用Direct Sound為MP3解碼器libmad播放輸出

1、用Direct Sound為MP3解碼器libmad播放輸出WIN32平臺下madplay默認(rèn)采用WaveOut播放輸出，本文實現(xiàn)為其增加Direct Sound輸出。在Windows XP，VC+ 6.0測試通過。 （一）優(yōu)秀的MP3解碼器libmad簡介 libmad是跨平臺的基于命令行的MP3播放解碼器，使用定點解碼，可用于沒有浮點運算的嵌入式系統(tǒng)。 （二）下載及測試 1、從官方網(wǎng)站下載madplay-0.15.2b.tar.gz，libmad-0.15.1b.tar.gz，libid3tag-0.15.1b.tar.gz，還要從下載libz-1.

2、1.4.tar.gz，共四個文件。將四個壓縮包保存在同一目錄，例如d:madplay。 2、用WINRAR“解碼壓到當(dāng)前目錄”方法將四個壓縮包解壓，在d:madplay下將有四個文件夾：madplay-0.15.2b，libmad-0.15.1b，libid3tag-0.15.1b，libz-1.1.4。 3、用VC+ 6.0打開D:madplaymadplay-0.15.2bmsvc+下的madplay工程。修改VC+ 6.0的編譯環(huán)境：Tools -> Options -> Directories標(biāo)簽 -> Directories框下增加如下兩行： D

3、:MADPLAYLIBMAD-0.15.1BMSVC+ D:MADPLAYLIBID3TAG-0.15.1B 點擊OK保存設(shè)置退出。再為編譯連接后的可執(zhí)行文件指定運行參數(shù)：Project -> settings -> 點中左側(cè)madplay -> 右側(cè)Program arguments框內(nèi)填入你硬盤上保存的一個MP3文件，例如：D:MP3test.mp3，單擊OK保存設(shè)置退出。 按Ctrl+F5編譯連接運行，就可以聽到播放你選擇的MP3歌曲了。 (三）為madplay增加Direct Sound輸出 madplay采用Wave

4、Out作為播放輸出，用DS輸出的優(yōu)點不再我說了吧。 1、在audio.h中查找到“audio_ctlfunc_t audio_win32;”這一行，在下面增加一行： audio_ctlfunc_t audio_dsound; 2、在config.h中找到“#define AUDIO_DEFAULT audio_win32”這一行，將這一行注釋掉，然后在下面增加一行： #define AUDIO_DEFAULT audio_dsound 3、在工作區(qū)中選擇FileView標(biāo)簽，點擊madplay files下的Source Files，添加文件a

5、duio_dsound.c 我寫的aduio_dsound.c的內(nèi)容如下，添加了比較詳細(xì)的注釋。   /* aduio_dsound.c功能: 用 Direct Sound 為MP3解碼器libmad播放輸出.兼容 VC+ 6.0 的directx 7.0接口函數(shù): audio_dsound()email: (請注明主題 mp3 decoder)2008.08*/ /*libmad解碼器頭文件*/#include "audio.h" /*Direct Sound 的頭文件和庫*/#include<dsound

6、.h>#pragma comment( lib, "dsound.lib" ) /*高精定時器的頭文件和庫*/#include<mmsystem.h>#pragma comment( lib, "winmm.lib") /*DS_N: 緩沖區(qū)塊數(shù),設(shè)為8塊.DS_ONEBUF: 一塊的長度.設(shè)解碼16幀的PCM數(shù)據(jù)長度,4608*16=73728(72KB).DS_BUFSIZE: Direct sound緩沖區(qū)長度,DS_N*DS_ONEBUF=589824(576KB).   

7、60;        最小4,最大0xfffffff,在dsound.h中由DSBSIZE_MIN和DSBSIZE_MAX定義.每一幀的時長26ms,一塊的時間長度為26*16=416ms;緩沖區(qū)總時間長度8*416=3328ms.*/#define DS_N   8#define DS_ONEBUF  73728#define DS_BUFSIZE  589824 /*pcm_data - 暫存寫入到時DSound Buffer的數(shù)據(jù),該數(shù)據(jù)是由audio_pcm()解碼M

8、P3幀得到的PCM數(shù)據(jù),不同的解碼器(如mpg123,libmad等)解碼一幀的函數(shù)都采用向外部提供的接收緩沖區(qū)寫入解碼得到的PCM數(shù)據(jù),將本模塊略作改寫可用于不同的MP3解碼器播放輸出.*/static unsigned char pcm_dataDS_ONEBUF+4608;static int pcm_length=0;static audio_pcmfunc_t *audio_pcm;static LPDIRECTSOUND   ds_lpDS=0;static LPDIRECTSOUNDBUFFER  ds_lpDSB=0;static HWND

