Table of Contents

Class HostClock

Namespace
Sigil.Sound
Assembly
Sigil.Sound.dll

The host's notion of "now": how many frames it has rendered and where it is on a musical grid. Put one on Sigil.Sound.RenderContext.Clock and time no longer starts over each time a sound is compiled, which is what keeps a live-coded LFO in phase and a looping pattern on the beat when the sound under them is swapped for another.

public sealed class HostClock

Inheritance

Inherited Members

Remarks

Without a clock every sound counts time from its own first frame, which is right for rendering a file and for one-shot demos. With one, these follow the clock instead: Sigil.Sound.Sounds.Fn(System.Func{System.Double,System.Double}) and function parameters read host time, sines, saws and pulses with a constant frequency continue the phase they would have had, and Pattern.Play without an explicit tempo follows Sigil.Sound.HostClock.Bpm and Sigil.Sound.HostClock.Beats. Notes played by a voice keep their own time, starting at zero with each note.

The renderer owns the clock: it calls Sigil.Sound.HostClock.Advance(System.Int32) after rendering each block (a Sigil.Sound.SoundContext given a clock does this itself) and Sigil.Sound.HostClock.Seek(System.Int64,System.Double) when the transport jumps. Only Sigil.Sound.HostClock.Bpm may be changed from another thread. Reading the clock is real-time safe.

Constructors

HostClock(int, double) 

public HostClock(int sampleRate, double bpm = 120)

Parameters

sampleRate int

Frames per second; must equal the sample rate of every Sigil.Sound.RenderContext that uses the clock.

bpm double

Beats (quarter notes) per minute. Defaults to 120.

Properties

Beats

The musical position, in beats, of the first frame of the block being rendered.

public double Beats { get; }

Property Value

double

Bpm

The tempo in beats per minute. Takes effect from the next block; safe to set from any thread.

public double Bpm { get; set; }

Property Value

double

Running

Whether the musical position moves. A host sets it to false while its transport is paused or stopped: Sigil.Sound.HostClock.Beats then stays where it is while Sigil.Sound.HostClock.SamplePosition keeps counting, so sounds that read host time (a live-coded LFO, an oscillator's phase) are not disturbed. Pattern.Play starts no new notes while the clock is held and carries on from the same beat, without repeating or skipping one, when it runs again. Notes already sounding finish. Safe to set from any thread.

public bool Running { get; set; }

Property Value

bool

SamplePosition

The frame number of the first frame of the block being rendered.

public long SamplePosition { get; }

Property Value

long

SampleRate

Frames per second the clock counts in.

public int SampleRate { get; }

Property Value

int

Seconds

Seconds at Sigil.Sound.HostClock.SamplePosition.

public double Seconds { get; }

Property Value

double

Methods

Advance(int)

Moves the clock past a rendered block of frames, advancing the beat position at the current tempo (unless Sigil.Sound.HostClock.Running is false, which advances only the sample position).

public void Advance(int frames)

Parameters

frames int

Seek(long, double)

Jumps to another place, as a transport locate does.

public void Seek(long samplePosition, double beats)

Parameters

samplePosition long

The frame number the next block starts at.

beats double

The musical position, in beats, of that frame.