mp4-remuxer: fix PTS/DTS adjustement of first audio/video samples on …

…first and non contiguous fragment

in case of first/non contiguous fragment, only adjust PTS/DTS if there is a huge (more than 10s) unexpected delta between expected and parsed timestamp
=> respect A/V sync delay as advertised in the MPEG2-TS
=> fix buffer hole that might happen on subsequent contiguous fragment

related to https://github.com/dailymotion/hls.js/issues/363
related to https://github.com/dailymotion/hls.js/issues/351

src/remux/mp4-remuxer.js

@@ -161,8 +161,8 @@ class MP4Remuxer {
 
     // check timestamp continuity accross consecutive fragments (this is to remove inter-fragment gap/hole)
     let delta = Math.round((firstDTS - nextAvcDts) / 90);
-    // if fragment are contiguous, or delta less than 600ms, ensure there is no overlap/hole between fragments
-    if (contiguous || Math.abs(delta) < 600) {
+    // if fragment are contiguous, or if there is a huge delta (more than 10s) between expected PTS and sample PTS
+    if (contiguous || Math.abs(delta) > 10000) {
       if (delta) {
         if (delta > 1) {
           logger.log(`AVC:${delta} ms hole between fragments detected,filling it`);
@@ -342,8 +342,8 @@ class MP4Remuxer {
         ptsnorm = this._PTSNormalize(pts, nextAacPts);
         dtsnorm = this._PTSNormalize(dts, nextAacPts);
         delta = Math.round(1000 * (ptsnorm - nextAacPts) / pesTimeScale);
-        // if fragment are contiguous, or delta less than 600ms, ensure there is no overlap/hole between fragments
-        if (contiguous || Math.abs(delta) < 600) {
+        // if fragment are contiguous, or if there is a huge delta (more than 10s) between expected PTS and sample PTS
+        if (contiguous || Math.abs(delta) > 10000) {
           // log delta
           if (delta) {
             if (delta > 0) {
@@ -355,7 +355,7 @@ class MP4Remuxer {
               track.len -= unit.byteLength;
               continue;
             }
-            // set DTS to next DTS
+            // set PTS/DTS to expected PTS/DTS
             ptsnorm = dtsnorm = nextAacPts;
           }
         }