Remove lingering frames of old data when appending a new segment

media/filters/source_buffer_stream.cc

Index: media/filters/source_buffer_stream.cc
diff --git a/media/filters/source_buffer_stream.cc b/media/filters/source_buffer_stream.cc
index 9da441ee65de2bb8827e6a518a6bf414ed6ce274..f8b1894e51bbc4bc7b4c3a47277de00e950ed9ea 100644
--- a/media/filters/source_buffer_stream.cc
+++ b/media/filters/source_buffer_stream.cc
@@ -153,6 +153,11 @@ class SourceBufferRange {
       const scoped_refptr<media::StreamParserBuffer>& buffer,
       base::TimeDelta timestamp) const;
 
+  // Returns true if |second_timestamp| is the timestamp of the next buffer in
+  // sequence after |first_timestamp|, false otherwise.
+  bool AreAdjacentInSequence(
+      base::TimeDelta first_timestamp, base::TimeDelta second_timestamp) const;
+
   int size_in_bytes() const { return size_in_bytes_; }
 
  private:
@@ -319,12 +324,20 @@ SourceBufferStream::~SourceBufferStream() {
 void SourceBufferStream::OnNewMediaSegment(
     base::TimeDelta media_segment_start_time) {
   media_segment_start_time_ = media_segment_start_time;
+  new_media_segment_ = true;
 
-  // Find the range that will house the buffers appended through the next
-  // Append() call.
+  RangeList::iterator last_range = range_for_next_append_;
   range_for_next_append_ = FindExistingRangeFor(media_segment_start_time);
-  new_media_segment_ = true;
-  last_buffer_timestamp_ = kNoTimestamp();
+
+  // Only reset |last_buffer_timestamp_| if this new media segment is not
+  // adjacent to the previous media segment appended to the stream.
+  if (range_for_next_append_ == ranges_.end() ||
+      !(*range_for_next_append_)->AreAdjacentInSequence(

[acolwell GONE FROM CHROMIUM, 2012/09/19 23:15:51]

This is a little awkward because it calls into the range just so the range can
call back into this class for the approximate duration value. I think making
this a helper method on SourceBufferStream would be better and just keep
SourceBufferRange::IsNextInSequence() as is for now.

You could create a static TimeDelta GetFudge(TimeDelta approximate_duration)
helper to avoid SourceBufferStream & SourceBufferRange getting out of sync.

[vrk (LEFT CHROMIUM), 2012/09/20 00:00:59]

Done.

+          last_buffer_timestamp_, media_segment_start_time)) {
+    last_buffer_timestamp_ = kNoTimestamp();
+  } else {
+    DCHECK(last_range == range_for_next_append_);
+  }
 }
 
 bool SourceBufferStream::Append(
@@ -1406,8 +1419,13 @@ base::TimeDelta SourceBufferRange::GetBufferedEndTimestamp() const {
 bool SourceBufferRange::IsNextInSequence(
     const scoped_refptr<media::StreamParserBuffer>& buffer,
     base::TimeDelta timestamp) const {
-  return buffer->GetDecodeTimestamp() < timestamp &&
-      timestamp <= buffer->GetDecodeTimestamp() + GetFudgeRoom();
+  return AreAdjacentInSequence(buffer->GetDecodeTimestamp(), timestamp);
+}
+
+bool SourceBufferRange::AreAdjacentInSequence(
+    base::TimeDelta first_timestamp, base::TimeDelta second_timestamp) const {
+  return first_timestamp < second_timestamp &&
+      second_timestamp <= first_timestamp + GetFudgeRoom();
 }
 
 base::TimeDelta SourceBufferRange::GetFudgeRoom() const {