nrf5340 Audio Shell audio_system start failed

[Tommy_Li]

Dear All:

I found that there is a shell interface for the nrf5340_audio project.

I wanted to test the sd card playback from the shell interface.

For the broadcast sink role, I added the macro "CONFIG_SD_CARD_PLAYBACK=y" to the prj.conf.

When i executed the command "sd_card_playback play_lc3 output_stere.lc3" from the shell, i got the error:

And then i tried to initialize the sw codec.

I exectued the command "audio_system start", i got the error:

I traced the code using ozone, the error occured by calling "LC3Initialize" function, which is provided by library.

The -5009 errror code means INVALID_SAMPLERATE.

But from the ozone debug, the enc_sample_rates and dec_sample_rates transfered to LC3Initialize were all 63.

Could you please help me to resolve this issue. 

the ncs version is v2.6.0-rc2

Thanks in advance.

Tommy.

Best Regards.

[ovrebekk]

Hi Tommy

Potentially this could be an issue with the encoded file. Would you be able to provide some details regarding how you created the lc3 file in the first place? 

Also, please be aware that the play_lc3 command will simply play back the file to the configured audio output, it will not transmit it over Bluetooth. I am guessing the end goal is to broadcast the lc3 file? 

Best regards
Torbjørn

[Tommy_Li]

Hi Ovrebekk,

I cloned the liblc3 repository from github, and compiled the source code on ubuntu.

and then i encoded my wav file using elc3 command, and the parameters of the wav file is 48khz stereo.

I copied the created lc3 file to the tf card. 

the nrf5340 audio dk could recorgnize the file.

You are right Ovrebekk, I wanted to broadcast the lc3 file from the sdcard.

But i think the first step is to play the lc3 file locally from the headphone jack

Ovrebekk, Could you please provied me a lc3 file which is considered correct from your point of view.

I will test the file to verify the process of playing lc3 file.

Best Regards.

Tommy.

[ovrebekk]

Hi Tommy

One of the developers tested this out on his end, through the following steps: 

1) Download and compile the Google liblc3 tool

2) Use the elc3 tool to encode a 48KSpS mono wave file in 96kbs bitrate:
     $ elc3 mono.wav -b 96000 mono.lc3

3) Copy the file into the SD card, and then on the BIS headset side, use the RTT terminal to run the following command: 

    rtt:~$ sd_card_playback play_lc3 mono.lc3

Raw and encoded files attached in the below zip: 

mono.zip

Can you test this out and see if it works better? 

Best regards
Torbjørn

[Tommy_Li]

Hi Ovrebekk:

Thanks for your kindly help.

I'm on a business trip and will test it immediately once i return to the office.

Best Regards.

Tommy.

[ovrebekk]

Hi Tommy

No problem, just let  me know when you've had time to test it. 

Regards
Torbjørn

[Tommy_Li]

Hi Ovrebekk,

I was able to successfully  play the mono.lc3 file on the BIS headset side.

But there is a prerequisite, which is that the BIS headset side needs to synchronized to the BIS gateway side.

I think some configuration actions have been performed during the sychronization process.

I will investigate how to play the lc3 file without synchronization.

Best Regards.

Tommy.