Types/Wave/Cosine.ps1
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<# .SYNOPSIS Cosine Tone Generator .DESCRIPTION Generates a Cosine Tone of a `-Frequency`, for `-Duration`, at `-Volume` .NOTES A cosine tone generator generates a wave with Cosine instead of Sine. This will be the opposite of a Sine tone. It will usually sound very similar to a sine tone, but may seem like it is coming from below, not above. #> [OutputType([double[]])] param( # The frequency [Alias('Hz')] [double] $Frequency = 440, # The duration to generate. [Timespan]$Duration = $( if ($this.BPM -is [TimeSpan]) {$this.BPM} else { [TimeSpan]::FromSeconds(60/128) } ), # The volume. # If the current wave has set a `volume`, # will use that volume. # Otherwise, will default to 0.5 [double]$Volume = $( if ($this.Volume) { $this.Volume } else { 0.5 } ), # The sample rate. # Will default to the `.SampleRate` of `$this` wave. # If there is no `$this` wave, will default to 44100 [uint32]$SampleRate = $( if ($this.SampleRate) { $this.SampleRate } else { 44100 } ), # The channel count. # Will default to the `.ChannelCount` of `$this` wave. # If there is no `$this` wave, will default to 1 (mono). [uint16]$channelCount = $( if ($this.ChannelCount) { $this.ChannelCount } else { 1 } ) ) # Calculate the number of samples $numberOfSamples = [Math]::Round( $Duration.TotalSeconds * $SampleRate * $channelCount ) # We can imagine each cycle as a series of circles # how many circles? Whatever our frequency may be. $cycle = 2 * [Math]::PI * $Frequency $stepAngle = $cycle/($sampleRate * $channelCount) # Return a `[double[]]` containing the samples return ,[double[]]@(for ($i = 0; $i -lt $numberOfSamples; $i++) { # Calculate the envelope $envelope = 1.0 - ($i / $numberOfSamples) # The sample is the sine of that angle at this moment in time. $sample = [Math]::Cos($stepAngle * $i) # We will scale this by the volume, and then by the envelope. $sample * $Volume * $envelope }) |