LE Audio Custom Application Questions

Question

Hello! 
 What would be the best way to start a custom LE Audio application with a different codec? 
 I mainly want to evaluate being able to stream 2-4 channels from a 53 acting as a gateway and on another 53 listening to the 2-4 channels. Should I start from scratch or should I modify the LE Audio samples? Is it even possible to do 4 channels broadcast/receive with the 5340? I noticed the LE Audio samples include drift and presentation compensation. If I use a different codec will have to come up with my own scheme? 
 
 Thank you for any information on where to get started.

Øyvind · Accepted Answer

Hello, 
 Nordic Semiconductor's BLE Audio solutions focuses on the use of the LC3 codec, to be compliant with BLE Audio. 
 That said, it should be possible to add your own codec but there is currently no documentation for this other than what we have in our documentation in the nRF Connect SDK - nRF53 Audio applications . 
 Have a look at how to configure codecs and the firmware architecture . There is a sw_codec_select layer that should allow you to add another codec. Note that during negotiations between the audio devices, these must agree on what codec should be used. This is not a trivial task and might need more work than the codec itself. 
 With regards to have more channels, please note that the nRF5340 running LC3 codec will on average use ~30% to encode a single channel. This might make it more difficult to encode four channels with the LC3, but perhaps another codec can provide better results. 
 With regards to adding other codecs you could use the "Vendor specific codec" mechanisms in the specification. 
 Should I start from scratch or should I modify the LE Audio samples? 
 If you need a comprehensive solution (time sync/I2S, volume control, media control, DFU, external codec (DAC/ADC)...) then the application is likely the place to start. If they need less features, they can look at the samples in zephyr and expand on those. 
 Let me know if you have any further questions! 
 Kind regards, Øyvind

Øyvind · Answer

Thanks for clarifying! 
 erickcinco said: I should have specified that I was talking about the hw codec 
 That happens, no worries 
 erickcinco said: Can any hw codec that accepts I2S be used? 
 Yes, any I2S capable hardware codec should work. We use the nRF53 audio PLL to slightly adjust the I2S frequency which may impact HW codecs differently. Have a look at the Zephyr drivers for supported hw codecs. 
 Kind regards, Øyvind

LE Audio Custom Application Questions

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