A UGen that reports the fractional sample offset of the current Synth from its requested scheduled start.

When a synth is created from a time stamped osc-bundle, it starts calculation at the next possible block (normally 64 samples). Using an OffsetOut UGen, one can delay the audio so that it matches sample accurately.

For some synthesis methods, one even needs subsample accuracy. SubsampleOffset provides the information where, within the current sample, the synth was scheduled. It can be used to offset envelopes or resample the audio output.

Examples

// print offset
SynthDef.recv("SubsampleOffset") {
  SubsampleOffset.ir.poll(0, "offset")
}

// create 2 pulse trains 1 sample apart, move one relatively to the other.
// when cursor is at the left, the impulses are adjacent, on the right, they are
// exactly 1 sample apart.

val dt = s.sampleRate.reciprocal // 1 sample delay

val x1, x2 = Synth(s)

// needed to use System.currentTimeMillis with osc.Bundle.secs
val SECONDS_FROM_1900_TO_1970 = 2208988800L

// We create two identical synths with a delay of half a sample,
// they should thus report offsets 0.5 apart (plus some floating point noise).

// execute the following three lines together!
val t0 = System.currentTimeMillis * 0.001 + SECONDS_FROM_1900_TO_1970
s ! osc.Bundle.secs(t0 + 0.2        , x1.newMsg("SubsampleOffset"))
s ! osc.Bundle.secs(t0 + 0.2 + dt/2 , x2.newMsg("SubsampleOffset"))