Creating multiple BIGs with one gateway (nRF5340 Audio DK)

[dark73]

My project goal is to broadcast four different languages simultaneously using Auracast. Each language will be transmitted on its own BIG so that Auracast-compatible devices, such as Galaxy Buds, can select and listen to the desired language.

As a first step, I am currently trying to receive two language streams and create two BIGs.

Before starting this work, I successfully built and ran the broadcast_source sample from the nrf_audio application in nRF Connect SDK.

I have two questions:

1. I would like to receive audio for multiple languages over a single USB connection by using multiple USB audio channels (or another recommended USB audio architecture). Is this the recommended approach? If so, are there any examples or documentation that I should refer to?
2. Before creating multiple BIGs, my understanding is that each audio stream needs to be encoded separately in encoder_thread() before being sent to the corresponding BIG. Is my understanding correct? If so, could you point me to the relevant source files, documentation, or examples that explain how this part of the audio pipeline is implemented?

I have tried to find documentation and examples related to these two topics, but I have not been able to find any useful references.

I would greatly appreciate it if you could provide some guidance on where I should start looking or which parts of the source code and documentation I should study.

Thank you very much.

[Øyvind]

Hello,

Thanks for registering your question with us. Please note that Nordic Semiconductor is currently in a summer break period and many of our resources are out of office. We will provide an answer back in a timely manner, and update you as soon as possible. In advance, thank you for you patience.

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Kind regards,
Øyvind

[dark73]

I have a few additional questions regarding a mono audio broadcasting configuration.

Assuming that I use mono audio, I would like to create 4 BIGs, where each BIG contains a single BIS (for a total of 4 BIGs and 4 BIS streams).

My questions are:

1. Is it sufficient to run four LC3 encoders (one encoder per BIS) in this configuration?
2. Is it possible to implement this on a single nRF5340 Audio DK?

In addition, I would like to ask about the following:

1. How can I configure the nRF5340 Audio DK to broadcast mono audio using 4 BIGs, with each BIG containing a single BIS (4 BIGs / 4 BIS in total)?
2. If I receive a single USB Audio stream from a host (e.g., Jetson), what is the recommended way to separate it into four channels (KOR, ENG, JAP, CHA) and feed them to four LC3 encoders? Is this architecture supported or recommended? (As I understand it, the audio_system.c receives audio as two channels (L/ R stereo))

Thank you for your help.

[dark73]

I understand that the broadcast_source sample is structured as follows:

Audio (L/R) → LC3 Encoder → BIG (L BIS / R BIS).

KOR (L/R) -> LC3 Enc - BiG( L BIS / R BIS )

ENG(L/R) -> LC3 Enc - BiG( L BIS / R BIS )

JAP (L/R) -> LC3 Enc - BiG( L BIS / R BIS )

CHA(L/R) -> LC3 Enc - BiG( L BIS / R BIS )

I will implement it using the example as much as possible.

I want to make at least two language BIGs with one gateway(nrf5340 audio dk)