mkvmuxer: Write last block in each Cluster with Duration

This helps browsers implementing Media Source Extensions (MSE) to
know the exact duration of a Cluster without relying on the next
Cluster.

Change-Id: Idd0422e432430c5702a4864740f89fc6d3c85189

mkvmuxer.cpp

@@ -18,6 +18,7 @@
 #include <ctime>
 #include <memory>
 #include <new>
+#include <vector>
 
 #include "mkvmuxerutil.hpp"
 #include "mkvparser/mkvparser.hpp"
@@ -148,6 +149,7 @@ Frame::Frame()
       additional_(NULL),
       additional_length_(0),
       duration_(0),
+      duration_set_(false),
       frame_(NULL),
       is_key_(false),
       length_(0),
@@ -180,6 +182,7 @@ bool Frame::CopyFrom(const Frame& frame) {
     return false;
   }
   duration_ = frame.duration();
+  duration_set_ = frame.duration_set();
   is_key_ = frame.is_key();
   track_number_ = frame.track_number();
   timestamp_ = frame.timestamp();
@@ -240,6 +243,11 @@ bool Frame::CanBeSimpleBlock() const {
   return additional_ == NULL && discard_padding_ == 0 && duration_ == 0;
 }
 
+void Frame::set_duration(uint64 duration) {
+  duration_ = duration;
+  duration_set_ = true;
+}
+
 void Frame::set_reference_block_timestamp(int64 reference_block_timestamp) {
   reference_block_timestamp_ = reference_block_timestamp;
   reference_block_timestamp_set_ = true;
@@ -2071,7 +2079,8 @@ bool Tags::ExpandTagsArray() {
 //
 // Cluster class
 
-Cluster::Cluster(uint64 timecode, int64 cues_pos, uint64 timecode_scale)
+Cluster::Cluster(uint64 timecode, int64 cues_pos, uint64 timecode_scale,
+                 bool write_last_frame_with_duration)
     : blocks_added_(0),
       finalized_(false),
       header_written_(false),
@@ -2080,6 +2089,7 @@ Cluster::Cluster(uint64 timecode, int64 cues_pos, uint64 timecode_scale)
       size_position_(-1),
       timecode_(timecode),
       timecode_scale_(timecode_scale),
+      write_last_frame_with_duration_(write_last_frame_with_duration),
       writer_(NULL) {}
 
 Cluster::~Cluster() {}
@@ -2092,7 +2102,9 @@ bool Cluster::Init(IMkvWriter* ptr_writer) {
   return true;
 }
 
-bool Cluster::AddFrame(const Frame* const frame) { return DoWriteFrame(frame); }
+bool Cluster::AddFrame(const Frame* const frame) {
+  return QueueOrWriteFrame(frame);
+}
 
 bool Cluster::AddFrame(const uint8* data, uint64 length, uint64 track_number,
                        uint64 abs_timecode, bool is_key) {
@@ -2102,7 +2114,7 @@ bool Cluster::AddFrame(const uint8* data, uint64 length, uint64 track_number,
   frame.set_track_number(track_number);
   frame.set_timestamp(abs_timecode);
   frame.set_is_key(is_key);
-  return DoWriteFrame(&frame);
+  return QueueOrWriteFrame(&frame);
 }
 
 bool Cluster::AddFrameWithAdditional(const uint8* data, uint64 length,
@@ -2121,7 +2133,7 @@ bool Cluster::AddFrameWithAdditional(const uint8* data, uint64 length,
   frame.set_track_number(track_number);
   frame.set_timestamp(abs_timecode);
   frame.set_is_key(is_key);
-  return DoWriteFrame(&frame);
+  return QueueOrWriteFrame(&frame);
 }
 
 bool Cluster::AddFrameWithDiscardPadding(const uint8* data, uint64 length,
@@ -2135,7 +2147,7 @@ bool Cluster::AddFrameWithDiscardPadding(const uint8* data, uint64 length,
   frame.set_track_number(track_number);
   frame.set_timestamp(abs_timecode);
   frame.set_is_key(is_key);
-  return DoWriteFrame(&frame);
+  return QueueOrWriteFrame(&frame);
 }
 
