mp4 格式中 mvhd tkhd mdhd 中的timescale和duration怎么确定阿？请教...

jin584930459 2009-10-15 05:45:58
大家好，问题如标题。小弟正在开发avi转mp4的程序，遇到了标题中的问题。我认为timescale是人为确定的，但是怎么确定才好，目的是为了更准确的计算时间。那么duration是不是知道了总时间后通过timescale 计算出来的？请教！请教！
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GoogleGeek 2009-10-16
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timescale怎么确定没有关系

你可以用600表示一秒，也可以用44100表示一秒

将duratation/timescale就是实际的用秒表示的时间。
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f=0,p=0,g=!1,v=0;!g&&r.bytesAvailable>1;){f=0;do{v=r.readUByte(),f+=v}while(255===v);p=0;do{v=r.readUByte(),p+=v}while(255===v);if(4===f&&0!==r.bytesAvailable){g=!0;if(181===r.readUByte()){if(49===r.readUShort()){if(1195456820===r.readUInt()){if(3===r.readUByte()){var y=r.readUByte(),m=r.readUByte(),b=31&y,E=[y,m];for(a=0;aduration=n._duration;var R=e.data.subarray(1,4),S="avc1.";for(a=0;a<3;a++){var A=R[a].toString(16);A.length0){if(e.pts>=t[r-1].pts)t.push(e);else for(var i=r-1;i>=0;i--)if(e.pts=0&&(i={data:t.subarray(c,s),type:n,state:u},h.push(i)),0===h.length){var g=this._getLastNalUnit();if(g){var v=new Uint8Array(g.data.byteLength+t.byteLength);v.set(g.data,0),v.set(t,g.data.byteLength),g.data=v}}return l.naluState=u,h},t.prototype.discardEPB=function(t){for(var e,r,i=t.byteLength,a=[],n=1;nduration:i,inputTimeScale:9e4}},t.prototype.resetTimeStamp=function(){},t.probe=function(t){var e,r,i=B.a.getID3Data(t,0);if(i&&void; 0!==B.a.getTimeStamp(i))for(e=i.length,r=Math.min(t.length-1,e+100);eTimeStamp(a),o=a.length,s=t.length,l=0,u=0,d=this._audioTrack,h=[{pts:n,dts:n,data:a}];o>24&255;,e[1]=i>>16&255;,e[2]=i>>8&255;,e[3]=255&i,e.set(t,4),a=0,i=8;a>24&255;,e>>16&255;,e>>8&255;,255&e,i>>24,i>>16&255;,i>>8&255;,255&i,a>>24,a>>16&255;,a>>8&255;,255&a,85,196,0,0]))},t.mdia=function(e){return t.box(t.types.mdia,t.mdhd(e.timescale,e.duration),t.hdlr(e.type),t.minf(e))},t.mfhd=function(e){return t.box(t.types.mfhd,new Uint8Array([0,0,0,0,e>>24,e>>16&255;,e>>8&255;,255&e]))},t.minf=function(e){return"audio"===e.type?t.box(t.types.minf,t.box(t.types.smhd,t.SMHD),t.DINF,t.stbl(e)):t.box(t.types.minf,t.box(t.types.vmhd,t.VMHD),t.DINF,t.stbl(e))},t.moof=function(e,r,i){return t.box(t.types.moof,t.mfhd(e),t.traf(i,r))},t.moov=function(e){for(var r=e.length,i=[];r--;)i[r]=t.trak(e[r]);return t.box.apply(null,[t.types.moov,t.mvhd(e[0].timescale,e[0].duration)].concat(i).concat(t.mvex(e)))},t.mvex=function(e){for(var r=e.length,i=[];r--;)i[r]=t.trex(e[r]);return t.box.apply(null,[t.types.mvex].concat(i))},t.mvhd=function(e,r){r*=e;var i=Math.floor(r/(it+1)),a=Math.floor(r%(it+1)),n=new Uint8Array([1,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,3,e>>24&255;,e>>16&255;,e>>8&255;,255&e,i>>24,i>>16&255;,i>>8&255;,255&i,a>>24,a>>16&255;,a>>8&255;,255&a,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255]);return t.box(t.types.mvhd,n)},t.sdtp=function(e){var r,i,a=e.samples||[],n=new Uint8Array(4+a.length);for(i=0;i>8&255;),n.push(255&a),n=n.concat(Array.prototype.slice.call(i));for(r=0;r>>8&255;),o.push(255&a),o=o.concat(Array.prototype.slice.call(i));var s=t.box(t.types.avcC,new Uint8Array([1,n[3],n[4],n[5],255,224|e.sps.length].concat(n).concat([e.pps.length]).concat(o))),l=e.width,u=e.height,d=e.pixelRatio[0],h=e.pixelRatio[1];return