Sound sometimes cuts out on WAV web server ( ESP32 + MAX9814 )

[PospelovDaniil]

Problem Description

Hello, I am using esp32 with a MAX9814 microphone. In my program, the sound on the web server is periodically interrupted, but I do not see any errors in the logs. Could you please advise what the issue might be?
In my application (but not in the example), I also periodically see “write to target has failed after 22 retries!” in the logs.

It is unlikely that the problem is with the Wi-Fi - the esp32 is located 1 meter from the router, and during testing, there are no other significant loads on the router.

Here is a simplified example of my application that reflects the problem.

I also made a video recording of the problem - https://drive.google.com/file/d/1-4pBwbqi63uQfzio6TC4T2Rb2zqK4L99/view?usp=sharing

Device Description

ESP32 Dev board

Sketch

#include "AudioTools.h"
#include "soc/adc_channel.h"

AudioWAVServer server("ssid_deleted",
                      "passw_deleted");

AudioInfo info(44100, 1, 16);
AnalogAudioStream microphone;

void setup() {
  Serial.begin(115200);
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Warning);

  auto config_microphone = microphone.defaultConfig(RX_MODE);
  config_microphone.setAudioInfo(info);
  config_microphone.channels = 1;
  config_microphone.adc_channels[0] = ADC_CHANNEL_7;
  microphone.begin(config_microphone);

  server.begin(microphone, info);
}

void loop() {
  server.copy();
}

Other Steps to Reproduce

By the way, I observe the same problem with the basic example - streams-generator-server_wav.ino

What is your development environment (incl. core version info)

ESP32 core - 3.3.0
Arduino Ide - 2.3.5
arduino-audio-tools - latest from github (65b3da5). Installed via "add ZIP library"

CPU freq - 240MHz
Events run on - Core 0
Arduino run on - Core 1

I have checked existing issues, discussions and online documentation (incl. the Wiki)

• I confirm I have checked existing issues, discussions and online documentation

[pschatzmann]

Did you try to test with a sine wave instread ?
My guess would be that it's just too slow to serrve such a high sample rate: try to halve it!

[PospelovDaniil]

Changing the sampling rate from 44100 to 20000 had an effect—the problem remained, but now occurs later, after about 30 seconds.

SineWaveGenerator works well with a sample rate of 10000 compared to a microphone.

Can you please advise how to fix the problem without significantly losing sound quality (for voice recording)?

[pschatzmann]

A sample rate of 8000 should be sufficient for voice.
Alternatively you can consider using a codec though mp3 or aac encoding is quite tricky...