播放音频PCM

1、如果是wav的文件，可以直接用playsound播放。

2、如果是PCM的流，使用waveout的一系列接口播放。下面的代码从网上看到的（重点是waveoutopen的时候使用了回调函数，waveoutwrite的时候，使用了双缓冲技术）：

//waveout.h

#ifndef waveout_h
#define waveout_h

#pragma once

#include <mmsystem.h>
#include <list>
using namespace std;

#define BUFFER_SIZE 16
#define BLOCK_SIZE 1280 + sizeof(WAVEHDR)

class waveout
{
WAVEFORMATEX wave_format;
HWAVEOUT h_waveout;

public:
char m_buf[BUFFER_SIZE][BLOCK_SIZE];
list<char*>m_buf_free;

waveout();
~waveout();

bool start();
bool stop();
int input(unsigned char* buf);
bool inlineis_start(){return (h_waveout != NULL);}
};

#endif

//waveout.cpp
#include "stdafx.h"
#include "waveout.h"

waveout::waveout(){
wave_format.wFormatTag= WAVE_FORMAT_PCM;
wave_format.nChannels= 1;
wave_format.nSamplesPerSec= 16000;
wave_format.wBitsPerSample= 16;
wave_format.nAvgBytesPerSec= 32000;
wave_format.nBlockAlign= 2;
wave_format.cbSize= 0;

h_waveout = NULL;
}

waveout::~waveout(){
stop();
}

void __stdcall waveOutProc(HWAVEOUT hwo, UINT uMsg, DWORD dwInstance,DWORD dwParam1, DWORD dwParam2){
if(uMsg == WOM_DONE){
  WAVEHDR* p_wavehdr = (WAVEHDR *) dwParam1;
  waveout* p_wvo = (waveout *) dwInstance;
  p_wvo->m_buf_free.push_back((char *) p_wavehdr);
}
}

int waveout::input(unsigned char* buf){
size_t nSize = m_buf_free.size();
if(nSize == 0)
  return 0;

WAVEHDR *p_wavehdr = (WAVEHDR *) m_buf_free.front();
m_buf_free.pop_front();

memcpy(p_wavehdr->lpData, buf, 1280);
waveOutWrite(h_waveout, p_wavehdr, sizeof(WAVEHDR));

return 0;
}

bool waveout::start(){
if(h_waveout != NULL)
  return true;

MMRESULT nRet = waveOutOpen(&h_waveout, WAVE_MAPPER, &wave_format, (DWORD) waveOutProc, (DWORD) this, CALLBACK_FUNCTION);
if(nRet != MMSYSERR_NOERROR)
  return false;

for(int i = 0; i < BUFFER_SIZE; ++ i)
{
  WAVEHDR *p_wavehdr = (WAVEHDR *)m_buf[i];
  p_wavehdr->dwBufferLength = 1280;
  p_wavehdr->lpData = m_buf[i] + sizeof(WAVEHDR);
  p_wavehdr->dwFlags = 0;

  waveOutPrepareHeader(h_waveout, p_wavehdr, sizeof(WAVEHDR));
  m_buf_free.push_back((char *) p_wavehdr);
}

return true;
}

bool waveout::stop(){
if(h_waveout != NULL){
  while(m_buf_free.size() != BUFFER_SIZE)
   Sleep(80);
  m_buf_free.clear();
  waveOutReset(h_waveout);

  for(int i = 0; i < BUFFER_SIZE; ++ i){
   WAVEHDR *p_wavehdr = (WAVEHDR *)m_buf[i];
   waveOutUnprepareHeader(h_waveout, p_wavehdr, sizeof(WAVEHDR));
  }

  waveOutClose(h_waveout);
  h_waveout = NULL;
}
return true;
}