 bool Cluster::AddMetadata(const uint8* data, uint64 length, uint64 track_number,
@@ -2147,13 +2159,58 @@ bool Cluster::AddMetadata(const uint8* data, uint64 length, uint64 track_number,
   frame.set_timestamp(abs_timecode);
   frame.set_duration(duration_timecode);
   frame.set_is_key(true);  // All metadata blocks are keyframes.
-  return DoWriteFrame(&frame);
+  return QueueOrWriteFrame(&frame);
 }
 
 void Cluster::AddPayloadSize(uint64 size) { payload_size_ += size; }
 
 bool Cluster::Finalize() {
-  if (!writer_ || finalized_ || size_position_ == -1)
+  return !write_last_frame_with_duration_ && Finalize(false, 0);
+}
+
+bool Cluster::Finalize(bool set_last_frame_duration, uint64 duration) {
+  if (!writer_ || finalized_)
+    return false;
+
+  if (write_last_frame_with_duration_) {
+    // Write out held back Frames. This essentially performs a k-way merge
+    // across all tracks in the increasing order of timestamps.
+    while (!stored_frames_.empty()) {
+      Frame* frame = stored_frames_.begin()->second.front();
+
+      // Get the next frame to write (frame with least timestamp across all
+      // tracks).
+      for (FrameMapIterator frames_iterator = ++stored_frames_.begin();
+           frames_iterator != stored_frames_.end(); ++frames_iterator) {
+        if (frames_iterator->second.front()->timestamp() < frame->timestamp()) {
+          frame = frames_iterator->second.front();
+        }
+      }
+
+      // Set the duration if it's the last frame for the track.
+      if (set_last_frame_duration &&
+          stored_frames_[frame->track_number()].size() == 1 &&
+          !frame->duration_set()) {
+        frame->set_duration(duration - frame->timestamp());
+        if (!frame->is_key() && !frame->reference_block_timestamp_set()) {
+          frame->set_reference_block_timestamp(
+              last_block_timestamp_[frame->track_number()]);
+        }
+      }
+
+      // Write the frame and remove it from |stored_frames_|.
+      const bool wrote_frame = DoWriteFrame(frame);
+      stored_frames_[frame->track_number()].pop_front();
+      if (stored_frames_[frame->track_number()].empty()) {
+        stored_frames_.erase(frame->track_number());
+      }
+      delete frame;
+      if (!wrote_frame)
+        return false;
+    }
+  }
+
+  if (size_position_ == -1)
     return false;
 
   if (writer_->Seekable()) {
@@ -2220,6 +2277,62 @@ bool Cluster::DoWriteFrame(const Frame* const frame) {
     return false;
 
   PostWriteBlock(element_size);
+  last_block_timestamp_[frame->track_number()] = frame->timestamp();
+  return true;
+}
+
+bool Cluster::QueueOrWriteFrame(const Frame* const frame) {
+  if (!frame || !frame->IsValid())
+    return false;
+
+  // If |write_last_frame_with_duration_| is not set, then write the frame right
+  // away.
+  if (!write_last_frame_with_duration_) {
+    return DoWriteFrame(frame);
+  }
+
+  // Queue the current frame.
+  uint64 track_number = frame->track_number();
+  Frame* const frame_to_store = new Frame();
+  frame_to_store->CopyFrom(*frame);
+  stored_frames_[track_number].push_back(frame_to_store);
+
+  // Iterate through all queued frames in the current track except the last one
+  // and write it if it is okay to do so (i.e.) no other track has an held back
+  // frame with timestamp <= the timestamp of the frame in question.
+  std::vector<std::list<Frame*>::iterator> frames_to_erase;
+  for (std::list<Frame *>::iterator
+           current_track_iterator = stored_frames_[track_number].begin(),
+           end = --stored_frames_[track_number].end();
+       current_track_iterator != end; ++current_track_iterator) {
+    const Frame* const frame_to_write = *current_track_iterator;
+    bool okay_to_write = true;
+    for (FrameMapIterator track_iterator = stored_frames_.begin();
+         track_iterator != stored_frames_.end(); ++track_iterator) {
+      if (track_iterator->first == track_number) {
+        continue;
+      }
+      if (track_iterator->second.front()->timestamp() <
+          frame_to_write->timestamp()) {
+        okay_to_write = false;
+        break;
+      }
+    }
+    if (okay_to_write) {
+      const bool wrote_frame = DoWriteFrame(frame_to_write);
+      delete frame_to_write;
+      if (!wrote_frame)
+        return false;
+      frames_to_erase.push_back(current_track_iterator);
+    } else {
+      break;
+    }
+  }
+  for (std::vector<std::list<Frame*>::iterator>::iterator iterator =
+           frames_to_erase.begin();
+       iterator != frames_to_erase.end(); ++iterator) {
+    stored_frames_[track_number].erase(*iterator);
+  }
   return true;
 }
 
