Fixing NetEqReplacementInput for reordered and missing packets

webrtc/modules/audio_coding/neteq/tools/neteq_replacement_input.cc

 /*
  *  Copyright (c) 2016 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 67 matching lines @@
   if (comfort_noise_types_.count(packet_->header.header.payloadType) != 0) {
     // If CNG, simply insert a zero-energy one-byte payload.
     uint8_t cng_payload[1] = {127};  // Max attenuation of CNG.
     packet_->payload.SetData(cng_payload);
     return;
   }
 
   rtc::Optional<RTPHeader> next_hdr = source_->NextHeader();
   RTC_DCHECK(next_hdr);
   uint8_t payload[12];
-  uint32_t input_frame_size_timestamps =
-      next_hdr->timestamp - packet_->header.header.timestamp;
-  if (next_hdr->sequenceNumber != packet_->header.header.sequenceNumber + 1) {
-    // Gap in packet sequence. Cannot estimate payload length based on timestamp
-    // difference.
-    input_frame_size_timestamps = 0;
+  uint32_t input_frame_size_timestamps = last_frame_size_timestamps_;
+  if (next_hdr->sequenceNumber == packet_->header.header.sequenceNumber + 1) {
+    // Packets are in order.
+    input_frame_size_timestamps =
+        next_hdr->timestamp - packet_->header.header.timestamp;
+    last_frame_size_timestamps_ = input_frame_size_timestamps;
   }
   FakeDecodeFromFile::PrepareEncoded(packet_->header.header.timestamp,
                                      input_frame_size_timestamps,
                                      packet_->payload.size(), payload);
   packet_->payload.SetData(payload);
   packet_->header.header.payloadType = replacement_payload_type_;
   return;
 }
 
 }  // namespace test
 }  // namespace webrtc