extTempoClock.sc

// redFrik 050621
// beatmatching, interpolation, clock synchronisation
// this will adjust tempo to assure downbeat after x seconds

+TempoClock {
        
        sync {|tempo, secs= 4, resolution= 1|
                var next, time, durCur, durNew, durDif, durAvg, stepsPerBeat,
                        delta, factor, steps, sum, durs, index= 0;
                secs= secs.max(0.03);                                   //saftey and lower jitter limit
                next= this.timeToNextBeat(1);
                time= secs-(this.tempo.reciprocal*next);
                if(time<next, {                                         //jump directly
                        this.tempo_(next/secs);         //set a high tempo
                        this.sched(next, {
                                this.tempo_(tempo);
                                nil;
                        });
                }, {                                                    //else interpolate
                        this.sched(next, {                              //offset the thing to next beat
                                durCur= this.tempo.reciprocal;
                                durNew= tempo.reciprocal;
                                durDif= durNew-durCur;
                                durAvg= durCur+durNew/2;                //average duration for number of steps
                                stepsPerBeat= resolution.max(0.001).reciprocal.round;
                                steps= (time/durAvg).round*stepsPerBeat;
                                delta= stepsPerBeat.reciprocal;         //quantized resolution
                                durs= Array.series(steps, durCur, durDif/steps);
                                sum= durs.sum/stepsPerBeat;
                                factor= time/sum;
                                this.sched(0, {
                                        var tmp;
                                        if(index<steps, {
                                                tmp= (durs[index]*factor).reciprocal;
                                                this.tempo_(tmp);
                                                index= index+1;
                                                delta;
                                        }, {
                                                this.tempo_(tempo);
                                                nil;
                                        });
                                });
                                nil;
                        });
                });
        }

}