Switching source make altered and crakling sound

[Artemia76]

Dear gentlemens , I actually trying to build an application to drive a radio (HAM) repeater. The repeater detect in input audio (RX) a 1750Hz tone to switch on repeating mode (TX) sequence : first play welcome message in WAV then back to copy input stream to output. If no sound is detected on input, the repeater send bye-bye message and back on IDLE mode.

The issue is when starting after boot, input signal is received correctly and pass the FFT and volume detection. But after the message played with AudioPlayer I switch again the output on in + fft + volume meter chain. Then I get a strange sound like saw, or like a mass default signal. If I try to play again message, the message is played nice. But when back to the first chain , random sound is hear.

Any idea about wrong ?

You can see sources on my repository : https://github.com/Artemia76/FFT
The hardware is an ESP32 devkit S3 with a Pmod I2S2 (ADC+DAC) module.

[pschatzmann]

I suggest to switch of the output if you don't use it or keep it busy by just sending some silence

[Artemia76]

Hi @pschatzmann , many thanks for your very fast answer. The output is always used : When player is not used, I send the input audio through the FFT -> VolMeter to the out. but both VolMeter and player have the same output. when I repeat the input audio , I use a copier(fft,in) and when player is used, the player.copy() . The most strange, is sometime after playing announce, the audio back good...
I made a video to show you the strange behavior : https://www.youtube.com/watch?v=O9mK3yw24b4

[pschatzmann]

Can you share your sketch ? The link above does not work...
What is the input source ? Maybe you start the reading on a wrong byte (in the middle of an int16_t) ?

[Artemia76]

Sorry , the repo was private. now it's public. The input source is the ADC from PmodI2S2. I inject with my rigol DG 852 Pro a sine waveform 1750Hz

[pschatzmann]

I think the following chain is not doing what you expect:

I2SStream out;
VolumeMeter VolMeter(out);
AudioRealFFT fft(VolMeter);

try to use a MultiOutput to send the audio both to FFT and the VolumeMeter.
If I remember right the output for FFT was intended for the reverse FFT only....