esp32~mp3播放实例解析

Sample Organization of Elements in Audio Pipeline

将MP3解码器和I2S流两个元素添加进管道，解码器的输入是MP3文件数据流，I2S流将解码后的音频数据输出到片外，各应用程序之间通过事件接口通信。

1. 代码分析

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”);

static int adf_music_mp3_pos;

int mp3_music_read_cb(audio_element_handle_t el, char *buf, int len, TickType_t wait_time, void *ctx)

{

int read_size = adf_music_mp3_end - adf_music_mp3_start - adf_music_mp3_pos;

if (read_size == 0) {

return AEL_IO_DONE;

} else if (len < read_size) {

read_size = len;

}

memcpy(buf, adf_music_mp3_start + adf_music_mp3_pos, read_size);

adf_music_mp3_pos += read_size;

return read_size;

}

void app_main(void)

{

audio_pipeline_handle_t pipeline; // 管道

audio_element_handle_t i2s_stream_writer, mp3_decoder; // 音频元素

esp_log_level_set(“*”, ESP_LOG_WARN);

es