Mixing two wav decoders: Distorted

[jonascant]

Sorry to bother you, but I need to mix up to five wav files to one mono channel. I tried for a long time, but it is always distorted.

#include "AudioTools.h"
#include "AudioLibs/FileLoop.h"
#include "SdFat.h"
#include "sdios.h"

//SD Pin
const uint8_t SD_CS_PIN = 5;

#define FS_NO_GLOBALS
#define SPI_CLOCK SD_SCK_MHZ(30)
#define SD_CONFIG SdSpiConfig(SD_CS_PIN, DEDICATED_SPI, SPI_CLOCK)

SdFat32 SD;
File32 file;
File32 file1;

AudioInfo info(48000, 1, 32);

I2SStream out; 
WAVDecoder wav;


OutputMixer<int32_t> mixer(out, 2);
EncodedAudioStream encoded(&mixer, &wav); // Decoding stream
EncodedAudioStream encoded1(&mixer, &wav); // Decoding stream

StreamCopy copier(mixer, file);
StreamCopy copier1(mixer, file1);


void setup(){
  Serial.begin(115200);
  AudioLogger::instance().begin(Serial, AudioLogger::Error);  

  //SD init
  if (!SD.begin(SD_CONFIG)) {
    SD.initErrorHalt(&Serial);
  }

  file = SD.open("/Jodler.wav");
  file1 = SD.open("/Baby.wav");

  // start I2S ou
  auto config_out = out.defaultConfig(TX_MODE);
  config_out.copyFrom(info); 
  config_out.port_no = 0;
  config_out.pin_bck = 15;
  config_out.pin_ws = 14;
  config_out.pin_data = 22;
  // setup I2S based on sampling rate provided by decoder
  encoded.begin();
  encoded1.begin();
  mixer.begin();
  out.begin(config_out);
}

void loop(){
  copier.copy();
  copier1.copy();
}

[pschatzmann]

Microcontrollers have only limited IO and CPU speed: The challenge is always to find out where the bottleneck is and engineer the solution accordingly.

5 * 48000 * 32 bits sounds absolutely crazy!

[jonascant]

yeah. I will bite the bullet and try to get it done on rpi4 using python... I was hoping, i could use your fantastic lib.

[pschatzmann]

You still can, but you will need to reduce the bits per sample and ev. sample rate....

ps. you could also use this library on a rpi4...

[jonascant]

i did reduce to 16000hz, 16bit with only two files. the same result. I am thinking the parallel reading of two files from sd is the issue. it plays fine if only one file is added to the mixer.

ps. you could also use this library on a rpi4...
I have no idea how to compile the code to run on the rpi. I have only ever used arduino-cli for all compiling.