[Cast] In Audio/VideoSender, drop frames when too-long a duration is in-flight.

media/cast/sender/frame_sender.h

 // 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.
 //
 // This is the base class for an object that send frames to a receiver.
 // TODO(hclam): Refactor such that there is no separate AudioSender vs.
 // VideoSender, and the functionality of both is rolled into this class.
 
 #ifndef MEDIA_CAST_SENDER_FRAME_SENDER_H_
 #define MEDIA_CAST_SENDER_FRAME_SENDER_H_
@@ skipping 76 matching lines @@
   // If true, we transmit the target playout delay to the receiver.
   bool send_target_playout_delay_;
 
   // Max encoded frames generated per second.
   double max_frame_rate_;
 
   // Maximum number of outstanding frames before the encoding and sending of
   // new frames shall halt.
   int max_unacked_frames_;
 
+  // Maximum difference between a new frame's RTP timestamp and the oldest
+  // unacked frame's RTP timestamp, before encoding and sending of new frames
+  // shall halt.
+  int64 max_unacked_rtp_delta_;

[hubbe, 2014/08/26 17:49:56]

Why not TimeDelta?

[miu, 2014/08/26 19:57:19]

It more convenient to have in the time calculations being done in
Audio/VideoSender::ShouldDropNextFrame().  Slightly less math since both
AudioSender and VideoSender already store the prior frame RTP timestamps in the
frame_id_to_rtp_timestamp_ map.

[hubbe, 2014/08/26 20:54:21]

This is an odd situation. Usually you're the one who wants to use
timetick/timedelta for all time calculations....  I'm not convinced that the
convenience is worth it, it seems the code will be clearer without modular math.

[miu, 2014/08/26 23:27:16]

Done.  I rewrote it the other way.  The ShouldDropNextFrame() code was about the
same in math, but the max_unacked_rtp_delta_ field could be removed and just use
target_playout_delay_.  So, I'll admit your way is cleaner.  ;-)

+
  private:
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<FrameSender> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameSender);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_SENDER_FRAME_SENDER_H_