c++ - 加载和保存 WAV 文件

Question

我正在尝试将 WAVE 文件加载到数据结构中，然后将其作为原始文件的拷贝保存回磁盘。加载和保存似乎工作正常，但复制的 WAVE 文件不会播放任何声音(尽管它打开时没有错误)。我想知道这是否与字节顺序有关？

这是我保存 WAVE 文件的数据结构:

struct WaveFile
{
public:

    static const uint16 NUM_CHARS = 4;

public:

    WaveFile() : Data(nullptr) {}

    ~WaveFile() { delete[] Data; }

    char ChunkID[NUM_CHARS];

    uint32 ChunkSize;

    char Format[NUM_CHARS];

    char SubChunkID[NUM_CHARS];

    uint32 SubChunkSize;

    uint16 AudioFormat;

    uint16 NumChannels;

    uint32 SampleRate;

    uint32 ByteRate;

    uint16 BlockAlign;

    uint16 BitsPerSample;

    char SubChunk2ID[NUM_CHARS];

    uint32 SubChunk2Size;

    byte* Data; 
};

这是我加载它的方式:

std::ifstream file(filename, std::ios::binary);

if (file.good())
{
    file.read(waveFile.ChunkID, WaveFile::NUM_CHARS);
    file.read(reinterpret_cast<char*>(&waveFile.ChunkSize), size_ui32);
    file.read(waveFile.Format, WaveFile::NUM_CHARS);
    file.read(waveFile.SubChunkID, WaveFile::NUM_CHARS);
    file.read(reinterpret_cast<char*>(&waveFile.SubChunkSize), size_ui32);
    file.read(reinterpret_cast<char*>(&waveFile.AudioFormat), size_ui16);
    file.read(reinterpret_cast<char*>(&waveFile.NumChannels), size_ui16);
    file.read(reinterpret_cast<char*>(&waveFile.SampleRate), size_ui32);
    file.read(reinterpret_cast<char*>(&waveFile.ByteRate), size_ui32);
    file.read(reinterpret_cast<char*>(&waveFile.BlockAlign), size_ui16);
    file.read(reinterpret_cast<char*>(&waveFile.BitsPerSample), size_ui16);
    file.read(waveFile.SubChunk2ID, WaveFile::NUM_CHARS);
    file.read(reinterpret_cast<char*>(&waveFile.SubChunk2Size), size_ui32);
    waveFile.Data = new byte[waveFile.SubChunk2Size];
    file.read(reinterpret_cast<char*>(waveFile.Data), sizeof(waveFile.SubChunk2Size));
    file.close();
}

这就是我将数据写回文件的方式:

std::ofstream file(outfile, std::ios::binary);

if (file.good())
{
    file.flush();
    file.write(waveFile.ChunkID, WaveFile::NUM_CHARS);
    file.write(reinterpret_cast<const char*>(&waveFile.ChunkSize), size_ui32);
    file.write(waveFile.Format, WaveFile::NUM_CHARS);
    file.write(waveFile.SubChunkID, WaveFile::NUM_CHARS);
    file.write(reinterpret_cast<const char*>(&waveFile.SubChunkSize), size_ui32);
    file.write(reinterpret_cast<const char*>(&waveFile.AudioFormat), size_ui16);
    file.write(reinterpret_cast<const char*>(&waveFile.NumChannels), size_ui16);
    file.write(reinterpret_cast<const char*>(&waveFile.SampleRate), size_ui32);
    file.write(reinterpret_cast<const char*>(&waveFile.ByteRate), size_ui32);
    file.write(reinterpret_cast<const char*>(&waveFile.BlockAlign), size_ui16);
    file.write(reinterpret_cast<const char*>(&waveFile.BitsPerSample), size_ui16);
    file.write(waveFile.SubChunk2ID, WaveFile::NUM_CHARS);
    file.write(reinterpret_cast<const char*>(&waveFile.SubChunk2Size), size_ui32);
    file.write(reinterpret_cast<const char*>(waveFile.Data), waveFile.SubChunk2Size);
    file.close();   
}

拷贝的大小也与原件相同。如果有人想知道，uint16、uint32 和 byte 只是 unsigned short、unsigned int 和 unsigned char 的类型定义。 size_ui32 变量就是这样:

static const uint32 size_ui32 = sizeof(uint32);
static const uint32 size_ui16 = sizeof(uint16);

差不多就这些了，好像找不到我哪里出错了。

欢迎任何帮助。

Answer 1

这适用于大多数波形文件，但某些 header 可能包含特定的用户数据。您可以使用 struct WAVEHEADER 的单写:

struct WAVEFILEHEADER
{
    // don't change the order of attributes
    char m_lpcChunkId[4];
    int m_iChunkSize;
    char m_lpcFormat[4];
    char m_lpcSubChunkFmt[4];
    int m_iSubChunkFmtSize;
    short int m_siAudioFormat;
    short int m_siNumChannels;

    int m_iSampleRate;
    int m_iByteRate;
    short int m_siBlockAlign;
    short int m_siBitsPerSample;

    char m_lpcChunkData[4];
    int m_iSubChunkDataSize;
    // unsigned char * m_data;
};

WAVEFILEHEADER whdr;
FILE* fid = fopen("newaudio.wav","wb"); // important to use binary file

// some inicialization for whdr - RIFF etc.
// You can use only 1 write to save whole header:
fwrite(&whdr, 1, sizeof(WAVEFILEHEADER), fid);

// or you can read wav header
fread(&whdr, 1, sizeof(WAVEFILEHEADER), fid); 
// check chunk size, few headers have aditional 2 bytes (by definition user data, but they was always 0x0000)