t.box(t.types.avc1,new Uint8Array([0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,l>>8&255;,255&l,u>>8&255;,255&u,0,72,0,0,0,72,0,0,0,0,0,0,0,1,18,100,97,105,108,121,109,111,116,105,111,110,47,104,108,115,46,106,115,0,0,0,0,0,0,0,0,0,0,0,0,0,0,24,17,17]),s,t.box(t.types.btrt,new Uint8Array([0,28,156,128,0,45,198,192,0,45,198,192])),t.box(t.types.pasp,new Uint8Array([d>>24,d>>16&255;,d>>8&255;,255&d,h>>24,h>>16&255;,h>>8&255;,255&h])))},t.esds=function(t){var e=t.config.length;return new Uint8Array([0,0,0,0,3,23+e,0,1,0,4,15+e,64,21,0,0,0,0,0,0,0,0,0,0,0,5].concat([e]).concat(t.config).concat([6,1,2]))},t.mp4a=function(e){var r=e.samplerate;return t.box(t.types.mp4a,new Uint8Array([0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,e.channelCount,0,16,0,0,0,0,r>>8&255;,255&r,0,0]),t.box(t.types.esds,t.esds(e)))},t.mp3=function(e){var r=e.samplerate;return t.box(t.types[".mp3"],new Uint8Array([0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,e.channelCount,0,16,0,0,0,0,r>>8&255;,255&r,0,0]))},t.stsd=function(e){return"audio"===e.type?e.isAAC||"mp3"!==e.codec?t.box(t.types.stsd,t.STSD,t.mp4a(e)):t.box(t.types.stsd,t.STSD,t.mp3(e)):t.box(t.types.stsd,t.STSD,t.avc1(e))},t.tkhd=function(e){var r=e.id,i=e.duration*e.timescale,a=e.width,n=e.height,o=Math.floor(i/(it+1)),s=Math.floor(i%(it+1));return t.box(t.types.tkhd,new Uint8Array([1,0,0,7,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,3,r>>24&255;,r>>16&255;,r>>8&255;,255&r,0,0,0,0,o>>24,o>>16&255;,o>>8&255;,255&o,s>>24,s>>16&255;,s>>8&255;,255&s,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,64,0,0,0,a>>8&255;,255&a,0,0,n>>8&255;,255&n,0,0]))},t.traf=function(e,r){var i=t.sdtp(e),a=e.id,n=Math.floor(r/(it+1)),o=Math.floor(r%(it+1));return t.box(t.types.traf,t.box(t.types.tfhd,new Uint8Array([0,0,0,0,a>>24,a>>16&255;,a>>8&255;,255&a])),t.box(t.types.tfdt,new Uint8Array([1,0,0,0,n>>24,n>>16&255;,n>>8&255;,255&n,o>>24,o>>16&255;,o>>8&255;,255&o])),t.trun(e,i.length+16+20+8+16+8+8),i)},t.trak=function(e){return e.duration=e.duration||4294967295,t.box(t.types.trak,t.tkhd(e),t.mdia(e))},t.trex=function(e){var r=e.id;return t.box(t.types.trex,new Uint8Array([0,0,0,0,r>>24,r>>16&255;,r>>8&255;,255&r,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,1]))},t.trun=function(e,r){var i,a,n,o,s,l,u=e.samples||[],d=u.length,h=12+16*d,c=new Uint8Array(h);for(r+=8+h,c.set([0,0,15,1,d>>>24&255;,d>>>16&255;,d>>>8&255;,255&d,r>>>24&255;,r>>>16&255;,r>>>8&255;,255&r],0),i=0;i>>24&255;,n>>>16&255;,n>>>8&255;,255&n,o>>>24&255;,o>>>16&255;,o>>>8&255;,255&o,s.isLeading<<2|s.dependsOn,s.isDependedOn<<6|s.hasRedundancy<<4|s.paddingValue<>>24&255;,l>>>16&255;,l>>>8&255;,255&l],12+16*i);return t.box(t.types.trun,c)},t.initSegment=function(e){t.types||t.init();var r,i=t.moov(e);return r=new Uint8Array(t.FTYP.byteLength+i.byteLength),r.set(t.FTYP),r.set(i,t.FTYP.byteLength),r},t}(),nt=at,ot=function(){function t(e,r,i,a){_(this,t),this.observer=e,this.config=r,this.typeSupported=i;var n=navigator.userAgent;this.isSafari=a&&a.indexOf("Apple")>-1&&n&&!n.match("CriOS"),this.ISGenerated=!1}return t.prototype.destroy=function(){},t.prototype.resetTimeStamp=function(t){this._initPTS=this._initDTS=t},t.prototype.resetInitSegment=function(){this.ISGenerated=!1},t.prototype.remux=function(t,e,r,i,a,n,o){if(this.ISGenerated){if(o){var s=this._initPTS,l=this._PTSNormalize,u=t.inputTimeScale||e.inputTimeScale,d=1/0,h=1/0,c=t.samples;if(c.length&&(d=h=l(c[0].pts-u*a,s)),c=e.samples,c.length){var f=c[0];d=Math.min(d,l(f.pts-u*a,s)),h=Math.min(h,l(f.dts-u*a,s))}if(d!