9、0;  ds_hWndMain=0;static HANDLE  ds_hSemaphoreNotify=0;static DWORD  ds_dwWriteCursor=0;static DWORD  ds_dwPlayCursorOld=0;static MMRESULT  ds_timerID=0;static int   ds_iWriteTimes=0; /#define DBGOUTPUT #ifdef DBGOUTPUT  #include <stdio.h>#endi

10、f /*DirectSoundBuffer 通知機(jī)制引發(fā)的問題:若采用DirectSoundBuffer通知機(jī)制,發(fā)現(xiàn)運行其它使用相同通知機(jī)制的播放程序時,會造成本程序的通知事件誤觸發(fā),如何識別是本程序還是其它程序引發(fā)的通知事件? 如何解決? 本程序采用定時器回調(diào)函數(shù)定時判斷播放位置、發(fā)信號(設(shè)置通知事件).ds_dwWriteCursor: 寫入光標(biāo),指向播放一塊后釋放的一個空閑塊首址,跟隨于播放光標(biāo)后.ds_dwPlayCursor: 播放光標(biāo),取值(0.n)*DS_ONEBUF ds_dwPlayCursorOld: 暫存播放光標(biāo)先前值,取值(0.n-1)*DS_ON

11、EBUF, 若使用寫入光標(biāo),     由于本函數(shù)中“讀”與audio_play()中“寫”不同步而出錯.*/ /*MyPlayPositionNotify()  - 定時器回調(diào)函數(shù),播放完一塊發(fā)一次信號.*/static void CALLBACKMyPlayPositionNotify(UINT uTimerID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2) DWORD dwPlayCursor=0; ds_lpDSB->lpVtbl->GetCurr

12、entPosition(ds_lpDSB,&dwPlayCursor, NULL); if(dwPlayCursor>ds_dwPlayCursorOld+DS_ONEBUF |  (dwPlayCursor<DS_ONEBUF && ds_dwPlayCursorOld=DS_BUFSIZE-DS_ONEBUF) #ifdef DBGOUTPUT  printf("nWriteCursor = %6d, PlayCursor = %6d, PlayCursorOld = %6d",  &

13、#160; ds_dwWriteCursor, dwPlayCursor, ds_dwPlayCursorOld);#endif  dwPlayCursor /= DS_ONEBUF;  ds_dwPlayCursorOld = dwPlayCursor*DS_ONEBUF;   /* 發(fā)信號,使audio_play()內(nèi)的等待函數(shù)返回. */  ReleaseSemaphore(ds_hSemaphoreNotify,1,NULL);  static int audio_open(int nChannels,long nS

14、amplesPerSec,unsigned int depth) DSBUFFERDESC dsbd; WAVEFORMATEX wvOut;  ds_dwWriteCursor=0; ds_dwPlayCursorOld=0; ds_iWriteTimes=0;  if(nSamplesPerSec = -1)  return -1;  /* Create DirectSound */ if ( DirectSoundCreate(NULL, &ds_lpDS, N

15、ULL) != DS_OK )   return -1;   if( ds_hWndMain = 0 )  ds_hWndMain=GetDesktopWindow();  /* Set Cooperative Level */ if ( ds_lpDS->lpVtbl->SetCooperativeLevel(ds_lpDS,ds_hWndMain, DSSCL_PRIORITY) != DS_OK )   return -1;   wvOut.wFormatT

16、ag      = WAVE_FORMAT_PCM; wvOut.wBitsPerSample  = depth; wvOut.nChannels       = nChannels; wvOut.nSamplesPerSec  = nSamplesPerSec; wvOut.nAvgBytesPerSec = wvOut.nSamplesPerSec * wvOut.nChannels * wvOut.wBitsPerSam

17、ple/8; wvOut.nBlockAlign     = wvOut.nChannels * wvOut.wBitsPerSample/8;  /* Create Secondary Sound Buffer */  ZeroMemory(&dsbd, sizeof(DSBUFFERDESC); dsbd.dwSize   = sizeof(DSBUFFERDESC); dsbd.dwFlags  = DSBCAPS_GLOBALFOCUS &

18、#160;     | DSBCAPS_CTRLVOLUME      | DSBCAPS_GETCURRENTPOSITION2; dsbd.dwBufferBytes = DS_BUFSIZE; dsbd.lpwfxFormat = &wvOut; if ( ds_lpDS->lpVtbl->CreateSoundBuffer(ds_lpDS,&dsbd, &ds_lpDSB, NULL) != DS_OK )   retur

19、n -1;   ds_hSemaphoreNotify = CreateSemaphore(NULL,DS_N,DS_N,NULL); if( ds_hSemaphoreNotify = NULL )  return -1;  return 0; /*audio_play() - 播放一塊,每解碼一幀被調(diào)用一次返回值: 寫入到 SoundBuffer 的字節(jié)數(shù),失敗返回0*/static int audio_play(struct audio_play *play) LPVOID lpDSBuf;

