nRF5340 Audio stereo streaming to a single device

RE: nRF5340 Audio stereo streaming to a single device

Priyanka — Mon, 22 Jan 2024 12:34:23 GMT

Hi Jon,

I would suggest that you begin a new ticket for the same so that any of the software experts in this can help you out regarding the matter and any future seekers can also find the Devzone search helpful. 🙂

Regards,

Priyanka

RE: nRF5340 Audio stereo streaming to a single device

Jon — Thu, 30 Nov 2023 23:51:57 GMT

Has there been any movement on this issue? I wired a stereo DAC to one of my Audio DK's, and have been trying to make changes to get both L and R channels sent to the single 'headset' board. I found that while the cis_gateway does indeed encode both channels of audio, it attempts to send them to independent headset boards. If I modify the code to send both channels to a single headset, I cannot get the connection to work. First of all, the SDU size would have to be increased, from 120 to 240 bytes. If I do this, the connection immediately drops. Is there a better way to accomplish this?

RE: nRF5340 Audio stereo streaming to a single device

MStreet — Wed, 19 Jul 2023 00:19:47 GMT

Hi Priyanka,

I understand that the DK cannot act as a stereo headset, which as you mentioned would need an external HW Codec/DAC. But the DK codec does have a stereo ADC connected to the line in jack. So, there is no reason why it can't be used as a gateway to stream stereo audio to headsets or Qualcomm based earbuds and not just to mono earbuds. Your gateway LE audio support is going to be very incomplete without this, so hopefully it's something you'll be adding soon.

RE: nRF5340 Audio stereo streaming to a single device

Priyanka — Tue, 04 Jul 2023 14:24:49 GMT

Hi Milo,

It doesn't look like we have plans for this as of now as we have a mono HW codec on the Audio DK. You can try this yourself and can add using an external HW Codec/DAC.

-Priyanka

RE: nRF5340 Audio stereo streaming to a single device

MStreet — Wed, 28 Jun 2023 18:33:54 GMT

Hi Priyanka,

Sorry if I didn't explain the issue clearly enough in the original post.

We have been developing with your DKs and our own nRF5340 hardware for over six months. We are operating as a CIS gateway and need to connect with LE audio capable earbuds, headphones, and smart speakers.

Over the ear headphones (not earbuds) and smart speakers will have one radio and need a single stereo CIS connection. There are also some earbuds that require a single LE audio/LC3 stereo stream to be sent to just one of the earbuds. Then that earbud will send audio to the other earbud by another method like they currently do for BT Classic. This appears to be the approach taken by Qualcomm and others (Apple?) may do the same.

An earlier post from last October suggested the following:

"You can modify the application to be able to stream stereo by combining the left and right channel after encoding and before sending the audio. In the application code, the combination needs to be done before streamctrl_encoded_data_send() is called in the encoder_thread() in src/audio/audio_system."

Before trying tackle something like this on our own, it would be nice to know out if Nordic will be enabling this in a future release and if so, when.

RE: nRF5340 Audio stereo streaming to a single device

Priyanka — Wed, 28 Jun 2023 09:10:18 GMT

Hi Milo,

I am not sure what you actually are looking for, but maybe this explanation helps. Previously there was the Classic Audio which operated on the Bluetooth Classic radio and it uses the SBC codec. Then there came the introduction of TWS (True Wireless Stereo), but then too, there was a master earbud to which the stereo data is sent to and then a mono channel is sent onward to the other earbud. This was changed with the Bluetooth LE Audio introduced now which uses the LC3 codec, and stereo audio is sent to both earbuds independently thereby reducing the radio usage and also lowering bit rates and battery usage. We support this LE audio and LC3 codec right now.

https://www.bluetooth.com/learn-about-bluetooth/feature-enhancements/le-audio/

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/applications/nrf5340_audio/README.html

Best Regards,

Priyanka