USB AUDIO + BROADCAST (NRF5340)

[heavyjo]

TOOL : NRF SDK 2.6.99 (VSC)

1.When connecting a broadcast audio source with USB audio to listen to music on the sync side, there seems to be some stuttering. How can I solve this issue?

I tried changing the broadcast audio source's send rate from BT_BAP_LC3_BROADCAST_PRESET_24_2_1 to BT_BAP_LC3_BROADCAST_PRESET_48_2_1.
To do this, I changed the sample rate in the USB audio settings by taking the value from usb-audio-hs.yaml and applied it.

However, this change doesn't seem to modify the descriptor. When connected to a PC, the headset is recognized but it cannot play audio.

2.Is there an appropriate way to change the descriptor so that audio can be played, or am I doing something wrong?

Please Let me know

[Elfving]

Hello,

TOOL : NRF SDK 2.6.99 (VSC)

I am surprised that there would be something wrong that would result in stuttering, but I would recommend you to try this on a stable tag of the SDK first, so that we know that there is nothing wrong there before we proceed.

Try NCS 2.6.0. The .99 is the main branch essentially.

Regards,

Elfving

[heavyjo]

It feels like the audio quality is poor rather than choppy

[Elfving]

In NCS 2.6.0 that is?

If I am understanding you correctly, you've now switched to NCS 2.6.0, and the music is no longer choppy, but poor.

[heavyjo]

I apologize for the poor explanation and any confusion it caused. I ran it on version 2.6.0 and confirmed that the audio quality has improved compared to 2.6.99.

The differences compared to 2.6.99 are as follows:

2.6.0:

• CONFIG_BT_BAP_BROADCAST_SRC_SUBGROUP_COUNT = 2
• CONFIG_BT_ISO_TX_BUF_COUNT = 4
• Sample rate hz on "usb-audio-hs" isn't existed

2.6.99:

• CONFIG_BT_BAP_BROADCAST_SRC_SUBGROUP_COUNT = 1
• CONFIG_BT_ISO_TX_BUF_COUNT = 6
• Sample rate hz on "usb-audio-hs" is existed

When I change the subgroup to 1, the audio quality degrades again.

Here are two questions:

1. Does the tx_buf_count significantly impact audio quality among the differences mentioned above?
2. When changing the subgroup to 2, does the audio quality degradation occur due to the left-right delay?
3. Are there any other options I could try to improve the audio quality?

[Elfving]

I'm glad we've cleared up some of the confusion. 

heavyjo said:

Are there any other options I could try to improve the audio quality?

I'm not sure myself about what exact changes have affected the audio quality unfortunately. I can forward this question to the relevant R&D team, though I am not sure if I understand why it would matter to you. Either way, you should optimally use a stable tag for this eg. 2.6.0 (but I just saw that 2.6.1 is out too, that should be stable as well).

The obvious way to improve the audio quality is to not use the main-branch.

And the configurations you mentioned are not the only things that have changed between the versions you've listed. Have a look here for instance.

Regards,

Elfving