sdl_dx5audio.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    [e-mail]
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id: SDL_dx5audio.c,v 1.6 2002/04/22 21:38:02 wmay Exp $";
#endif

/* Allow access to a raw mixing buffer */

#include <stdio.h>

#include "SDL_types.h"
#include "SDL_error.h"
#include "SDL_timer.h"
#include "SDL_audio.h"
#include "SDL_audio_c.h"
#include "SDL_dx5audio.h"

/* Define this if you want to use DirectX 6 DirectSoundNotify interface */
//#define USE_POSITION_NOTIFY

/* DirectX function pointers for audio */
HRESULT (WINAPI *DSoundCreate)(LPGUID, LPDIRECTSOUND *, LPUNKNOWN);

/* Audio driver functions */
static int DX5_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void DX5_ThreadInit(_THIS);
static void DX5_WaitAudio_BusyWait(_THIS);
#ifdef USE_POSITION_NOTIFY
static void DX6_WaitAudio_EventWait(_THIS);
#endif
static void DX5_PlayAudio(_THIS);
static Uint8 *DX5_GetAudioBuf(_THIS);
static void DX5_WaitDone(_THIS);
static void DX5_CloseAudio(_THIS);
static int DX5_AudioDelayMsec(_THIS);

/* Audio driver bootstrap functions */

static int Audio_Available(void)
{
	HINSTANCE DSoundDLL;
	int dsound_ok;

	/* Version check DSOUND.DLL (Is DirectX okay?) */
	dsound_ok = 0;
	DSoundDLL = LoadLibrary("DSOUND.DLL");
	if ( DSoundDLL != NULL ) {
		/* We just use basic DirectSound, we're okay */
		/* Yay! */
		/* Unfortunately, the sound drivers on NT have
		   higher latencies than the audio buffers used
		   by many SDL applications, so there are gaps
		   in the audio - it sounds terrible.  Punt for now.
		 */
		OSVERSIONINFO ver;
		ver.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
		GetVersionEx(&ver);
		switch (ver.dwPlatformId) {
			case VER_PLATFORM_WIN32_NT:
				if ( ver.dwMajorVersion > 4 ) {
					/* Win2K */
					dsound_ok = 1;
				} else {
					/* WinNT */
					dsound_ok = 0;
				}
				break;
			default:
				/* Win95 or Win98 */
				dsound_ok = 1;
				break;
		}
		/* Now check for DirectX 5 or better - otherwise
		 * we will fail later in DX5_OpenAudio without a chance
		 * to fall back to the DIB driver. */
		if (dsound_ok) {
			/* DirectSoundCaptureCreate was added in DX5 */
			if (!GetProcAddress(DSoundDLL, "DirectSoundCaptureCreate"))
				dsound_ok = 0;

		}
		/* Clean up.. */
		FreeLibrary(DSoundDLL);
	}
	return(dsound_ok);
}

/* Functions for loading the DirectX functions dynamically */
static HINSTANCE DSoundDLL = NULL;

static void DX5_Unload(void)
{
	if ( DSoundDLL != NULL ) {
		FreeLibrary(DSoundDLL);
		DSoundCreate = NULL;
		DSoundDLL = NULL;
	}
}
static int DX5_Load(void)
{
	int status;

	DX5_Unload();
	DSoundDLL = LoadLibrary("DSOUND.DLL");
	if ( DSoundDLL != NULL ) {
		DSoundCreate = (void *)GetProcAddress(DSoundDLL,
					"DirectSoundCreate");
	}
	if ( DSoundDLL && DSoundCreate ) {
		status = 0;
	} else {
		DX5_Unload();
		status = -1;
	}
	return status;
}

static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
	DX5_Unload();
	free(device->hidden);
	free(device);
}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
	SDL_AudioDevice *this;

	/* Load DirectX */
	if ( DX5_Load() < 0 ) {
		return(NULL);
	}

	/* Initialize all variables that we clean on shutdown */
	this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
	if ( this ) {
		memset(this, 0, (sizeof *this));
		this->hidden = (struct SDL_PrivateAudioData *)
				malloc((sizeof *this->hidden));
	}
	if ( (this == NULL) || (this->hidden == NULL) ) {
		SDL_OutOfMemory();
		if ( this ) {
			free(this);
		}
		return(0);
	}
	memset(this->hidden, 0, (sizeof *this->hidden));

	/* Set the function pointers */
	this->OpenAudio = DX5_OpenAudio;
	this->ThreadInit = DX5_ThreadInit;
	this->WaitAudio = DX5_WaitAudio_BusyWait;
	this->PlayAudio = DX5_PlayAudio;
	this->GetAudioBuf = DX5_GetAudioBuf;
	this->WaitDone = DX5_WaitDone;
	this->CloseAudio = DX5_CloseAudio;
	this->AudioDelayMsec = DX5_AudioDelayMsec;

	this->free = Audio_DeleteDevice;

	return this;
}

AudioBootStrap DSOUND_bootstrap = {
	"dsound", "Win95/98/2000 DirectSound",
	Audio_Available, Audio_CreateDevice
};

static void SetDSerror(const char *function, int code)
{
	static const char *error;
	static char  errbuf[BUFSIZ];

