MSE: Record counts of detected MSE audio, video and text tracks

media/formats/mp4/box_definitions.cc

 // Copyright 2014 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/formats/mp4/box_definitions.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 443 matching lines @@
     // Check that the length of the Pascal-style string is correct.
     RCHECK(name_bytes[0] == (name_bytes.size() - 1));
     // Skip the first byte, containing the length of the Pascal-string.
     name = std::string(name_bytes.begin() + 1, name_bytes.end());
   }
 
   if (hdlr_type == FOURCC_VIDE) {
     type = kVideo;
   } else if (hdlr_type == FOURCC_SOUN) {
     type = kAudio;
+  } else if (hdlr_type == FOURCC_META || hdlr_type == FOURCC_SUBT ||

[wolenetz, 2016/03/23 01:45:50]

Note, this follows the logic in
https://dev.w3.org/html5/html-sourcing-inband-tracks/#mpeg4
Note also that 608/708 caption data inside a video track is not yet detected
(see also new https://crbug.com/597073 and new MSE spec bug
https://github.com/w3c/media-source/issues/58). tl;dr: we don't have enough
information in just an initialization segment to detect that caption data.
Discussion is ongoing in the spec bug to see how the spec might need to change
to support 608 / 708 caption data population into SourceBuffer.textTracks and
HTMLMediaElement.textTrcks.

[chcunningham, 2016/03/23 23:05:56]

Acknowledged.

+             hdlr_type == FOURCC_TEXT) {
+    type = kText;
   } else {
     type = kInvalid;
   }
   return true;
 }
 
 AVCDecoderConfigurationRecord::AVCDecoderConfigurationRecord()
     : version(0),
       profile_indication(0),
       profile_compatibility(0),
@@ skipping 673 matching lines @@
 SampleDependsOn IndependentAndDisposableSamples::sample_depends_on(
     size_t i) const {
   if (i >= sample_depends_on_.size())
     return kSampleDependsOnUnknown;
 
   return sample_depends_on_[i];
 }
 
 }  // namespace mp4
 }  // namespace media