| |
| export class PlaybackClock { |
| constructor(context){this.context=context;this.segments=[];this.inputLatency=null;this.acousticLatency=0;this.delay=0;this.method='unavailable';this.missing=[];} |
| observe(now=performance.now()){ |
| const c=this.context,t=c.getOutputTimestamp?.(); |
| const plausible=t&&t.contextTime>0&&t.performanceTime>0&&Math.abs(now-t.performanceTime)<1500; |
| const presented=plausible?t.contextTime+(now-t.performanceTime)/1000:NaN; |
| const measured=c.currentTime-presented; |
| if(plausible&&measured>=-0.015&&measured<1.5){this.delay=Math.max(0,measured);this.method='output timestamp';} |
| else{this.delay=Math.max(0,(c.baseLatency||0)+(c.outputLatency||0));this.method='reported latency fallback';} |
| this.missing=[]; |
| if(this.inputLatency===null)this.missing.push('input latency'); |
| if(!plausible&&!c.outputLatency)this.missing.push('output timestamp/latency'); |
| return this.delay; |
| } |
| outputHead(now=performance.now()){this.observe(now);return this.context.currentTime-this.delay;} |
| position(now=performance.now()){ |
| const head=this.outputHead(now),s=this.segments.find(v=>v.t0<=head&&head<v.t1); |
| return s?{id:s.id,sample:s.first+Math.floor((head-s.t0)*24000)}:null; |
| } |
| heardTime(captureTime,now=performance.now()){ |
| this.observe(now);return captureTime-this.delay-(this.inputLatency||0)-this.acousticLatency; |
| } |
| add(id,t0,count,first){this.segments.push({id,t0,t1:t0+count/24000,first});} |
| tag(captureTime,now=performance.now()){ |
| const heard=this.heardTime(captureTime,now); |
| const segment=this.segments.find(s=>s.t0<=heard&&heard<s.t1); |
| this.segments=this.segments.filter(s=>s.t1>this.context.currentTime-12); |
| return segment?[segment.id,segment.first+Math.floor((heard-segment.t0)*24000)]:[0,-1]; |
| } |
| pieces(captureTime,count,rate=16000,now=performance.now()){ |
| const heard=this.heardTime(captureTime,now),cuts=new Set([0,count]); |
| for(const s of this.segments)for(const edge of [s.t0,s.t1]){ |
| const index=Math.ceil((edge-heard)*rate-1e-7);if(index>0&&index<count)cuts.add(index); |
| } |
| const positions=[...cuts].sort((a,b)=>a-b),out=[]; |
| for(let j=0;j<positions.length-1;j++){ |
| const first=positions[j],end=positions[j+1],at=heard+first/rate; |
| const s=this.segments.find(v=>v.t0<=at+1e-9&&at<v.t1-1e-9); |
| out.push({first,end,id:s?s.id:0,at:s?s.first+Math.max(0,Math.floor((at-s.t0)*24000+1e-7)):-1}); |
| } |
| this.segments=this.segments.filter(s=>s.t1>this.context.currentTime-12); |
| return out; |
| } |
| stop(at=this.context.currentTime){ |
| |
| for(const s of this.segments)s.t1=Math.min(s.t1,at); |
| this.segments=this.segments.filter(s=>s.t1>s.t0); |
| } |
| report(){return {output_ms:this.delay*1000,input_ms:this.inputLatency===null?null:this.inputLatency*1000, |
| method:this.method,uncertain:this.missing.length>0,missing:this.missing};} |
| } |
|
|
