streams-adc-i2s: audio is high pitched and constant popping

[joawesome]

Hi, I want to experiment with inputting an audio signal into the adc pins of an esp32 and output the audio signal to a pcm5102A DAC. My goal is to create a simple audio filter device, like to add a compressor or eq filter effect. The built in example works but the output audio is high pitched and pops. The pops starts after a few seconds when the esp32 is booted up (no pops for 1 second and pops occur. Audio is high pitched at all times). I am wondering if there is a way to correct this. I’ve already tried disabling the info logs. It makes no changes. I tried changing the channels to 1, it didn’t help. I tried another example (streams-generator-i2s) and it pops but resolved when logging is disabled. I tried 2 of my dacs, same issue.

I am using arduino IDE 2.3.6 and using esp32 by Espressif Systems board manager. I am also using a esp32-WROOM-32D connected to an adaptor board.

[pschatzmann]

I never tried this: Mabe you are doing something wrong ?
Can you share your minimual sketch ?

[joawesome]

Maybe i am doing something wrong but i am not sure. I am using the default example sketch that's provided with the logging disabled:

`/**

• @file streams-analog-i2s.ino
• @author Phil Schatzmann
• @brief see https://github.com/pschatzmann/arduino-audio-tools/blob/main/examples/examples-stream/streams-adc-i2s/README.md
• @author Phil Schatzmann
• @copyright GPLv3
  */

#include "AudioTools.h"

AudioInfo info(44100, 1, 16);
AnalogAudioStream in;
I2SStream out;
StreamCopy copier(out, in); // copy in to out

// Arduino Setup
void setup(void) {
//Serial.begin(115200);
//AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);

// RX automatically uses port 0 with pin GPIO34
auto cfgRx = in.defaultConfig(RX_MODE);
cfgRx.copyFrom(info);
in.begin(cfgRx);

// TX on I2S_NUM_1
auto cfgTx = out.defaultConfig(TX_MODE);
cfgTx.port_no = 1;
cfgTx.copyFrom(info);
out.begin(cfgTx);
}

// Arduino loop - copy data
void loop() {
copier.copy();
}`

I also tried using another example to play my own provided mp3 to the i2s DAC and that work perfectly fine. No pops with logging enabled, audio is normal pitched. So that means my DAC hardware can be ruled out. Maybe something with the adc is wrong or something with my setup. I forgot mention that I did try two different esp32's as well

[pschatzmann]

Did you follow this advice ?
The ESP32 ADC is very buggy and provides inconsistent sample rates, so you will need to implement your own logic to avoid this issue e.g. by dynamically resampling from the actual rate to the target rate

[joawesome]

that is interesting. i am not sure how to approach this solution for now but thanks for the help. I did see that page beforehand but didn't understand if it would have helped my situation.

[pschatzmann]

You could set up a processing chain that writes to a buffer and implement a dynamic resampling: if the buffer gets rather full slightly decrease the sampling rate, if it gets rather empty slightly increase it: This way you can dynamically prevent buffer under and overflows.

However is much easier to just replace the analog input with an I2S one....