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   def AddResults(self, tab, results):
  38     """Reports all recorded metrics as Telemetry perf results."""
  39     trace_names = []
  40     for media_metric in self._results:
  41       trace_names.append(self._AddResultsForMediaElement(media_metric, results))
  42
  43     return '_'.join(trace_names) or tab.url
  44
  45   def _AddResultsForMediaElement(self, media_metric, results):
  46     """Reports metrics for one media element.
  47
  48     Media metrics contain an ID identifying the media element and values:
  49     media_metric = {
  50       'id': 'video_1',
  51       'metrics': {
  52           'time_to_play': 120,
  53           'decoded_bytes': 13233,
  54           ...
  55       }
  56     }
  57     """
  58     def AddOneResult(metric, unit):
  59       metrics = media_metric['metrics']
  60       for m in metrics:
  61         if m.startswith(metric):
  62           special_label = m[len(metric):]
  63           trace_name = '%s.%s%s' % (metric, trace, special_label)
  64           if isinstance(metrics[m], list):
  65             results.AddValue(list_of_scalar_values.ListOfScalarValues(
  66                 results.current_page, trace_name, unit,
  67                 values=[float(v) for v in metrics[m]],
  68                 important=True))
  69           else:
  70             results.AddValue(scalar.ScalarValue(
  71                 results.current_page, trace_name, unit, value=float(metrics[m]),
  72                 important=True))
  73
  74     trace = media_metric['id']
  75     if not trace:
  76       logging.error('Metrics ID is missing in results.')
  77       return
  78
  79     if not self._skip_basic_metrics:
  80       AddOneResult('buffering_time', 'ms')
  81       AddOneResult('decoded_audio_bytes', 'bytes')
  82       AddOneResult('decoded_video_bytes', 'bytes')
  83       AddOneResult('decoded_frame_count', 'frames')
  84       AddOneResult('dropped_frame_count', 'frames')
  85       AddOneResult('time_to_play', 'ms')
  86
  87     AddOneResult('avg_loop_time', 'ms')
  88     AddOneResult('seek', 'ms')
  89     return trace