tools/perf/metrics/media.py

   1 # Copyright 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4 import logging
   5 import os
   6
   7 from metrics import Metric
   8 from telemetry.value import list_of_scalar_values
   9 from telemetry.value import scalar
  10
  11
  12 class MediaMetric(Metric):
  13   """MediaMetric class injects and calls JS responsible for recording metrics.
  14
  15   Default media metrics are collected for every media element in the page,
  16   such as decoded_frame_count, dropped_frame_count, decoded_video_bytes, and
  17   decoded_audio_bytes.
  18   """
  19
  20   def __init__(self, tab):
  21     super(MediaMetric, self).__init__()
  22     with open(os.path.join(os.path.dirname(__file__), 'media.js')) as f:
  23       js = f.read()
  24       tab.ExecuteJavaScript(js)
  25     self._results = None
  26     self._skip_basic_metrics = False
  27
  28   def Start(self, page, tab):
  29     """Create the media metrics for all media elements in the document."""
  30     if hasattr(page, 'skip_basic_metrics'):
  31       self._skip_basic_metrics = page.skip_basic_metrics
  32     tab.ExecuteJavaScript('window.__createMediaMetricsForDocument()')
  33
  34   def Stop(self, page, tab):
  35     self._results = tab.EvaluateJavaScript('window.__getAllMetrics()')
  36
  37   # Optional |exclude_metrics| args are not in base class Metric.
  38   # pylint: disable=W0221
  39   def AddResults(self, tab, results, exclude_metrics=None):
  40     """Reports all recorded metrics as Telemetry perf results."""
  41     exclude_metrics = exclude_metrics or []
  42     trace_names = []
  43     for media_metric in self._results:
  44       trace_names.append(self._AddResultsForMediaElement(media_metric, results,
  45                                                          exclude_metrics))
  46
  47     return '_'.join(trace_names) or tab.url
  48
  49   def _AddResultsForMediaElement(self, media_metric, results, exclude_metrics):
  50     """Reports metrics for one media element.
  51
  52     Media metrics contain an ID identifying the media element and values:
  53     media_metric = {
  54       'id': 'video_1',
  55       'metrics': {
  56           'time_to_play': 120,
  57           'decoded_bytes': 13233,
  58           ...
  59       }
  60     }
  61     """
  62     def AddOneResult(metric, unit):
  63       if metric in exclude_metrics:
  64         return
  65
  66       metrics = media_metric['metrics']
  67       for m in metrics:
  68         if m.startswith(metric):
  69           special_label = m[len(metric):]
  70           trace_name = '%s.%s%s' % (metric, trace, special_label)
  71           if isinstance(metrics[m], list):
  72             results.AddValue(list_of_scalar_values.ListOfScalarValues(
  73                 results.current_page, trace_name, unit,
  74                 values=[float(v) for v in metrics[m]],
  75                 important=True))
  76           else:
  77             results.AddValue(scalar.ScalarValue(
  78                 results.current_page, trace_name, unit, value=float(metrics[m]),
  79                 important=True))
  80
  81     trace = media_metric['id']
  82     if not trace:
  83       logging.error('Metrics ID is missing in results.')
  84       return
  85
  86     if not self._skip_basic_metrics:
  87       AddOneResult('buffering_time', 'ms')
  88       AddOneResult('decoded_audio_bytes', 'bytes')
  89       AddOneResult('decoded_video_bytes', 'bytes')
  90       AddOneResult('decoded_frame_count', 'frames')
  91       AddOneResult('dropped_frame_count', 'frames')
  92       AddOneResult('time_to_play', 'ms')
  93
  94     AddOneResult('avg_loop_time', 'ms')
  95     AddOneResult('seek', 'ms')
  96     return trace