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Timeline mixing

Arrange sounds on a beat grid, on tracks, with pumping and ducking.

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Arrange sounds on a beat grid, on tracks, with pumping and ducking.

audioTimeline

Create a multi track timeline for mixing sounds

audioTimeline( bpm=120, beatsPerBar=4, sampleRate=44100, channels=2 )

Argument	Type	Default
`bpm`	double	`120`	The tempo in beats per minute. Defaults to 120.
`beatsPerBar`	integer	`4`	Beats in one bar. Defaults to 4.
`sampleRate`	integer	`44100`	The sample rate of the mix in Hz. Defaults to 44100.
`channels`	integer	`2`	1 for mono or 2 for stereo. Defaults to 2.

Returns The timeline. Use timeline.beat( n ) and timeline.bar( n ) to turn beats and bars into seconds.

Place a sound on a timeline track

audioAdd( timeline, sound, at=0, track="main", db=0, pan=0 )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`sound`	any	required	The audio buffer to place. A different sample rate is converted automatically, mono is panned in a stereo timeline.
`at`	double	`0`	Where the sound starts, in seconds. Use timeline.beat( n ) or timeline.bar( n ) to place it on the grid. Defaults to 0.
`track`	string	`"main"`	The track name, created on first use. Defaults to main.
`db`	double	`0`	Gain in decibels. Defaults to 0.
`pan`	double	`0`	From -1 (left) to 1 (right). Defaults to 0.

Returns The same timeline, so calls can be chained.

List moments on the beat grid of a timeline, in seconds

audioBeats( timeline, start=0, end, step=1 )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`start`	double	`0`	The first beat. Defaults to 0.
`end`	double	required	Where to stop, in beats. The end itself is not included.
`step`	double	`1`	Beats between moments, for example 0.5 for eighth notes in 4/4. Defaults to 1.

Returns An array of times in seconds, ready for audioAdd( at= ) or audioPump( times= ).

Set the volume of a whole timeline track

audioTrackGain( timeline, track, db )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`track`	string	required	The track name, created if it does not exist yet.
`db`	double	required	The track gain in decibels, applied when the timeline is rendered.

Returns The same timeline, so calls can be chained.

Duck a timeline track at given moments, like a kick drum sidechain

audioPump( timeline, track, times, amountDb=-5, recovery=0.18 )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`track`	string	required	The track to duck.
`times`	array	required	An array of start times in seconds, for example from audioBeats().
`amountDb`	double	`-5`	How far the gain drops at each time, a negative number of decibels. Defaults to -5.
`recovery`	double	`0.18`	Seconds the gain takes to return to normal. Defaults to 0.18.

Returns The same timeline, so calls can be chained.

Duck a timeline track while another track is loud, like music under a voice-over

audioDuck( timeline, track, trigger, amountDb=-12, thresholdDb=-40, attack=0.01, release=0.3 )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`track`	string	required	The track to lower, for example the music.
`trigger`	string	required	The track whose level controls the ducking, for example the voice. It must already have sound on it.
`amountDb`	double	`-12`	How far to lower the track, a negative number of decibels. Defaults to -12.
`thresholdDb`	double	`-40`	The trigger level above which ducking starts, relative to full scale. Defaults to -40.
`attack`	double	`0.01`	Seconds taken to lower the track. Defaults to 0.01.
`release`	double	`0.3`	Seconds taken to bring the track back. Defaults to 0.3.

Returns The same timeline, so calls can be chained.

Mix a timeline down to one audio buffer

audioRender( timeline, tail=0 )

Argument	Type	Default
`timeline`	any	required	The timeline from audioTimeline().
`tail`	double	`0`	Seconds of silence to leave after the last sound, for example for a fade out. Defaults to 0.

Returns The mixed audio buffer. The timeline is left as it was, so it can be changed and rendered again.