Help with I2S to A2DP

[Kageni-wq]

Hey, first thanks for this awesome resource.

I am lost in how to utilize different streams together and was hoping for some help. I have a ESP32 with I2S mic input, and I have a working sketch to transmit I2s input to A2DP. The targeted sounds I am attempting to auscultate are bettween 200 Hz to 2000 Hz, which aren't picked up well by a mems microphone. So I wanted to incorporate volume stream to allow boost to increase volume of I2S source as well as apply a low pass filter to filter frequencies >5kHz. I have tried incorporating a Volume Stream and a FilteredStream seperately at first, both of which aren't working as expected.

First the volume stream, I get appropriate sounds through A2DP but altering volume value has no effect.
#include "AudioTools.h"
#include "AudioLibs/AudioA2DP.h"

bool allow_boost = true;
AudioInfo info32(44100, 1, 32);
AudioInfo info16(44100, 2, 16);
BluetoothA2DPSource a2dp_source;
I2SStream i2s;
VolumeStream volume(i2s);
FormatConverterStream conv(&volume);
ConverterFillLeftAndRight<int32_t> bothChannels;
const int BYTES_PER_FRAME = 4;

int32_t get_sound_data(Frame* data, int32_t frameCount) {
return conv.readBytes((uint8_t*)data, frameCount*BYTES_PER_FRAME)/BYTES_PER_FRAME;
}

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

// setup conversion
conv.begin(info32, info16);

// start i2s input with default configuration
Serial.println("starting I2S...");
auto cfg = i2s.defaultConfig(RX_MODE);
cfg.pin_bck = 27;
cfg.pin_ws = 26;
cfg.pin_data_rx = 15;
cfg.i2s_format = I2S_PHILIPS_FORMAT; // or try with I2S_LSB_FORMAT
cfg.bits_per_sample = 32;
cfg.sample_rate = 8000;
cfg.channels = 1;
cfg.buffer_count = 4;
cfg.buffer_size = 8;
cfg.copyFrom(info32);
cfg.is_master = true;
i2s.begin(cfg);

// set initial volume

volume.begin(cfg); // we need to provide the bits_per_sample and channels
volume.setVolume(1.3);

// start the bluetooth
Serial.println("starting A2DP...");
// a2dp_source.set_auto_reconnect(false);
a2dp_source.start("", get_sound_data);

Serial.println("A2DP started");

a2dp_source.set_volume(255);
}

// Arduino loop - repeated processing
void loop() { delay(1000); }

Then the filtered stream, which does not produce any audio through A2DP, although it complies correctly and I can connect to bluetooth, I don't get any audio when connected.

#include "AudioTools.h"
#include "AudioLibs/AudioA2DP.h"

AudioInfo info32(44100, 1, 32);
AudioInfo info16(44100, 2, 16);
BluetoothA2DPSource a2dp_source;
I2SStream in;
I2SStream out;

FormatConverterStream conv(out);
ConverterFillLeftAndRight<int32_t> bothChannels;
const int BYTES_PER_FRAME = 4;

int32_t get_sound_data(Frame* data, int32_t frameCount) {
return conv.readBytes((uint8_t*)data, frameCount*BYTES_PER_FRAME)/BYTES_PER_FRAME;
}

FilteredStream<int32_t, float> filtered(in, info32.channels); // Assuming your filter has 64 coefficients
StreamCopy copier(out, filtered); // copies sound into i2s

// define FIR filter parameters
float coef[] = {
0.000000000000000000,
0.000001511297925605,
0.000045825231132587,
0.000101933246976758,
0.000000000000000000,
-0.000325252705726674,
-0.000542934652017849,
-0.000111225314686988,
0.000973652950212339,
0.001661972405759001,
0.000587058394428470,
-0.002140929286881939,
-0.004003924383454057,
-0.001928339829814701,
0.003909210106703326,
0.008340270816237191,
0.005014346569892968,
-0.006200715636442397,
-0.015797621445604364,
-0.011400390693660504,
0.008736283732024654,
0.028561496928001990,
0.024508952141171887,
-0.011075526033059554,
-0.053639524213326052,
-0.056754029493375331,
0.012733664734546927,
0.141263776411347297,
0.267475614950405893,
0.320009687542567145,
0.267475614950405893,
0.141263776411347297,
0.012733664734546927,
-0.056754029493375324,
-0.053639524213326045,
-0.011075526033059557,
0.024508952141171898,
0.028561496928001983,
0.008736283732024655,
-0.011400390693660513,
-0.015797621445604371,
-0.006200715636442400,
0.005014346569892968,
0.008340270816237200,
0.003909210106703332,
-0.001928339829814702,
-0.004003924383454063,
-0.002140929286881942,
0.000587058394428470,
0.001661972405759002,
0.000973652950212338,
-0.000111225314686988,
-0.000542934652017848,
-0.000325252705726674,
0.000000000000000000,
0.000101933246976758,
0.000045825231132587,
0.000001511297925605,
0.000000000000000000,
};

