Support encrypted audio stream in demuxer.

media/webm/webm_tracks_parser.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/webm/webm_tracks_parser.h"
 
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "media/base/buffers.h"
 #include "media/webm/webm_constants.h"
 #include "media/webm/webm_content_encodings.h"
 
 namespace media {
 
 // Values for TrackType element.
 static const int kWebMTrackTypeVideo = 1;
 static const int kWebMTrackTypeAudio = 2;
 
 WebMTracksParser::WebMTracksParser()
     : track_type_(-1),
       track_num_(-1),
       audio_track_num_(-1),
       video_track_num_(-1) {
 }
 
 WebMTracksParser::~WebMTracksParser() {}
 
-const std::string& WebMTracksParser::video_encryption_key_id() const {
-  if (!video_content_encodings_client_.get())
-    return EmptyString();
-
-  DCHECK(!video_content_encodings_client_->content_encodings().empty());
-  return video_content_encodings_client_->content_encodings()[0]->
-      encryption_key_id();
-}
-
 int WebMTracksParser::Parse(const uint8* buf, int size) {
   track_type_ =-1;
   track_num_ = -1;
   audio_track_num_ = -1;
   video_track_num_ = -1;
 
   WebMListParser parser(kWebMIdTracks, this);
   int result = parser.Parse(buf, size);
 
   if (result <= 0)
     return result;
 
   // For now we do all or nothing parsing.
   return parser.IsParsingComplete() ? result : 0;
 }
 
-
 WebMParserClient* WebMTracksParser::OnListStart(int id) {
   if (id == kWebMIdContentEncodings) {
     DCHECK(!track_content_encodings_client_.get());
     track_content_encodings_client_.reset(new WebMContentEncodingsClient);
     return track_content_encodings_client_->OnListStart(id);
   }
 
   if (id == kWebMIdTrackEntry) {
     track_type_ = -1;
     track_num_ = -1;
@@ skipping 10 matching lines @@
   }
 
   if (id == kWebMIdTrackEntry) {
     if (track_type_ == -1 || track_num_ == -1) {
       DVLOG(1) << "Missing TrackEntry data"
                << " TrackType " << track_type_
                << " TrackNum " << track_num_;
       return false;
     }
 
     if (track_type_ == kWebMTrackTypeVideo) {

[ddorwin, 2012/10/11 05:18:22]

Strange that video is processed first here. It seems to be the opposite order
most places and in the header file.

[xhwang, 2012/10/11 16:36:10]

Done.

       video_track_num_ = track_num_;
       if (track_content_encodings_client_.get()) {
-        video_content_encodings_client_ =
-            track_content_encodings_client_.Pass();
+        DCHECK(!track_content_encodings_client_->content_encodings().empty());
+        video_encryption_key_id_ = track_content_encodings_client_->
+            content_encodings()[0]->encryption_key_id();

[ddorwin, 2012/10/11 05:18:22]

Why is it the first encoding? Maybe we should comment this.
I'm guessing because we only support one type of encoding. Is there a way to
DCHECK the type of the encoding?

[xhwang, 2012/10/11 16:36:10]

Added more comments and more checks. fgalligan@: please double check if this is
correct as per WebM encryption RFC.

       }
     } else if (track_type_ == kWebMTrackTypeAudio) {
       audio_track_num_ = track_num_;
       if (track_content_encodings_client_.get()) {
-        audio_content_encodings_client_ =
-            track_content_encodings_client_.Pass();
+        DCHECK(!track_content_encodings_client_->content_encodings().empty());
+        audio_encryption_key_id_ = track_content_encodings_client_->
+            content_encodings()[0]->encryption_key_id();
       }
     } else {
       DVLOG(1) << "Unexpected TrackType " << track_type_;
       return false;
     }
 
     track_type_ = -1;
     track_num_ = -1;
     track_content_encodings_client_.reset();
     return true;
@@ skipping 36 matching lines @@
 bool WebMTracksParser::OnString(int id, const std::string& str) {
   if (id == kWebMIdCodecID && str != "A_VORBIS" && str != "V_VP8") {
     DVLOG(1) << "Unexpected CodecID " << str;
     return false;
   }
 
   return true;
 }
 
 }  // namespace media