Add live mode detection in WebM MediaSource parser.

media/formats/webm/webm_stream_parser.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/webm/webm_stream_parser.h"
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "media/formats/webm/webm_cluster_parser.h"
 #include "media/formats/webm/webm_constants.h"
 #include "media/formats/webm/webm_content_encodings.h"
 #include "media/formats/webm/webm_crypto_helpers.h"
 #include "media/formats/webm/webm_info_parser.h"
 #include "media/formats/webm/webm_tracks_parser.h"
 
 namespace media {
 
+static const int64 kUnknownElementSize = 0xffffffffffffff;

[acolwell GONE FROM CHROMIUM, 2014/04/23 16:06:02]

nit: Please remove and use the kWebMUnknownSize constant defined in
webm_constants.h

+
 WebMStreamParser::WebMStreamParser()
     : state_(kWaitingForInit),
+      unknown_segment_size_(false),
       parsing_cluster_(false) {
 }
 
 WebMStreamParser::~WebMStreamParser() {
 }
 
 void WebMStreamParser::Init(const InitCB& init_cb,
                             const NewConfigCB& config_cb,
                             const NewBuffersCB& new_buffers_cb,
                             bool ignore_text_tracks,
@@ skipping 110 matching lines @@
     case kWebMIdCues:
     case kWebMIdChapters:
       if (cur_size < (result + element_size)) {
         // We don't have the whole element yet. Signal we need more data.
         return 0;
       }
       // Skip the element.
       return result + element_size;
       break;
     case kWebMIdSegment:
+      // Segment of unknown size indicates live stream.
+      if (element_size == kUnknownElementSize)
+        unknown_segment_size_ = true;
       // Just consume the segment header.
       return result;
       break;
     case kWebMIdInfo:
       // We've found the element we are looking for.
       break;
     default: {
       MEDIA_LOG(log_cb_) << "Unexpected element ID 0x" << std::hex << id;
       return -1;
     }
   }
 
   WebMInfoParser info_parser;
   result = info_parser.Parse(cur, cur_size);
 
   if (result <= 0)
     return result;
 
   cur += result;
   cur_size -= result;
   bytes_parsed += result;
 
-  WebMTracksParser tracks_parser(log_cb_, ignore_text_tracks_);
+  bool live_mode = unknown_segment_size_ && (info_parser.duration() <= 0) &&
+                   !info_parser.date_utc().is_null();
+
+  WebMTracksParser tracks_parser(
+      log_cb_, ignore_text_tracks_, live_mode);
   result = tracks_parser.Parse(cur, cur_size);
 
   if (result <= 0)
     return result;
 
   bytes_parsed += result;
 
   double timecode_scale_in_us = info_parser.timecode_scale() / 1000.0;
   base::TimeDelta duration = kInfiniteDuration();
 
@@ skipping 10 matching lines @@
   if (video_config.is_encrypted())
     FireNeedKey(tracks_parser.video_encryption_key_id());
 
   if (!config_cb_.Run(audio_config,
                       video_config,
                       tracks_parser.text_tracks())) {
     DVLOG(1) << "New config data isn't allowed.";
     return -1;
   }
 
-
   cluster_parser_.reset(new WebMClusterParser(
       info_parser.timecode_scale(),
       tracks_parser.audio_track_num(),
       tracks_parser.GetAudioDefaultDuration(timecode_scale_in_us),
       tracks_parser.video_track_num(),
       tracks_parser.GetVideoDefaultDuration(timecode_scale_in_us),
       tracks_parser.text_tracks(),
       tracks_parser.ignored_tracks(),
       tracks_parser.audio_encryption_key_id(),
       tracks_parser.video_encryption_key_id(),
@@ skipping 68 matching lines @@
 
   return bytes_parsed;
 }
 
 void WebMStreamParser::FireNeedKey(const std::string& key_id) {
   std::vector<uint8> key_id_vector(key_id.begin(), key_id.end());
   need_key_cb_.Run(kWebMEncryptInitDataType, key_id_vector);
 }
 
 }  // namespace media