stm32h743_player/User/audio/audio_flac.c

#include "audio_flac.h"
#include "main.h"
#include <string.h>
#include "ff.h"
#include "FreeRTOS.h"
#include "queue.h"
#include "elog.h"
#include "heap.h"
#include "bsp_aic3204.h"
#include "dr_flac.h"

const static char *TAG = "audio_flac";

static size_t flac_read(void* pUserData, void* pBufferOut, size_t bytesToRead)
{
  HAL_GPIO_TogglePin(LED_Y_GPIO_Port, LED_Y_Pin);

  UINT br;
  FRESULT f_result = f_read(pUserData, pBufferOut, bytesToRead, &br); //从文件中读取新的内容

  if (f_result != FR_OK) {
    elog_error(TAG, "file read error");
    return 0;
  }

  return br;
}

static drflac_bool32 flac_seek(void* pUserData, int offset, drflac_seek_origin origin)
{
  FIL *file = (FIL*)pUserData;
  uint32_t fptr = f_tell(file);
  uint32_t fsize = f_size(file);

  HAL_GPIO_TogglePin(LED_G_GPIO_Port, LED_G_Pin);

  switch (origin) {
  case drflac_seek_origin_start:
    if (offset < fsize) { //未超过文件末尾
      f_lseek(file, offset);
      return DRFLAC_TRUE;
    } else {
      elog_warn(TAG, "flac_seek: seeking beyond the end of the file");
      return DRFLAC_FALSE;
    }
  case drflac_seek_origin_current:
    if (fptr + offset < fsize) { //未超过文件末尾
      f_lseek(file, fptr + offset);
      return DRFLAC_TRUE;
    } else {
      elog_warn(TAG, "flac_seek: seeking beyond the end of the file");
      return DRFLAC_FALSE;
    }

  default:
    elog_warn(TAG, "flac_seek: unimplemented seek origin type: %d", origin);
    return DRFLAC_FALSE;
  }
}

static void* flac_malloc(size_t sz, void* pUserData)
{
  UNUSED(pUserData);

  void *ptr = malloc(sz);

  // tlsf_pool_statistics *axi_heap_statistics = get_axi_heap_statistics();
  // tlsf_pool_statistics *ahb_heap_statistics = get_ahb_heap_statistics();
  // elog_debug(TAG, "flac_malloc: allocated %d bytes memory @%p, free memory: AXI %d bytes, AHB %d bytes",
  //                 sz, ptr, axi_heap_statistics->free_size, ahb_heap_statistics->free_size);
  if (ptr == NULL) {
    elog_error(TAG, "flac_malloc: error while allocating %d bytes of memory", sz);
  }

  return ptr;
}

static void* flac_realloc(void* p, size_t sz, void* pUserData)
{
  UNUSED(pUserData);

  void *ptr = realloc(p, sz);

  if (ptr == NULL) {
    elog_error(TAG, "flac_realloc: error while allocating %d bytes of new memory", sz);
  }

  return ptr;
}

static void flac_free(void* p, void* pUserData)
{
  UNUSED(pUserData);

  // tlsf_pool_statistics *axi_heap_statistics = get_axi_heap_statistics();
  // tlsf_pool_statistics *ahb_heap_statistics = get_ahb_heap_statistics();
  // elog_debug(TAG, "flac_free: memory freed @%p, free memory: AXI %d bytes, AHB %d bytes",
  //                 p, axi_heap_statistics->free_size, ahb_heap_statistics->free_size);

  free(p);
}

static const drflac_allocation_callbacks flac_allocation_cbs = {
  .onMalloc = flac_malloc,
  .onFree = flac_free,
  .onRealloc = flac_realloc,
  .pUserData = NULL
};

void music_flac_play(const char *file_name)
{
  FIL *file = malloc(sizeof(FIL));
  if (file == NULL) {
    elog_error(TAG, "error while allocating file object");
    return;
  }

  FRESULT f_result = f_open(file, file_name, FA_READ);
  if (f_result == FR_OK) {
    elog_info(TAG, "successfully opened %s for playing", file_name);
  } else {
    elog_error(TAG, "error while opening %s, error code=%d", file_name, f_result);
    free(file);
    return;
  }

  drflac* pFlac = drflac_open(flac_read, flac_seek, file, &flac_allocation_cbs); //创建flac解码器
  if (pFlac == NULL) {
    elog_error(TAG, "error while opening flac file");
    goto exit;
  }

  elog_info(TAG, "music_flac_play: maxBlockSizeInPCMFrames=%d, channels=%d, bitsPerSample=%d",
                 pFlac->maxBlockSizeInPCMFrames, pFlac->channels, pFlac->bitsPerSample);

  /* TODO: 判断flac文件参数并返回错误 */

  bsp_aic3204_set_fs(&hi2c1, pFlac->sampleRate); //设置采样率

  /* 初始化SAI */
  uint32_t pcm_sample_count = pFlac->maxBlockSizeInPCMFrames * pFlac->channels; //PCM块中所有声道总的采样数量
  uint32_t pcm_sample_size = pFlac->bitsPerSample / 8; //PCM块中每个采样的字节数(采样精度)
  audio_hal_start(pcm_sample_count, pcm_sample_size); //初始化SAI

  while(1) {
    /* 如果当前是最后一个frame 则frame_count可能小于maxBlockSizeInPCMFrames 因此需要将pcm_sample初始化为全0 将空白区域静音 */
    drflac_int16 *pcm_sample = malloc(pcm_sample_count * pcm_sample_size); //申请内存 存储1个PCM块
    if (pcm_sample == NULL) {
      elog_error(TAG, "music_flac_play: sample buffer allocation failed, size=%d bytes", pcm_sample_count * pcm_sample_size);
      break;
    }
    memset(pcm_sample, 0, pcm_sample_count * pcm_sample_size);

    /* 此处的framesToRead指的是PCM块中采样的数量(可以理解为时间层面的采样数) 不考虑声道数量与每个采样的字节数 */
    uint32_t frame_count = drflac_read_pcm_frames_s16(pFlac, pFlac->maxBlockSizeInPCMFrames, pcm_sample); //解码一帧FLAC数据

    if (frame_count != 0) {
      /* 即使frame_count小于maxBlockSizeInPCMFrames也写入完整的一块 缓冲区后面空缺的部分在前面已经清0 */
      audio_hal_write(pcm_sample, pcm_sample_count * pcm_sample_size); //将解码后的PCM数据写入SAI
    } else { //文件已经读取完毕
      free(pcm_sample);
      elog_info(TAG, "play done");
      break; //结束播放
    }

    if (HAL_GPIO_ReadPin(KEY2_GPIO_Port, KEY2_Pin) == GPIO_PIN_RESET) {
      vTaskDelay(pdMS_TO_TICKS(100));
      while (HAL_GPIO_ReadPin(KEY2_GPIO_Port, KEY2_Pin) == GPIO_PIN_RESET) {
        vTaskDelay(pdMS_TO_TICKS(1));
      }
      break;
    }
  }

exit:
  audio_hal_stop(); //停止SAI播放

  if (file != NULL) {
    f_close(file); //关闭文件
    free(file);
  }

  if (pFlac != NULL) { //释放解码器
    drflac_close(pFlac);
  }
}