tsdemuxer: fix parsing of NALu with start code prefix splitted accros…

…s PES packets

https://github.com/dailymotion/hls.js/issues/98

src/demux/tsdemuxer.js

@@ -38,14 +38,14 @@
   switchLevel() {
     this.pmtParsed = false;
     this._pmtId = -1;
-    this.lastAacPTS = null;
-    this.aacOverFlow = null;
     this._avcTrack = {container : 'video/mp2t', type: 'video', id :-1, sequenceNumber: 0, samples : [], len : 0, nbNalu : 0};
     this._aacTrack = {container : 'video/mp2t', type: 'audio', id :-1, sequenceNumber: 0, samples : [], len : 0};
     this._id3Track = {type: 'id3', id :-1, sequenceNumber: 0, samples : [], len : 0};
     this._txtTrack = {type: 'text', id: -1, sequenceNumber: 0, samples: [], len: 0};
     // flush any partial content
     this.aacOverFlow = null;
+    this.aacLastPTS = null;
+    this.avcNaluState = 0;
     this.remuxer.switchLevel();
   }
 
@@ -349,6 +349,23 @@
     pes.data = null;
     var debugString = '';
 
+    var pushAccesUnit = function() {
+      if (units2.length) {
+        // only push AVC sample if keyframe already found in this fragment OR
+        //    keyframe found in last fragment (track.sps) AND
+        //        samples already appended (we already found a keyframe in this fragment) OR fragment is contiguous
+        if (key === true ||
+            (track.sps && (samples.length || this.contiguous))) {
+          avcSample = {units: { units : units2, length : length}, pts: pes.pts, dts: pes.dts, key: key};
+          samples.push(avcSample);
+          track.len += length;
+          track.nbNalu += units2.length;
+        }
+        units2 = [];
+        length = 0;
+      }
+    };
+
     units.forEach(unit => {
       switch(unit.type) {
         //NDR
@@ -485,6 +502,7 @@
           if(debug) {
             debugString += 'AUD ';
           }
+          pushAccesUnit();
           break;
         default:
           push = false;
@@ -499,20 +517,7 @@
     if(debug || debugString.length) {
       logger.log(debugString);
     }
-    //build sample from PES
-    // Annex B to MP4 conversion to be done
-    if (units2.length) {
-      // only push AVC sample if keyframe already found in this fragment OR
-      //    keyframe found in last fragment (track.sps) AND
-      //        samples already appended (we already found a keyframe in this fragment) OR fragment is contiguous
-      if (key === true ||
-          (track.sps && (samples.length || this.contiguous))) {
-        avcSample = {units: { units : units2, length : length}, pts: pes.pts, dts: pes.dts, key: key};
-        samples.push(avcSample);
-        track.len += length;
-        track.nbNalu += units2.length;
-      }
-    }
+    pushAccesUnit();
   }
 
   _insertSampleInOrder(arr, data) {
@@ -537,7 +542,7 @@
   }
 
   _parseAVCNALu(array) {
-    var i = 0, len = array.byteLength, value, overflow, state = 0;
+    var i = 0, len = array.byteLength, value, overflow, state = this.avcNaluState;
     var units = [], unit, unitType, lastUnitStart, lastUnitType;
     //logger.log('PES:' + Hex.hexDump(array));
     while (i < len) {
@@ -568,14 +573,37 @@
               //logger.log('pushing NALU, type/size:' + unit.type + '/' + unit.data.byteLength);
               units.push(unit);
             } else {
+              // lastUnitStart is undefined => this is the first start code found in this PES packet
+              // first check if start code delimiter is overlapping between 2 PES packets,
+              // ie it started in last packet (lastState not zero)
+              // and ended at the beginning of this PES packet (i <= 4 - lastState)
+              let lastState = this.avcNaluState;
+              if(lastState &&  (i <= 4 - lastState)) {
+                // start delimiter overlapping between PES packets
+                // strip start delimiter bytes from the end of last NAL unit
+                let track = this._avcTrack,
+                    samples = track.samples;
+                if (samples.length) {
+                  let lastavcSample = samples[samples.length - 1],
+                      lastUnits = lastavcSample.units.units,
+                      lastUnit = lastUnits[lastUnits.length - 1];
+                  // check if lastUnit had a state different from zero
+                  if (lastUnit.state) {
+                    // strip last bytes
+                    lastUnit.data = lastUnit.data.subarray(0,lastUnit.data.byteLength - lastState);
+                    lastavcSample.units.length -= lastState;
+                    track.len -= lastState;
+                  }
+                }
+              }
               // If NAL units are not starting right at the beginning of the PES packet, push preceding data into previous NAL unit.
               overflow  = i - state - 1;
-              if (overflow) {
-                var track = this._avcTrack,
+              if (overflow > 0) {
+                let track = this._avcTrack,
                     samples = track.samples;
                 //logger.log('first NALU found with overflow:' + overflow);
                 if (samples.length) {
-                  var lastavcSample = samples[samples.length - 1],
+                  let lastavcSample = samples[samples.length - 1],
                       lastUnits = lastavcSample.units.units,
                       lastUnit = lastUnits[lastUnits.length - 1],
                       tmp = new Uint8Array(lastUnit.data.byteLength + overflow);
@@ -599,9 +627,10 @@
       }
     }
     if (lastUnitStart) {
-      unit = {data: array.subarray(lastUnitStart, len), type: lastUnitType};
+      unit = {data: array.subarray(lastUnitStart, len), type: lastUnitType, state : state};
       units.push(unit);
-      //logger.log('pushing NALU, type/size:' + unit.type + '/' + unit.data.byteLength);
+      //logger.log('pushing NALU, type/size/state:' + unit.type + '/' + unit.data.byteLength + '/' + state);
+      this.avcNaluState = state;
     }
     return units;
   }
@@ -658,7 +687,7 @@
         duration = this._duration,
         audioCodec = this.audioCodec,
         aacOverFlow = this.aacOverFlow,
-        lastAacPTS = this.lastAacPTS,
+        aacLastPTS = this.aacLastPTS,
         config, frameLength, frameDuration, frameIndex, offset, headerLength, stamp, len, aacSample;
     if (aacOverFlow) {
       var tmp = new Uint8Array(aacOverFlow.byteLength + data.byteLength);
@@ -702,8 +731,8 @@
 
     // if last AAC frame is overflowing, we should ensure timestamps are contiguous:
     // first sample PTS should be equal to last sample PTS + frameDuration
-    if(aacOverFlow && lastAacPTS) {
-      var newPTS = lastAacPTS+frameDuration;
+    if(aacOverFlow && aacLastPTS) {
+      var newPTS = aacLastPTS+frameDuration;
       if(Math.abs(newPTS-pts) > 1) {
         logger.log(`AAC: align PTS for overlapping frames by ${Math.round((newPTS-pts)/90)}`);
         pts=newPTS;
@@ -745,7 +774,7 @@
       aacOverFlow = null;
     }
     this.aacOverFlow = aacOverFlow;
-    this.lastAacPTS = stamp;
+    this.aacLastPTS = stamp;
   }
 
   _parseID3PES(pes) {