Reenable edit lists without keyframe again but remove samples before keyframe.

Ignoring all edit lists if they don't start with a keyframe causes A/V sync
issues when valid edit lists are applied at the beginning.

This change allows such edit lists again but removes all samples before the
first keyframe (these samples would be ignored by the renderer anyway if at
the beginning OR cause visible distortions when appended to an unrelated
keyframe).

Issue:#4774
Issue:#4348

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=212244407

RELEASENOTES.md

@@ -120,6 +120,8 @@
   [#4634](https://github.com/google/ExoPlayer/issues/4634)).
 * Fix issue where errors of upcoming playlist items are thrown too early
   ([#4661](https://github.com/google/ExoPlayer/issues/4661)).
+* Allow edit lists which do not start with a sync sample.
+  ([#4774](https://github.com/google/ExoPlayer/issues/4774)).
 * IMA extension:
   * Refine the previous fix for empty ad groups to avoid discarding ad breaks
     unnecessarily ([#4030](https://github.com/google/ExoPlayer/issues/4030)),

library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -382,19 +382,29 @@ import java.util.List;
     int editedSampleCount = 0;
     int nextSampleIndex = 0;
     boolean copyMetadata = false;
+    int[] startIndices = new int[track.editListDurations.length];
+    int[] endIndices = new int[track.editListDurations.length];
     for (int i = 0; i < track.editListDurations.length; i++) {
       long editMediaTime = track.editListMediaTimes[i];
       if (editMediaTime != -1) {
         long editDuration =
             Util.scaleLargeTimestamp(
                 track.editListDurations[i], track.timescale, track.movieTimescale);
-        int startIndex = Util.binarySearchCeil(timestamps, editMediaTime, true, true);
-        int endIndex =
+        startIndices[i] = Util.binarySearchCeil(timestamps, editMediaTime, true, true);
+        endIndices[i] =
             Util.binarySearchCeil(
                 timestamps, editMediaTime + editDuration, omitClippedSample, false);
-        editedSampleCount += endIndex - startIndex;
-        copyMetadata |= nextSampleIndex != startIndex;
-        nextSampleIndex = endIndex;
+        while (startIndices[i] < endIndices[i]
+            && (flags[startIndices[i]] & C.BUFFER_FLAG_KEY_FRAME) == 0) {
+          // Applying the edit correctly would require prerolling from the previous sync sample. In
+          // the current implementation we advance to the next sync sample instead. Only other
+          // tracks (i.e. audio) will be rendered until the time of the first sync sample.
+          // See https://github.com/google/ExoPlayer/issues/1659.
+          startIndices[i]++;
+        }
+        editedSampleCount += endIndices[i] - startIndices[i];
+        copyMetadata |= nextSampleIndex != startIndices[i];
+        nextSampleIndex = endIndices[i];
       }
     }
     copyMetadata |= editedSampleCount != sampleCount;
@@ -409,37 +419,26 @@ import java.util.List;
     int sampleIndex = 0;
     for (int i = 0; i < track.editListDurations.length; i++) {
       long editMediaTime = track.editListMediaTimes[i];
-      long editDuration = track.editListDurations[i];
-      if (editMediaTime != -1) {
-        long endMediaTime =
-            editMediaTime
-                + Util.scaleLargeTimestamp(editDuration, track.timescale, track.movieTimescale);
-        int startIndex = Util.binarySearchCeil(timestamps, editMediaTime, true, true);
-        int endIndex = Util.binarySearchCeil(timestamps, endMediaTime, omitClippedSample, false);
-        if (copyMetadata) {
-          int count = endIndex - startIndex;
-          System.arraycopy(offsets, startIndex, editedOffsets, sampleIndex, count);
-          System.arraycopy(sizes, startIndex, editedSizes, sampleIndex, count);
-          System.arraycopy(flags, startIndex, editedFlags, sampleIndex, count);
-        }
-        if (startIndex < endIndex && (editedFlags[sampleIndex] & C.BUFFER_FLAG_KEY_FRAME) == 0) {
-          // Applying the edit list would require prerolling from a sync sample.
-          Log.w(TAG, "Ignoring edit list: edit does not start with a sync sample.");
-          throw new UnhandledEditListException();
-        }
-        for (int j = startIndex; j < endIndex; j++) {
-          long ptsUs = Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.movieTimescale);
-          long timeInSegmentUs =
-              Util.scaleLargeTimestamp(
-                  timestamps[j] - editMediaTime, C.MICROS_PER_SECOND, track.timescale);
-          editedTimestamps[sampleIndex] = ptsUs + timeInSegmentUs;
-          if (copyMetadata && editedSizes[sampleIndex] > editedMaximumSize) {
-            editedMaximumSize = sizes[j];
-          }
-          sampleIndex++;
+      int startIndex = startIndices[i];
+      int endIndex = endIndices[i];
+      if (copyMetadata) {
+        int count = endIndex - startIndex;
+        System.arraycopy(offsets, startIndex, editedOffsets, sampleIndex, count);
+        System.arraycopy(sizes, startIndex, editedSizes, sampleIndex, count);
+        System.arraycopy(flags, startIndex, editedFlags, sampleIndex, count);
+      }
+      for (int j = startIndex; j < endIndex; j++) {
+        long ptsUs = Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.movieTimescale);
+        long timeInSegmentUs =
+            Util.scaleLargeTimestamp(
+                timestamps[j] - editMediaTime, C.MICROS_PER_SECOND, track.timescale);
+        editedTimestamps[sampleIndex] = ptsUs + timeInSegmentUs;
+        if (copyMetadata && editedSizes[sampleIndex] > editedMaximumSize) {
+          editedMaximumSize = sizes[j];
         }
+        sampleIndex++;
       }
-      pts += editDuration;
+      pts += track.editListDurations[i];
     }
     long editedDurationUs = Util.scaleLargeTimestamp(pts, C.MICROS_PER_SECOND, track.timescale);
     return new TrackSampleTable(