Need improvment in Zephyr LC3 encoding execution time for NRF53 MCU

RE: Need improvment in Zephyr LC3 encoding execution time for NRF53 MCU

Maria Gilje — Fri, 06 Jun 2025 14:16:44 GMT

Hello,

Based on the nRF Connect SDK repository revisions table, this means that you are using nRF Connect SDK v2.6.2, which is quite old at this point. This means that we are not able to support everything in this release.

If you have to stay with v2.6.2, we will do our best.

[quote user="Dhruv@1997"] Do we have any benchmark document which gives CPU utilisation information? [/quote]

We don't have any documents which we can release, but information I can share is that LC3 encoding typically uses about 30% of the CPU, while decoding uses about half of that at 15-16%.

[quote user="Dhruv@1997"]As of now, we have used a bit rate of 32000, so what is the minimum range of bitrate?[/quote]

32000 kpbs is the minimum bitrate for LC3, unfortunately.

So, since you are working on a quite old SDK version, is it feasable for you to upgrade to v3.0.2? We have migration guides which cover the biggest changes. The most important one is v2.7.0 which introduces both the hardware model v2 and sysbuild. I linked the separate migration guides for both those features.

Best regards,

Maria

RE: Need improvment in Zephyr LC3 encoding execution time for NRF53 MCU

Dhruv@1997 — Fri, 30 May 2025 15:53:56 GMT

We have used Zephyr NCS version 3.5.99-ncs1-2 and nrfxlib v2.6.2. I am encoding the stream in one thread, so ideally, it is parallel. Do we have any benchmark document which gives CPU utilisation information? As of now, we have used a bit rate of 32000, so what is the minimum range of bitrate?

RE: Need improvment in Zephyr LC3 encoding execution time for NRF53 MCU

Maria Gilje — Fri, 30 May 2025 13:13:34 GMT

Hello,

Which nRF Connect SDK are you working with?

As a general advice, the way to reduce encoding time is to decrease the bitrate.

In the current setup, are you encoding the stream sequentially or in parallel?

Best regards,

Maria