nRF5340 Audio - 6 streams broadcasting

[catalinio]

Dear Nordic team,

I'm evaluating nRF5340 Audio DK for the use-case of broadcasting multiple streams.

Until now I've succeeded in broadcasting 4 streams (LC4 bitrate set up to 48kbps) and I would like to to increase to 6. I've increased all the configuration parameters to support 6 streams, but I receive an error in initializing the broadcast source.

I'm attaching the whole debug log, but the main error is here:

GW [00:00:02.445,953] <wrn> bt_hci_core: opcode 0x2068 status 0x0d

GW [00:00:02.445,953] <dbg> bt_iso: bt_iso_big_create: Could not create BIG -5

 

Opcode 0x68 is BT_HCI_OP_LE_CREATE_BIG.

The status code 0x0D is BT_HCI_ERR_INSUFFICIENT_RESOURCES, and I've added warn log messages to all the C-code returning this value, but it's not printed. So I suspect this could be in the LE Audio controller from the Network Core (binary release). Most of the code is indeed in the BT Controller (C:\ncs\v2.2.0-rc1\zephyr\subsys\bluetooth\controller).

I'm attaching the prj.conf with the modified configuration values, of the nRF5340 Audio application.

I'm using the nRF Connect SDK v2.2.0-rc1.

I understand the LC3 encoding processing requirements are quite high, but as it takes 6 milisec for 4 streams (10milisec PCM slice, 32kbps), I suppose there is time for 6 streams @32kbps.

Please let me know if there's any more configuration values that needs to be tuned, in order for the 6 (or maybe 8) streams to be broadcasted, or maybe some timeouts increased.

Thank you!

6036.terminal_for_support.txt

[dejans]

Hi,

If possible, could you provide information why you would need 6 BIS streams and what would they be used for?

Best regards,
Dejan

[catalinio]

Hi,

The main idea is to demonstrate the BLE Audio capabilities of nRF5340; the use-case is: multiple audio-streams will be distributed in a room to multiple listeners, and each will choose their active stream.

For now 2 streams will be from I2S (left and right from audio stereo), while the channels #3 to #6 will be generated sinewaves.

On long-term, minimum 16 channels should be broadcasted; most-likely the LC3 encoding should be done on a more powerful MCU, so nRF5340 will remain just to handle LE Audio stack and decoding (only on the receiving kit).

Would broadcasting 16 BIS (without LC3 encoding, 48kbps each stream (probably 2 retransmissions min), so this is 96KB/sec audio-data for all streams) is achievable for nRF5340 and BLE Audio stack?

Thank you!

[dejans]

Hi,

As there is theoretical limit for 2M Phy of around 1.4 Mbps, that would enable support for less than 10 streams (with 48 Kbps) with 2 retransmissions each. Even with only 1 retransmission, maximum number of streams would be 14. However, these are only theoretical considerations, since audio controller currently supports maximum 4 BISes.

Best regards,
Dejan

[catalinio]

Hi,

Any news on releasing a new BL Controller with 6 or 8 BIS streams?

thanks,

Catalin

[dejans]

Hi,

It is not supported at the moment. For any other information related to future plans and releases please contact your regional sales manager.

Best regards,
Dejan