每天一个问题35天3问：wav信息的读取

lkl0305 · 发表于 2015-9-28 22:17:05

本帖最后由 lkl0305 于 2015-9-29 09:54 编辑

一、问题提出：
之前给大家分享了定义一个结构体来存储wav文件的信息，那如何编程实现呢？

二、解决办法：
1、有了前面的结构体变量，程序就容易实现了。
2、今天调试了一个程序，给大家分享一下：
这个函数返回值为0时，表示读取信息错误，为1时，表示读取正确
参数时指向内存中的wav文件信息的片段，可以时数据缓冲区。wavPoint指向wav文件的开始。

uint8_t ReadWAVInf(uint8_t * wavPoint)
{
      if (0 == strcompare("RIFF", (uint8_t *)wavPoint, 4))
      {
            return 0;
      }
      else
      {
            strncpy(wavFile.wavRiffChunk.szRiffID, (uint8_t *)wavPoint, 4);
      }

      if (0 == strcompare("WAVE", (uint8_t *)wavPoint + 8, 4))
      {
            return 0;
      }
      else
      {
            strncpy(wavFile.wavRiffChunk.szRiffFormat, wavPoint + 8, 4);
      }

      wavFile.wavRiffChunk.dwRiffSize = ((uint32_t)*(wavPoint + 4)) +
                                                                              (((uint32_t)*(wavPoint + 5)) << 8) +
                                                                              (((uint32_t)*(wavPoint + 6)) << 16) +
                                                                              (((uint32_t)*(wavPoint + 7)) << 24);

      wavPoint += 12;

      if (0 == strcompare("fmt ", (uint8_t *)wavPoint, 4))
      {
            return 0;
      }
      else
      {
            strncpy(wavFile.wavFmtChunk.szFmtID, (uint8_t *)wavPoint, 4);
      }

      wavFile.wavFmtChunk.dwFmtSize = ((uint32_t)*(wavPoint + 4)) +
                                                                     (((uint32_t)*(wavPoint + 5)) << 8) +
                                                                     (((uint32_t)*(wavPoint + 6)) << 16) +
                                                                     (((uint32_t)*(wavPoint + 7)) << 24);

      wavFile.wavFmtChunk.wavFormat.wFormatTag = ((uint32_t)*(wavPoint + 8)) +
                                                                                             (((uint32_t)*(wavPoint + 9)) << 8);

      wavFile.wavFmtChunk.wavFormat.wChannels = ((uint32_t)*(wavPoint + 10)) +
                                                                                             (((uint32_t)*(wavPoint + 11)) << 8);

      wavFile.wavFmtChunk.wavFormat.dwSamplesPerSec = ((uint32_t)*(wavPoint + 12)) +
                                                                                                      (((uint32_t)*(wavPoint + 13)) << 8) +
                                                                                                      (((uint32_t)*(wavPoint + 14)) << 16) +
                                                                                                      (((uint32_t)*(wavPoint + 15)) << 24);

      wavFile.wavFmtChunk.wavFormat.dwAvgBytesPerSec = ((uint32_t)*(wavPoint + 16)) +
                                                                                                      (((uint32_t)*(wavPoint + 17)) << 8) +
                                                                                                      (((uint32_t)*(wavPoint + 18)) << 16) +
                                                                                                      (((uint32_t)*(wavPoint + 19)) << 24);

      wavFile.wavFmtChunk.wavFormat.wBlockAlign = ((uint32_t)*(wavPoint + 20)) +
                                                                                             (((uint32_t)*(wavPoint + 21)) << 8);

      wavFile.wavFmtChunk.wavFormat.wBitsPerSample = ((uint32_t)*(wavPoint + 22)) +
                                                                                                      (((uint32_t)*(wavPoint + 23)) << 8);

      wavPoint += wavFile.wavFmtChunk.dwFmtSize + 8;

      while (0 == strcompare("data", (uint8_t *)wavPoint, 4))
      {
            wavPoint += ((uint32_t)*(wavPoint + 4)) +
                                    (((uint32_t)*(wavPoint + 5)) << 8) +
                                    (((uint32_t)*(wavPoint + 6)) << 16) +
                                    (((uint32_t)*(wavPoint + 7)) << 24) + 8;
      }

      strncpy(wavFile.wavDataChunk.szDataID, (uint8_t *)wavPoint, 4);

      wavFile.wavDataChunk.dwDataSize = ((uint32_t)*(wavPoint + 4)) +
                                                                              (((uint32_t)*(wavPoint + 5)) << 8) +
                                                                              (((uint32_t)*(wavPoint + 6)) << 16) +
                                                                              (((uint32_t)*(wavPoint + 7)) << 24);
      return 1;
}

三、感想与收获：
1、有了这个程序，就可以实现wav信息读取了，为下一步wav的播放提供了基础。

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