.default
     

   • Try commenting out this line and see if the echo persists. If it does, you might need to reconfigure how the audio streams are routed.

5. Testing with BlueALSA:

   • Since you are using PulseAudio, you might want to test with BlueALSA as an alternative to see if it handles the audio streams better. BlueALSA is specifically designed for Bluetooth audio and might provide better performance for HFP.

6. Hardware Considerations:

   • Ensure that the microphone and speakers are properly connected and configured. Sometimes hardware issues can cause echo and latency problems.

7. Debugging Tools:

   • Use tools like pavucontrol to monitor and adjust audio streams in real-time. This can help you identify which streams are causing the echo and adjust their properties accordingly.

8. Update Software:

   • Ensure that you are using the latest versions of PulseAudio, BlueZ, and other related software. Sometimes, updates contain fixes for issues like the one you are experiencing.

If these steps do not resolve the issue, you might need to provide more specific logs or details about the behavior of the system during a call. This can help in diagnosing the problem more accurately.

Please, also check if these links can help you solve your problem:

Audio output with TorizonCore

I’m trying to get headphone audio output working and i’ve tried following this guide. It seems like TorizonCore does not comes with ALSA utilities installed. Currently I’m testing my qt application in a docker container. What is the preferable way to get headphone audio output working with Qt inside docker? As i understood, I need to have Pulseaudio running to get Qt audio output. Thank you. Hardware Apalis iMX8QM 4GB WB IT v1.1 B Ixora V1.1A with TorizonCore 5.7

https://community.toradex.com/tag/bluetooth

Bluetooth HFP echo on receiver side.