Snaps and crackles when using "bt_music_sender.ino"

[calint]

Hello,

I doubt that it is a problem in the library.

Maybe same problem has been encountered by others.

The problem is "bt_music_sender.ino" which makes "snaps" and "crackles" at a frequency of about 1 second.

The "bt_music_sender_write_8bit.ino" example works well though without the artifacts.

I don't know if it is the device or the callback that is not called often enough.

Any reply is appreciated :)

Below is info about my setup.

device: ESP32-2432S028R a.k.a. cheap-yellow-display (cyd)

#include "BluetoothA2DPSource.h"
#include <cmath>

#define c3_frequency 130.81

BluetoothA2DPSource a2dp_source;

// The supported audio codec in ESP32 A2DP is SBC. SBC audio stream is encoded
// from PCM data normally formatted as 44.1kHz sampling rate, two-channel 16-bit
// sample data
int32_t get_data_frames(Frame *frame, int32_t frame_count) {
  // ESP_LOGD("MAIN", "frame_count: %d", frame_count);

  static float m_time = 0.0;
  float m_amplitude = 10000.0; // -32,768 to 32,767
  float m_deltaTime = 1.0 / 44100.0;
  float m_phase = 0.0;
  float pi_2 = M_PI * 2.0;
  // fill the channel data
  for (int sample = 0; sample < frame_count; ++sample) {
    float angle = pi_2 * c3_frequency * m_time + m_phase;
    frame[sample].channel1 = m_amplitude * sin(angle);
    frame[sample].channel2 = frame[sample].channel1;
    m_time += m_deltaTime;
  }
  // to prevent watchdog
  delay(1);
  // esp_task_wdt_reset();

  return frame_count;
}

void setup() {
  a2dp_source.set_auto_reconnect(false);
  a2dp_source.start("JBL Go 3", get_data_frames);
  a2dp_source.set_volume(50);
}

void loop() {
  // to prevent watchdog in release > 1.0.6
  delay(1000);
}

Processing esp32dev (platform: espressif32; board: esp32dev; framework: arduino)
-----------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32dev.html
PLATFORM: Espressif 32 (6.6.0) > Espressif ESP32 Dev Module
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES: 
 - framework-arduinoespressif32 @ 3.20014.231204 (2.0.14) 
 - tool-esptoolpy @ 1.40501.0 (4.5.1) 
 - toolchain-xtensa-esp32 @ 8.4.0+2021r2-patch5
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 34 compatible libraries
Scanning dependencies...
Dependency Graph
|-- ESP32-A2DP @ 1.7.3
Building in release mode
Retrieving maximum program size .pio/build/esp32dev/firmware.elf
Checking size .pio/build/esp32dev/firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [=         ]  11.7% (used 38468 bytes from 327680 bytes)
Flash: [===       ]  33.1% (used 1041121 bytes from 3145728 bytes)
============================== [SUCCESS] Took 1.72 seconds ==============================

[pschatzmann]

It might be just an overflow in the sine generator: I suggest to try with a proper implementation from the audio tools

[calint]

Thanks for the reply!

It is as suggested; something with the generation.

I changed the function and the sound is now without artifacts.

Kind Regards

int32_t get_data_frames(Frame *frame, int32_t frame_count) {
  // ESP_LOGD("MAIN", "frame_count: %d", frame_count);

  static int16_t amp = 0;
  for (int sample = 0; sample < frame_count; ++sample) {
    frame[sample].channel1 = amp;
    frame[sample].channel2 = frame[sample].channel1;
    amp += 10000;
  }
  // to prevent watchdog
  delay(1);
  // esp_task_wdt_reset();

  return frame_count;
}