==1/0){var p=s-d;Math.abs(p)>10*u&&(N.b.warn("timestamp inconsistency, "+(p/u).toFixed(3)+"s delta against expected value: missing discontinuity ? reset initPTS/initDTS"),this._initPTS=d,this._initDTS=h,this.observer.trigger(D.a.INIT_PTS_FOUND,{initPTS:d}))}}}else this.generateIS(t,e,a);if(this.ISGenerated)if(t.samples.length){t.timescale||(N.b.warn("regenerate InitSegment as audio detected"),this.generateIS(t,e,a));var g=this.remuxAudio(t,a,n,o);if(e.samples.length){var v=void 0;g&&(v=g.endPTS-g.startPTS),e.timescale||(N.b.warn("regenerate InitSegment as video detected"),this.generateIS(t,e,a)),this.remuxVideo(e,a,n,v,o)}}else{var y=void 0;e.samples.length&&(y=this.remuxVideo(e,a,n,o)),y&&t.codec&&this;.remuxEmptyAudio(t,a,n,y)}r.samples.length&&this;.remuxID3(r,a),i.samples.length&&this;.remuxText(i,a),this.observer.trigger(D.a.FRAG_PARSED)},t.prototype.generateIS=function(t,e,r){var i,a,n=this.observer,o=t.samples,s=e.samples,l=this.typeSupported,u="audio/mp4",d={},h={tracks:d},c=void 0===this._initPTS;if(c&&(i=a=1/0),t.config&&o.length&&(t.timescale=t.samplerate,N.b.log("audio sampling rate : "+t.samplerate),t.isAAC||(l.mpeg?(u="audio/mpeg",t.codec=""):l.mp3&&(t.codec="mp3")),d.audio={container:u,codec:t.codec,initSegment:!t.isAAC&&l.mpeg?new Uint8Array:nt.initSegment([t]),metadata:{channelCount:t.channelCount}},c&&(i=a=o[0].pts-t.inputTimeScale*r)),e.sps&&e.pps&&s.length){var f=e.inputTimeScale;e.timescale=f,d.video={container:"video/mp4",codec:e.codec,initSegment:nt.initSegment([e]),metadata:{width:e.width,height:e.height}},c&&(i=Math.min(i,s[0].pts-f*r),a=Math.min(a,s[0].dts-f*r),this.observer.trigger(D.a.INIT_PTS_FOUND,{initPTS:i}))}Object.keys(d).length?(n.trigger(D.a.FRAG_PARSING_INIT_SEGMENT,h),this.ISGenerated=!0,c&&(this._initPTS=i,this._initDTS=a)):n.trigger(D.a.ERROR,{type:k.b.MEDIA_ERROR,details:k.a.FRAG_PARSING_ERROR,fatal:!1,reason:"no audio/video samples found"})},t.prototype.remuxVideo=function(t,e,r,i,a){var n,o,s,l,u,d,h,c=8,f=t.timescale,p=t.samples,g=[],v=p.length,y=this._PTSNormalize,m=this._initDTS,b=this.nextAvcDts,E=this.isSafari;E&&(r|=p.length&&b&&(a&&Math;.abs(e-b/f)<.1||Math.abs(p[0].pts-b-m)$?(n=Z-q,n-1){var et=g[0].flags;et.dependsOn=2,et.isNonSync=0}t.samples=g,s=nt.moof(t.sequenceNumber++,u,t),t.samples=[];var rt={data1:s,data2:o,startPTS:l/f,endPTS:(d+n)/f,startDTS:u/f,endDTS:this.nextAvcDts/f,type:"video",nb:g.length,dropped:tt};return this.observer.trigger(D.a.FRAG_PARSING_DATA,rt),rt},t.prototype.remuxAudio=function(t,e,r,i){var a,n,o,s,l,u,d,h=t.inputTimeScale,c=t.timescale,f=h/c,p=t.isAAC?1024:1152,g=p*f,v=this._PTSNormalize,y=this._initDTS,m=!t.isAAC&&this;.typeSupported.mpeg,b=t.samples,E=[],T=this.nextAudioPts;if(r|=b.length&&T&&(i&&Math;.abs(e-T/h)<.1||Math.abs(b[0].pts-T-y)<20*g),r||(T=e*h),b.forEach(function(t){t.pts=t.dts=v(t.pts-y,T)}),b.sort(function(t,e){return t.pts-e.pts}),i&&t.isAAC)for(var R=0,S=T;Rduration,n.duration=W),V){this.nextAudioPts=T=d+f*W,t.len=0,t.samples=E,l=m?new Uint8Array:nt.moof(t.sequenceNumber++,u/f,t),t.samples=[];var Y=u/h,X=T/h,z={data1:l,data2:s,startPTS:Y,endPTS:X,startDTS:Y,endDTS:X,type:"audio",nb:V};return this.observer.trigger(D.a.FRAG_PARSING_DATA,z),z}return null},t.prototype.remuxEmptyAudio=function(t,e,r,i){var a=t.inputTimeScale,n=t.samplerate?t.samplerate:a,o=a/n,s=this.nextAudioPts,l=(void 0!