Utilities

rescale(maxamp :: Real, samples :: AbstractArray) :: Vector{Float32}

Rescales the samples so that the maximum extent fits within the given maxamp (which must be positive). The renderer automatically rescales to avoid clamping.

dBscale(::Real)
dBscale(::Signal)

Converts a dB value to a scaling factor

interp4(x, x1, x2, x3, x4)

Four point interpolation.

• x is expected to be in the range [0,1].

This is a cubic function of x such that -

• f(-1) = x1
• f(0) = x2
• f(1) = x3
• f(2) = x4

raisedcos(x, overlap, scale=1.0f0)

A "raised cosine" curve has a rising part that is shaped like cos(x-π/2)+1 and a symmetrically shaped falling part. If the overlap is 0.5, then there is no intervening portion between the rising and falling parts (x is in the range [0,1]). For overlap values less than 0.5, the portion between the rising and falling parts will be clamped to 1.0.

For example, raisedcos(x, 0.25) will give you a curve that will smoothly rise from 0.0 at x=0.0 to 1.0 at x=0.25, stay fixed at 1.0 until x = 0.75 and smoothly decrease to 0.0 at x=1.0.

midi2hz(midi::Real)
midi2hz(::Signal)

Converts a MIDI note number into a frequency using the equal tempered tuning.

hz2midi(hz::Real)
hz2midi(::Signal)

Converts a frequency in Hz to its MIDI note number in the equal tempered tuning.

easeinout(t::Float64)

For values of t in range [0.0,1.0], this curve rises smoothly from 0.0 and settles smoothly into 1.0. We're not usually interested in its values outside the [0.0,1.0] range.

curve(segments :: Vector{Seg}; stop=false)
curve(ty::Type, v::AbstractVector{<:Tuple{Real,Real}}; stop = false)
curve(v::AbstractVector{<:Tuple{Real,Real}}; stop = false)

Makes a piece-wise curve given a vector of segment specifications. Each Seg captures the start value, end value, duration of the segment, and the interpolation method to use in between.

If you pass true for stop, it means the curve will be done once all the segments are done. Otherwise the curve will yield the last value forever.

The "tuple" variants take a vector of (t,v) pairs and construct a curve out of it using a common interpolation mechanism. The Vector{Seg} is the most general since it can accommodate a combination of linear, exponential, etc., but these are convenient for use when a common interpolation type is required.

Curves support map and basic arithmetic combinations with real numbers. See also stretch and concat

abstract type Seg end

Abstract type represents a "segment" of a curve.

circular(v::AbstractArray{T}) :: Circular{T,AbstractArray{T}}

Makes a circular array that handles the modulo calculations.