	errbuf[0] = 0;
	switch (code) {
		case E_NOINTERFACE:
			error = 
		"Unsupported interface\n-- Is DirectX 5.0 or later installed?";
			break;
		case DSERR_ALLOCATED:
			error = "Audio device in use";
			break;
		case DSERR_BADFORMAT:
			error = "Unsupported audio format";
			break;
		case DSERR_BUFFERLOST:
			error = "Mixing buffer was lost";
			break;
		case DSERR_CONTROLUNAVAIL:
			error = "Control requested is not available";
			break;
		case DSERR_INVALIDCALL:
			error = "Invalid call for the current state";
			break;
		case DSERR_INVALIDPARAM:
			error = "Invalid parameter";
			break;
		case DSERR_NODRIVER:
			error = "No audio device found";
			break;
		case DSERR_OUTOFMEMORY:
			error = "Out of memory";
			break;
		case DSERR_PRIOLEVELNEEDED:
			error = "Caller doesn't have priority";
			break;
		case DSERR_UNSUPPORTED:
			error = "Function not supported";
			break;
		default:
			sprintf(errbuf, "%s: Unknown DirectSound error: 0x%x",
								function, code);
			break;
	}
	if ( ! errbuf[0] ) {
		sprintf(errbuf, "%s: %s", function, error);
	}
	SDL_SetError("%s", errbuf);
	return;
}

/* DirectSound needs to be associated with a window */
static HWND mainwin = NULL;
/* */
void DX5_SoundFocus(HWND hwnd)
{
	mainwin = hwnd;
}

static void DX5_ThreadInit(_THIS)
{
	SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST);
}

static void DX5_WaitAudio_BusyWait(_THIS)
{
	DWORD status;
	DWORD cursor, junk;
	HRESULT result;

	/* Semi-busy wait, since we have no way of getting play notification
	   on a primary mixing buffer located in hardware (DirectX 5.0)
	*/
	result = IDirectSoundBuffer_GetCurrentPosition(mixbuf, &cursor, &junk);
	if ( result != DS_OK ) {
		if ( result == DSERR_BUFFERLOST ) {
			IDirectSoundBuffer_Restore(mixbuf);
		}
#ifdef DEBUG_SOUND
		SetDSerror("DirectSound GetCurrentPosition", result);
#endif
		return;
	}
	cursor /= mixlen;

	while ( cursor == playing ) {
		/* FIXME: find out how much time is left and sleep that long */
		SDL_Delay(10);

		/* Try to restore a lost sound buffer */
		IDirectSoundBuffer_GetStatus(mixbuf, &status);
		if ( (status&DSBSTATUS_BUFFERLOST) ) {
			IDirectSoundBuffer_Restore(mixbuf);
			IDirectSoundBuffer_GetStatus(mixbuf, &status);
			if ( (status&DSBSTATUS_BUFFERLOST) ) {
				break;
			}
		}
		if ( ! (status&DSBSTATUS_PLAYING) ) {
			result = IDirectSoundBuffer_Play(mixbuf, 0, 0, DSBPLAY_LOOPING);
			if ( result == DS_OK ) {
				continue;
			}
#ifdef DEBUG_SOUND
			SetDSerror("DirectSound Play", result);
#endif
			return;
		}

		/* Find out where we are playing */
		result = IDirectSoundBuffer_GetCurrentPosition(mixbuf,
								&cursor, &junk);
		if ( result != DS_OK ) {
			SetDSerror("DirectSound GetCurrentPosition", result);
			return;
		}
		cursor /= mixlen;
	}
}

#ifdef USE_POSITION_NOTIFY
static void DX6_WaitAudio_EventWait(_THIS)
{
	DWORD status;
	HRESULT result;

	/* Try to restore a lost sound buffer */
	IDirectSoundBuffer_GetStatus(mixbuf, &status);
	if ( (status&DSBSTATUS_BUFFERLOST) ) {
		IDirectSoundBuffer_Restore(mixbuf);
		IDirectSoundBuffer_GetStatus(mixbuf, &status);
		if ( (status&DSBSTATUS_BUFFERLOST) ) {
			return;
		}
	}
	if ( ! (status&DSBSTATUS_PLAYING) ) {
		result = IDirectSoundBuffer_Play(mixbuf, 0, 0, DSBPLAY_LOOPING);
		if ( result != DS_OK ) {
#ifdef DEBUG_SOUND
			SetDSerror("DirectSound Play", result);
#endif
			return;
		}
	}
	WaitForSingleObject(audio_event, INFINITE);
}
#endif /* USE_POSITION_NOTIFY */

static void DX5_PlayAudio(_THIS)
{
	/* Unlock the buffer, allowing it to play */
	if ( locked_buf ) {
		IDirectSoundBuffer_Unlock(mixbuf, locked_buf, mixlen, NULL, 0);
	}

}

static Uint8 *DX5_GetAudioBuf(_THIS)
{
	DWORD   cursor, junk;
	HRESULT result;
	DWORD   rawlen;

	/* Figure out which blocks to fill next */
	locked_buf = NULL;
	result = IDirectSoundBuffer_GetCurrentPosition(mixbuf, &cursor, &junk);
	if ( result == DSERR_BUFFERLOST ) {
		IDirectSoundBuffer_Restore(mixbuf);
		result = IDirectSoundBuffer_GetCurrentPosition(mixbuf,
								&cursor, &junk);
	}
	if ( result != DS_OK ) {