如何将音频字节转换为样本 [英] How to convert audio byte to samples
问题描述
这是我的结构
/* wave data block header */
typedef struct wavehdr_tag {
LPSTR lpData; /* pointer to locked data buffer */
DWORD dwBufferLength; /* length of data buffer */
DWORD dwBytesRecorded; /* used for input only */
DWORD_PTR dwUser; /* for client's use */
DWORD dwFlags; /* assorted flags (see defines) */
DWORD dwLoops; /* loop control counter */
struct wavehdr_tag FAR *lpNext; /* reserved for driver */
DWORD_PTR reserved; /* reserved for driver */
} WAVEHDR, *PWAVEHDR, NEAR *NPWAVEHDR, FAR *LPWAVEHDR;
我有此变量 WAVEHDR waveHeader;
我从麦克风录制了10秒,并且 waveHeader-> lpData
有我的原始记录数据,而 waveHeader-> dwBytesRecorded
是原始数据的长度
现在,我想计算每秒的音量,以说出哪一秒的音量最高,哪一秒的音量最低。
I record 10 secs from microphone and waveHeader->lpData
has my raw recorded data, and waveHeader->dwBytesRecorded
is the raw data's length
Now I want to calculate the volume in each second to say which second has highest volume and which one has the lowest.
我知道我应该对绝对值求和并除以样本数量
I know I should sum the absolute values and divide by the number of samples
我使用了 sum + = abs(waveHeader-> lpData [i]);
对于i从0到1秒的数据长度,但效果不佳
I used sum += abs(waveHeader->lpData[i]);
for i from 0 to length of one secs data, but it doesn't give me a good result
它始终为我每秒提供相同的结果,但我在几秒钟内保持沉默,并在某些时候说话...
it always gives me the same result for each second, but I am silent in some seconds and speak in some...
我阅读了我必须添加样本,而不是字节 如何将 waveHeader-> lpData [i]
转换为样本?
I read I have to add samples, not bytes How should I convert waveHeader->lpData[i]
to samples?
//len = length of one secs data (waveHeader->dwBytesRecorded/10)
for (int i=0; i<len; i++)
{
sum += abs(waveHeader->lpData[i]);
}
推荐答案
您已将WAVEFORMATEX用于捕捉音频,对不对?如果是这样,则可以修改以下例程以满足您的需要:
You have the WAVEFORMATEX used for capturing the audio, right? If so, you can modify the following routine to meet your needs:
void ProcessSamples(WAVEHDR* header, WAVEFORMATEX* format)
{
BYTE* pData = (BYTE*)(header->data);
DWORD dwNumSamples = header->dwBytesRecorded / format->nBlockAlign;
// 16-bit stereo, the most common format
if ((format->wBitsPerSample == 16) && (format->nChannels == 2))
{
for (DWORD index = 0; index < dwNumSamples; index++)
{
short left = *(short*)pData; pData+=2;
short right = *(short*)pData; pData+=2;
}
}
else if ((format->wBitsPerSample == 16) && (format->nChannels == 1))
{
for (DWORD index = 0; index < dwNumSamples; index++)
{
short monoSample = *(short*)pData; pData+=2;
}
}
else if ((format->wBitsPerSample == 8) && (format->nChannels == 2))
{
// 8-bit samples are unsigned.
// "128" is the median silent value
// normalize to a "signed" value
for (DWORD index = 0; index < dwNumSamples; index++)
{
signed char left = (*(signed char*)pData) - 128; pData += 1;
signed char right = (*(signed char*)pData) - 128; pData += 1;
}
}
else if ((format->wBitsPerSample == 8) && (format->nChannels == 1))
{
for (DWORD index = 0; index < dwNumSamples; index++)
{
signed char monosample = (*(signed char*)pData) - 128; pData += 1;
}
}
}
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