nrf5340 Stereo Audio

[Adarsh_1]

Hello team,

I was not able to receive a suitable reply for this post for almost two weeks. I started thinking the engineer had gone for vacation. That is the reason I am reposting and asking for guidance here once again. 

I am hoping to receive response from any other engineers if at all Karl Ylvisaker is on vacation. You can refer the post where I am looking for a solution for sending a stereo audio from the gateway and hoping to collect and reproduce stereo audio at the headphone side using stereo hardware codec. I have detaily mentioned my queries in the previous post. As mentioned in the post, I am working on ncs V17.0.0. 

Thanks for your time. 

best regards,

Adarsh

[Einarh]

Hi

You should here modify the le_audio_send function so that it sends stereo data

If you compare the implementation of streamctrl_encoded_data_send in 2.1 and 2.0:

https://github.com/nrfconnect/sdk-nrf/blob/v2.1-branch/applications/nrf5340_audio/src/audio/streamctrl.c#L211

https://github.com/nrfconnect/sdk-nrf/blob/v2.0-branch/applications/nrf5340_audio/src/audio/streamctrl.c#L226

It seems like ble_trans_iso_tx is the function you're looking for, and it seems to take an option for mono/stereo.

make the headset device expect to receive a stereo stream

These seem to be the corresponding functions in 2.1 and 2.0:

https://github.com/nrfconnect/sdk-nrf/blob/v2.1-branch/applications/nrf5340_audio/src/audio/audio_system.c#L68

https://github.com/nrfconnect/sdk-nrf/blob/v2.0-branch/applications/nrf5340_audio/src/audio/audio_codec.c#L308

Hope this helps

-Einar

[Adarsh_1]

Hai Einarh,

Thank you for your reply. Yours suggestions are on point.

I have decided to use NCS V2.1.0. 

Einarh said:

If you compare the implementation of streamctrl_encoded_data_send in 2.1 and 2.0:

I am struggling here somehow. I am not able to modify the le_audio_send function to make it work.

Einarh said:

It seems like ble_trans_iso_tx is the function you're looking for, and it seems to take an option for mono/stereo.

Since now I am using NCSV2.1.0, I cannot find this function anymore. What is the equivalent function in ncsv2.1.0?

Einarh said:

You should here modify the le_audio_send function so that it sends stereo data

Can you please shed more light on how this can be done. I assume it is not that easy as changing the parameter in ble_trans_iso_tx from mono to stereo. 

iso_stream_send () does not seems to support stereo. I assume this function has to be properly modified. Is it correct? How you please explain how this could be done?

ret = iso_stream_send(data, sdu_size, AUDIO_CH_L);
	if (ret) {
		LOG_DBG("Failed to send data to left channel");
	}

Thanks for your time.

best regards,

Adarsh

[Einarh]

Hi

Looking at the le_audio_send function, the stereo stream is split into two mono streams by two different calls of iso_stream_send.

Here AUDIO_CH_R and AUDIO_CH_L simply indicate what iso channel to send the data on.

So if you want to send a stereo stream, you can simply send all the data with a single call of iso_stream_send by doubling the sdu_size.

You'll then have to split the received data in two on the headset side.

Best regards,

Einar

[Adarsh_1]

Hi,

Thank you Einarh for your reply. 

I will leave it open just in case I face problems while implementing the suggested methods. 

Best regards,

Adarsh