ESP32-WROOM Bluetooth transmitter audio issues

[stevenhunt77]

Hi all, I have an ESP32_WROOM connected to an SD Card module.
I then have a button connected to a GPIO pin.
I'm just testing pressing the button to then play some wav files from the SD Card.

The ESP is then connecting to my Bluetooth speaker to transmit the audio.

Everything is working, but I get a small static pop at the end of each sound played.
The files are wav files, 44,100 & 16 bit. They are Mono to the code is duplicates it over both channels.

Any ideas what can be causing that pop and how I get rid of it...?

Thankyou!

[pschatzmann]

In theory if the audio is phased out at the end, there should be no pop: double check your recording.

If this does not help you can replace your logic which stops at the end if the file to just continue to write silence by calling writeSilence() on the i2s object.

[stevenhunt77]

Unless I'm mistaken an ESP32-WROOM cannot output I2S to a speaker directly....

[pschatzmann]

My mistake: I thought you were using an A2DPSink, but in fact you use the A2DPSource!

So you will need to provide the 0 data yourself in the callback: or you can use the A2DPStream from the AudioTools instead and configure it with silence_on_nodata = true.

[stevenhunt77]

Perfect, that has worked and the static pop has gone for the most part.
I am testing a sound loop (Darth Vader breathing). The idea is its a 9 second file. 5 Seconds breath, 4 seconds silence and then it loops.
This sound still has the static pop when it loops. Any ideas on how to fix that?

[pschatzmann]

Double check the content e.g. in Audacity. You get a pop e.g. if there is a big gap between the last and the first sample

[pschatzmann]

ps. if you don't play the file via a wav decoder, don't forget to start at pos 44 to ignore the WAV header!

[stevenhunt77]

So I tweaked the audio file and added a small fade in. That resolved the issues.
Thankyou for your help.