play_mp3_dac_example.c

/* Play mp3 file by audio pipeline using ESP32 on-board DAC

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#include "esp_log.h"
#include "audio_element.h"
#include "audio_pipeline.h"
#include "audio_event_iface.h"
#include "audio_mem.h"
#include "audio_common.h"
#include "i2s_stream.h"
#include "mp3_decoder.h"

static const char *TAG = "PLAY_MP3_FLASH";
/*
   To embed it in the app binary, the mp3 file is named
   in the component.mk COMPONENT_EMBED_TXTFILES variable.
*/
extern const uint8_t adf_music_mp3_start[] asm("_binary_adf_music_mp3_start");
extern const uint8_t adf_music_mp3_end[]   asm("_binary_adf_music_mp3_end");

int mp3_music_read_cb(audio_element_handle_t el, char *buf, int len, TickType_t wait_time, void *ctx)
{
    static int mp3_pos;
    int read_size = adf_music_mp3_end - adf_music_mp3_start - mp3_pos;
    if (read_size == 0) {
        return AEL_IO_DONE;
    } else if (len < read_size) {
        read_size = len;
    }
    memcpy(buf, adf_music_mp3_start + mp3_pos, read_size);
    mp3_pos += read_size;
    return read_size;
}

void app_main(void)
{
    audio_pipeline_handle_t pipeline;
    audio_element_handle_t i2s_stream_writer, mp3_decoder;
    esp_log_level_set("*", ESP_LOG_WARN);
    esp_log_level_set(TAG, ESP_LOG_INFO);

    ESP_LOGI(TAG, "[ 1 ] Create audio pipeline, add all elements to pipeline, and subscribe pipeline event");
    audio_pipeline_cfg_t pipeline_cfg = DEFAULT_AUDIO_PIPELINE_CONFIG();
    pipeline = audio_pipeline_init(&pipeline_cfg);
    mem_assert(pipeline);

    ESP_LOGI(TAG, "[1.1] Create mp3 decoder to decode mp3 file and set custom read callback");
    mp3_decoder_cfg_t mp3_cfg = DEFAULT_MP3_DECODER_CONFIG();
    mp3_decoder = mp3_decoder_init(&mp3_cfg);
    audio_element_set_read_cb(mp3_decoder, mp3_music_read_cb, NULL);

    ESP_LOGI(TAG, "[1.2] Create i2s stream to write data to ESP32 internal DAC");
    i2s_stream_cfg_t i2s_cfg = I2S_STREAM_INTERNAL_DAC_CFG_DEFAULT();
    i2s_cfg.type = AUDIO_STREAM_WRITER;
    i2s_stream_writer = i2s_stream_init(&i2s_cfg);

    ESP_LOGI(TAG, "[1.3] Register all elements to audio pipeline");
    audio_pipeline_register(pipeline, mp3_decoder, "mp3");
    audio_pipeline_register(pipeline, i2s_stream_writer, "i2s");

    ESP_LOGI(TAG, "[1.4] Link it together [mp3_music_read_cb]-->mp3_decoder-->i2s_stream-->[ESP32 DAC]");
    const char *link_tag[2] = {"mp3", "i2s"};
    audio_pipeline_link(pipeline, &link_tag[0], 2);

    ESP_LOGI(TAG, "[ 2 ] Set up  event listener");
    audio_event_iface_cfg_t evt_cfg = AUDIO_EVENT_IFACE_DEFAULT_CFG();
    audio_event_iface_handle_t evt = audio_event_iface_init(&evt_cfg);

    ESP_LOGI(TAG, "[2.1] Listening event from all elements of pipeline");
    audio_pipeline_set_listener(pipeline, evt);

    ESP_LOGI(TAG, "[ 3 ] Start audio_pipeline");
    audio_pipeline_run(pipeline);

    while (1) {
        audio_event_iface_msg_t msg;
        esp_err_t ret = audio_event_iface_listen(evt, &msg, portMAX_DELAY);
        if (ret != ESP_OK) {
            ESP_LOGE(TAG, "[ * ] Event interface error : %d", ret);
            continue;
        }

        if (msg.source_type == AUDIO_ELEMENT_TYPE_ELEMENT && msg.source == (void *) mp3_decoder
            && msg.cmd == AEL_MSG_CMD_REPORT_MUSIC_INFO) {
            audio_element_info_t music_info = {0};
            audio_element_getinfo(mp3_decoder, &music_info);

            ESP_LOGI(TAG, "[ * ] Receive music info from mp3 decoder, sample_rates=%d, bits=%d, ch=%d",
                     music_info.sample_rates, music_info.bits, music_info.channels);

            audio_element_setinfo(i2s_stream_writer, &music_info);
            i2s_stream_set_clk(i2s_stream_writer, music_info.sample_rates, music_info.bits, music_info.channels);
            continue;
        }
        /* Stop when the last pipeline element (i2s_stream_writer in this case) receives stop event */
        if (msg.source_type == AUDIO_ELEMENT_TYPE_ELEMENT && msg.source == (void *) i2s_stream_writer
            && msg.cmd == AEL_MSG_CMD_REPORT_STATUS
            && (((int)msg.data == AEL_STATUS_STATE_STOPPED) || ((int)msg.data == AEL_STATUS_STATE_FINISHED))) {
            break;
        }
    }

    ESP_LOGI(TAG, "[ 4 ] Stop audio_pipeline");
    audio_pipeline_stop(pipeline);
    audio_pipeline_wait_for_stop(pipeline);
    audio_pipeline_terminate(pipeline);

    audio_pipeline_unregister(pipeline, mp3_decoder);
    audio_pipeline_unregister(pipeline, i2s_stream_writer);

    /* Terminate the pipeline before removing the listener */
    audio_pipeline_remove_listener(pipeline);

    /* Make sure audio_pipeline_remove_listener is called before destroying event_iface */
    audio_event_iface_destroy(evt);

    /* Release all resources */
    audio_pipeline_deinit(pipeline);
    audio_element_deinit(i2s_stream_writer);
    audio_element_deinit(mp3_decoder);
}