Add initial support for edit lists in MSE BMFF.

media/mp4/track_run_iterator.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/mp4/track_run_iterator.h"
 
 #include <algorithm>
 
 #include "media/base/stream_parser_buffer.h"
 #include "media/mp4/rcheck.h"
@@ skipping 53 matching lines @@
 
 TrackRunIterator::TrackRunIterator(const Movie* moov)
     : moov_(moov), sample_offset_(0) {
   CHECK(moov);
 }
 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()) {
     sample_info->size = trun.sample_sizes[i];
   } else if (tfhd.default_sample_size > 0) {
     sample_info->size = tfhd.default_sample_size;
   } else {
     sample_info->size = trex.default_sample_size;
   }
 
   if (i < trun.sample_durations.size()) {
     sample_info->duration = trun.sample_durations[i];
   } else if (tfhd.default_sample_duration > 0) {
     sample_info->duration = tfhd.default_sample_duration;
   } else {
     sample_info->duration = trex.default_sample_duration;
   }
 
   if (i < trun.sample_composition_time_offsets.size()) {
     sample_info->cts_offset = trun.sample_composition_time_offsets[i];
   } else {
     sample_info->cts_offset = 0;
   }
+  sample_info->cts_offset += edit_list_offset;
 
   uint32 flags;
   if (i < trun.sample_flags.size()) {
     flags = trun.sample_flags[i];
   } else if (tfhd.has_default_sample_flags) {
     flags = tfhd.default_sample_flags;
   } else {
     flags = trex.default_sample_flags;
   }
   sample_info->is_keyframe = !(flags & kSampleIsDifferenceSampleFlagMask);
@@ skipping 50 matching lines @@
         trak->media.information.sample_table.description;
     if (stsd.type != kAudio && stsd.type != kVideo) {
       DVLOG(1) << "Skipping unhandled track type";
       continue;
     }
     size_t desc_idx = traf.header.sample_description_index;
     if (!desc_idx) desc_idx = trex->default_sample_description_index;
     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. Other uses of edit lists are not supported, as they are
+    // both uncommon and better served by higher-level protocols.

[acolwell GONE FROM CHROMIUM, 2012/08/07 20:12:13]

nit: It looks like there should be a 

if (stuff we don't support) { 
  DVLOG(1) << "we don't support that crazy feature"; 
  return false;
} 

in here?

[strobe_, 2012/08/07 22:54:39]

Done.

+    int64 edit_list_offset = 0;
+    const std::vector<EditListEntry>& edits = trak->edit.list.edits;
+    if (!edits.empty() && edits[0].media_time > 0) {
+      edit_list_offset = -edits[0].media_time;
+    }
+
     int64 run_start_dts = traf.decode_time.decode_time;
     int sample_count_sum = 0;
 
     for (size_t j = 0; j < traf.runs.size(); j++) {
       const TrackFragmentRun& trun = traf.runs[j];
       TrackRunInfo tri;
       tri.track_id = traf.header.track_id;
       tri.timescale = trak->media.header.timescale;
       tri.start_dts = run_start_dts;
       tri.sample_start_offset = trun.data_offset;
@@ skipping 42 matching lines @@
             tri.aux_info_total_size += tri.aux_info_sizes[k];
           }
         }
       } else {
         tri.aux_info_start_offset = -1;
         tri.aux_info_total_size = 0;
       }
 
       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);
       sample_count_sum += trun.sample_count;
     }
   }
 
   std::sort(runs_.begin(), runs_.end(), CompareMinTrackRunDataOffset());
   run_itr_ = runs_.begin();
   ResetRun();
@@ skipping 179 matching lines @@
       std::string(reinterpret_cast<const char*>(&kid[0]), kid.size()),
       std::string(reinterpret_cast<const char*>(cenc_info.iv),
                   arraysize(cenc_info.iv)),
       std::string(),  // No checksum in MP4 using CENC.
       0,  // No offset to start of media data in MP4 using CENC.
       cenc_info.subsamples));
 }
 
 }  // namespace mp4
 }  // namespace media