Allow padding packet in video streams.

webrtc/video/rtp_stream_receiver.cc

 /*
  *  Copyright (c) 2012 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 232 matching lines @@
     const uint8_t* payload_data,
     size_t payload_size,
     const WebRtcRTPHeader* rtp_header) {
   WebRtcRTPHeader rtp_header_with_ntp = *rtp_header;
   rtp_header_with_ntp.ntp_time_ms =
       ntp_estimator_.Estimate(rtp_header->header.timestamp);
   VCMPacket packet(payload_data, payload_size, rtp_header_with_ntp);
   packet.timesNacked =
       nack_module_ ? nack_module_->OnReceivedPacket(packet) : -1;
 
+  // In the case of a video stream without picture ids and no rtx the
+  // RtpFrameReferenceFinder will need to know about padding to
+  // correctly calculate frame references.
+  if (packet.sizeBytes == 0) {
+    reference_finder_->PaddingReceived(packet.seqNum);
+    return 0;
+  }
+
   if (packet.codec == kVideoCodecH264) {
     // Only when we start to receive packets will we know what payload type
     // that will be used. When we know the payload type insert the correct
     // sps/pps into the tracker.
     if (packet.payloadType != last_payload_type_) {
       last_payload_type_ = packet.payloadType;
       InsertSpsPpsIntoTracker(packet.payloadType);
     }
 
     switch (tracker_.CopyAndFixBitstream(&packet)) {
@@ skipping 386 matching lines @@
     return;
 
   if (!sprop_decoder.DecodeSprop(sprop_base64_it->second.c_str()))
     return;
 
   tracker_.InsertSpsPpsNalus(sprop_decoder.sps_nalu(),
                              sprop_decoder.pps_nalu());
 }
 
 }  // namespace webrtc