@@ -2716,15 +2829,17 @@ bool Segment::Finalize() {
   if (WriteFramesAll() < 0)
     return false;
 
+  if (cluster_list_size_ > 0) {
+    // Update last cluster's size
+    Cluster* const old_cluster = cluster_list_[cluster_list_size_ - 1];
+
+    // For the last frame of the last Cluster, we don't write it as a BlockGroup
+    // with Duration unless the frame itself has duration set explicitly.
+    if (!old_cluster || !old_cluster->Finalize(false, 0))
+      return false;
+  }
+
   if (mode_ == kFile) {
-    if (cluster_list_size_ > 0) {
-      // Update last cluster's size
-      Cluster* const old_cluster = cluster_list_[cluster_list_size_ - 1];
-
-      if (!old_cluster || !old_cluster->Finalize())
-        return false;
-    }
-
     if (chunking_ && chunk_writer_cluster_) {
       chunk_writer_cluster_->Close();
       chunk_count_++;
@@ -3023,6 +3138,10 @@ bool Segment::AddGenericFrame(const Frame* frame) {
 
 void Segment::OutputCues(bool output_cues) { output_cues_ = output_cues; }
 
+void Segment::AccurateClusterDuration(bool accurate_cluster_duration) {
+  accurate_cluster_duration_ = accurate_cluster_duration;
+}
+
 bool Segment::SetChunking(bool chunking, const char* filename) {
   if (chunk_count_ > 0)
     return false;
@@ -3288,19 +3407,17 @@ bool Segment::MakeNewCluster(uint64 frame_timestamp_ns) {
   if (!WriteFramesLessThan(frame_timestamp_ns))
     return false;
 
-  if (mode_ == kFile) {
-    if (cluster_list_size_ > 0) {
-      // Update old cluster's size
-      Cluster* const old_cluster = cluster_list_[cluster_list_size_ - 1];
+  if (cluster_list_size_ > 0) {
+    // Update old cluster's size
+    Cluster* const old_cluster = cluster_list_[cluster_list_size_ - 1];
 
-      if (!old_cluster || !old_cluster->Finalize())
-        return false;
-    }
-
-    if (output_cues_)
-      new_cuepoint_ = true;
+    if (!old_cluster || !old_cluster->Finalize(true, frame_timestamp_ns))
+      return false;
   }
 
+  if (output_cues_)
+    new_cuepoint_ = true;
+
   if (chunking_ && cluster_list_size_ > 0) {
     chunk_writer_cluster_->Close();
     chunk_count_++;
@@ -3327,8 +3444,9 @@ bool Segment::MakeNewCluster(uint64 frame_timestamp_ns) {
 
   Cluster*& cluster = cluster_list_[cluster_list_size_];
   const int64 offset = MaxOffset();
-  cluster = new (std::nothrow) Cluster(cluster_timecode,  // NOLINT
-                                       offset, segment_info_.timecode_scale());
+  cluster = new (std::nothrow)
+      Cluster(cluster_timecode, offset, segment_info_.timecode_scale(),
+              accurate_cluster_duration_);
   if (!cluster)
     return false;
 

mkvmuxer.hpp

@@ -10,6 +10,8 @@
 #define MKVMUXER_HPP
 
 #include <cstddef>
+#include <list>
+#include <map>
 
 #include "mkvmuxertypes.hpp"
 #include "webmids.hpp"
@@ -101,8 +103,9 @@ class Frame {
   uint64 add_id() const { return add_id_; }
   const uint8* additional() const { return additional_; }
   uint64 additional_length() const { return additional_length_; }
-  void set_duration(uint64 duration) { duration_ = duration; }
+  void set_duration(uint64 duration);
   uint64 duration() const { return duration_; }
+  bool duration_set() const { return duration_set_; }
   const uint8* frame() const { return frame_; }
   void set_is_key(bool key) { is_key_ = key; }
   bool is_key() const { return is_key_; }
@@ -134,6 +137,11 @@ class Frame {
   // Duration of the frame in nanoseconds.
   uint64 duration_;
 
