Comparison of videos with reference frame not starting from zero

webrtc/tools/compare_videos.py

 #!/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.
 
 import optparse
@@ skipping 30 matching lines @@
                           'will assume we can find it in barcode_tools/'
                           'relative to this directory.'))
   parser.add_option('--ffmpeg_path', type='string',
                     help=('The path to where the ffmpeg executable is located. '
                           'If omitted, it will be assumed to be present in the '
                           'PATH with the name ffmpeg[.exe].'))
   parser.add_option('--zxing_path', type='string',
                     help=('The path to where the zxing executable is located. '
                           'If omitted, it will be assumed to be present in the '
                           'PATH with the name zxing[.exe].'))
-  parser.add_option('--stats_file', type='string', default='stats.txt',
+  parser.add_option('--stats_file_ref', type='string', default='stats_ref.txt',
+                    help=('Path to the temporary stats file to be created and '
+                          'used. Default: %default'))
+  parser.add_option('--stats_file_test', type='string',
+                    default='stats_test.txt',
                     help=('Path to the temporary stats file to be created and '
                           'used. Default: %default'))
   parser.add_option('--yuv_frame_width', type='int', default=640,
                     help='Width of the YUV file\'s frames. Default: %default')
   parser.add_option('--yuv_frame_height', type='int', default=480,
                     help='Height of the YUV file\'s frames. Default: %default')
   options, _ = parser.parse_args()
 
   if not options.ref_video:
     parser.error('You must provide a path to the reference video!')
   if not os.path.exists(options.ref_video):
     parser.error('Cannot find the reference video at %s' % options.ref_video)
 
   if not options.test_video:
     parser.error('You must provide a path to the test video!')
   if not os.path.exists(options.test_video):
     parser.error('Cannot find the test video at %s' % options.test_video)
 
   if not options.frame_analyzer:
     parser.error('You must provide the path to the frame analyzer executable!')
   if not os.path.exists(options.frame_analyzer):
     parser.error('Cannot find frame analyzer executable at %s!' %
                  options.frame_analyzer)
   return options
 
+def _DevNull():
+  """On Windows, sometimes the inherited stdin handle from the parent process
+  fails. Workaround this by passing null to stdin to the subprocesses commands.
+  This function can be used to create the null file handler.
+  """
+  return open(os.devnull, 'r')
+
+def DecodeBarcodesInVideo(options, path_to_decoder, video, stat_file):
+  # Run barcode decoder on the test video to identify frame numbers.
+  png_working_directory = tempfile.mkdtemp()
+  cmd = [
+    sys.executable,
+    path_to_decoder,
+    '--yuv_file=%s' % video,
+    '--yuv_frame_width=%d' % options.yuv_frame_width,
+    '--yuv_frame_height=%d' % options.yuv_frame_height,
+    '--stats_file=%s' % stat_file,
+    '--png_working_dir=%s' % png_working_directory,
+  ]
+  if options.zxing_path:
+    cmd.append('--zxing_path=%s' % options.zxing_path)
+  if options.ffmpeg_path:
+    cmd.append('--ffmpeg_path=%s' % options.ffmpeg_path)
+
+
+  barcode_decoder = subprocess.Popen(cmd, stdin=_DevNull(),
+                                     stdout=sys.stdout, stderr=sys.stderr)
+  barcode_decoder.wait()
+
+  shutil.rmtree(png_working_directory)
+  if barcode_decoder.returncode != 0:
+    print 'Failed to run barcode decoder script.'
+    return 1
+  return 0
 
 def main():
   """The main function.
 
   A simple invocation is:
   ./webrtc/tools/barcode_tools/compare_videos.py
   --ref_video=<path_and_name_of_reference_video>
   --test_video=<path_and_name_of_test_video>
   --frame_analyzer=<path_and_name_of_the_frame_analyzer_executable>
 
   Notice that the prerequisites for barcode_decoder.py also applies to this
   script. The means the following executables have to be available in the PATH:
   * zxing
   * ffmpeg
   """
   options = _ParseArgs()
 
   if options.barcode_decoder:
     path_to_decoder = options.barcode_decoder
   else:
     path_to_decoder = os.path.join(SCRIPT_DIR, 'barcode_tools',
                                    'barcode_decoder.py')
 
-  # On Windows, sometimes the inherited stdin handle from the parent process
-  # fails. Work around this by passing null to stdin to the subprocesses.
-  null_filehandle = open(os.devnull, 'r')
-
-  # Run barcode decoder on the test video to identify frame numbers.
-  png_working_directory = tempfile.mkdtemp()
-  cmd = [
-    sys.executable,
-    path_to_decoder,
-    '--yuv_file=%s' % options.test_video,
-    '--yuv_frame_width=%d' % options.yuv_frame_width,
-    '--yuv_frame_height=%d' % options.yuv_frame_height,
-    '--stats_file=%s' % options.stats_file,
-    '--png_working_dir=%s' % png_working_directory,
-  ]
-  if options.zxing_path:
-    cmd.append('--zxing_path=%s' % options.zxing_path)
-  if options.ffmpeg_path:
-    cmd.append('--ffmpeg_path=%s' % options.ffmpeg_path)
-  barcode_decoder = subprocess.Popen(cmd, stdin=null_filehandle,
-                                     stdout=sys.stdout, stderr=sys.stderr)
-  barcode_decoder.wait()
-
-  shutil.rmtree(png_working_directory)
-  if barcode_decoder.returncode != 0:
-    print 'Failed to run barcode decoder script.'
+  if DecodeBarcodesInVideo(options, path_to_decoder,
+                           options.ref_video, options.stats_file_ref) != 0:
+    return 1
+  if DecodeBarcodesInVideo(options, path_to_decoder,
+                           options.test_video, options.stats_file_test) != 0:
     return 1
 
   # Run frame analyzer to compare the videos and print output.
   cmd = [
     options.frame_analyzer,
     '--label=%s' % options.label,
     '--reference_file=%s' % options.ref_video,
     '--test_file=%s' % options.test_video,
-    '--stats_file=%s' % options.stats_file,
+    '--stats_file_ref=%s' % options.stats_file_ref,
+    '--stats_file_test=%s' % options.stats_file_test,
     '--width=%d' % options.yuv_frame_width,
     '--height=%d' % options.yuv_frame_height,
   ]
-  frame_analyzer = subprocess.Popen(cmd, stdin=null_filehandle,
+  frame_analyzer = subprocess.Popen(cmd, stdin=_DevNull(),
                                     stdout=sys.stdout, stderr=sys.stderr)
   frame_analyzer.wait()
   if frame_analyzer.returncode != 0:
     print 'Failed to run frame analyzer.'
     return 1
 
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())