--- a/dom/media/mp4/Index.cpp
+++ b/dom/media/mp4/Index.cpp
@@ -404,17 +404,20 @@ Index::Index(const IndiceWrapper& aIndic
         return;
       }
       if (indice.sync || mIsAudio) {
         haveSync = true;
       }
       if (!haveSync) {
         continue;
       }
-
+      if (indice.start_composition == indice.end_composition) {
+        // Ignore this sample as it doesn't account for the buffered range.
+        continue;
+      }
       Sample sample;
       sample.mByteRange =
           MediaByteRange(indice.start_offset, indice.end_offset);
       sample.mCompositionRange = MP4Interval<Microseconds>(
           indice.start_composition, indice.end_composition);
       sample.mDecodeTime = indice.start_decode;
       sample.mSync = indice.sync || mIsAudio;
       // FIXME: Make this infallible after bug 968520 is done.