Add script to ensure virtual webcam is running.

This script will check that a webcam is running and start it if it's
not currently running.
It's tailored to the way our buildbots are currently configured.

TEST=local execution on Windows, Mac and Linux.
BUG=none
R=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1406005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3981 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/test/buildbot/ensure_webcam_is_running.py

@@ -0,0 +1,73 @@
+#!/usr/bin/env python
+#  Copyright (c) 2013 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.
+
+"""Checks if a virtual webcam is running and starts it if not.
+
+Returns a non-zero return code if the webcam could not be started.
+
+Prerequisites:
+* Python must have the psutil package installed.
+* Windows: a scheduled task named 'ManyCam' must exist and be configured to
+  launch ManyCam preconfigured to auto-play the test clip.
+* Mac: ManyCam must be installed in the default location and be preconfigured
+  to auto-play the test clip.
+* Linux: The v4l2loopback must be loaded to the kernel already (with the
+  devices=2 argument) and the v4l2_file_player application must be compiled and
+  put in the location specified below.
+"""
+
+import psutil
+import subprocess
+import sys
+
+
+WEBCAM_WIN = ['schtasks', '/run', '/tn', 'ManyCam']
+WEBCAM_MAC = ['open', '/Applications/ManyCam/ManyCam.app']
+WEBCAM_LINUX = (
+    '$HOME/fake-webcam-driver/linux/v4l2_file_player/v4l2_file_player '
+    '$HOME/webrtc_video_quality/reference_video.yuv 640 480 /dev/video1 &')
+
+
+def IsWebCamRunning():
+  if sys.platform == 'win32':
+    process_name = 'ManyCam.exe'
+  elif sys.platform.startswith('darwin'):
+    process_name = 'ManyCam'
+  elif sys.platform.startswith('linux'):
+    process_name = 'v4l2_file_player'
+  else:
+    raise Exception('Unsupported platform: %s' % sys.platform)
+  for p in psutil.get_process_list():
+    if process_name == p.name:
+      print 'Found a running virtual webcam (%s with PID %s)' % (p.name, p.pid)
+      return True
+  return False
+
+
+def Main():
+  if IsWebCamRunning():
+    return 0
+
+  try:
+    if sys.platform == 'win32':
+      subprocess.check_call(WEBCAM_WIN)
+    elif sys.platform.startswith('darwin'):
+      subprocess.check_call(WEBCAM_MAC)
+    elif sys.platform.startswith('linux'):
+      subprocess.check_call(WEBCAM_LINUX, shell=True)
+
+    print 'Successfully launched virtual webcam.'
+    return 0
+
+  except Exception as e:
+    print 'Failed to launch virtual webcam: %s' % e
+
+
+if __name__ == '__main__':
+  sys.exit(Main())