==s?s:i.startDTS*a)+this._initDTS,u=i.endDTS*a+this._initDTS,d=1024*o,h=Math.ceil((u-l)/d),c=rt.getSilentFrame(t.manifestCodec||t.codec,t.channelCount);if(N.b.warn("remux empty Audio"),!c)return void N.b.trace("Unable to remuxEmptyAudio since we were unable to get a silent frame for given audio codec!");for(var f=[],p=0;pTimeScale,n=this._initPTS,o=this._initDTS;if(i){for(var s=0;sTimeScale,n=this._initPTS;if(i){for(var o=0;oTimeStamp=function(){},t.prototype.resetInitSegment=function(){},t.prototype.remux=function(t,e,r,i,a,n,o,s){var l=this.observer,u="";t&&(u+="audio"),e&&(u+="video"),l.trigger(D.a.FRAG_PARSING_DATA,{data1:s,startPTS:a,startDTS:a,type:u,nb:1,dropped:0}),l.trigger(D.a.FRAG_PARSED)},t}(),ut=lt,dt=function(){function t(e,r,i,a){w(this,t),this.observer=e,this.typeSupported=r,this.config=i,this.vendor=a}return t.prototype.destroy=function(){var t=this.demuxer;t&&t.destroy()},t.prototype.push=function(t,e,r,i,a,n,o,s,l,u,d,h){if(t.byteLength>0&&null;!=e&&null;!=e.key&&"AES-128"===e.method){var c=this.decrypter;null==c&&(c=this.decrypter=new U(this.observer,this.config));var f,p=this;try{f=performance.now()}catch(t){f=Date.now()}c.decrypt(t,e.key.buffer,e.iv.buffer,function(t){var c;try{c=performance.now()}catch(t){c=Date.now()}p.observer.trigger(D.a.FRAG_DECRYPTED,{stats:{tstart:f,tdecrypt:c}}),p.pushDecrypted(new Uint8Array(t),e,new Uint8Array(r),i,a,n,o,s,l,u,d,h)})}else this.pushDecrypted(new Uint8Array(t),e,new Uint8Array(r),i,a,n,o,s,l,u,d,h)},t.prototype.pushDecrypted=function(t,e,r,i,a,n,o,s,l,u,d,h){var c=this.demuxer;if(!c||o&&!this.probe(t)){for(var f=this.observer,p=this.typeSupported,g=this.config,v=[{demux:$,remux:st},{demux:H,remux:st},{demux:tt,remux:st},{demux:W,remux:ut}],y=0,m=v.length;ye?i.start+i.duration:Math.max(i.start-a.duration,0):r>e?(i.duration=n-i.start,i.duration<0&&wt;.b.warn("negative duration computed for frag "+i.sn+",level "+i.level+", there should be some duration drift between playlist and fragment!")):(a.duration=i.start-n,a.duration<0&&wt;.b.warn("negative duration computed for frag "+a.sn+",level "+a.level+", there should be some duration drift between playlist and fragment!"))}function v(t,e,r,i,a,n){if(!isNaN(e.startPTS)){var o=Math.abs(e.startPTS-r);isNaN(e.deltaPTS)?e.deltaPTS=o:e.deltaPTS=Math.max(o,e.deltaPTS),r=Math.min(r,e.startPTS),i=Math.max(i,e.endPTS),a=Math.min(a,e.startDTS),n=Math.max(n,e.endDTS)}var s=r-e.start;e.start=e.startPTS=r,e.endPTS=i,e.startDTS=a,e.endDTS=n,e.duration=i-r;var l=e.sn;if(!t||lt.endSN)return 0;var u,d,h;for(u=l-t.startSN,d=t.fragments,e=d[u],h=u;h>0;h--)g(d,h,h-1);for(h=u;hduration=d.duration,h.backtracked=d.backtracked,h.dropped=d.dropped,r=h))}if(l)for(wt.b.log("discontinuity sliding from playlist, take drift into account"),u=0;u=0&&n
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