RE: Change the bitrate LC3 codec.

Edvin — Thu, 20 Feb 2025 14:45:46 GMT

Hello,

In unicast, we can't change the bitrate arbitrarily. We need to stick to the preset defined in BAP:

CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_48KHZ=y  //result to 48KHz SpS, 96kbps
CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_24KHZ=y  //result to 24KHz SpS, 48kbps
CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_16KHZ=y  //result to 16KHz SpS, 32kbps

please note that CONFIG_BT_AUDIO_BITRATE_UNICAST_SRC/SINK has no effect.

When broadcasting, you are a bit more free to do as you like. You can set the bitrate and sample rate, e.g. like this:

CONFIG_BT_AUDIO_BITRATE_BROADCAST_SRC=32000  # set the bitrate
CONFIG_BT_AUDIO_PREF_SAMPLE_RATE_24KHZ=y # set the sampling rate to 24KHz, we also support 16KHz
CONFIG_BT_AUDIO_RETRANSMITS=2 # the default is 2, just for reference if you would like to change it

Best regards,

Edvin