Bluetooth HFP audio echo on receiver side
Summary
When making a bluetooth hands free phone call, the person on the receiving end of the call hears an echo (or loopback) of their own voice with an aprox 1 second delay.
environment
root@verdin-imx8mp-15006329:~# tdx-info
Software summary
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Bootloader: U-Boot
Kernel version: 5.15.129-6.4.0-devel+git.67c3153d20ff #1 SMP PREEMPT Wed Sep 27 12:30:36 UTC 2023
Kernel command line: root=PARTUUID=72b5ae8b-02 ro rootwait console=tty1 console=ttymxc2,115200 consoleblank=0 earlycon
Distro name: NAME="TDX Wayland with XWayland"
Distro version: VERSION_ID=6.4.0-devel-20231220205908-build.0
Hostname: verdin-imx8mp-15006329
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Hardware info
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HW model: Toradex Verdin iMX8M Plus WB on Verdin Development Board
Toradex version: 0058 V1.1A
Serial number: 15006329
Processor arch: aarch64
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Bluetooth chip is the Azurewave AW-CM276NF
Steps to reproduce
- Connect phone to device using
bluetoothctl
- Initiate a phone call
- Load loopback modules
pactl load-module module-loopback source=bluez_source.<address>.handsfree_audio_gateway sink=alsa_output.platform-sound.stereo-fallback
pactl load-module module-loopback source=alsa_input.platform-sound.stereo-fallback sink=bluez_sink.<address>.handsfree_audio_gateway
What is the current bug behavior?
On the receiver end, which is answered on a cell phone, there is a very annoying echo or "loopback" of their own voice, which occurs aprox 1 second after speaking. On the caller end, a headset is being used and no echo is heard.
What is the expected correct behavior?
There should not be an echo.