Switching between audio modes: MP3 player -> BT sink -> MP3 player(again)

[jsonslim]

Problem Description

Hello Phill,
Thank you for your hard work with the library!

Currently, I'm implementing a device (ESP32 + PCM5102) with the following logic: Boot -> playing a mp3 startup sound -> enabling BT sink mode(after pressing a button) -> disabling BT mode, and enabling mp3 player again(after pressing another button). Ideally, it should it should be able to change the modes continuously.

There are a couple of concerns:

• It's clear, that after stopping a2dp_sink, it's impossible to start it again. Is there some workaround maybe?
• I'm not sure about how to deal with the I2SStream instance. Should I reuse the "I2SStream i2s" object, or should I instantiate multiple objects for each application(mp3, BT, WIFI-radio)?

I'm asking your general advice, if it's possible to implement, such logic.
Thank you in advance!

Device Description

ESP32-Wrover, Wroom.

Sketch

#include <Arduino.h>
#include "AudioTools.h"
#include "AudioTools/Disk/AudioSourceSPIFFS.h"
#include "AudioTools/AudioCodecs/CodecMP3Helix.h"
#include "driver/i2s.h"
#include "esp_bt.h"

#include "BluetoothA2DPSink.h"
#include "utilities.h"

// 1 - Hello sound; 0 - Bye sound; 2 - bt pair ready
enum SoundFile
{
    F_BYE_SND,
    F_HELLO_SND,
    F_BT_PAIR_SND
};

// Audio objects
AudioInfo info(44100, 2, 16);
I2SStream i2s;

// mp3 startup sound setup
MP3DecoderHelix helix;
AudioSourceSPIFFS *source = nullptr;
AudioPlayer *player = nullptr;
EncodedAudioStream out(&i2s, &helix); // output to decoder
BluetoothA2DPSink a2dp_sink(i2s);

// i2s callback for printind audio data from the file
void printMetaData(MetaDataType type, const char *str, int len)
{
    Serial.print("==> ");
    Serial.print(toStr(type));
    Serial.print(": ");
    Serial.println(str);
}

void playMp3File(int choice)
{
    Serial.println("Init new player");
    // Create a new AudioSourceSPIFFS for this file
    source = new AudioSourceSPIFFS("/", ".mp3");
    player = new AudioPlayer(*source, i2s, helix);
    player->setMetadataCallback(printMetaData);

    if (!player->begin(choice))
    {
        Serial.println("Failed to start player");
        return;
    }

    player->copyAll();
}

// Start BT sink. 
void startBtSink()
{
    auto cfg = i2s.defaultConfig(TX_MODE);
    cfg.copyFrom(info);
    i2s.begin(cfg);

    a2dp_sink.start("ESP32 Music");
}

void stopBtSink()
{
    Serial.println("Stopping A2DP sink...");
    a2dp_sink.pause();
    vTaskDelay(600 / portTICK_PERIOD_MS);
    a2dp_sink.disconnect();
    vTaskDelay(600 / portTICK_PERIOD_MS);
}

///////////// RTOS /////////////
void appTask(void *param)
{
    while (1)
    {
        playMp3File(0);
        i2s.end();
        vTaskDelay(600 / portTICK_PERIOD_MS);

        startBtSink();
        vTaskDelay(20000 / portTICK_PERIOD_MS); // 20sec

        stopBtSink();
        vTaskDelay(600 / portTICK_PERIOD_MS);
    }
}

void setup()
{
    Serial.begin(115200);

    if (!SPIFFS.begin(true))
    {
        Serial.println("Failed to mount SPIFFS");
    }

    // I2S and audio setup
    AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);
    Serial.println("Starting I2S...");
    auto cfg = i2s.defaultConfig(TX_MODE);
    cfg.copyFrom(info);
    i2s.begin(cfg);

    Serial.printf("Free heap after BT start: %u bytes\n", esp_get_free_heap_size());

    // Tasks setup
    xTaskCreatePinnedToCore(appTask, "appTask", 4096, NULL, 2, NULL, 1);
}

void loop()
{
    // Feed watchdog
    vTaskDelay(pdMS_TO_TICKS(100));

    // Monitor heap usage
    if (esp_get_free_heap_size() < 10000)
    {
        Serial.println("Low memory warning!");
    }
}

Other Steps to Reproduce

No response

Provide your Version of the EP32 Arduino Core (or the IDF Version)

2.0.17

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

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

[pschatzmann]

I don't see any bug/issue here, so I am converting this to a discussion

[pschatzmann]

• I don't see any reason why restarting a2dp should not work: restarting would only not work if you would call end(true) as you can read in the documentation.
• I do not recommend to allocate objects via new because you can easily mess up by forgetting to delete them. Just define them as global variables and call end() when they are not needed.
• I think you should just use one I2S instance: however in any case you need to make sure that they are not used by the player and a2dp at the same time. Monitor the connection state or playback state via the available callbacks.
• A2DP and mp3 needs a lot of RAM, so I recomment to use a ESP32 with PSRAM and don't forget to activate it in the tools menu.

[jsonslim]

Thank you!

I'm testing the code now, and the only problem is following: After booting it doesn't play mp3 files(it should play 2 different files, one after the other), but I can see the stream->copy in the terminal. More importantly - after switching to BT sink mode, and successfully streaming the audio from BT, it starts to play mp3 successfully as well! So the question is why doesn't it play it initially after booting?