delta (256hz ticks)

[p] data:
	if bit7 is set, then this data is 7 bits longer with another length bit
	(upto 28 bits)

delta:
	[p] in 256hz ticks

commands:
***command byte is 6bit + 2bit upper param data (&40h=p1,&80h=p2)
	00h:end of track

	(channel commands)
	01h:channel select (0-31) (this may be re-mapped per track)
	02h:source - direct pcm8
	03h:source - direct pcm16
	04h:source - direct adpcm
		p1 = looped sound
		[32] source address
		[16] source loop point (words)
		[16] source length (words)
	06h:source - psg
	07h:source - from table
		[16] source table index
	08h:period
		[16] 16-bit period
	09h:envelope
		p1=enable
			[8] attack	(0->1 = x/y seconds)
			[8] decay		(1->0 = x/y seconds)
			[8] sustain level	(0=disabled)
			[8] sustain decay rate (1->0 = x/y seconds)
			[8] release rate	(1->0 = x/y seconds)
		p1=0
			(fixed max volume)
	0Ah:volume
		[16] 11-bit volume
	0Bh:panning
		[8] 7-bit panning
	0Ch:cue
		[8] cue data
	0Dh:keyon
	0Eh:keyoff

	(global commands)
	10h:key-on
		[32] keyon bits (1/channel)
	11h:key-off
		[32] keyoff bits (1/channel)
	
	12h:end of block

channels:
0-7: first 8 hardware channels
8-15: psg-capable hardware channels
16-31: software channels

special use:
1,3 used for reverb (left,right)
4,5 used for audio stream
6,7 used for software mixer

*****************************************************************
stream format:

[1 byte] : [delta]
 bits 0-7: 8-bit delta value (in 256hz 
[1 byte] : [selection] [channel]
 bits 0-4: channel selection
 bit5: