private boolean available(int h, int curmask) {
		return (h & curmask) == curmask
			&& ((h >> 19) & 3) != 1		// version ID:  '01' - reserved
			&& ((h >> 17) & 3) != 0		// Layer index: '00' - reserved
			&& ((h >> 12) & 15) != 15	// Bitrate Index: '1111' - reserved
			&& ((h >> 12) & 15) != 0	// Bitrate Index: '0000' - free
			&& ((h >> 10) & 3) != 3;	// Sampling Rate Index: '11' - reserved
	}