Multisampling
Multisampling involves grouping several samples together to make a single program on a sampler. This usually occurs on the pitch axis, but can also occur on the velocity axis.
If you play a sample back more than about half an octave or so out, either sped up or slowed down, it starts to sound unnatural. For example, playing back a recording of a piano's C5 at half the original speed doesn't sound like a piano playing a C4. It sounds like something bigger than a piano. The opposite is also true, with sped up recordings sounding tiny.
This is where multisampling comes in, by taking more than a single sample of any given instrument you want to recreate. For example, when sampling a piano, you might sample each octave's C♯, E, G, and A♯ (those being equidistant), so that whichever note you play on the resulting program never needs its closest sample to be transposed (sped up or slowed down) more than a single semitone.
Given hardware samplers' minimal RAM, it's more likely you'll only be able to fit in one or two samples per octave, such as each C and F♯, or even just each C.
Similarly, on the velocity axis, several samples may be used to represent different volumes or brightness of note, from piano (quiet) through to forte (loud).
When it comes to romplers and sample CDs, this will have already been done for you. When a sample CD's inlay card proudly proclaims that its programs are multisampled, it means that instead of stretching one sample too thin across the entire range of the keyboard, each program is instead employing several samples to each stretch less far, for greater realism.
As with looping samples, multisampling an instrument takes a lot of time and effort, which is one of the main reasons sample CDs are generally best bought as CD-ROMs rather than regular audio CDs. This was a big advantage for the S1000 over its predecessors.
Sampling: A cappella | Breakbeat | DJ battle tool | Multisampling | Personal sample library | Pingpong loop | Program (sampler) | Sample CD
