为什么要播放单声道? [英] Why play it mono?

问题描述

为什么要单声道播放?

Why play it mono?

#pragma comment (lib, "winmm.lib")
#include <windows.h>
#include <mmsystem.h>
#include <stdlib.h> 

void CALLBACK waveInProc(HWAVEIN hwi,UINT uMsg,DWORD dwInstance,DWORD dwParam1,DWORD dwParam2);
bool addbuffer(WAVEHDR *pWaveHdr);

#define system_buf_len 4410
const int num_buff = 3;

HWAVEOUT hvo; 
HWAVEIN hvi; 

WAVEFORMATEX waveFormat;
WAVEHDR *whdrO; 
WAVEHDR buffer[num_buff];

int main()
{
	whdrO=(WAVEHDR*)malloc(sizeof(WAVEHDR));

	waveFormat.wFormatTag      = WAVE_FORMAT_PCM;
	waveFormat.wBitsPerSample  = 16;
	waveFormat.nChannels       = 2;
	waveFormat.nSamplesPerSec  = 44100;
	waveFormat.nBlockAlign     = (waveFormat.nChannels * waveFormat.wBitsPerSample) / 8;
	waveFormat.nAvgBytesPerSec = (waveFormat.nSamplesPerSec * waveFormat.nBlockAlign);
	waveFormat.cbSize          = 0;

	UINT uDevice = 0; 

	MMRESULT mmres;
	mmres = waveInOpen(&hvi,uDevice,&waveFormat,(DWORD)waveInProc,0,CALLBACK_FUNCTION);
	mmres = waveOutOpen(&hvo,WAVE_MAPPER,&waveFormat,0,0,CALLBACK_NULL);

	for (int i=0; i<num_buff; i++)
	{
		buffer[i].lpData          = (char*)malloc(system_buf_len);
		buffer[i].dwBufferLength  = system_buf_len;
		buffer[i].dwBytesRecorded = 0;
		buffer[i].dwUser          = 0;
		buffer[i].dwFlags         = 0;
		buffer[i].dwLoops         = 0;
		waveInPrepareHeader(hvi, &buffer[i], sizeof(WAVEHDR));
		waveInAddBuffer(hvi, &buffer[i], sizeof(WAVEHDR));
	}

	waveInStart(hvi);
	system("pause");
	waveInClose(hvi);
	waveOutClose(hvo);
	return 0;
}

void CALLBACK waveInProc(HWAVEIN hwi,UINT uMsg,DWORD dwInstance,DWORD dwParam1,DWORD dwParam2)
{
	WAVEHDR* pWaveHdr;
	switch(uMsg)
	{
		case MM_WIM_DATA:
			pWaveHdr = ((WAVEHDR*)dwParam1);
			if (pWaveHdr && hwi)
				if (pWaveHdr->dwFlags && WHDR_DONE == WHDR_DONE)
				{
					addbuffer(pWaveHdr); 
					waveInAddBuffer(hwi, pWaveHdr, sizeof(WAVEHDR)); 
				}
		break;
	}
}

bool addbuffer(WAVEHDR *waveHdr)
{	
	memcpy(whdrO,waveHdr,sizeof(WAVEHDR));
	waveInUnprepareHeader(hvi,waveHdr,sizeof(WAVEHDR));
	waveOutPrepareHeader(hvo,waveHdr,sizeof(WAVEHDR));
	waveOutWrite(hvo,whdrO, sizeof(WAVEHDR)); 

	return true;
}

推荐答案

我遇到一个问题，即16位立体声音频只能从一个扬声器播放.这听起来像您在这里所描述的.如果那是问题，请尝试以下看起来"解决方案，它解决了我的问题:

waveOutSetVolume(hwo，0xFFFFFFFF);

即使音量混音器运行良好，并且我可以检查混音器应用程序并使用winamp立体声播放声音，但我的程序仍在一个扬声器中以单声道播放.

I had a problem where the 16-bit stereo audio was only playing from one speaker. This sounds like what you are describing here. If that is the problem try this "what seems'' obvious solution. It fixed my problem:

waveOutSetVolume( hwo, 0xFFFFFFFF );

Even though the volume mixer was fine and I could check the mixer application and play sound with winamp in stereo, my program was playing in mono from one speaker.

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