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# Copyright 2013 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.
import logging
import os
from metrics import Metric
from telemetry.value import list_of_scalar_values
from telemetry.value import scalar
class MediaMetric(Metric):
"""MediaMetric class injects and calls JS responsible for recording metrics.
Default media metrics are collected for every media element in the page,
such as decoded_frame_count, dropped_frame_count, decoded_video_bytes, and
decoded_audio_bytes.
"""
def __init__(self, tab):
super(MediaMetric, self).__init__()
with open(os.path.join(os.path.dirname(__file__), 'media.js')) as f:
js = f.read()
tab.ExecuteJavaScript(js)
self._results = None
self._skip_basic_metrics = False
def Start(self, page, tab):
"""Create the media metrics for all media elements in the document."""
if hasattr(page, 'skip_basic_metrics'):
self._skip_basic_metrics = page.skip_basic_metrics
tab.ExecuteJavaScript('window.__createMediaMetricsForDocument()')
def Stop(self, page, tab):
self._results = tab.EvaluateJavaScript('window.__getAllMetrics()')
def AddResults(self, tab, results):
"""Reports all recorded metrics as Telemetry perf results."""
trace_names = []
for media_metric in self._results:
trace_names.append(self._AddResultsForMediaElement(media_metric, results))
return '_'.join(trace_names) or tab.url
def _AddResultsForMediaElement(self, media_metric, results):
"""Reports metrics for one media element.
Media metrics contain an ID identifying the media element and values:
media_metric = {
'id': 'video_1',
'metrics': {
'time_to_play': 120,
'decoded_bytes': 13233,
...
}
}
"""
def AddOneResult(metric, unit):
metrics = media_metric['metrics']
for m in metrics:
if m.startswith(metric):
special_label = m[len(metric):]
trace_name = '%s.%s%s' % (metric, trace, special_label)
if isinstance(metrics[m], list):
results.AddValue(list_of_scalar_values.ListOfScalarValues(
results.current_page, trace_name, unit,
values=[float(v) for v in metrics[m]],
important=True))
else:
results.AddValue(scalar.ScalarValue(
results.current_page, trace_name, unit, value=float(metrics[m]),
important=True))
trace = media_metric['id']
if not trace:
logging.error('Metrics ID is missing in results.')
return
if not self._skip_basic_metrics:
AddOneResult('buffering_time', 'ms')
AddOneResult('decoded_audio_bytes', 'bytes')
AddOneResult('decoded_video_bytes', 'bytes')
AddOneResult('decoded_frame_count', 'frames')
AddOneResult('dropped_frame_count', 'frames')
AddOneResult('time_to_play', 'ms')
AddOneResult('avg_loop_time', 'ms')
AddOneResult('seek', 'ms')
return trace
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