7.5 Music triggered effects
Apart from setting parameters according to music characteristics in order to make the effect music-responsive, you can trigger effects such as decaying flashes to occur at specific beat points in the music.
cut-hints - Indicates suitable points for inserting a video “cut” that aligns with some significant event in the music. The strength value of a cut-hint (range 0.0 to 1.0) gives an indication of how loud the music event is. Cut hints are based on events in the music with perceptible “attack” and capture snare and base drum hits rather well.
flash-hints - These capture high spectral frequency events in the music such as hi-hats. The strength value of a flash-hint indicates how loud the high frequency event is. Flash-hints are called so because they are ideal times for inserting decaying flashes in the result muvee.
7.5.1 triggered-effect
(triggered-effect start-time-expr stop-time-expr effect-expr)
triggered-effect makes available a hint’s time and value in the symbols time and value in all the three parts of its body.
start-time-expr is an expression that derives an effect start time from time and value. For example - (- time 0.05)
stop-time-expr is an expression that derives an effect stop time from time and value. For example - (+ time 0.35)
effect-expr is any effect specification expression. You can use (effect ....) or a combined effect such as (effect-selector (looping-sequence ....)). Additionally, the body of this effect specification can refer to time and value to derive any aspect of the effect.
(effect@cut-hints hints-per-min min-sep-secs trig-effect)
(effect@flash-hints hints-per-min min-sep-secs trig-effect)
hints-per-min is the number of trigger points per minute that you want the effect to be triggered on.
min-sep-secs is the minimum time-separation between two consecutive trigger points.
trig-effect is a triggered effect created using triggered-effect.