Cast: Only ACK decodable frames

media/cast/audio_receiver/audio_receiver.cc

 // Copyright 2013 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/cast/audio_receiver/audio_receiver.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 152 matching lines @@
 void AudioReceiver::EmitAvailableEncodedFrames() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
 
   while (!frame_request_queue_.empty()) {
     // Attempt to peek at the next completed frame from the |framer_|.
     // TODO(miu): We should only be peeking at the metadata, and not copying the
     // payload yet!  Or, at least, peek using a StringPiece instead of a copy.
     scoped_ptr<transport::EncodedAudioFrame> encoded_frame(
         new transport::EncodedAudioFrame());
     bool is_consecutively_next_frame = false;
+    bool have_multiple_complete_frames = false;
     if (!framer_.GetEncodedAudioFrame(encoded_frame.get(),
-                                      &is_consecutively_next_frame)) {
+                                      &is_consecutively_next_frame,
+                                      &have_multiple_complete_frames)) {
       VLOG(1) << "Wait for more audio packets to produce a completed frame.";
       return;  // OnReceivedPayloadData() will invoke this method in the future.
     }
 
+    const base::TimeTicks now = cast_environment_->Clock()->NowTicks();
+    const base::TimeTicks playout_time =
+        GetPlayoutTime(now, encoded_frame->rtp_timestamp);
+
+    // If we have multiple decodable frames, and the current frame is
+    // too old, then skip it and decode the next frame instead.
+    if (have_multiple_complete_frames && now > playout_time) {
+      framer_.ReleaseFrame(encoded_frame->frame_id);
+      continue;
+    }
+
     // If |framer_| has a frame ready that is out of sequence, examine the
     // playout time to determine whether it's acceptable to continue, thereby
     // skipping one or more frames.  Skip if the missing frame wouldn't complete
     // playing before the start of playback of the available frame.
-    const base::TimeTicks now = cast_environment_->Clock()->NowTicks();
-    const base::TimeTicks playout_time =
-        GetPlayoutTime(now, encoded_frame->rtp_timestamp);
     if (!is_consecutively_next_frame) {
       // TODO(miu): Also account for expected decode time here?
       const base::TimeTicks earliest_possible_end_time_of_missing_frame =
           now + base::TimeDelta::FromMilliseconds(kTypicalAudioFrameDurationMs);
       if (earliest_possible_end_time_of_missing_frame < playout_time) {
         VLOG(1) << "Wait for next consecutive frame instead of skipping.";
         if (!is_waiting_for_consecutive_frame_) {
           is_waiting_for_consecutive_frame_ = true;
           cast_environment_->PostDelayedTask(
               CastEnvironment::MAIN,
@@ skipping 168 matching lines @@
 }
 
 void AudioReceiver::SendNextCastMessage() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   framer_.SendCastMessage();  // Will only send a message if it is time.
   ScheduleNextCastMessage();
 }
 
 }  // namespace cast
 }  // namespace media