+  // Flag indicating that |duration_| has been set. Setting duration causes the
+  // frame to be written out as a Block with BlockDuration instead of as a
+  // SimpleBlock.
+  bool duration_set_;
+
   // Pointer to the data. Owned by this class.
   uint8* frame_;
 
@@ -978,7 +986,8 @@ class Cluster {
   // |timecode| is the absolute timecode of the cluster. |cues_pos| is the
   // position for the cluster within the segment that should be written in
   // the cues element. |timecode_scale| is the timecode scale of the segment.
-  Cluster(uint64 timecode, int64 cues_pos, uint64 timecode_scale);
+  Cluster(uint64 timecode, int64 cues_pos, uint64 timecode_scale,
+          bool write_last_frame_with_duration = false);
   ~Cluster();
 
   bool Init(IMkvWriter* ptr_writer);
@@ -1055,9 +1064,22 @@ class Cluster {
   void AddPayloadSize(uint64 size);
 
   // Closes the cluster so no more data can be written to it. Will update the
-  // cluster's size if |writer_| is seekable. Returns true on success.
+  // cluster's size if |writer_| is seekable. Returns true on success. This
+  // variant of Finalize() fails when |write_last_frame_with_duration_| is set
+  // to true.
   bool Finalize();
 
+  // Closes the cluster so no more data can be written to it. Will update the
+  // cluster's size if |writer_| is seekable. Returns true on success.
+  // Inputs:
+  //   set_last_frame_duration: Boolean indicating whether or not the duration
+  //                            of the last frame should be set. If set to
+  //                            false, the |duration| value is ignored and
+  //                            |write_last_frame_with_duration_| will not be
+  //                            honored.
+  //   duration: Duration of the Cluster in timecode scale.
+  bool Finalize(bool set_last_frame_duration, uint64 duration);
+
   // Returns the size in bytes for the entire Cluster element.
   uint64 Size() const;
 
@@ -1071,8 +1093,17 @@ class Cluster {
   int64 position_for_cues() const { return position_for_cues_; }
   uint64 timecode() const { return timecode_; }
   uint64 timecode_scale() const { return timecode_scale_; }
+  void set_write_last_frame_with_duration(bool write_last_frame_with_duration) {
+    write_last_frame_with_duration_ = write_last_frame_with_duration;
+  }
+  bool write_last_frame_with_duration() const {
+    return write_last_frame_with_duration_;
+  }
 
  private:
+  // Iterator type for the |stored_frames_| map.
+  typedef std::map<uint64, std::list<Frame*> >::iterator FrameMapIterator;
+
   // Utility method that confirms that blocks can still be added, and that the
   // cluster header has been written. Used by |DoWriteFrame*|. Returns true
   // when successful.
@@ -1085,6 +1116,10 @@ class Cluster {
   // Does some verification and calls WriteFrame.
   bool DoWriteFrame(const Frame* const frame);
 
+  // Either holds back the given frame, or writes it out depending on whether or
+  // not |write_last_frame_with_duration_| is set.
+  bool QueueOrWriteFrame(const Frame* const frame);
+
   // Outputs the Cluster header to |writer_|. Returns true on success.
   bool WriteClusterHeader();
 
@@ -1112,6 +1147,19 @@ class Cluster {
   // The timecode scale of the Segment containing the cluster.
   const uint64 timecode_scale_;
 
+  // Flag indicating whether the last frame of the cluster should be written as
+  // a Block with Duration. If set to true, then it will result in holding back
+  // of frames and the parameterized version of Finalize() must be called to
+  // finish writing the Cluster.
+  bool write_last_frame_with_duration_;
+
+  // Map used to hold back frames, if required. Track number is the key.
+  std::map<uint64, std::list<Frame*> > stored_frames_;
+
+  // Map from track number to the timestamp of the last block written for that
+  // track.
+  std::map<uint64, uint64> last_block_timestamp_;
+
   // Pointer to the writer object. Not owned by this class.
   IMkvWriter* writer_;
 
@@ -1387,6 +1435,9 @@ class Segment {
   // Toggles whether to output a cues element.
   void OutputCues(bool output_cues);
 
