music.c

SDL_mixer 是一个基于 SDL 的混音器

Mix_Music *Mix_LoadMUS(const char *file)
{
	FILE *fp;
	char *ext;
	Uint8 magic[5], moremagic[9];
	Mix_Music *music;

	/* Figure out what kind of file this is */
	fp = fopen(file, "rb");
	if ( (fp == NULL) || !fread(magic, 4, 1, fp) ) {
		if ( fp != NULL ) {
			fclose(fp);
		}
		Mix_SetError("Couldn't read from '%s'", file);
		return(NULL);
	}
	if (!fread(moremagic, 8, 1, fp)) {
		Mix_SetError("Couldn't read from '%s'", file);
		return(NULL);
	}
	magic[4] = '\0';
	moremagic[8] = '\0';
	fclose(fp);

	/* Figure out the file extension, so we can determine the type */
	ext = strrchr(file, '.');
	if ( ext ) ++ext; /* skip the dot in the extension */

	/* Allocate memory for the music structure */
	music = (Mix_Music *)malloc(sizeof(Mix_Music));
	if ( music == NULL ) {
		Mix_SetError("Out of memory");
		return(NULL);
	}
	music->error = 0;

#ifdef CMD_MUSIC
	if ( music_cmd ) {
		music->type = MUS_CMD;
		music->data.cmd = MusicCMD_LoadSong(music_cmd, file);
		if ( music->data.cmd == NULL ) {
			music->error = 1;
		}
	} else
#endif
#ifdef WAV_MUSIC
	/* WAVE files have the magic four bytes "RIFF"
	   AIFF files have the magic 12 bytes "FORM" XXXX "AIFF"
	 */
	if ( (ext && MIX_string_equals(ext, "WAV")) ||
	     ((strcmp((char *)magic, "RIFF") == 0) && (strcmp((char *)(moremagic+4), "WAVE") == 0)) ||
	     (strcmp((char *)magic, "FORM") == 0) ) {
		music->type = MUS_WAV;
		music->data.wave = WAVStream_LoadSong(file, (char *)magic);
		if ( music->data.wave == NULL ) {
		  	Mix_SetError("Unable to load WAV file");
			music->error = 1;
		}
	} else
#endif
#ifdef MID_MUSIC
	/* MIDI files have the magic four bytes "MThd" */
	if ( (ext && MIX_string_equals(ext, "MID")) ||
	     (ext && MIX_string_equals(ext, "MIDI")) ||
	     strcmp((char *)magic, "MThd") == 0  ||
	     ( strcmp((char *)magic, "RIFF") == 0  &&
	  	strcmp((char *)(moremagic+4), "RMID") == 0 ) ) {
		music->type = MUS_MID;
#ifdef USE_NATIVE_MIDI
  		if ( native_midi_ok ) {
  			music->data.nativemidi = native_midi_loadsong((char *)file);
	  		if ( music->data.nativemidi == NULL ) {
		  		Mix_SetError("%s", native_midi_error());
			  	music->error = 1;
			}
	  	} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			music->data.midi = Timidity_LoadSong((char *)file);
			if ( music->data.midi == NULL ) {
				Mix_SetError("%s", Timidity_Error());
				music->error = 1;
			}
		} else {
			Mix_SetError("%s", Timidity_Error());
			music->error = 1;
		}
#endif
	} else
#endif
#ifdef OGG_MUSIC
	/* Ogg Vorbis files have the magic four bytes "OggS" */
	if ( (ext && MIX_string_equals(ext, "OGG")) ||
	     strcmp((char *)magic, "OggS") == 0 ) {
		music->type = MUS_OGG;
		music->data.ogg = OGG_new(file);
		if ( music->data.ogg == NULL ) {
			music->error = 1;
		}
	} else
#endif
#ifdef MP3_MUSIC
	if ( (ext && MIX_string_equals(ext, "MPG")) ||
	     (ext && MIX_string_equals(ext, "MP3")) ||
	     (ext && MIX_string_equals(ext, "MPEG")) ||
	     (magic[0] == 0xFF && (magic[1] & 0xF0) == 0xF0) ) {
		if ( Mix_InitMP3() == 0 ) {
			SMPEG_Info info;
			music->type = MUS_MP3;
			music->data.mp3 = smpeg.SMPEG_new(file, &info, 0);
			if ( !info.has_audio ) {
				Mix_SetError("MPEG file does not have any audio stream.");
				music->error = 1;
			} else {
				smpeg.SMPEG_actualSpec(music->data.mp3, &used_mixer);
			}
		} else {
			music->error = 1;
		}
	} else
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	if ( 1 ) {
		music->type = MUS_MOD;
		music->data.module = MikMod_LoadSong((char *)file, 64);
		if ( music->data.module == NULL ) {
			Mix_SetError("%s", MikMod_strerror(MikMod_errno));
			music->error = 1;
		} else {
			/* Stop implicit looping, fade out and other flags. */
			music->data.module->extspd  = 1;
			music->data.module->panflag = 1;
			music->data.module->wrap    = 0;
			music->data.module->loop    = 1;
#if 0 /* Don't set fade out by default - unfortunately there's no real way
         to query the status of the song or set trigger actions.  Hum. */
			music->data.module->fadeout = 1;
#endif
		}
	} else
#endif
	{
		Mix_SetError("Unrecognized music format");
		music->error = 1;
	}
	if ( music->error ) {
		free(music);
		music = NULL;
	}
	return(music);
}

