[Video] Collect average keyframe distance for video

media/filters/decoder_stream_traits.cc

 // 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.
 
 #include "media/filters/decoder_stream_traits.h"
 
 #include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "media/base/audio_buffer.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/video_decoder.h"
 #include "media/base/video_frame.h"
 
 namespace media {
 
 // Audio decoder stream traits implementation.
 
@@ skipping 90 matching lines @@
     DemuxerStream* stream,
     CdmContext* cdm_context,
     const InitCB& init_cb,
     const OutputCB& output_cb) {
   DCHECK(stream->video_decoder_config().IsValidConfig());
   decoder->Initialize(stream->video_decoder_config(),
                       stream->liveness() == DemuxerStream::LIVENESS_LIVE,
                       cdm_context, init_cb, output_cb);
 }
 
+void DecoderStreamTraits<DemuxerStream::VIDEO>::OnStreamReset(
+    DemuxerStream* stream) {
+  DCHECK(stream);
+  last_keyframe_timestamp_ = base::TimeDelta();
+}
+
+void DecoderStreamTraits<DemuxerStream::VIDEO>::OnDecode(
+    const scoped_refptr<DecoderBuffer>& buffer) {
+  if (buffer->end_of_stream()) {
+    if (!buffer)

[DaleCurtis, 2016/12/07 23:02:43]

This can't ever be true or you've already deref'd a nullptr :)

[whywhat, 2016/12/08 00:23:30]

Oops, weird auto formatting obscuring a missing return I guess...

+      return;
+
+    last_keyframe_timestamp_ = base::TimeDelta();
+    return;
+  }
+
+  if (!buffer->is_key_frame())
+    return;
+
+  base::TimeDelta current_frame_timestamp = buffer->timestamp();
+  if (last_keyframe_timestamp_.is_zero()) {
+    last_keyframe_timestamp_ = current_frame_timestamp;
+    return;
+  }
+
+  UMA_HISTOGRAM_MEDIUM_TIMES(
+      "Media.Video.KeyFrameDistance",
+      current_frame_timestamp - last_keyframe_timestamp_);
+}
+
 }  // namespace media