Adding OnReceivedOverhead to AudioEncoder.

webrtc/modules/audio_coding/codecs/audio_encoder.h

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 163 matching lines @@
   // |uplink_packet_loss_fraction| is in the range [0.0, 1.0].
   virtual void OnReceivedUplinkPacketLossFraction(
       float uplink_packet_loss_fraction);
 
   // Provides target audio bitrate to this encoder to allow it to adapt.
   virtual void OnReceivedTargetAudioBitrate(int target_audio_bitrate_bps);
 
   // Provides RTT to this encoder to allow it to adapt.
   virtual void OnReceivedRtt(int rtt_ms);
 
+  // Provides overhead to this encoder to adapt. The overhead is the number of
+  // bytes that will be add to each payload the encoder generates. With this

[kwiberg-webrtc, 2016/12/03 00:30:56]

"add" -> "added"

And maybe "payload" -> "packet"?

[minyue-webrtc, 2016/12/06 09:04:19]

Done.

+  // and the total bandwidth and target bitrate provided by
+  // |OnReceivedUplinkBandwidth| and |OnReceivedTargetAudioBitrate|
+  // respectively, the encoder can decide its frame length and payload rate.

[kwiberg-webrtc, 2016/12/03 00:30:56]

Aren't the round-trip time and the packet loss rate relevant too? Maybe it's
best to just say "together with the other run-time parameters", or perhaps drop
this sentence altogether?

[minyue-webrtc, 2016/12/06 09:04:19]

Round trip time is not taken into account right now, but yet, I like to make the
description generalized. With that we need to say "together with the other
run-time parameters, the encoder can decide its encoding mode." This is
redundant given that we put "Provides overhead to this encoder to adapt" as the
first sentence already. So dropping this sentence is best. 

[kwiberg-webrtc, 2016/12/06 09:43:25]

Acknowledged.

+  virtual void OnReceivedOverhead(size_t overhead_bytes_per_packet);
+
   // To allow encoder to adapt its frame length, it must be provided the frame
   // length range that receivers can accept.
   virtual void SetReceiverFrameLengthRange(int min_frame_length_ms,
                                            int max_frame_length_ms);
 
  protected:
   // Subclasses implement this to perform the actual encoding. Called by
   // Encode().
   virtual EncodedInfo EncodeImpl(uint32_t rtp_timestamp,
                                  rtc::ArrayView<const int16_t> audio,
                                  rtc::Buffer* encoded) = 0;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_ENCODER_H_