mp4-remuxer: remove audio frame PTS sorting to avoid audio glitch on …

…broken audio streams

BUT always fix audio frame duration (no matter if the timeOffset provided is accurate or not)

related to video-dev#1453 video-dev#1334

src/remux/mp4-remuxer.js

@@ -457,30 +457,29 @@ class MP4Remuxer {
                     Math.abs((inputSamples[0].pts-nextAudioPts-initDTS)) < 20*inputSampleDuration)
                     );
 
-    if (!contiguous) {
-      // if fragments are not contiguous, let's use timeOffset to compute next Audio PTS
-      nextAudioPts = timeOffset*inputTimeScale;
-    }
 
     // compute normalized PTS
     inputSamples.forEach(function(sample) {
-      sample.pts = sample.dts = ptsNormalize(sample.pts - initDTS, nextAudioPts);
+      sample.pts = sample.dts = ptsNormalize(sample.pts - initDTS, timeOffset*inputTimeScale);
     });
 
-    // sort based on normalized PTS (this is to avoid sorting issues in case timestamp
-    // reloop in the middle of our samples array)
-    inputSamples.sort(function(a, b) {
-      return a.pts - b.pts;
-    });
+    if (!contiguous) {
+      if (!accurateTimeOffset) {
+        // if frag are mot contiguous and if we cant trust time offset, let's use first sample PTS as next audio PTS
+        nextAudioPts = inputSamples[0].pts;
+      } else {
+        // if timeOffset is accurate, let's use it as predicted next audio PTS
+        nextAudioPts = timeOffset*inputTimeScale;
+      }
+    }
 
     // If the audio track is missing samples, the frames seem to get "left-shifted" within the
     // resulting mp4 segment, causing sync issues and leaving gaps at the end of the audio segment.
     // In an effort to prevent this from happening, we inject frames here where there are gaps.
     // When possible, we inject a silent frame; when that's not possible, we duplicate the last
     // frame.
 
-    // only inject/drop audio frames in case time offset is accurate
-    if (accurateTimeOffset && track.isAAC) {
+    if ( track.isAAC) {
       const maxAudioFramesDrift = this.config.maxAudioFramesDrift;
       for (let i = 0, nextPts = nextAudioPts; i < inputSamples.length; ) {
         // First, let's see how far off this frame is from where we expect it to be