/* Free a music chunk previously loaded */
void Mix_FreeMusic(Mix_Music *music)
{
	if ( music ) {
		/* Stop the music if it's currently playing */
		SDL_LockAudio();
		if ( music == music_playing ) {
			/* Wait for any fade out to finish */
			while ( music->fading == MIX_FADING_OUT ) {
				SDL_UnlockAudio();
				SDL_Delay(100);
				SDL_LockAudio();
			}
			if ( music == music_playing ) {
				music_internal_halt();
			}
		}
		SDL_UnlockAudio();
		switch (music->type) {
#ifdef CMD_MUSIC
			case MUS_CMD:
				MusicCMD_FreeSong(music->data.cmd);
				break;
#endif
#ifdef WAV_MUSIC
			case MUS_WAV:
				WAVStream_FreeSong(music->data.wave);
				break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
			case MUS_MOD:
				MikMod_FreeSong(music->data.module);
				break;
#endif
#ifdef MID_MUSIC
			case MUS_MID:
#ifdef USE_NATIVE_MIDI
  				if ( native_midi_ok ) {
					native_midi_freesong(music->data.nativemidi);
				} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
				if ( timidity_ok ) {
					Timidity_FreeSong(music->data.midi);
				}
#endif
				break;
#endif
#ifdef OGG_MUSIC
			case MUS_OGG:
				OGG_delete(music->data.ogg);
				break;
#endif
#ifdef MP3_MUSIC
			case MUS_MP3:
				smpeg.SMPEG_delete(music->data.mp3);
				Mix_QuitMP3();
				break;
#endif
			default:
				/* Unknown music type?? */
				break;
		}
		free(music);
	}
}

/* Find out the music format of a mixer music, or the currently playing
   music, if 'music' is NULL.
*/
Mix_MusicType Mix_GetMusicType(const Mix_Music *music)
{
	Mix_MusicType type = MUS_NONE;

	if ( music ) {
		type = music->type;
	} else {
		SDL_LockAudio();
		if ( music_playing ) {
			type = music_playing->type;
		}
		SDL_UnlockAudio();
	}
	return(type);
}

/* Play a music chunk.  Returns 0, or -1 if there was an error.
 */
static int music_internal_play(Mix_Music *music, double position)
{
	int retval = 0;

	/* Note the music we're playing */
	if ( music_playing ) {
		music_internal_halt();
	}
	music_playing = music;

	/* Set the initial volume */
	if ( music->type != MUS_MOD ) {
		music_internal_initialize_volume();
	}

	/* Set up for playback */
	switch (music->type) {
#ifdef CMD_MUSIC
	    case MUS_CMD:
		MusicCMD_Start(music->data.cmd);
		break;
#endif
#ifdef WAV_MUSIC
	    case MUS_WAV:
		WAVStream_Start(music->data.wave);
		break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	    case MUS_MOD:
		Player_Start(music->data.module);
		/* Player_SetVolume() does nothing before Player_Start() */
		music_internal_initialize_volume();
		break;
#endif
#ifdef MID_MUSIC
	    case MUS_MID:
#ifdef USE_NATIVE_MIDI
		if ( native_midi_ok ) {
			native_midi_start(music->data.nativemidi);
		} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			Timidity_Start(music->data.midi);
		}
#endif
		break;
#endif
#ifdef OGG_MUSIC
	    case MUS_OGG:
		OGG_play(music->data.ogg);
		break;
#endif
#ifdef MP3_MUSIC
	    case MUS_MP3:
		smpeg.SMPEG_enableaudio(music->data.mp3,1);
		smpeg.SMPEG_enablevideo(music->data.mp3,0);
		smpeg.SMPEG_play(music_playing->data.mp3);
		break;
#endif
	    default:
		Mix_SetError("Can't play unknown music type");
		retval = -1;
		break;
	}

