stream-controller: only force reloading previous fragment if last rem…

…uxed fragment does not start with a keyframe

related to https://github.com/dailymotion/hls.js/issues/517

src/controller/stream-controller.js

@@ -87,7 +87,7 @@ class StreamController extends EventHandler {
       this.tick();
     } else {
       logger.warn('cannot start loading as manifest not parsed yet');
-      this.state = State.STOPPED; 
+      this.state = State.STOPPED;
     }
   }
 
@@ -377,10 +377,10 @@ class StreamController extends EventHandler {
           let deltaPTS = fragPrevious.deltaPTS,
           curSNIdx = frag.sn - levelDetails.startSN;
           // if there is a significant delta between audio and video, larger than max allowed hole,
-          // it might be because video fragment does not start with a keyframe.
+          // and if previous remuxed fragment did not start with a keyframe. (fragPrevious.dropped)
           // let's try to load previous fragment again to get last keyframe
           // then we will reload again current fragment (that way we should be able to fill the buffer hole ...)
-          if (deltaPTS && deltaPTS > config.maxBufferHole) {
+          if (deltaPTS && deltaPTS > config.maxBufferHole && fragPrevious.dropped) {
             frag = fragments[curSNIdx-1];
             logger.warn(`SN just loaded, with large PTS gap between audio and video, maybe frag is not starting with a keyframe ? load previous one to try to overcome this`);
             // decrement previous frag load counter to avoid frag loop loading error when next fragment will get reloaded
@@ -874,7 +874,7 @@ class StreamController extends EventHandler {
           }
         }
         this.pendingAppending = 0;
-        logger.log(`Demuxing ${sn} of [${details.startSN} ,${details.endSN}],level ${level}`);
+        logger.log(`Demuxing ${sn} of [${details.startSN} ,${details.endSN}],level ${level}, cc ${fragCurrent.cc}`);
         let demuxer = this.demuxer;
         if (demuxer) {
           demuxer.push(data.payload, audioCodec, currentLevel.videoCodec, start, fragCurrent.cc, level, sn, duration, fragCurrent.decryptdata);
@@ -981,12 +981,17 @@ class StreamController extends EventHandler {
       var level = this.levels[this.level],
           frag = this.fragCurrent;
 
-      logger.log(`parsed ${data.type},PTS:[${data.startPTS.toFixed(3)},${data.endPTS.toFixed(3)}],DTS:[${data.startDTS.toFixed(3)}/${data.endDTS.toFixed(3)}],nb:${data.nb}`);
+      logger.log(`parsed ${data.type},PTS:[${data.startPTS.toFixed(3)},${data.endPTS.toFixed(3)}],DTS:[${data.startDTS.toFixed(3)}/${data.endDTS.toFixed(3)}],nb:${data.nb},dropped:${data.dropped || 0}`);
 
       var drift = LevelHelper.updateFragPTSDTS(level.details,frag.sn,data.startPTS,data.endPTS,data.startDTS,data.endDTS),
           hls = this.hls;
       hls.trigger(Event.LEVEL_PTS_UPDATED, {details: level.details, level: this.level, drift: drift});
 
+      // has remuxer dropped video frames located before first keyframe ?
+      if(data.type === 'video') {
+        frag.dropped = data.dropped;
+      }
+
       [data.data1, data.data2].forEach(buffer => {
         if (buffer) {
           this.pendingAppending++;

src/demux/demuxer-worker.js

@@ -38,7 +38,7 @@ var DemuxerWorker = function (self) {
   });
 
   observer.on(Event.FRAG_PARSING_DATA, function(ev, data) {
-    var objData = {event: ev, id : data.id, level : data.level, sn : data.sn, type: data.type, startPTS: data.startPTS, endPTS: data.endPTS, startDTS: data.startDTS, endDTS: data.endDTS, data1: data.data1.buffer, data2: data.data2.buffer, nb: data.nb};
+    var objData = {event: ev, id : data.id, level : data.level, sn : data.sn, type: data.type, startPTS: data.startPTS, endPTS: data.endPTS, startDTS: data.startDTS, endDTS: data.endDTS, data1: data.data1.buffer, data2: data.data2.buffer, nb: data.nb, , dropped : data.dropped};
     // pass data1/data2 as transferable object (no copy)
     self.postMessage(objData, [objData.data1, objData.data2]);
   });

src/demux/demuxer.js

@@ -94,7 +94,8 @@ class Demuxer {
           startDTS: data.startDTS,
           endDTS: data.endDTS,
           type: data.type,
-          nb: data.nb
+          nb: data.nb,
+          dropped: data.dropped,
         });
         break;
         case Event.FRAG_PARSING_METADATA:

src/demux/tsdemuxer.js

@@ -39,7 +39,7 @@
   switchLevel() {
     this.pmtParsed = false;
     this._pmtId = -1;
-    this._avcTrack = {container : 'video/mp2t', type: 'video', id :-1, sequenceNumber: 0, samples : [], len : 0, nbNalu : 0};
+    this._avcTrack = {container : 'video/mp2t', type: 'video', id :-1, sequenceNumber: 0, samples : [], len : 0, nbNalu : 0, dropped : 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};
@@ -361,6 +361,9 @@
           samples.push(avcSample);
           track.len += length;
           track.nbNalu += units2.length;
+        } else {
+          // dropped samples, track it
+          track.dropped++;
         }
         units2 = [];
         length = 0;

src/remux/mp4-remuxer.js

@@ -315,8 +315,10 @@ class MP4Remuxer {
     }
     // next AVC sample DTS should be equal to last sample DTS + last sample duration (in PES timescale)
     this.nextAvcDts = lastDTS + mp4SampleDuration*pes2mp4ScaleFactor;
+    let dropped = track.dropped;
     track.len = 0;
     track.nbNalu = 0;
+    track.dropped = 0;
     if(outputSamples.length && navigator.userAgent.toLowerCase().indexOf('chrome') > -1) {
       let flags = outputSamples[0].flags;
     // chrome workaround, mark first sample as being a Random Access Point to avoid sourcebuffer append issue
@@ -339,7 +341,8 @@ class MP4Remuxer {
       startDTS: firstDTS / pesTimeScale,
       endDTS: this.nextAvcDts / pesTimeScale,
       type: 'video',
-      nb: outputSamples.length
+      nb: outputSamples.length,
+      dropped : dropped
     };
     this.observer.trigger(Event.FRAG_PARSING_DATA, data);
     return data;

src/remux/passthrough-remuxer.js

@@ -64,7 +64,8 @@ class PassThroughRemuxer {
       startPTS: timeOffset,
       startDTS: timeOffset,
       type: 'audiovideo',
-      nb: 1
+      nb: 1,
+      dropped : 0
     });
   }
 }