* @param *spec A @c FSSpec structure referencing a file.

 */

static void SetMIDITypeIfNeeded(const FSSpec *spec)

{

	FInfo info;

	assert(spec);

	if (noErr != FSpGetFInfo(spec, &info)) return;

	/* Set file type to 'Midi' if the file is _not_ an alias. */

	if (info.fdType != midiType && !(info.fdFlags & kIsAlias)) {

		info.fdType = midiType;

		FSpSetFInfo(spec, &info);

		DEBUG(driver, 3, "qtmidi: changed filetype to 'Midi'");

	}

}

/**

 * Loads a MIDI file and returns it as a QuickTime Movie structure.

 *

 * @param *path String with the path of an existing MIDI file.

 * @param *moov Pointer to a @c Movie where the result will be stored.

 * @return Wether the file was loaded and the @c Movie successfully created.

 */

static bool LoadMovieForMIDIFile(const char *path, Movie *moov)

{

	int fd;

	int ret;

	char magic[4];

	FSSpec fsspec;

	short refnum = 0;

	short resid  = 0;

	assert(path != NULL);

	assert(moov != NULL);

	DEBUG(driver, 2, "qtmidi: start loading '%s'...", path);

	/*

	 * XXX Manual check for MIDI header ('MThd'), as I don't know how to make

	 * QuickTime load MIDI files without a .mid suffix without knowing it's

	 * a MIDI file and setting the OSType of the file to the 'Midi' value.

	 * Perhahaps ugly, but it seems that it does the Right Thing(tm).

	 */

	fd = open(path, O_RDONLY, 0);

	if (fd == -1) return false;

	ret = read(fd, magic, 4);

	close(fd);

	if (ret < 4) return false;

	DEBUG(driver, 3, "qtmidi: header is '%.4s'", magic);

	if (magic[0] != 'M' || magic[1] != 'T' || magic[2] != 'h' || magic[3] != 'd')

		return false;

	if (!PathToFSSpec(path, &fsspec)) return false;

	SetMIDITypeIfNeeded(&fsspec);

	if (OpenMovieFile(&fsspec, &refnum, fsRdPerm) != noErr) return false;

	DEBUG(driver, 3, "qtmidi: '%s' successfully opened", path);

	if (noErr != NewMovieFromFile(moov, refnum, &resid, NULL,

				newMovieActive | newMovieDontAskUnresolvedDataRefs, NULL)) {

		CloseMovieFile(refnum);

		return false;

	}

	DEBUG(driver, 3, "qtmidi: movie container created");

	CloseMovieFile(refnum);

	return true;

}

/**

 * Flag which has the @c true value when QuickTime is available and

 * initialized.

 */

static bool _quicktime_started = false;

/**

 * Initialize QuickTime if needed. This function sets the

 * #_quicktime_started flag to @c true if QuickTime is present in the system

 * and it was initialized properly.

 */

static void InitQuickTimeIfNeeded(void)

{

	OSStatus dummy;

	if (_quicktime_started) return;

	DEBUG(driver, 2, "qtmidi: initializing Quicktime");

	/* Be polite: check wether QuickTime is available and initialize it. */

	_quicktime_started =

		(noErr == Gestalt(gestaltQuickTime, &dummy)) &&

		(noErr == EnterMovies());

}

/** Possible states of the QuickTime music driver. */

enum {

	QT_STATE_IDLE, /**< No file loaded. */

	QT_STATE_PLAY, /**< File loaded, playing. */

	QT_STATE_STOP, /**< File loaded, stopped. */

};

static Movie _quicktime_movie;                  /**< Current QuickTime @c Movie. */

static byte  _quicktime_volume = 127;           /**< Current volume. */

static int   _quicktime_state  = QT_STATE_IDLE; /**< Current player state. */

/**

 * Maps OpenTTD volume to QuickTime notion of volume.

 */

#define VOLUME  ((short)((0x00FF & _quicktime_volume) << 1))

static void StopSong(void);

/**

 * Initialized the MIDI player, including QuickTime initialization.

 *

 * @todo Give better error messages by inspecting error codes returned by

 * @c Gestalt() and @c EnterMovies(). Needs changes in

 * #InitQuickTimeIfNeeded.

 */

static const char* StartDriver(const char * const *parm)

{

	InitQuickTimeIfNeeded();

	return (_quicktime_started) ? NULL : "can't initialize QuickTime";

}

/**

 * Checks wether the player is active.

 *

 * This function is called at regular intervals from OpenTTD's main loop, so

 * we call @c MoviesTask() from here to let QuickTime do its work.

 */

static bool SongIsPlaying(void)

{

	if (!_quicktime_started) return true;

	switch (_quicktime_state) {

		case QT_STATE_IDLE:

		case QT_STATE_STOP:

			/* Do nothing. */

			break;

		case QT_STATE_PLAY:

			MoviesTask(_quicktime_movie, 0);

			/* Check wether movie ended. */

			if (IsMovieDone(_quicktime_movie) ||

					(GetMovieTime(_quicktime_movie, NULL) >=

					 GetMovieDuration(_quicktime_movie)))

				_quicktime_state = QT_STATE_STOP;

	}

	return _quicktime_state == QT_STATE_PLAY;

}

/**

 * Stops the MIDI player.

 *

 * Stops playing and frees any used resources before returning. As it

 * deinitilizes QuickTime, the #_quicktime_started flag is set to @c false.

 */

static void StopDriver(void)

{

	if (!_quicktime_started) return;

	DEBUG(driver, 2, "qtmidi: stopping driver...");

	switch (_quicktime_state) {

		case QT_STATE_IDLE:

			DEBUG(driver, 3, "qtmidi: stopping not needed, already idle");

			/* Do nothing. */

			break;

		case QT_STATE_PLAY:

			StopSong();

		case QT_STATE_STOP:

			DisposeMovie(_quicktime_movie);

	}

	ExitMovies();

	_quicktime_started = false;

}

/**

 * Starts playing a new song.