MEDIA_LOG for large encoded timestamp gaps in decoder stream.

media/filters/decoder_stream.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_FILTERS_DECODER_STREAM_H_
 #define MEDIA_FILTERS_DECODER_STREAM_H_
 
 #include <list>
+#include <memory>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "media/base/audio_decoder.h"
+#include "media/base/audio_timestamp_helper.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/media_export.h"
 #include "media/base/media_log.h"
 #include "media/base/moving_average.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/timestamp_constants.h"
 #include "media/filters/decoder_selector.h"
 #include "media/filters/decoder_stream_traits.h"
 
 namespace base {
@@ skipping 158 matching lines @@
   void ReinitializeDecoder();
 
   // Callback for Decoder reinitialization.
   void OnDecoderReinitialized(bool success);
 
   void CompleteDecoderReinitialization(bool success);
 
   void ResetDecoder();
   void OnDecoderReset();
 
+  // These methods monitor DecoderBuffer timestamps for gaps for the purpose of
+  // warning developers when gaps may cause AV sync drift. A DecoderBuffer's
+  // timestamp should roughly equal the timestamp of the previous buffer offset
+  // by the previous buffer's duration.
+  void CheckForTimestampGap(const scoped_refptr<DecoderBuffer>& buffer);
+  void RecordOutputDuration(const scoped_refptr<Output>& output);
+
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   scoped_refptr<MediaLog> media_log_;
 
   State state_;
 
   StatisticsCB statistics_cb_;
   InitCB init_cb_;
   base::Closure waiting_for_decryption_key_cb_;
 
   ReadCB read_cb_;
   base::Closure reset_cb_;
 
   DemuxerStream* stream_;
 
+  // Stores the timestamp from the DecoderBuffer corresponding to the first
+  // decoded output. See CheckForTimestampGap().
+  base::TimeDelta audio_base_ts_;
+
+  // Initially false, set to true when we observe gap between encoded timestamps
+  // match gap between output decoder buffers.
+  bool stable_audio_times_;
+
+  // Counts attempts to adjust |audio_ts_offset_| while trying to meet
+  // audio timestamp expectations. Give up making adjustments when count exceeds
+  // |kLimitTriesForStableTiming|.
+  int num_unstable_audio_tries_;
+
+  // Initially zero, we adjust the offset as needed for the first few buffers

[DaleCurtis, 2016/05/17 21:32:54]

Am I understanding correctly that this is equivalent to the following:

|last_provided_input_ts_ - first_output_buffer_ts|?

[chcunningham, 2016/05/18 00:18:00]

I would say that, once stable, this is
= last_provided_input_ts - expected_input_ts_based_on_output_frames.

+  // of decoded output to make encoded buffer timestamp gaps line up with
+  // expectations. See implementation of CheckForTimestampGap().
+  base::TimeDelta audio_ts_offset_;
+
+  // Accumulates time as from decoded audio frames. See CheckForTimestampGap().
+  std::unique_ptr<AudioTimestampHelper> audio_output_ts_helper_;
+
+  // How many milliseconds can DecoderBuffer timestamps differ from expectations
+  // before we MEDIA_LOG warn developers. Threshold initially set from
+  // kGapWarningThresholdMsec. Once hit, the threshold is increased by
+  // the detected gap amount. This avoids log spam while still emitting
+  // logs if things get worse. See CheckTimestampForGap().
+  uint32_t drift_warning_threshold_msec_;
+
   std::unique_ptr<DecoderSelector<StreamType>> decoder_selector_;
 
   std::unique_ptr<Decoder> decoder_;
   // When falling back from H/W decoding to S/W decoding, destructing the
   // GpuVideoDecoder too early results in black frames being displayed.
   // |previous_decoder_| is used to keep it alive.  It is destroyed once we've
   // decoded at least media::limits::kMaxVideoFrames frames after fallback.
   int decoded_frames_since_fallback_;
   std::unique_ptr<Decoder> previous_decoder_;
   std::unique_ptr<DecryptingDemuxerStream> decrypting_demuxer_stream_;
@@ skipping 50 matching lines @@
 
 template <>
 int DecoderStream<DemuxerStream::AUDIO>::GetMaxDecodeRequests() const;
 
 typedef DecoderStream<DemuxerStream::VIDEO> VideoFrameStream;
 typedef DecoderStream<DemuxerStream::AUDIO> AudioBufferStream;
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_DECODER_STREAM_H_