+  // Toggles whether to write the last frame in each Cluster with Duration.
+  void AccurateClusterDuration(bool accurate_cluster_duration);
+
   // Sets if the muxer will output files in chunks or not. |chunking| is a
   // flag telling whether or not to turn on chunking. |filename| is the base
   // filename for the chunk files. The header chunk file will be named
@@ -1587,6 +1638,10 @@ class Segment {
   // Flag whether or not the muxer should output a Cues element.
   bool output_cues_;
 
+  // Flag whether or not the last frame in each Cluster will have a Duration
+  // element in it.
+  bool accurate_cluster_duration_;
+
   // The size of the EBML header, used to validate the header if
   // WriteEbmlHeader() is called more than once.
   int32 ebml_header_size_;

sample_muxer.cpp

@@ -54,6 +54,8 @@ void Usage() {
   printf("  -video_track_number <int>   >0 Changes the video track number\n");
   printf("  -chunking <string>          Chunk output\n");
   printf("  -copy_tags <int>            >0 Copies the tags\n");
+  printf("  -accurate_cluster_duration <int> ");
+  printf(">0 Writes the last frame in each cluster with Duration\n");
   printf("\n");
   printf("Video options:\n");
   printf("  -display_width <int>        Display width in pixels\n");
@@ -164,6 +166,7 @@ int main(int argc, char* argv[]) {
   bool chunking = false;
   bool copy_tags = false;
   const char* chunk_name = NULL;
+  bool accurate_cluster_duration = false;
 
   bool output_cues_block_number = true;
 
@@ -219,6 +222,10 @@ int main(int argc, char* argv[]) {
       chunk_name = argv[++i];
     } else if (!strcmp("-copy_tags", argv[i]) && i < argc_check) {
       copy_tags = strtol(argv[++i], &end, 10) == 0 ? false : true;
+    } else if (!strcmp("-accurate_cluster_duration", argv[i]) &&
+               i < argc_check) {
+      accurate_cluster_duration =
+          strtol(argv[++i], &end, 10) == 0 ? false : true;
     } else if (!strcmp("-display_width", argv[i]) && i < argc_check) {
       display_width = strtol(argv[++i], &end, 10);
     } else if (!strcmp("-display_height", argv[i]) && i < argc_check) {
@@ -297,6 +304,8 @@ int main(int argc, char* argv[]) {
     return EXIT_FAILURE;
   }
 
+  muxer_segment.AccurateClusterDuration(accurate_cluster_duration);
+
   if (live_mode)
     muxer_segment.set_mode(libwebm::mkvmuxer::Segment::kLive);
   else

testing/muxer_tests.cc

@@ -96,13 +96,14 @@ class MuxerTest : public testing::Test {
     is_writer_open_ = false;
   }
 
-  bool SegmentInit(bool output_cues) {
+  bool SegmentInit(bool output_cues, bool accurate_cluster_duration) {
     if (!segment_.Init(writer_.get()))
       return false;
     SegmentInfo* const info = segment_.GetSegmentInfo();
     info->set_writing_app(kAppString);
     info->set_muxing_app(kAppString);
     segment_.OutputCues(output_cues);
+    segment_.AccurateClusterDuration(accurate_cluster_duration);
     return true;
   }
 
@@ -116,7 +117,7 @@ class MuxerTest : public testing::Test {
 };
 
 TEST_F(MuxerTest, SegmentInfo) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   SegmentInfo* const info = segment_.GetSegmentInfo();
   info->set_timecode_scale(kTimeCodeScale);
   info->set_duration(2.345);
@@ -133,7 +134,7 @@ TEST_F(MuxerTest, SegmentInfo) {
 }
 
 TEST_F(MuxerTest, AddTracks) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
 
   // Add a Video Track
   AddVideoTrack();
@@ -177,7 +178,7 @@ TEST_F(MuxerTest, AddTracks) {
 }
 
 TEST_F(MuxerTest, AddChapters) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   // Add a Chapter
@@ -194,7 +195,7 @@ TEST_F(MuxerTest, AddChapters) {
 }
 
 TEST_F(MuxerTest, SimpleBlock) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   // Valid Frame
@@ -222,7 +223,7 @@ TEST_F(MuxerTest, SimpleBlock) {
 }
 
 TEST_F(MuxerTest, SimpleBlockWithAddGenericFrame) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   Frame frame;
@@ -254,7 +255,7 @@ TEST_F(MuxerTest, SimpleBlockWithAddGenericFrame) {
 }
 