20、0;DWORD dwDSLockSize; UINT len=0; HRESULT hr;  /* 1. 調(diào)用audio_pcm()解碼一幀,得到的PCM寫入到暫存區(qū)audio_pcm */  len = audio_pcm(pcm_data+pcm_length, play->nsamples,play->samples0,     play->samples1, play->mode, play->stats); pcm_length += len;&

21、#160;if (pcm_length < DS_ONEBUF)  return 0;  /* 2. 若audio_pcm已寫滿DS_ONEBUF字節(jié),等待播放完一塊后釋放一個空閑塊 */  WaitForSingleObject(ds_hSemaphoreNotify,INFINITE);  /* 3. 將audio_pcm寫入到 SoundBuffer,使完成播放一塊 */  hr = ds_lpDSB->lpVtbl->Lock(ds_lpDSB,ds_dwWriteCursor,

22、pcm_length,&lpDSBuf,&dwDSLockSize,NULL,0,0); if(hr = DSERR_BUFFERLOST)   ds_lpDSB->lpVtbl->Restore(ds_lpDSB);  ds_lpDSB->lpVtbl->Lock(ds_lpDSB,ds_dwWriteCursor,pcm_length,&lpDSBuf,&dwDSLockSize,NULL,0,0);  if(FAILED(hr)  return 0; CopyMe

23、mory(lpDSBuf,pcm_data,dwDSLockSize); ds_lpDSB->lpVtbl->Unlock(ds_lpDSB,lpDSBuf,dwDSLockSize,NULL,0);  /* 4. 更新相關(guān)變量! */  pcm_length=0; ds_dwWriteCursor += dwDSLockSize; if( ds_dwWriteCursor >= DS_BUFSIZE)  ds_dwWriteCursor -= DS_BUFSIZE;  /*

24、5. 首次寫滿Direct SoundBuffer后,啟動定時器,開始播放 */  if(ds_iWriteTimes < DS_N)   ds_iWriteTimes+;  if(ds_iWriteTimes = DS_N)    UINT uRs = DS_ONEBUF / 4608 / 2 * 26;   ds_timerID = timeSetEvent( uRs/2, uRs, (LPTIMECALLBACK)MyPlayPositionNotify, 0,    &#

25、160;        TIME_PERIODIC | TIME_CALLBACK_FUNCTION );   ds_lpDSB->lpVtbl->SetCurrentPosition(ds_lpDSB,0);   ds_lpDSB->lpVtbl->Play(ds_lpDSB,0, 0, DSBPLAY_LOOPING);  #ifdef DBGOUTPUT  printf("nWriteTimes= %2d, WriteByte

26、s= %d",ds_iWriteTimes,dwDSLockSize);#endif   return dwDSLockSize; static int audio_init(struct audio_init *init)  SetPriorityClass(GetCurrentProcess(), HIGH_PRIORITY_CLASS);  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST);   return 0; 

27、;static int audio_config(struct audio_config *config)  unsigned int bitdepth;   bitdepth = config->precision & 7;  if (bitdepth = 0)    bitdepth = 16;  else if (bitdepth > 32)    bitdepth = 32;   audio_close();   if

28、 (audio_open(config->channels,config->speed, bitdepth) = -1)   return -1;   switch (config->precision = bitdepth)   case 8:    audio_pcm = audio_pcm_u8;    break;   case 16:    audio_pcm = audio_pcm_s16le; 

29、   break;   case 24:    audio_pcm = audio_pcm_s24le;    break;   case 32:    audio_pcm = audio_pcm_s32le;    break;     return 0; static int audio_pause(int bPause) static int paused;&#

30、160;if(ds_lpDSB = 0)  return -1; if (bPause && !paused)   ds_lpDSB->lpVtbl->Stop(ds_lpDSB);  return 0;  else if (!bPause && paused)   ds_lpDSB->lpVtbl->Play(ds_lpDSB,0, 0, DSBPLAY_LOOPING);  return 0;   paused = bPaus

31、e; return 0; static int audio_stop() if(ds_lpDSB = 0)  return -1; ds_lpDSB->lpVtbl->Stop(ds_lpDSB); return 0; /*audio_flush() - 播放完Direct Sound緩沖區(qū)ds_lpDSB中的數(shù)據(jù),DS_N-1塊*/static void audio_flush() int i; for( i=1; i<DS_N; i+ )  WaitForSingleObj

32、ect(ds_hSemaphoreNotify,INFINITE); static int audio_close() SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_NORMAL); SetPriorityClass(GetCurrentProcess(), NORMAL_PRIORITY_CLASS);  if (ds_lpDSB != 0)   ds_lpDSB->lpVtbl->Stop(ds_lpDSB);  ds_lpDSB->lpVtbl->Release(ds_lpDSB);  ds_lpDSB = 0;  if (ds_timerID != 0)   timeKillEvent(ds_timerID);  ds_t