Add initial support for edit lists in MSE BMFF.

BUG=135665
TEST=TrackRunIteratorTest.ReorderingTest

Review URL: https://chromiumcodereview.appspot.com/10832176

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150478 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 56 insertions, 5 deletions

diff --git a/media/mp4/mp4_stream_parser.cc b/media/mp4/mp4_stream_parser.cc
index 9c9b750..1aa8c70 100644
--- a/media/mp4/mp4_stream_parser.cc
+++ b/media/mp4/mp4_stream_parser.cc
@@ -145,7 +145,6 @@ bool MP4StreamParser::ParseBox(bool* err) {
 
 
 bool MP4StreamParser::ParseMoov(BoxReader* reader) {
-  // TODO(strobe): Respect edit lists.
   moov_.reset(new Movie);
   RCHECK(moov_->Parse(reader));
   runs_.reset(new TrackRunIterator(moov_.get()));
diff --git a/media/mp4/track_run_iterator.cc b/media/mp4/track_run_iterator.cc
index 59bc229..073eeee 100644
--- a/media/mp4/track_run_iterator.cc
+++ b/media/mp4/track_run_iterator.cc
@@ -71,6 +71,7 @@ TrackRunIterator::~TrackRunIterator() {}
 static void PopulateSampleInfo(const TrackExtends& trex,
                                const TrackFragmentHeader& tfhd,
                                const TrackFragmentRun& trun,
+                               const int64 edit_list_offset,
                                const uint32 i,
                                SampleInfo* sample_info) {
   if (i < trun.sample_sizes.size()) {
@@ -94,6 +95,7 @@ static void PopulateSampleInfo(const TrackExtends& trex,
   } else {
     sample_info->cts_offset = 0;
   }
+  sample_info->cts_offset += edit_list_offset;
 
   uint32 flags;
   if (i < trun.sample_flags.size()) {
@@ -164,6 +166,23 @@ bool TrackRunIterator::Init(const MovieFragment& moof) {
     RCHECK(desc_idx > 0);  // Descriptions are one-indexed in the file
     desc_idx -= 1;
 
+    // Process edit list to remove CTS offset introduced in the presence of
+    // B-frames (those that contain a single edit with a nonnegative media
+    // time). Other uses of edit lists are not supported, as they are
+    // both uncommon and better served by higher-level protocols.
+    int64 edit_list_offset = 0;
+    const std::vector<EditListEntry>& edits = trak->edit.list.edits;
+    if (!edits.empty()) {
+      if (edits.size() > 1)
+        DVLOG(1) << "Multi-entry edit box detected; some components ignored.";
+
+      if (edits[0].media_time < 0) {
+        DVLOG(1) << "Empty edit list entry ignored.";
+      } else {
+        edit_list_offset = -edits[0].media_time;
+      }
+    }
+
     int64 run_start_dts = traf.decode_time.decode_time;
     int sample_count_sum = 0;
 
@@ -226,7 +245,8 @@ bool TrackRunIterator::Init(const MovieFragment& moof) {
 
       tri.samples.resize(trun.sample_count);
       for (size_t k = 0; k < trun.sample_count; k++) {
-        PopulateSampleInfo(*trex, traf.header, trun, k, &tri.samples[k]);
+        PopulateSampleInfo(*trex, traf.header, trun, edit_list_offset,
+                           k, &tri.samples[k]);
         run_start_dts += tri.samples[k].duration;
       }
       runs_.push_back(tri);
diff --git a/media/mp4/track_run_iterator_unittest.cc b/media/mp4/track_run_iterator_unittest.cc
index e1c1a03..40385cc 100644
--- a/media/mp4/track_run_iterator_unittest.cc
+++ b/media/mp4/track_run_iterator_unittest.cc
@@ -261,23 +261,55 @@ TEST_F(TrackRunIteratorTest, MinDecodeTest) {
 }
 
 TEST_F(TrackRunIteratorTest, ReorderingTest) {
+  // Test frame reordering and edit list support. The frames have the following
+  // decode timestamps:
+  //
+  //   0ms 40ms   120ms     240ms
+  //   | 0 | 1  - | 2  -  - |
+  //
+  // ...and these composition timestamps, after edit list adjustment:
+  //
+  //   0ms 40ms       160ms  240ms
+  //   | 0 | 2  -  -  | 1 - |
+
+  // Create an edit list with one entry, with an initial start time of 80ms
+  // (that is, 2 / kVideoTimescale) and a duration of zero (which is treated as
+  // infinite according to 14496-12:2012). This will cause the first 80ms of the
+  // media timeline - which will be empty, due to CTS biasing - to be discarded.
   iter_.reset(new TrackRunIterator(&moov_));
+  EditListEntry entry;
+  entry.segment_duration = 0;
+  entry.media_time = 2;
+  entry.media_rate_integer = 1;
+  entry.media_rate_fraction = 0;
+  moov_.tracks[1].edit.list.edits.push_back(entry);
+
+  // Add CTS offsets. Without bias, the CTS offsets for the first three frames
+  // would simply be [0, 3, -2]. Since CTS offsets should be non-negative for
+  // maximum compatibility, these values are biased up to [2, 5, 0], and the
+  // extra 80ms is removed via the edit list.
   MovieFragment moof = CreateFragment();
   std::vector<int32>& cts_offsets =
     moof.tracks[1].runs[0].sample_composition_time_offsets;
   cts_offsets.resize(10);
   cts_offsets[0] = 2;
-  cts_offsets[1] = -1;
+  cts_offsets[1] = 5;
+  cts_offsets[2] = 0;
   moof.tracks[1].decode_time.decode_time = 0;
+
   ASSERT_TRUE(iter_->Init(moof));
   iter_->AdvanceRun();
   EXPECT_EQ(iter_->dts(), TimeDeltaFromRational(0, kVideoScale));
-  EXPECT_EQ(iter_->cts(), TimeDeltaFromRational(2, kVideoScale));
+  EXPECT_EQ(iter_->cts(), TimeDeltaFromRational(0, kVideoScale));
   EXPECT_EQ(iter_->duration(), TimeDeltaFromRational(1, kVideoScale));
   iter_->AdvanceSample();
   EXPECT_EQ(iter_->dts(), TimeDeltaFromRational(1, kVideoScale));
-  EXPECT_EQ(iter_->cts(), TimeDeltaFromRational(0, kVideoScale));
+  EXPECT_EQ(iter_->cts(), TimeDeltaFromRational(4, kVideoScale));
   EXPECT_EQ(iter_->duration(), TimeDeltaFromRational(2, kVideoScale));
+  iter_->AdvanceSample();
+  EXPECT_EQ(iter_->dts(), TimeDeltaFromRational(3, kVideoScale));
+  EXPECT_EQ(iter_->cts(), TimeDeltaFromRational(1, kVideoScale));
+  EXPECT_EQ(iter_->duration(), TimeDeltaFromRational(3, kVideoScale));
 }
 
 TEST_F(TrackRunIteratorTest, IgnoreUnknownAuxInfoTest) {