nrf5340 Audio interference and packet loss

RE: nrf5340 Audio interference and packet loss

Maria Gilje — Wed, 22 Jan 2025 12:41:11 GMT

Hello,

There could be two explanations for the playback artifacts: packet loss and non-optimized encoding. The packet loss concealment is good for music and speech but can be noticed for a tone. The LC3 codec is optimized for speech and music, so hearing artifacts on a transmittied tone is somewhat expected.

Best regards,

Maria

RE: nrf5340 Audio interference and packet loss

adunk — Tue, 21 Jan 2025 15:07:47 GMT

Was there ever any attempt to duplicate playing a tone on the audio demo? We are able to hear glitches and interruptions when playing a tone from the gateway to the headset when 10-20 feet away. Is this expected? Is it possible there is something different playing a tone versus audio? Maybe it can't be compressed?

RE: nrf5340 Audio interference and packet loss

Maria Gilje — Tue, 22 Oct 2024 14:01:11 GMT

Hello,

Thank you for your significant patience.

[quote user="adunk"]Our tests indicate the way Nordic implemented it is that the latency setting sets the flush out time and although the maximum number of retransmissions is 30, if the flush out time occurs before then, it will stop retransmitting and move on to the next packet. But I'd like to see some documentation to illustrate this.[/quote]

The Bluetooth controller will select a suitable set of parameter based on what the host configures, see the documentation for SoftDevice Controller LE Isochronous Channels for details.

There are some nice examples which illustrates the effects of the audio quality and robustness parameters in Ch. 4.3.2 of the Introducing Bluetooth LE Audio book by Nick Hunn. Is that the kind of documentation you are looking for?

Best regards,

Maria

RE: nrf5340 Audio interference and packet loss

adunk — Mon, 07 Oct 2024 11:06:52 GMT

I have increased the retransmissions to the maximum value of 30 and am seeing very positive results on the audio quality. From our measurements, it doesn't appear to be increasing the latency, but I am still hoping to see some documentation on how the QoS values are used and implemented. Our tests indicate the way Nordic implemented it is that the latency setting sets the flush out time and although the maximum number of retransmissions is 30, if the flush out time occurs before then, it will stop retransmitting and move on to the next packet. But I'd like to see some documentation to illustrate this.

It would be very challenging to measure the latency only during times of poor audio quality so I'd like to ensure the latency is a constant and controls the maximum number of retries rather than the other way around.

RE: nrf5340 Audio interference and packet loss

adunk — Fri, 27 Sep 2024 13:30:30 GMT

SDK 2.6.1
Covering headset or you can just start to walk away

RE: nrf5340 Audio interference and packet loss

Maria Gilje — Fri, 27 Sep 2024 06:32:41 GMT

Hello,

Which nRF Connect SDK version are you using?

Please specify which device you are covering: headset or gateway?

Best regards,

Maria