Audio quality degradation with dual CIS connections on nRF5340

RE: Audio quality degradation with dual CIS connections on nRF5340

Maria Gilje — Mon, 29 Dec 2025 10:31:30 GMT

Hi Valentin,

Good find! It's always nice to return to work to find solved cases.

Happy holidays to you as well!

Best regards,

Maria

RE: Audio quality degradation with dual CIS connections on nRF5340

Valentin Sagstetter — Mon, 22 Dec 2025 10:37:49 GMT

Hello Maria,

I looked into the CodecConfig and realized I had the same Location set for both Encoders when creating the unicast group. I changed one Encoder to use Location FRONT_LEFT and the other to Location FRONT_RIGHT. I tested this configuration with the Galaxy Buds 3 Pro and it worked well.

Thank you for your help and Happy Holidays!

Kind regards,

Valentin

RE: Audio quality degradation with dual CIS connections on nRF5340

Maria Gilje — Thu, 18 Dec 2025 15:03:57 GMT

Hi Valentin,

The characteristics I'm thinking of are the ones in Lc3AudioDecoder::extractLc3Config(). When using that function in Lc3AudioDecoder::initialize, could you verify that the sample rate and frame duration stays the same when adding a second connection? It can also be worth to verify the configurations in the equivalent functions on the encoder side as well.

If the configuration stays the same, please let me know what type of audio you are streaming: is it voice or audio?

Just so you are aware: I will take some time off starting this evening due to christmas holidays. I will continue supporting you when I return the week after christmas.

Best regards,

Maria

RE: Audio quality degradation with dual CIS connections on nRF5340

Valentin Sagstetter — Thu, 18 Dec 2025 11:57:56 GMT

Hello Maria,

Thank you for your help. I've uploaded the source code to GitHub: github.com/.../le_audio_to_uac2.
Let me know if you need any additional information.

Kind regards,

Valentin

RE: Audio quality degradation with dual CIS connections on nRF5340

Maria Gilje — Wed, 17 Dec 2025 16:00:35 GMT

Hi Valentin Sagstetter,

Could you please check if the characteristics for the audio streams changes when you add a second connection? I can help to find out how check for this in your firmware, but a link to the source code you are using is very helpful (i.e. a GitHub-link).

Best regards,

Maria