LC3 codec support for nRF5340 DK

[ShuMan]

Hi,

I have a nRF5340 DK (not the audio DK). I read the specification of nRF5340 Audio DK and found that it supports LC3 codec. However, I want to ask, is it possible to use an external codec with nRF5340 DK. If yes then is there any example available for it?

Thanks.

[Adarsh_1]

Hallo ShuMan,

I assume that you are talking about software codec.

LC3 codec is mandetory for standard LE Audio application. However, the initial release of nrf5340 audio application also have support for SBC codec. According to my understanding, Nordic does not provide support for additional codec (most of them are private / closed source). However, it should be possible to integrate any codec with LE standards. The standard supports this, but you will have to buy the software codec from the corresponding vendor and integrate it with LE Audio yourself.

best regards,

Adarsh

[Jared]

Hi,

This is correct. LC3 is mandatory for all LE Audio devices, but the specification gives the possibility to have a secondary codec, but this requires that both sides of the connection has support for it. 

I would also like to add that the nrf5340_audio reference application is made specifically for the nRF5340 Audio DK (not the regular DK) so it will not run without modification on the regular nRF5340 DK. However, there are no technical limitations on the nRF5340 DK for it to be used for LE Audio - we would of course recommend that you use the nRF5340 Audio DK for all audio development, since it is made specifically to make such development easier.

Regarding the external codec part of the question - our LC3 implementation is also specifically made, and optimized for, the nRF5340, but there is nothing stopping you from exchanging it for any other codec, just keep in mind that the LC3 codec is mandatory for all LE Audio certified devices. The reference application currently only supports the LC3 and SBC codecs, so if you intend to use any other codec you will have to add this yourself, but it should be pretty straight forward so long as the new codec also uses 10 ms frames, and has the same API as the LC3 and SBC.

regards
Jared

[ShuMan]

Hi,

Thanks Adarsh and Jared for the information.

In our application we are using the file stored on an SD card rather than streaming it from external device (unlike the given LE Audio application for Audio DK). So, in our case we can either use LC3 or any other codec, right (as ours is not LE audio streaming application)?

Thanks

[Adarsh_1]

Hi,

ShuMan said:

So, in our case we can either use LC3 or any other codec, right (as ours is not LE audio streaming application)?

Ofcourse you could use LC3 or any other codec for LE Audio transfer. But as already mentioned, keep in mind that LC3 codec is mandatory for all LE Audio certification. You will not get your device certified without including LC3 codec / support for LC3 codec. 

ShuMan said:

In our application we are using the file stored on an SD card rather than streaming it from external device

In the reference application, the data/audio is accessed from USB through a hardware codec ( from cirrus logic). Audio source does not defines your audio streaming capability. You will infact be using LE Audio standards for audio streaming and hence LC3 codec is mandatory for certification. You could however test the nrf5340 audio application sample with SBC as well. 

Best regards,

Adarsh