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

// setup filters for all available channels
filtered.setFilter(0, new FIR(coef));
filtered.setFilter(1, new FIR(coef));

// setup conversion
conv.begin(info32, info16);

// start i2s input with default configuration
Serial.println("starting I2S...");
auto cfg = in.defaultConfig(RX_MODE); // Use 'in' for input stream
cfg.pin_bck = 27;
cfg.pin_ws = 26;
cfg.pin_data_rx = 15;
cfg.i2s_format = I2S_PHILIPS_FORMAT;
cfg.bits_per_sample = 32;
cfg.sample_rate = 44100;
cfg.channels = 1;
cfg.buffer_count = 4;
cfg.buffer_size = 8;
cfg.copyFrom(info32);
cfg.is_master = true;
in.begin(cfg);

// start the bluetooth
Serial.println("starting A2DP...");
a2dp_source.start("", get_sound_data);

Serial.println("A2DP started");

a2dp_source.set_volume(255);
}

// Arduino loop - repeated processing
void loop() {
copier.copy();
}

[pschatzmann]

No, it's not working like this. You need to build a chain: e.g. I2SStream -> FormatConverterStream -> ConverterStream -> VolumeStream -> FilteredStream. In each constructor you indicate the source.
And the callback will then just read from the FilteredStream object.

No copy is needed/allowed in this chain.

The good thing is that you can build and test this step by step

[Kageni-wq]

Thanks for the reply, I tried updating the volume stream and I got it to compile but it is just producing loud static out of only the L side. Here is the updated sketch:

#include "AudioTools.h"
#include "AudioLibs/AudioA2DP.h"

AudioInfo info32(16000, 1, 32);
AudioInfo info16(16000, 2, 16);
bool allow_boost = true;
BluetoothA2DPSource a2dp_source;
I2SStream i2s;
FormatConverterStream conv(i2s);
ConverterFillLeftAndRight<int32_t> bothChannels;
VolumeStream volume(conv);
const int BYTES_PER_FRAME = 4;

int32_t get_sound_data(Frame* data, int32_t frameCount) {
return volume.readBytes((uint8_t*)data, frameCount*BYTES_PER_FRAME)/BYTES_PER_FRAME;
}

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

// setup conversion
conv.begin(info32, info16);

// start i2s input with default configuration
Serial.println("starting I2S...");
auto cfg = i2s.defaultConfig(RX_MODE);
cfg.pin_bck = 27;
cfg.pin_ws = 26;
cfg.pin_data_rx = 15;
cfg.i2s_format = I2S_PHILIPS_FORMAT; // or try with I2S_LSB_FORMAT
cfg.bits_per_sample = 32;
cfg.sample_rate = 16000;
cfg.channels = 1;
cfg.buffer_count = 4;
cfg.buffer_size = 8;
cfg.copyFrom(info32);
cfg.is_master = true;
i2s.begin(cfg);

// Start Volume Stream
volume.begin(cfg); // we need to provide the bits_per_sample and channels
volume.setVolume(0.3);

// start the bluetooth
Serial.println("starting A2DP...");
a2dp_source.set_auto_reconnect(true);
a2dp_source.start("", get_sound_data);

Serial.println("A2DP started");

a2dp_source.set_volume(255);
}

// Arduino loop - repeated processing
void loop() { delay(1000); }

[pschatzmann]

Double check the bit sizes at each step: You define volume to be 32 bits, but after the conversion it's 16
Use the info16 and info32 that you have defined!