加载和保存 WAV 文件

Posted 2023-02-25

【中文标题】加载和保存 WAV 文件

【英文标题】：Loading and Saving WAV file

【发布时间】：2013-07-31 11:02:16

【问题描述】：

我正在尝试将 WAVE 文件加载到数据结构中，然后将其作为原始副本保存回磁盘。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（尽管它确实打开没有错误）。我想知道这是否与字节序有关？

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();   

副本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 typedef。 size_ui32 变量就是这样：

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

这不是它，似乎无法找出我哪里出错了。

为任何帮助干杯。

【参考方案1】：

这适用于大多数波形文件，但某些标题可能包含特定的用户数据。您可以使用结构 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)

【参考方案2】：

发布此问题后，我刚刚发现了问题。

在读取数据时，我已经这样做了：

file.read(reinterpret_cast<char*>(waveFile.Data), sizeof(waveFile.SubChunk2Size));

应该是：

file.read(reinterpret_cast<char*>(waveFile.Data), waveFile.SubChunk2Size);  

当我删除 sizeof() 时工作​​。傻我。