Maximum iso data length of NRF5340 audio increased

[LandyWang]

Hello,

I am using bis gateway on nrf5340 audio dk to transmit data.

In addition to audio encoded data, I also wanted to send some additional data, so I put these data after the audio encoded data and sent them together, and then I encountered the -EMSGSIZE error.

It seems that the maximum iso data length is 120, if the data length exceeds this size, it will not be transmitted.

Can this maximum length be increased?

[dejans]

Hi,

On the gateway, you could try to replace

BT_CODEC_LC3_QOS_10_UNFRAMED(251u, 4u,20u, LE_AUDIO_PRES_DELAY_US))

with 

BT_CODEC_LC3_QOS_10_UNFRAMED(251u, 2u,20u, LE_AUDIO_PRES_DELAY_US))

Generally, we highly recommend that you upgrade to the NCS v2.6.1 (or NCS v2.7.0 when it becomes available).

Best regards,
Dejan

[LandyWang]

Thanks for your assistance, it works.

Now I can successfully transfer 250 bytes of data through bis.

Then, I tried to increase the sdu size to 512 bytes. The following are my modifications on the gateway.

BT_CODEC_LC3_QOS_10_UNFRAMED(512u, 0u,20u, LE_AUDIO_PRES_DELAY_US))

I tried to send 480 bytes of data, written as follows:

streamctrl_encoded_data_send(my_data, 480);

Although the bis headset connect to the gateway successfully, it did not receive any data.

What is the limit on the data size that is bis gateway can transmit?

[dejans]

Hi,

I would need to check this internally. I will get back to you during next week.

Best regards,
Dejan

[dejans]

Hi,

The audio application currently supports max PDU (containing one SDU) of 251. 

Best regards,
Dejan

[LandyWang]

Ok, I see. Thank you for your assistance.