 TEST_F(MuxerTest, MetadataBlock) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   Track* const track = segment_.AddTrack(kMetadataTrackNumber);
   track->set_uid(kMetadataTrackNumber);
   track->set_type(kMetadataTrackType);
@@ -285,7 +286,7 @@ TEST_F(MuxerTest, MetadataBlock) {
 }
 
 TEST_F(MuxerTest, TrackType) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   Track* const track = segment_.AddTrack(kMetadataTrackNumber);
   track->set_uid(kMetadataTrackNumber);
   track->set_codec_id(kMetadataCodecId);
@@ -305,7 +306,7 @@ TEST_F(MuxerTest, TrackType) {
 }
 
 TEST_F(MuxerTest, BlockWithAdditional) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   // Valid Frame
@@ -346,7 +347,7 @@ TEST_F(MuxerTest, BlockWithAdditional) {
 }
 
 TEST_F(MuxerTest, BlockAdditionalWithAddGenericFrame) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   Frame frame;
@@ -381,7 +382,7 @@ TEST_F(MuxerTest, BlockAdditionalWithAddGenericFrame) {
 }
 
 TEST_F(MuxerTest, SegmentDurationComputation) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   Frame frame;
@@ -409,7 +410,7 @@ TEST_F(MuxerTest, SegmentDurationComputation) {
 }
 
 TEST_F(MuxerTest, ForceNewCluster) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
 
   EXPECT_TRUE(segment_.AddFrame(dummy_data_, kFrameLength, kVideoTrackNumber, 0,
@@ -431,7 +432,7 @@ TEST_F(MuxerTest, ForceNewCluster) {
 }
 
 TEST_F(MuxerTest, OutputCues) {
-  EXPECT_TRUE(SegmentInit(true));
+  EXPECT_TRUE(SegmentInit(true, false));
   AddVideoTrack();
 
   EXPECT_TRUE(
@@ -451,7 +452,7 @@ TEST_F(MuxerTest, OutputCues) {
 }
 
 TEST_F(MuxerTest, CuesBeforeClusters) {
-  EXPECT_TRUE(SegmentInit(true));
+  EXPECT_TRUE(SegmentInit(true, false));
   AddVideoTrack();
 
   EXPECT_TRUE(
@@ -484,7 +485,7 @@ TEST_F(MuxerTest, CuesBeforeClusters) {
 }
 
 TEST_F(MuxerTest, MaxClusterSize) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
   const uint64 kMaxClusterSize = 20;
   segment_.set_max_cluster_size(kMaxClusterSize);
@@ -509,7 +510,7 @@ TEST_F(MuxerTest, MaxClusterSize) {
 }
 
 TEST_F(MuxerTest, MaxClusterDuration) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddVideoTrack();
   const uint64 kMaxClusterDuration = 4000000;
   segment_.set_max_cluster_duration(kMaxClusterDuration);
@@ -537,7 +538,7 @@ TEST_F(MuxerTest, MaxClusterDuration) {
 
 TEST_F(MuxerTest, SetCuesTrackNumber) {
   const uint64 kTrackNumber = 10;
-  EXPECT_TRUE(SegmentInit(true));
+  EXPECT_TRUE(SegmentInit(true, false));
   const uint64 vid_track =
       segment_.AddVideoTrack(kWidth, kHeight, kTrackNumber);
   EXPECT_EQ(kTrackNumber, vid_track);
@@ -566,7 +567,7 @@ TEST_F(MuxerTest, SetCuesTrackNumber) {
 }
 
 TEST_F(MuxerTest, BlockWithDiscardPadding) {
-  EXPECT_TRUE(SegmentInit(false));
+  EXPECT_TRUE(SegmentInit(false, false));
   AddAudioTrack();
 
   int timecode = 1000;
@@ -588,6 +589,120 @@ TEST_F(MuxerTest, BlockWithDiscardPadding) {
   EXPECT_TRUE(CompareFiles(GetTestFilePath("discard_padding.webm"), filename_));
 }
 
