Chaining Mozzi

[jaapnoordzij]

Hi Phil and all,

I would like to use Mozzi in a chain. In its simples form this would combine the input and the output example. In my case I want to build the following chain:

Read file from SD -> Decode MP3 -> Convert (44100,2,16) to (16000,1,16) -> process with Mozzi -> Output to I2s (Audio-kit board)

I have build this in the following sketch. The first part works nicely. I can send the output of the converter to CSV or I2S to see or hear the mono output. But when I send it to Mozzi nothing happens.

How can I have Mozzi propagate the results to I2S (or CSV for viewing) ?
MozziStream has setInput put not a setOutput
I have tried a second copier but that crashes my program.
What am I missing here ?

/**
 * - Mozzi Example:  04 Audio_Input_with_Knob_Filter
 * - Read mp3 file -> decode -> convert to (16000,1,16) -> process in mozzi -> i2s out
 * - AudioKit I2S
 * - Use PS4-controller with Bluetooth to simuate LDRs and Knobs
 */
#include <SD.h>
#include <SPI.h>
#include "AudioTools.h"
#include "AudioLibs/AudioBoardStream.h"
#include "AudioLibs/MozziStream.h"
#include "AudioCodecs/CodecMP3Helix.h"

AudioInfo from(44100, 2, 16);
AudioInfo to(16000,1,16);

CsvStream<int16_t> csv(Serial); // Output to Serial for testing
AudioBoardStream i2s(AudioKitEs8388V1);  // final output of decoded stream

MozziStream mozzi;

const int chipSelect=PIN_AUDIO_KIT_SD_CARD_CS;
File audioFile;

FormatConverterStream conv(mozzi);  // converter to mozzi does not work
// FormatConverterStream conv(csv); // converter to csv works
// FormatConverterStream conv(i2s); // converter to i2s works (mono sound)
MP3DecoderHelix mp3;
// EncodedAudioOutput mp3dec(&i2s,&mp3); // stereo 44100 directly to I2s- works
EncodedAudioOutput mp3dec(&conv,&mp3);   // mono 16000 to converter - works

StreamCopy copier;
StreamCopy extra_copier;

/*****************************************************************************/

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

  // Setup Audiokit I2S output
  auto i2s_cfg = i2s.defaultConfig(TX_MODE);
  i2s_cfg.sd_active = true;
  i2s_cfg.copyFrom(to);
  i2s.begin(i2s_cfg);
  i2s.setVolume(0.6);

  // Setup SD files
  SD.begin(chipSelect);
  audioFile = SD.open("/mp3/miss-marple.mp3");

  mp3dec.begin(from);

  // start converter
  conv.addNotifyAudioChange(mozzi);
  conv.begin(from,to);

  // start CSV Stream
  csv.begin(to);

  // Setup mozzi
  auto mozzi_cfg = mozzi.defaultConfig();
  mozzi_cfg.control_rate = CONTROL_RATE;
  mozzi_cfg.copyFrom(to);
  mozzi.begin(mozzi_cfg);

  // setup data source for mozzi
  mozzi.setInput(conv);

  // Start copier
  copier.begin(mp3dec,audioFile);
  // extra_copier.begin(csv,mozzi);
}

void loop() { 
  copier.copy(); 
  // extra_copier.copy();
}

/*****************************************************************************/

void updateControl () {
}

int updateAudio(){
  int asig = mozzi.getAudioInput();  // range 0-1023
  // signed range required by all Mozzi units:  -512 to 511
  asig = asig - 512;
  return asig > 1; // to simulate 50% volume
}

[pschatzmann]

Your input chain should be theoretically:

EncodedAudioStream mp3dec(&file,&mp3); // you intend to read the decoded file
FormatConverterStream conv(mp3dec); // you intent to read converted data from the mp3dec

Then you can read the converted, decoded data using conv
Since the file is not known at that point of time, you will need to define it in setup by calling setInput(&file);

[jaapnoordzij]

Thank you for the reply, I guess I need some more study.
In the meantime I have made the modifications and I started with copier.begin(i2s, mozzi). At least sound comes out but it is half the speed and very disturbed so I probably do something wrong with the conversion.