Fix FFmpegAudioDecoder monotonically increasing timestamp check to ignore kNoTimestamp()

media/filters/ffmpeg_audio_decoder.cc

 // Copyright (c) 2012 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.
 
 #include "media/filters/ffmpeg_audio_decoder.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/message_loop_proxy.h"
@@ skipping 182 matching lines @@
     if (last_input_timestamp_ == kNoTimestamp()) {
       if (is_vorbis && (input->GetTimestamp() < base::TimeDelta())) {
         // Dropping frames for negative timestamps as outlined in section A.2
         // in the Vorbis spec. http://xiph.org/vorbis/doc/Vorbis_I_spec.html
         int frames_to_drop = floor(
             0.5 + -input->GetTimestamp().InSecondsF() * samples_per_second_);
         output_bytes_to_drop_ = bytes_per_frame_ * frames_to_drop;
       } else {
         last_input_timestamp_ = input->GetTimestamp();
       }
-    } else if (input->GetTimestamp() < last_input_timestamp_) {
-      base::TimeDelta diff = input->GetTimestamp() - last_input_timestamp_;
-      DVLOG(1) << "Input timestamps are not monotonically increasing! "
-               << " ts " << input->GetTimestamp().InMicroseconds() << " us"
-               << " diff " << diff.InMicroseconds() << " us";
-      base::ResetAndReturn(&read_cb_).Run(kDecodeError, NULL);
-      return;
+    } else if (input->GetTimestamp() != kNoTimestamp()) {
+      if (input->GetTimestamp() < last_input_timestamp_) {
+        base::TimeDelta diff = input->GetTimestamp() - last_input_timestamp_;
+        DVLOG(1) << "Input timestamps are not monotonically increasing! "
+                 << " ts " << input->GetTimestamp().InMicroseconds() << " us"
+                 << " diff " << diff.InMicroseconds() << " us";
+        base::ResetAndReturn(&read_cb_).Run(kDecodeError, NULL);
+        return;
+      }
+
+      last_input_timestamp_ = input->GetTimestamp();
     }
   }
 
   AVPacket packet;
   av_init_packet(&packet);
   packet.data = const_cast<uint8*>(input->GetData());
   packet.size = input->GetDataSize();
 
   PipelineStatistics statistics;
   statistics.audio_bytes_decoded = input->GetDataSize();
@@ skipping 108 matching lines @@
       &FFmpegAudioDecoder::DoDecodeBuffer, this, status, buffer));
 }
 
 base::TimeDelta FFmpegAudioDecoder::GetNextOutputTimestamp() const {
   DCHECK(output_timestamp_base_ != kNoTimestamp());
   double decoded_us = (total_frames_decoded_ / samples_per_second_) *
       base::Time::kMicrosecondsPerSecond;
   return output_timestamp_base_ + base::TimeDelta::FromMicroseconds(decoded_us);
 }
 }  // namespace media