Added UMA metrics for MediaSourcePlayer and MediaCodecPlayer

media/base/android/media_statistics.cc

+#include "media/base/android/media_statistics.h"

[xhwang, 2015/09/30 21:02:57]

Add license header

[Tima Vaisburd, 2015/10/01 20:05:15]

Done.

+
+#include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
+#include "media/base/android/demuxer_stream_player_params.h"
+#include "media/base/timestamp_constants.h"
+
+namespace media {
+
+namespace {
+
+// Minimum duration to report.
+const int kMinDurationInSeconds = 2;
+
+// Maximum duration to report.
+const int kMaxDurationInSeconds = 3600;
+
+// Number of slots in the histogram for duration.
+const int kNumDurationSlots = 60;

[Ilya Sherman, 2015/10/01 07:19:20]

Please keep in mind that histogram buckets are sized logarithmically, so even
with 60 buckets, you won't get one per minute.  Rather, the smallest buckets
will be very fine-grained, and the larger buckets will be less fine grained.

[Tima Vaisburd, 2015/10/01 20:05:15]

Wow, that's great! Changed to 50.

+
+}
+
+void FrameStatistics::AddLateFrame(base::TimeDelta delay) {
+  // Do not collect the late frame if this is the first frame after start.
+  // This simplifies the MediaSourcePlayer case.
+  if (total == 1)
+    return;
+
+  DVLOG(1) << stream_type << " " << __FUNCTION__ << " delay:" << delay
+           << " total:" << total;

[xhwang, 2015/09/30 21:02:57]

This seems to be the only place to use |stream_type|, if you move the logging to
the caller you can remove this member variable.

With that, you can also omit the |delay| parameter.

[Tima Vaisburd, 2015/10/01 20:05:15]

It would be in 4 places instead of one though: audio/video and two players. I
removed the variable for now, but still thinking.

The delay is interesting on its own, maybe we need two more histograms.

+  ++late;
+}
+
+MediaStatistics::MediaStatistics()
+    : start_time_(kNoTimestamp()),
+      audio_frames_(DemuxerStream::AUDIO),
+      video_frames_(DemuxerStream::VIDEO),
+      num_starvations_(0) {

[xhwang, 2015/09/30 21:02:57]

nit: consider using Non-Static Class Member Initializers:

https://chromium-cpp.appspot.com/

[Tima Vaisburd, 2015/10/01 20:05:15]

Done.

+}
+
+MediaStatistics::~MediaStatistics() {}
+
+void MediaStatistics::Start(base::TimeDelta current_playback_time) {
+  DVLOG(1) << "MediaStatistics::" << __FUNCTION__;
+
+  Clear();
+  start_time_ = current_playback_time;
+}
+
+void MediaStatistics::StopAndReport(base::TimeDelta current_playback_time) {
+  DVLOG(1) << "MediaStatistics::" << __FUNCTION__;
+
+  if (start_time_ == kNoTimestamp())
+    return;  // skip if there was no prior Start().

[xhwang, 2015/09/30 21:02:57]

Should this ever happen?

[Tima Vaisburd, 2015/10/01 20:05:15]

Yes, in MediaCodecPlayer this method is called from methods that might come one
after another, e.g. Seek and Release. The Seek might come several times in a row
without a true start in between. 

+
+  base::TimeDelta duration = current_playback_time - start_time_;
+
+  // Reset start time.
+  start_time_ = kNoTimestamp();
+
+  if (duration < base::TimeDelta::FromSeconds(kMinDurationInSeconds))
+    return;  // duration is too short.
+
+  if (duration > base::TimeDelta::FromSeconds(kMaxDurationInSeconds))
+    return;  // duration is too long.
+
+  Report(duration);
+}
+
+void MediaStatistics::Clear() {
+  start_time_ = kNoTimestamp();
+  audio_frames_.Clear();
+  video_frames_.Clear();
+  num_starvations_ = 0;
+}
+
+void MediaStatistics::Report(base::TimeDelta duration) {
+  DVLOG(1) << "MediaStatistics::" << __FUNCTION__ << " duration:" << duration
+           << " audio frames:"
+           << audio_frames_.late << "/" << audio_frames_.total
+           << " video frames:"
+           << video_frames_.late << "/" << video_frames_.total;
+
+  UMA_HISTOGRAM_CUSTOM_TIMES(
+      "Media.MSE.Duration", duration,
+      base::TimeDelta::FromSeconds(kMinDurationInSeconds),
+      base::TimeDelta::FromSeconds(kMaxDurationInSeconds), kNumDurationSlots);
+
+  // Number of late frames per one million frames.
+
+  if (audio_frames_.total) {
+    UMA_HISTOGRAM_COUNTS("Media.MSE.LateAudioFrames",
+                         1000000 * audio_frames_.late / audio_frames_.total);
+  }
+
+  if (video_frames_.total) {
+    UMA_HISTOGRAM_COUNTS("Media.MSE.LateVideoFrames",
+                         1000000 * video_frames_.late / video_frames_.total);
+  }
+
+  // Number of starvations per one million frames.
+
+  uint32_t total_frames =
+      audio_frames_.total ? audio_frames_.total : video_frames_.total;
+  if (total_frames) {
+    UMA_HISTOGRAM_COUNTS("Media.MSE.Starvations",
+                         1000000 * num_starvations_ / total_frames);
+  }
+}
+
+}  // namespace media