[Video] Disable bg optimization if avg keyframe distance is >10s

media/filters/decoder_stream_traits.cc

Index: media/filters/decoder_stream_traits.cc
diff --git a/media/filters/decoder_stream_traits.cc b/media/filters/decoder_stream_traits.cc
index fcbc19e4baa8e7f680afb3b22f3caa0d6842a03c..a2f8c99c11b5ad97dd7d7d4796387bcfda15d2c8 100644
--- a/media/filters/decoder_stream_traits.cc
+++ b/media/filters/decoder_stream_traits.cc
@@ -4,6 +4,8 @@
 
 #include "media/filters/decoder_stream_traits.h"
 
+#include <limits>
+
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "media/base/audio_buffer.h"
@@ -28,15 +30,6 @@ bool DecoderStreamTraits<DemuxerStream::AUDIO>::NeedsBitstreamConversion(
 }
 
 // static
-void DecoderStreamTraits<DemuxerStream::AUDIO>::ReportStatistics(
-    const StatisticsCB& statistics_cb,
-    int bytes_decoded) {
-  PipelineStatistics statistics;
-  statistics.audio_bytes_decoded = bytes_decoded;
-  statistics_cb.Run(statistics);
-}
-
-// static
 scoped_refptr<DecoderStreamTraits<DemuxerStream::AUDIO>::OutputType>
     DecoderStreamTraits<DemuxerStream::AUDIO>::CreateEOSOutput() {
   return OutputType::CreateEOSBuffer();
@@ -46,6 +39,14 @@ DecoderStreamTraits<DemuxerStream::AUDIO>::DecoderStreamTraits(
     const scoped_refptr<MediaLog>& media_log)
     : media_log_(media_log) {}
 
+void DecoderStreamTraits<DemuxerStream::AUDIO>::ReportStatistics(
+    const StatisticsCB& statistics_cb,
+    int bytes_decoded) {
+  PipelineStatistics statistics;
+  statistics.audio_bytes_decoded = bytes_decoded;
+  statistics_cb.Run(statistics);
+}
+
 void DecoderStreamTraits<DemuxerStream::AUDIO>::InitializeDecoder(
     DecoderType* decoder,
     DemuxerStream* stream,
@@ -90,18 +91,32 @@ bool DecoderStreamTraits<DemuxerStream::VIDEO>::NeedsBitstreamConversion(
 }
 
 // static
+scoped_refptr<DecoderStreamTraits<DemuxerStream::VIDEO>::OutputType>
+DecoderStreamTraits<DemuxerStream::VIDEO>::CreateEOSOutput() {
+  return OutputType::CreateEOSFrame();
+}
+
+DecoderStreamTraits<DemuxerStream::VIDEO>::DecoderStreamTraits(
+    const scoped_refptr<MediaLog>& media_log)
+    // Randomly selected number of samples to keep.
+    : keyframe_distance_average_(16) {}
+
 void DecoderStreamTraits<DemuxerStream::VIDEO>::ReportStatistics(
     const StatisticsCB& statistics_cb,
     int bytes_decoded) {
   PipelineStatistics statistics;
   statistics.video_bytes_decoded = bytes_decoded;
-  statistics_cb.Run(statistics);
-}
 
-// static
-scoped_refptr<DecoderStreamTraits<DemuxerStream::VIDEO>::OutputType>
-    DecoderStreamTraits<DemuxerStream::VIDEO>::CreateEOSOutput() {
-  return OutputType::CreateEOSFrame();
+  // Before we have enough keyframes to calculate the average distance, we will
+  // assume the average keyframe distance is infinitely large.
+  if (keyframe_distance_average_.count() < 3) {
+    statistics.video_keyframe_distance_average = base::TimeDelta::Max();

[DaleCurtis, 2017/01/11 23:44:48]

We typically use kNoTimestamp() in media for this.

[whywhat, 2017/01/12 00:16:32]

That would be a minimum value though so we will enable the optimization (unless
we special case kNoTimestamp in ShouldDisableVideoIfHidden) -- my intention was
to put the max value so we don't disable the video track in this case. WDYT?

[DaleCurtis, 2017/01/12 01:13:38]

Ah, I guess that works, but anyone looking at statistics may be a bit surprised.

+  } else {
+    statistics.video_keyframe_distance_average =
+        keyframe_distance_average_.Average();
+  }
+
+  statistics_cb.Run(statistics);
 }
 
 void DecoderStreamTraits<DemuxerStream::VIDEO>::InitializeDecoder(
@@ -120,6 +135,7 @@ void DecoderStreamTraits<DemuxerStream::VIDEO>::OnStreamReset(
     DemuxerStream* stream) {
   DCHECK(stream);
   last_keyframe_timestamp_ = base::TimeDelta();
+  keyframe_distance_average_.Reset();
 }
 
 void DecoderStreamTraits<DemuxerStream::VIDEO>::OnDecode(
@@ -141,10 +157,11 @@ void DecoderStreamTraits<DemuxerStream::VIDEO>::OnDecode(
     return;
   }
 
-  UMA_HISTOGRAM_MEDIUM_TIMES(
-      "Media.Video.KeyFrameDistance",
-      current_frame_timestamp - last_keyframe_timestamp_);
+  base::TimeDelta frame_distance =
+      current_frame_timestamp - last_keyframe_timestamp_;
+  UMA_HISTOGRAM_MEDIUM_TIMES("Media.Video.KeyFrameDistance", frame_distance);
   last_keyframe_timestamp_ = current_frame_timestamp;
+  keyframe_distance_average_.AddSample(frame_distance);
 }
 
 }  // namespace media