Treat negative ntp time as unset.

webrtc/video/vie_encoder.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 446 matching lines @@
 void ViEEncoder::OnFrame(const VideoFrame& video_frame) {
   RTC_DCHECK_RUNS_SERIALIZED(&incoming_frame_race_checker_);
   VideoFrame incoming_frame = video_frame;
 
   // Local time in webrtc time base.
   int64_t current_time = clock_->TimeInMilliseconds();
   incoming_frame.set_render_time_ms(current_time);
 
   // Capture time may come from clock with an offset and drift from clock_.
   int64_t capture_ntp_time_ms;
-  if (video_frame.ntp_time_ms() != 0) {
+  if (video_frame.ntp_time_ms() > 0) {
     capture_ntp_time_ms = video_frame.ntp_time_ms();
   } else if (video_frame.render_time_ms() != 0) {
     capture_ntp_time_ms = video_frame.render_time_ms() + delta_ntp_internal_ms_;
   } else {
     capture_ntp_time_ms = current_time + delta_ntp_internal_ms_;
   }
   incoming_frame.set_ntp_time_ms(capture_ntp_time_ms);
 
   // Convert NTP time, in ms, to RTP timestamp.
   const int kMsToRtpTimestamp = 90;
@@ skipping 276 matching lines @@
   --scale_counter_[reason];
   source_proxy_->RequestHigherResolutionThan(current_pixel_count);
   LOG(LS_INFO) << "Scaling up resolution.";
   for (size_t i = 0; i < kScaleReasonSize; ++i) {
     LOG(LS_INFO) << "Scaled " << scale_counter_[i]
                  << " times for reason: " << (i ? "cpu" : "quality");
   }
 }
 
 }  // namespace webrtc