	/* Set the playback position, note any errors if an offset is used */
	if ( retval == 0 ) {
		if ( position > 0.0 ) {
			if ( music_internal_position(position) < 0 ) {
				Mix_SetError("Position not implemented for music type");
				retval = -1;
			}
		} else {
			music_internal_position(0.0);
		}
	}

	/* If the setup failed, we're not playing any music anymore */
	if ( retval < 0 ) {
		music_playing = NULL;
	}
	return(retval);
}
int Mix_FadeInMusicPos(Mix_Music *music, int loops, int ms, double position)
{
	int retval;

	/* Don't play null pointers :-) */
	if ( music == NULL ) {
		Mix_SetError("music parameter was NULL");
		return(-1);
	}

	/* Setup the data */
	if ( ms ) {
		music->fading = MIX_FADING_IN;
	} else {
		music->fading = MIX_NO_FADING;
	}
	music->fade_step = 0;
	music->fade_steps = ms/ms_per_step;

	/* Play the puppy */
	SDL_LockAudio();
	/* If the current music is fading out, wait for the fade to complete */
	while ( music_playing && (music_playing->fading == MIX_FADING_OUT) ) {
		SDL_UnlockAudio();
		SDL_Delay(100);
		SDL_LockAudio();
	}
	music_active = 1;
	music_loops = loops;
	retval = music_internal_play(music, position);
	SDL_UnlockAudio();

	return(retval);
}
int Mix_FadeInMusic(Mix_Music *music, int loops, int ms)
{
	return Mix_FadeInMusicPos(music, loops, ms, 0.0);
}
int Mix_PlayMusic(Mix_Music *music, int loops)
{
	return Mix_FadeInMusicPos(music, loops, 0, 0.0);
}

/* Set the playing music position */
int music_internal_position(double position)
{
	int retval = 0;

	switch (music_playing->type) {
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	    case MUS_MOD:
		Player_SetPosition((UWORD)position);
		break;
#endif
#ifdef OGG_MUSIC
	    case MUS_OGG:
		OGG_jump_to_time(music_playing->data.ogg, position);
		break;
#endif
#ifdef MP3_MUSIC
	    case MUS_MP3:
		if ( position > 0.0 ) {
			smpeg.SMPEG_skip(music_playing->data.mp3, (float)position);
		} else {
			smpeg.SMPEG_rewind(music_playing->data.mp3);
			smpeg.SMPEG_play(music_playing->data.mp3);
		}
		break;
#endif
	    default:
		/* TODO: Implement this for other music backends */
		retval = -1;
		break;
	}
	return(retval);
}
int Mix_SetMusicPosition(double position)
{
	int retval;

	SDL_LockAudio();
	if ( music_playing ) {
		retval = music_internal_position(position);
		if ( retval < 0 ) {
			Mix_SetError("Position not implemented for music type");
		}
	} else {
		Mix_SetError("Music isn't playing");
		retval = -1;
	}
	SDL_UnlockAudio();

	return(retval);
}

/* Set the music's initial volume */
static void music_internal_initialize_volume(void)
{
	if ( music_playing->fading == MIX_FADING_IN ) {
		music_internal_volume(0);
	} else {
		music_internal_volume(music_volume);
	}
}

/* Set the music volume */
static void music_internal_volume(int volume)
{
	switch (music_playing->type) {
#ifdef CMD_MUSIC
	    case MUS_CMD:
		MusicCMD_SetVolume(volume);
		break;
#endif
#ifdef WAV_MUSIC
	    case MUS_WAV:
		WAVStream_SetVolume(volume);
		break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	    case MUS_MOD:
		Player_SetVolume((SWORD)volume);
		break;
#endif
#ifdef MID_MUSIC
	    case MUS_MID:
#ifdef USE_NATIVE_MIDI
		if ( native_midi_ok ) {
			native_midi_setvolume(volume);
		} MIDI_ELSE
#endif
#ifdef USE_TIMIDITY_MIDI
		if ( timidity_ok ) {
			Timidity_SetVolume(volume);
		}
#endif
		break;
#endif
#ifdef OGG_MUSIC
	    case MUS_OGG:
		OGG_setvolume(music_playing->data.ogg, volume);
		break;
#endif
#ifdef MP3_MUSIC
	    case MUS_MP3:
		smpeg.SMPEG_setvolume(music_playing->data.mp3,(int)(((float)volume/(float)MIX_MAX_VOLUME)*100.0));
		break;
#endif
	    default:
		/* Unknown music type?? */
		break;
	}
}
int Mix_VolumeMusic(int volume)
{
	int prev_volume;

	prev_volume = music_volume;
	if ( volume < 0 ) {
		return prev_volume;
	}
	if ( volume > SDL_MIX_MAXVOLUME ) {
		volume = SDL_MIX_MAXVOLUME;