# Copyright (c) 2012 The Chromium Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import logging
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from autotest_lib.client.bin import test
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from autotest_lib.client.common_lib import error
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from autotest_lib.client.cros.audio import audio_helper
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from autotest_lib.client.cros.audio import cras_utils
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_DEFAULT_VOLUME_LEVEL = 100
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_DEFAULT_CAPTURE_GAIN = 2500
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_LATENCY_DIFF_LIMIT_US = 3000
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_NOISE_THRESHOLD = 1600
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class audio_LoopbackLatency(test.test):
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"""Verifies if the measured latency is as accurate as reported"""
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version = 1
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def initialize(self,
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default_volume_level=_DEFAULT_VOLUME_LEVEL,
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default_capture_gain=_DEFAULT_CAPTURE_GAIN):
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"""Setup the deps for the test.
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Args:
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default_volume_level: The default volume level.
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defalut_capture_gain: The default capture gain.
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Raises: error.TestError if the deps can't be run
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"""
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self._volume_level = default_volume_level
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self._capture_gain = default_capture_gain
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super(audio_LoopbackLatency, self).initialize()
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def run_once(self):
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"""Entry point of this test"""
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audio_helper.set_volume_levels(self._volume_level, self._capture_gain)
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success = False
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# Run loopback latency check once, which takes at most 1 sec to
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# complete and parse the latency values measured in loopback path
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# and reported by system. Assert the difference is within
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# acceptable range.
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result = audio_helper.loopback_latency_check(n=_NOISE_THRESHOLD)
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if result:
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diff = abs(result[0] - result[1])
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logging.info('Tested latency with threshold %d.\nMeasured %d,'
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'reported %d uS, diff %d us\n', _NOISE_THRESHOLD,
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result[0], result[1], diff)
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perf_value_description = 'loopback_latency'
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if cras_utils.get_selected_output_device_type() == 'USB':
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perf_value_description += '_usb'
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self.output_perf_value(
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description=perf_value_description, value=result[0],
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units='uS', higher_is_better=False)
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# Difference between measured and reported latency should
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# within _LATENCY_DIFF_LIMIT_US.
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if diff < _LATENCY_DIFF_LIMIT_US:
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success = True
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else:
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# Raise error if audio is not detected at all in the loopback path.
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raise error.TestError('Audio not detected at threshold %d' %
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_NOISE_THRESHOLD)
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if not success:
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# Test fails when latency difference is greater then the limit.
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raise error.TestFail('Latency difference too much, diff limit '
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'%d us, measured %d us, reported %d us' %
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(_LATENCY_DIFF_LIMIT_US, result[0], result[1]))
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