Introduce DecodeTimestamp class to make it easier to distiguish presentation and decode timestamps.

media/base/stream_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/base/stream_parser.h"
 
 #include "media/base/buffers.h"
 #include "media/base/stream_parser_buffer.h"
 
 namespace media {
@@ skipping 30 matching lines @@
   // for being appended to |merged_buffers|.
   size_t num_itrs = buffer_queues.size();
   std::vector<StreamParser::BufferQueue::const_iterator> itrs(num_itrs);
   for (size_t i = 0; i < num_itrs; ++i)
     itrs[i] = buffer_queues[i]->begin();
 
   // |last_decode_timestamp| tracks the lower bound, if any, that all candidate
   // buffers must not be less than. If |merged_buffers| already has buffers,
   // initialize |last_decode_timestamp| to the decode timestamp of the last
   // buffer in it.
-  base::TimeDelta last_decode_timestamp = kNoTimestamp();
+  DecodeTimestamp last_decode_timestamp = kNoDecodeTimestamp();
   if (!merged_buffers->empty())
     last_decode_timestamp = merged_buffers->back()->GetDecodeTimestamp();
 
   // Repeatedly select and append the next buffer from the candidate buffers
   // until either:
   // 1) returning false, to indicate detection of decreasing DTS in some queue,
   //    when a candidate buffer has decode timestamp below
   //    |last_decode_timestamp|, which means either an input buffer wasn't
   //    sorted correctly or had a buffer with decode timestamp below the last
   //    buffer, if any, in |merged_buffers|, or
   // 2) returning true when all buffers have been merged successfully;
   //    equivalently, when all of the iterators in |itrs| have reached the end
   //    of their respective queue from |buffer_queues|.
   // TODO(wolenetz/acolwell): Ideally, we would use a heap to store the head of
   // all queues and pop the head with lowest decode timestamp in log(N) time.
   // However, N will typically be small and usage of this implementation is
   // meant to be short-term. See http://crbug.com/338484.
   while (true) {
     // Tracks which queue's iterator is pointing to the candidate buffer to
     // append next, or -1 if no candidate buffers found. This indexes |itrs|.
     int index_of_queue_with_next_decode_timestamp = -1;
-    base::TimeDelta next_decode_timestamp = kNoTimestamp();
+    DecodeTimestamp next_decode_timestamp = kNoDecodeTimestamp();
 
     // Scan each of the iterators for |buffer_queues| to find the candidate
     // buffer, if any, that has the lowest decode timestamp.
     for (size_t i = 0; i < num_itrs; ++i) {
       if (itrs[i] == buffer_queues[i]->end())
         continue;
 
       // Extract the candidate buffer's decode timestamp.
-      base::TimeDelta ts = (*itrs[i])->GetDecodeTimestamp();
+      DecodeTimestamp ts = (*itrs[i])->GetDecodeTimestamp();
 
-      if (last_decode_timestamp != kNoTimestamp() &&
+      if (last_decode_timestamp != kNoDecodeTimestamp() &&
           ts < last_decode_timestamp)
         return false;
 
       if (ts < next_decode_timestamp ||
-          next_decode_timestamp == kNoTimestamp()) {
+          next_decode_timestamp == kNoDecodeTimestamp()) {
         // Remember the decode timestamp and queue iterator index for this
         // potentially winning candidate buffer.
         next_decode_timestamp = ts;
         index_of_queue_with_next_decode_timestamp = i;
       }
     }
 
     // All done if no further candidate buffers exist.
     if (index_of_queue_with_next_decode_timestamp == -1)
       return true;
@@ skipping 28 matching lines @@
        map_itr++) {
     if (!map_itr->second.empty())
       buffer_queues.push_back(&(map_itr->second));
   }
 
   // Do the merge.
   return MergeBufferQueuesInternal(buffer_queues, merged_buffers);
 }
 
 }  // namespace media