C++解析wav文件方法介紹
一、前言
一開始本來在網(wǎng)上找代碼,不過改了好幾個都不是很好用。因為很多wav文件的fmt塊后面并不是data塊,經(jīng)常還帶有其他塊,正確的方法應(yīng)該是按MSDN的方法,找到data塊再讀取。
二、接口
最后接口如下:
class AudioReader
{
public:
struct PCM
{
int _numChannel;//通道數(shù) 1,2 AL_FORMAT_MONO8,AL_FORMAT_STEREO8
int _bitPerSample;//采樣數(shù) 8,16
byte* _data;
size_t _size;
size_t _freq;//采樣率
void Delete() { delete[] _data; }
};
static bool ReadWAV(string_view path_name, PCM& pcm);
};三、具體步驟
打開文件,這里就是普通的文件流,按二進(jìn)制、只讀打開文件即可:
ifstream ifs;
if (!g_file->GetFile(path_name, ifs))
{
debug_err(format("打開文件失?。簕}", path_name));
return false;
}查找riff塊:
uint32_t dwChunkSize;
uint32_t dwChunkPosition;
//查找riff塊
FindChunk(ifs, fourccRIFF, dwChunkSize, dwChunkPosition);
uint32_t filetype;
ReadChunkData(ifs, &filetype, sizeof(uint32_t), dwChunkPosition);
if (filetype != fourccWAVE)
{
debug_err(format("匹配標(biāo)記失?。╢ourccWAVE):{}", path_name));
return false;
}其中fourccRIFF和fourccWAVE是我們定義的標(biāo)記,也就是處理了下大小端,如下:
#ifdef DND_ENDIAN_BIG #define fourccRIFF 'RIFF' #define fourccDATA 'data' #define fourccFMT 'fmt ' #define fourccWAVE 'WAVE' #define fourccXWMA 'XWMA' #define fourccDPDS 'dpds' #endif #ifdef DND_ENDIAN_LITTLE #define fourccRIFF 'FFIR' #define fourccDATA 'atad' #define fourccFMT ' tmf' #define fourccWAVE 'EVAW' #define fourccXWMA 'AMWX' #define fourccDPDS 'sdpd' #endif
而FindChunk和ReadChunkData兩個函數(shù),分別是查找一個塊,和讀取一個塊。代碼實現(xiàn)有點長,可以參考后面我給出的完整源碼。
接著,查找并讀取fmt塊,這個塊描述了wav文件的音頻屬性,結(jié)構(gòu)如下(部分字段會用到):
//16字節(jié)
struct WAVEFormat
{
int16_t audioFormat;
int16_t numChannels;
int32_t sampleRate;
int32_t byteRate;
int16_t blockAlign;
int16_t bitsPerSample;
};//查找fmt塊
if (!FindChunk(ifs, fourccFMT, dwChunkSize, dwChunkPosition))
{
debug_err(format("查找塊失?。╢ourccFMT):{}", path_name));
return false;
}
//讀wave信息
WAVEFormat wave_format;
if (!ReadChunkData(ifs, &wave_format, dwChunkSize, dwChunkPosition))
{
debug_err(format("讀取塊失?。╳ave_format):{}", path_name));
return false;
};接下來查找data塊,根據(jù)返回的大小分配內(nèi)存:
//查找音頻數(shù)據(jù)
if (!FindChunk(ifs, fourccDATA, dwChunkSize, dwChunkPosition))
{
debug_err(format("查找塊失?。╢ourccDATA):{}", path_name));
return false;
};
pcm._data = new byte[dwChunkSize];然后讀取data塊,將數(shù)據(jù)讀取到我們分配的內(nèi)存pcm._data。然后記錄下一些重要的字段。由于OpenaAL不能直接播放32位(只8、16)的數(shù)據(jù),這里簡單返回失敗。
if (!ReadChunkData(ifs, pcm._data, dwChunkSize, dwChunkPosition))
{
debug_err(format("讀取塊失?。╬cm數(shù)據(jù)):{}", path_name));
pcm.Delete();
return false;
};
pcm._size = dwChunkSize;
pcm._numChannel = wave_format.numChannels;
pcm._bitPerSample = wave_format.bitsPerSample;
pcm._freq = wave_format.sampleRate;
if (pcm._bitPerSample == 32)
{
debug_err(format("不支持32位:{}", path_name));
pcm.Delete();
return false;
}
return true;四、完整源碼
可以此處獲取最新的源碼(我將來會添加ogg格式的解析),也可以用下面的:傳送門
//.h
class AudioReader
{
public:
struct PCM
{
int _numChannel;//通道數(shù) 1,2 AL_FORMAT_MONO8,AL_FORMAT_STEREO8
int _bitPerSample;//采樣數(shù) 8,16
byte* _data;
size_t _size;
size_t _freq;//采樣率
void Delete() { delete[] _data; }
};
static bool ReadWAV(string_view path_name, PCM& pcm);
};
//16字節(jié)
struct WAVEFormat
{
int16_t audioFormat;
int16_t numChannels;
