BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Øyvind — Mon, 16 Sep 2024 08:48:16 GMT

Hello,

[quote user="Engr Abdul"]Here’s the dongle I’m referring to: LE Audio Dongle.[/quote]

We are not familiar with this product and cannot provide any feedback on this.

[quote user="Engr Abdul"]Would using this dongle allow us to add LC3 codec support to older Android phones (or phones that don't support LC3 by default) and enable these phones to stream audio using BLE to the nRF5340 Audio DK, which already has LC3 support?[/quote]

I can only answer for the nRF5340 Audio DK, as the LC3 support on the phones is not something we can control. I cannot answer in regards to any dongle on the phone. You will need to reach out to e.g. Android community for the support on LC3 codec on the phone side.

Kind regards,
Øyvind

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Engr Abdul — Sun, 15 Sep 2024 10:27:53 GMT

Any suggestion please?

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Engr Abdul — Fri, 13 Sep 2024 12:03:14 GMT

Here's your reply message:

Hi Øyvind,

I hope you're doing well!

Thanks for your detailed and valuable feedback on my question. Your explanation helped me better understand LE audio, the LC3 codec, and how the bandwidth is managed without LC3.

I have just one technical question remaining regarding the nRF5340 Audio DK. As we know, the LC3 codec is available in most recent Android phones, but it isn't easily accessible for developers to use directly. To address compatibility issues with older Android versions that do not natively support the LC3 codec, I was wondering if it would be possible to use an LE Audio Dongle, such as the LE Audio USB C Bluetooth 5.4 Audio Transmitter with APTX Adaptive Low Latency LC3, to add LC3 codec functionality to these older devices.

Here’s the dongle I’m referring to: LE Audio Dongle.

Would using this dongle allow us to add LC3 codec support to older Android phones (or phones that don't support LC3 by default) and enable these phones to stream audio using BLE to the nRF5340 Audio DK, which already has LC3 support? Essentially, we want to know if this dongle can act as a bridge to provide LC3 codec functionality on the phone side, allowing the nRF5340 Audio DK to receive and play high-quality LE Audio.

I hope this clarifies my question. I’m eager to hear your thoughts on whether this solution would work!

Thank you so much for your time and guidance. :)

Best regards,
Engr. Abdul

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Øyvind — Thu, 12 Sep 2024 09:06:21 GMT

You can also have a look at our BLE Audio webinars covering this topic.

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Øyvind — Thu, 12 Sep 2024 09:03:58 GMT

Hello, I've discussed this internally and have the following answers to you.

[quote user="Engr Abdul"] However, I am now uncertain how to manage the app side in Flutter. Specifically:[/quote]

I'm afraid we can't provide much help with the Android side. We have no knowledge of Flutter and how that uses codecs. I suspect that the LC3 codec is available somewhere general in Android and can be used. LC3 is mandatory in LE Audio, but in case he just wants to get audio over the air in a proprietary manner, it is possible to use a different compression algorithm, but that needs to be on the kit side as well. As we only support LC3 in our SDK, you will need to add this compression algorithm yourself.

[quote user=""]Data Rate Concerns:[/quote]

Yes, sending uncompressed data is only possible for low/medium quality or one PCM stream. The total effective bandwidth of Bluetooth on a 2MPHY is around 1.4 Mbit/s, and will be a bit less if you want to use CIS ISO as there are some data used for the ACL connection. See more information on BL Audio here
You can possibly get 1 Mbit/s over ISO and that means a single channel in one direction at e.g. 48000 Hz * 16 bit = 0.768 Mbit/s. This leaves no room for re-transmits so the sound will easily get choppy. 24000 Hz * 16 bit at least leaves room for one retransmit. This is all in all a hacky option.

[quote user=""]I would greatly appreciate any guidance, links, or example projects you can share.[/quote]

The nRF5340 Audio applications is the best starting point for understanding BLE Audio. This should also let you stream sound from an Android phone to the nRF5340 Audio DK without any Android app.

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Engr Abdul — Tue, 10 Sep 2024 16:32:00 GMT

Hi Øyvind,

Thanks for your response 🙂

Yes, I am using a phone with an Android version that supports the LC3 codec and Bluetooth LE Audio.

In my project, I am building a customized Android app using Flutter to stream music to the nRF5340 Audio DK. Additionally, I have connected an ADC module to the nRF5340 Audio DK via I2C (SCL and SDA pins). My goal is to process incoming values from the ADC module on the nRF5340 Audio DK and send them back to the Android app while simultaneously streaming audio.

I previously attempted the same project using the nRF52840 DK. In that implementation, I was successfully receiving values from the ADC on the Android app, but I faced challenges with the audio streaming. I tried converting .mp3 files to .pcm format on the app side and sent them over BLE packets to the nRF52840 DK, but the audio was distorted, possibly due to the data rate limitations of BLE.

Because of this issue, I have now moved my project to the nRF5340 Audio DK to leverage its support for LC3 and better handle audio streaming. However, I am now uncertain how to manage the app side in Flutter. Specifically:

Previously, I converted the .mp3 to .pcm format on the app side before sending it to the nRF52840 DK.
Now, I am confused about how I should encode the audio data to the LC3 codec on the app side or if there is another approach I should follow to stream the audio efficiently.
My aim is to get audio streaming working alongside receiving real-time values from the ADC module connected to the nRF5340 Audio DK.

I am relatively new to BLE, and I would appreciate your guidance on the best approach to take to achieve both tasks simultaneously. I apologize for the lengthy details and truly appreciate your patience.

Looking forward to your valuable feedback.

RE: BLE Audio Streaming from Android App to nRF5340 Audio DK: Seeking Guidance on LC3 Codec Implementation

Øyvind — Mon, 09 Sep 2024 13:08:05 GMT

Hello,

[quote user=""]I am working on a project where I want to stream audio from a customized Android app to the nRF5340 Audio DK over Bluetooth Low Energy (BLE). The nRF5340 Audio DK supports LC3 codec for efficient BLE audio streaming, but I am facing the following challenges:[/quote]

What phone are you using? Does it support Bluetooth LE Audio? As long as the phone has support, you should be able to connect to the nRF5340 Audio DK running the correct FW.

More information can be found on our website.

Kind regards
Øyvind