Continue previous article : Understand wave format, and implement a wave reader , In here , I will demonstrate how to play audio in windows.(Zeroth are wave format, you could refer to previous article.)First , the struct WAVEFORMATEX would be used, the members of WAVEFORMATEX are very explicit, I do not explain that.Second, the structure WAVEHDR, which is for managing audio buffer. One should set audio buffer in the WAVEHDR structure to require windows to play that audio.The functions will be used:waveOutOpen: open the audio output device for playback. The function needs a HWAVEOUT as output. One should have set WAVEHDR to feed the waveOutOpen. The function needs to set a callback function, waveOutProc. waveOutPrepareHeader/waveOutPrepareHeader: Set the the structure WAVEHDR be prepared/cleaned.waveOutWrite: Set the audio data to the audio output device.To ensure the audio playback be smooth, it is necessary to use 2 block of buffer:one for preparing, one for playing, in interleave form(very similar to producer consumer semaphores problem). In here, I use EnterCriticalSection/LeaveCriticalSection.My code is below, the full code with previouse is too long, I omit the previous code:The part should be inserted after the line
#define MAX_STR_LEN256
CRITICAL_SECTION waveCriticalSection;WAVEFORMATEX wFmt; /*for debug, or the should not be global variable*/void CALLBACK WaveOutProc( HWAVEOUT device,UINT uMsg,DWORD dwInstance,DWORD dwParam1,DWORD dwParam2 ) {cnt = 0; DWORD *pFreeBlockCounter; pFreeBlockCounter = (DWORD*)(long long)dwInstance;switch(uMsg) {case WOM_DONE:printf(, cnt*BLOCK_SIZE/(float)(wFmt.nAvgBytesPerSec));cnt++;EnterCriticalSection(&waveCriticalSection); (*pFreeBlockCounter)++; LeaveCriticalSection(&waveCriticalSection); break; case WOM_OPEN: InitializeCriticalSection(&waveCriticalSection); break; case WOM_CLOSE: DeleteCriticalSection(&waveCriticalSection); break; }/*if uMsg == WOM_DONE*/}/*WaveCallBack*/
Below code should be insert in front of the "return" line in main:
char *pAudioData; pAudioData = (char*)malloc(audioDataLen); fread(pAudioData, 1, audioDataLen, pWaveFile); fclose(pWaveFile); /*step 0, variables*/ MMRESULT ret; HWAVEOUT hDevice; int waveFreeBlockCount; WAVEHDR *pWaveHeaderWithBlock; int waveCurrentBlock; /*step 1: initialize */ hDevice = NULL; /*set WAVEFORMATEX*/ wFmt.wFormatTag = (WORD)WAVE_FORMAT_PCM; wFmt.nSamplesPerSec = (WORD)nSamplesPerSec; wFmt.wBitsPerSample = (WORD)bitsPerSample; wFmt.nChannels = (WORD)nChannel; wFmt.nBlockAlign = (WORD)(wFmt.nChannels*(bitsPerSample/8)); wFmt.nAvgBytesPerSec = wFmt.nSamplesPerSec* wFmt.nBlockAlign; wFmt.cbSize = 0; /*set up callback function to play audio*/ ret = waveOutOpen( &hDevice, WAVE_MAPPER, &wFmt, (DWORD_PTR)WaveOutProc, (DWORD_PTR)&waveFreeBlockCount, CALLBACK_FUNCTION); if(0 != ret) { char errStr[MAX_STR_LEN]; waveOutGetErrorText(ret, &errStr[0], MAX_STR_LEN); printf(, &errStr[0]); goto Flag_end_main; }pWaveHeaderWithBlock = (WAVEHDR*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, (BLOCK_SIZE + sizeof(WAVEHDR)) * BLOCK_COUNT);if(NULL == pWaveHeaderWithBlock) goto Flag_end_main;WAVEHDR *pBlockHeader; pBlockHeader = (WAVEHDR*)pWaveHeaderWithBlock; for(int i = 0; i < BLOCK_COUNT; i++) { pBlockHeader[i].dwBufferLength = BLOCK_SIZE; pBlockHeader[i].lpData =(LPSTR)(pWaveHeaderWithBlock) + sizeof(WAVEHDR) * BLOCK_COUNT + i*BLOCK_SIZE; }/*for i*/ waveFreeBlockCount = BLOCK_COUNT; waveCurrentBlock = 0;if(NULL == pWaveHeaderWithBlock) goto Flag_end_main;unsigned int remainderLen; remainderLen = audioDataLen; char *pMovAudioData; pMovAudioData = pAudioData;pMovAudioData ); remainderLen ); unsigned int cnt; cnt = 0; while(remainderLen > SEND_SIZE) {printf(, cnt*SEND_SIZE/((float)bytesPerSec) ); cnt++; WAVEHDR* pCurrentWaveHeader; unsigned long remain;unsigned int size; char *pData; size = SEND_SIZE; pCurrentWaveHeader = &pWaveHeaderWithBlock[waveCurrentBlock]; pData = (char*)pMovAudioData; while(size > 0) { (WHDR_PREPARED & pCurrentWaveHeader->dwFlags)waveOutUnprepareHeader(hDevice, pCurrentWaveHeader, sizeof(WAVEHDR));if(size < (int)(BLOCK_SIZE – pCurrentWaveHeader->dwUser)){ memcpy(pCurrentWaveHeader->lpData + pCurrentWaveHeader->dwUser, pData, size);pCurrentWaveHeader->dwUser += size;break; }/*if*//*the buffer would be full */ remain = BLOCK_SIZE – (unsigned long)pCurrentWaveHeader->dwUser; memcpy(pCurrentWaveHeader->lpData + pCurrentWaveHeader->dwUser, pData, remain);/*remaining would be stowed in the other WAVEHDR, note the size here */ size -= remain; pData += remain;/*full size of the WAVEHDR’s buffer is BLOCK_SIZE */ pCurrentWaveHeader->dwBufferLength = BLOCK_SIZE;/*preparation…*/waveOutPrepareHeader(hDevice, pCurrentWaveHeader, sizeof(WAVEHDR)); /*write the data to audio device */ waveOutWrite(hDevice, pCurrentWaveHeader, sizeof(WAVEHDR));EnterCriticalSection(&waveCriticalSection); waveFreeBlockCount–; LeaveCriticalSection(&waveCriticalSection);(0 == waveFreeBlockCount)Sleep(5);waveCurrentBlock++; waveCurrentBlock %= BLOCK_COUNT; pCurrentWaveHeader = &pWaveHeaderWithBlock[waveCurrentBlock]; pCurrentWaveHeader->dwUser = 0; }/*while*/pMovAudioData += SEND_SIZE; remainderLen -= SEND_SIZE; }(int i = 0; i < waveFreeBlockCount; i++){ if(NULL != pWaveHeaderWithBlock) { if(pWaveHeaderWithBlock[i].dwFlags & WHDR_PREPARED)waveOutUnprepareHeader(hDevice, &pWaveHeaderWithBlock[i], sizeof(WAVEHDR)); }/*if*/ pWaveHeaderWithBlock = NULL; }hDevice) waveOutClose(hDevice); hDevice = NULL;if(NULL != pWaveHeaderWithBlock) HeapFree(GetProcessHeap(), 0, pWaveHeaderWithBlock); pWaveHeaderWithBlock = NULL;
Now, you have a hand-made wave player in windows.
，人生就是一次充满未知的旅行，在乎的是沿途的风景，
