Bug 1062514 - Fix range handling for regular MP4 with b-frames; r=rillian

media/libstagefright/frameworks/av/media/libstagefright/MPEG4Extractor.cpp

@@ -3724,6 +3724,12 @@ status_t MPEG4Source::fragmentedRead(
     }
 }
 
+static int compositionOrder(MediaSource::Indice* const* indice0,
+        MediaSource::Indice* const* indice1)
+{
+  return (*indice0)->start_composition - (*indice1)->start_composition;
+}
+
 Vector<MediaSource::Indice> MPEG4Source::exportIndex()
 {
   Vector<Indice> index;
@@ -3748,12 +3754,31 @@ Vector<MediaSource::Indice> MPEG4Source::exportIndex()
       Indice indice;
       indice.start_offset = offset;
       indice.end_offset = offset + size;
-      indice.start_composition = (compositionTime * 1000000ll) / mTimescale,
+      indice.start_composition = (compositionTime * 1000000ll) / mTimescale;
+      // end_composition is overwritten everywhere except the last frame, where
+      // the presentation duration is equal to the sample duration.
       indice.end_composition = ((compositionTime + duration) * 1000000ll) /
               mTimescale;
       indice.sync = isSyncSample;
       index.add(indice);
   }
+
+  // Fix up composition durations so we don't end up with any unsightly gaps.
+  if (index.size() != 0) {
+      Indice* array = index.editArray();
+      Vector<Indice*> composition_order;
+      composition_order.reserve(index.size());
+      for (uint32_t i = 0; i < index.size(); i++) {
+          composition_order.add(&array[i]);
+      }
+
+      composition_order.sort(compositionOrder);
+      for (uint32_t i = 0; i + 1 < composition_order.size(); i++) {
+        composition_order[i]->end_composition =
+                composition_order[i + 1]->start_composition;
+      }
+  }
+
   return index;
 }