int32_t sampleRate;
int32_t byteRate;
int16_t blockAlign;
int16_t bitsPerSample;
};
//.cpp
#ifdef DND_ENDIAN_BIG
#define fourccRIFF 'RIFF'
#define fourccDATA 'data'
#define fourccFMT 'fmt '
#define fourccWAVE 'WAVE'
#define fourccXWMA 'XWMA'
#define fourccDPDS 'dpds'
#endif
#ifdef DND_ENDIAN_LITTLE
#define fourccRIFF 'FFIR'
#define fourccDATA 'atad'
#define fourccFMT ' tmf'
#define fourccWAVE 'EVAW'
#define fourccXWMA 'AMWX'
#define fourccDPDS 'sdpd'
#endif
bool FindChunk(ifstream& ifs, uint32_t fourcc, uint32_t& size, uint32_t& pos)
{
bool ret = true;
ifs.seekg(0);
if (ifs.fail())
return false;
uint32_t dwChunkType;
uint32_t dwChunkDataSize;
uint32_t dwRIFFDataSize = 0;
uint32_t dwFileType;
uint32_t bytesRead = 0;
uint32_t dwOffset = 0;
while (ret)
{
ifs.read((char*)&dwChunkType, sizeof(uint32_t));
ifs.read((char*)&dwChunkDataSize, sizeof(uint32_t));
switch (dwChunkType)
{
case fourccRIFF:
dwRIFFDataSize = dwChunkDataSize;
dwChunkDataSize = 4;
ifs.read((char*)&dwFileType, sizeof(uint32_t));
break;
default:
ifs.seekg(dwChunkDataSize, std::ios::cur);
if (ifs.fail())
return false;
break;
}
dwOffset += sizeof(uint32_t) * 2;
if (dwChunkType == fourcc)
{
size = dwChunkDataSize;
pos = dwOffset;
return true;
}
dwOffset += dwChunkDataSize;
if (bytesRead >= dwRIFFDataSize)
return false;
}
return true;
}
bool ReadChunkData(ifstream& ifs, void* buffer, uint32_t size, uint32_t pos)
{
ifs.seekg(pos);
if (ifs.fail())
return false;
ifs.read((char*)buffer, size);
return true;
}
bool AudioReader::ReadWAV(string_view path_name, PCM& pcm)
{
ifstream ifs;
if (!g_file->GetFile(path_name, ifs))
{
debug_err(format("打開文件失?。簕}", path_name));
return false;
}
uint32_t dwChunkSize;
uint32_t dwChunkPosition;
//查找riff塊
FindChunk(ifs, fourccRIFF, dwChunkSize, dwChunkPosition);
uint32_t filetype;
ReadChunkData(ifs, &filetype, sizeof(uint32_t), dwChunkPosition);
if (filetype != fourccWAVE)
{
debug_err(format("匹配標(biāo)記失?。╢ourccWAVE):{}", path_name));
return false;
}
//查找fmt塊
if (!FindChunk(ifs, fourccFMT, dwChunkSize, dwChunkPosition))
{
debug_err(format("查找塊失?。╢ourccFMT):{}", path_name));
return false;
}
//讀wave信息
WAVEFormat wave_format;
if (!ReadChunkData(ifs, &wave_format, dwChunkSize, dwChunkPosition))
{
debug_err(format("讀取塊失敗(wave_format):{}", path_name));
return false;
};
//查找音頻數(shù)據(jù)
if (!FindChunk(ifs, fourccDATA, dwChunkSize, dwChunkPosition))
{
debug_err(format("查找塊失?。╢ourccDATA):{}", path_name));
return false;
};
pcm._data = new byte[dwChunkSize];
if (!ReadChunkData(ifs, pcm._data, dwChunkSize, dwChunkPosition))
{
debug_err(format("讀取塊失敗(pcm數(shù)據(jù)):{}", path_name));
pcm.Delete();
return false;
};
pcm._size = dwChunkSize;
pcm._numChannel = wave_format.numChannels;
pcm._bitPerSample = wave_format.bitsPerSample;
pcm._freq = wave_format.sampleRate;
if (pcm._bitPerSample == 32)
{
debug_err(format("不支持32位:{}", path_name));
pcm.Delete();
return false;
}
return true;
}到此這篇關(guān)于C++解析wav文件方法介紹的文章就介紹到這了,更多相關(guān)C++解析wav內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家!
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