+TEST_F(MuxerTest, AccurateClusterDuration) {
+  EXPECT_TRUE(SegmentInit(false, true));
+  AddVideoTrack();
+
+  Frame frame;
+  frame.Init(dummy_data_, kFrameLength);
+  frame.set_track_number(kVideoTrackNumber);
+  frame.set_timestamp(0);
+  frame.set_is_key(true);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.ForceNewClusterOnNextFrame();
+  frame.set_timestamp(2000000);
+  frame.set_is_key(false);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  frame.set_timestamp(4000000);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.ForceNewClusterOnNextFrame();
+  frame.set_timestamp(6000000);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.Finalize();
+
+  CloseWriter();
+
+  EXPECT_TRUE(CompareFiles(GetTestFilePath("accurate_cluster_duration.webm"),
+                           filename_));
+}
+
+// Tests AccurateClusterDuration flag with the duration of the very last block
+// of the file set explicitly.
+TEST_F(MuxerTest, AccurateClusterDurationExplicitLastFrameDuration) {
+  EXPECT_TRUE(SegmentInit(false, true));
+  AddVideoTrack();
+
+  Frame frame;
+  frame.Init(dummy_data_, kFrameLength);
+  frame.set_track_number(kVideoTrackNumber);
+  frame.set_timestamp(0);
+  frame.set_is_key(true);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.ForceNewClusterOnNextFrame();
+  frame.set_timestamp(2000000);
+  frame.set_is_key(false);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  frame.set_timestamp(4000000);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.ForceNewClusterOnNextFrame();
+  frame.set_timestamp(6000000);
+  frame.set_duration(2000000);
+  EXPECT_TRUE(segment_.AddGenericFrame(&frame));
+  segment_.Finalize();
+
+  // SegmentInfo's duration is in timecode scale
+  EXPECT_EQ(8, segment_.GetSegmentInfo()->duration());
+
+  CloseWriter();
+
+  EXPECT_TRUE(CompareFiles(
+      GetTestFilePath("accurate_cluster_duration_last_frame.webm"), filename_));
+}
+
+TEST_F(MuxerTest, AccurateClusterDurationTwoTracks) {
+  EXPECT_TRUE(SegmentInit(false, true));
+  AddVideoTrack();
+  AddAudioTrack();
+
+  Frame video_frame;
+  video_frame.Init(dummy_data_, kFrameLength);
+  video_frame.set_track_number(kVideoTrackNumber);
+  Frame audio_frame;
+  audio_frame.Init(dummy_data_, kFrameLength);
+  audio_frame.set_track_number(kAudioTrackNumber);
+  std::array<std::uint64_t, 2> cluster_timestamps = {{0, 40000000}};
+  for (const std::uint64_t cluster_timestamp : cluster_timestamps) {
+    // Add video and audio frames with timestamp 0.
+    video_frame.set_timestamp(cluster_timestamp);
+    video_frame.set_is_key(true);
+    EXPECT_TRUE(segment_.AddGenericFrame(&video_frame));
+    audio_frame.set_timestamp(cluster_timestamp);
+    audio_frame.set_is_key(true);
+    EXPECT_TRUE(segment_.AddGenericFrame(&audio_frame));
+
+    // Add 3 consecutive audio frames.
+    std::array<std::uint64_t, 3> audio_timestamps = {
+        {10000000, 20000000, 30000000}};
+    for (const std::uint64_t audio_timestamp : audio_timestamps) {
+      audio_frame.set_timestamp(cluster_timestamp + audio_timestamp);
+      // Explicitly set duration for the very last audio frame.
+      if (cluster_timestamp == 40000000 && audio_timestamp == 30000000) {
+        audio_frame.set_duration(10000000);
+      }
+      EXPECT_TRUE(segment_.AddGenericFrame(&audio_frame));
+    }
+
+    // Add a video frame with timestamp 33ms.
+    video_frame.set_is_key(false);
+    // Explicitly set duration for the very last video frame.
+    if (cluster_timestamp == 40000000) {
+      video_frame.set_duration(7000000);
+    }
+    video_frame.set_timestamp(cluster_timestamp + 33000000);
+    EXPECT_TRUE(segment_.AddGenericFrame(&video_frame));
+    segment_.ForceNewClusterOnNextFrame();
+  }
+  segment_.Finalize();
+
+  // SegmentInfo's duration is in timecode scale
+  EXPECT_EQ(80, segment_.GetSegmentInfo()->duration());
+
+  CloseWriter();
+
+  EXPECT_TRUE(CompareFiles(
+      GetTestFilePath("accurate_cluster_duration_two_tracks.webm"), filename_));
+}
+
 }  // namespace test
 }  // namespace libwebm