smpl chunk

The smpl chunk lets a sampler play a WAV file as an instrument. It gives the note the recording was made at, a fine tuning, and any number of loops, so a short sample can sustain for as long as a key is held.

Fields

Offset	Size	Type	Name	Description
0	4	u32	`dwManufacturer`	MIDI manufacturer ID of the intended sampler, or 0
4	4	u32	`dwProduct`	the manufacturer’s product code, or 0
8	4	u32	`dwSamplePeriod`	the length of one sample in nanoseconds: 22,675 for 44,100 Hz
12	4	u32	`dwMIDIUnityNote`	the MIDI note that plays the sample unchanged: 60 is middle C
16	4	u32	`dwMIDIPitchFraction`	a fraction of a semitone above the unity note: `0x80000000` is 50 cents
20	4	u32	`dwSMPTEFormat`	0, or a SMPTE frame rate: 24, 25, 29 (30 drop frame) or 30
24	4	u32	`dwSMPTEOffset`	a SMPTE time at which the sample starts
28	4	u32	`cSampleLoops`	the number of loop records
32	4	u32	`cbSamplerData`	the size of extra sampler data after the loops
36	24 each	record	`loops`	the loops, laid out below

Offsets are from the start of the chunk’s data.

Loop

Offset	Size	Type	Name	Description
0	4	u32	`dwIdentifier`	an ID, which can match a cue point
4	4	u32	`dwType`	0 forward, 1 alternating (forward then backward), 2 backward
8	4	u32	`dwStart`	the first sample frame of the loop
12	4	u32	`dwEnd`	the last sample frame of the loop, which is played
16	4	u32	`dwFraction`	a fraction of a sample for finer loop points
20	4	u32	`dwPlayCount`	how many times to play the loop: 0 means forever