APM QA refactoring: render stream support, echo path simulation, new export engine

webrtc/modules/audio_processing/test/py_quality_assessment/quality_assessment/input_mixer.py

Index: webrtc/modules/audio_processing/test/py_quality_assessment/quality_assessment/input_mixer.py
diff --git a/webrtc/modules/audio_processing/test/py_quality_assessment/quality_assessment/input_mixer.py b/webrtc/modules/audio_processing/test/py_quality_assessment/quality_assessment/input_mixer.py
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@@ -0,0 +1,93 @@
+# Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+"""Input mixer module.
+"""
+
+import logging
+import os
+
+from . import exceptions
+from . import signal_processing
+
+
+class ApmInputMixer(object):
+  """Class to mix a set of audio segments down to the APM input."""
+
+  _HARD_CLIPPING_LOG_MSG = 'hard clipping detected in the  mixed signal'
+
+  def __init__(self):
+    pass
+
+  @classmethod
+  def HardClippingLogMessage(cls):
+    """Returns the log message used when hard clipping is detected in the mix.
+
+    This method is mainly intended to be used by the unit tests.
+    """
+    return cls._HARD_CLIPPING_LOG_MSG
+
+  @classmethod
+  def Mix(cls, output_path, capture_input_filepath, echo_filepath):
+    """Mixes capture and echo.
+
+    Creates the overall capture input for APM by mixing the "echo-free" capture
+    signal with the echo signal (e.g., echo simulated via the
+    echo_path_simulation module).
+
+    The echo signal cannot be shorter than the capture signal and the generated
+    mix will have the same duration of the capture signal. The latter property
+    is enforced in order to let the input of APM and the reference signal
+    created by TestDataGenerator have the same length (required for the
+    evaluation step).
+
+    Hard-clipping may occur in the mix; a warning is raised when this happens.
+
+    If |echo_filepath| is None, nothing is done and |capture_input_filepath| is
+    returned.
+
+    Args:
+      speech: AudioSegment instance.
+      echo_path: AudioSegment instance or None.
+
+    Returns:
+      Path to the mix audio track file.
+    """
+    if echo_filepath is None:
+      return capture_input_filepath
+
+    # Build the mix output file name as a function of the echo file name.
+    # This ensures that if the internal parameters of the echo path simulator
+    # change, no erroneous cache hit occurs.
+    echo_file_name, _ = os.path.splitext(os.path.split(echo_filepath)[1])
+    mix_filepath = os.path.join(output_path, 'mix_capture_{}.wav'.format(
+        echo_file_name))
+
+    # Create the mix if not done yet.
+    mix = None
+    if not os.path.exists(mix_filepath):
+      echo_free_capture = signal_processing.SignalProcessingUtils.LoadWav(
+          capture_input_filepath)
+      echo = signal_processing.SignalProcessingUtils.LoadWav(echo_filepath)
+
+      if signal_processing.SignalProcessingUtils.CountSamples(echo) < (
+          signal_processing.SignalProcessingUtils.CountSamples(
+              echo_free_capture)):
+        raise exceptions.InputMixerException(
+            'echo cannot be shorter than capture')
+
+      mix = echo_free_capture.overlay(echo)
+      signal_processing.SignalProcessingUtils.SaveWav(mix_filepath, mix)
+
+    # Check if hard clipping occurs.
+    if mix is None:
+      mix = signal_processing.SignalProcessingUtils.LoadWav(mix_filepath)
+    if signal_processing.SignalProcessingUtils.DetectHardClipping(mix):
+      logging.warning(cls._HARD_CLIPPING_LOG_MSG)
+
+    return mix_filepath