A tool that crops the top pixel rows of a YUV video.

TEST=./tools/barcode_tools/yuv_cropper.py --width=640
--height=480 --crop_height=32
--yuv_file=<path_and_name_to_yuv_file>
--output_file=<path_and_name_to_output_file>

Review URL: https://webrtc-codereview.appspot.com/765005

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2692 4adac7df-926f-26a2-2b94-8c16560cd09d

tools/barcode_tools/yuv_cropper.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 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
+import os
+import sys
+
+
+def _crop_one_frame(yuv_file, output_file, component_sizes):
+  """Crops one frame.
+
+  This function crops one frame going through all the YUV planes and cropping
+  respective amount of rows.
+
+  Args:
+    yuv_file(file): The opened (for binary reading) YUV file.
+    output_file(file): The opened (for binary writing) file.
+    component_sizes(list of 3 3-ples): The list contains the sizes for all the
+      planes (Y, U, V) of the YUV file plus the crop_height scaled for every
+      plane. The sizes equal width, height and crop_height for the Y plane,
+      and are equal to width/2, height/2 and crop_height/2 for the U and V
+      planes.
+  Return:
+    (bool): True if there are more frames to crop, False otherwise.
+  """
+  for comp_width, comp_height, comp_crop_height in component_sizes:
+    for row in range(comp_height):
+      # Read the plane data for this row.
+      yuv_plane = yuv_file.read(comp_width)
+
+      # If the plane is empty, we have reached the end of the file.
+      if yuv_plane == "":
+        return False
+
+      # Only write the plane data for the rows bigger than crop_height.
+      if row >= comp_crop_height:
+        output_file.write(yuv_plane)
+  return True
+
+
+def crop_frames(yuv_file_name, output_file_name, width, height, crop_height):
+  """Crops rows of pixels from the top of the YUV frames.
+
+  This function goes through all the frames in a video and crops the crop_height
+  top pixel rows of every frame.
+
+  Args:
+    yuv_file_name(string): The name of the YUV file to be cropped.
+    output_file_name(string): The name of the output file where the result will
+      be written.
+    width(int): The width of the original YUV file.
+    height(int): The height of the original YUV file.
+    crop_height(int): The height (the number of pixel rows) to be cropped from
+      the frames.
+  """
+  # Component sizes = [Y_sizes, U_sizes, V_sizes].
+  component_sizes = [(width, height, crop_height),
+                     (width/2, height/2, crop_height/2),
+                     (width/2, height/2, crop_height/2)]
+
+  yuv_file = open(yuv_file_name, 'rb')
+  output_file = open(output_file_name, 'wb')
+
+  data_left = True
+  while data_left:
+    data_left = _crop_one_frame(yuv_file, output_file, component_sizes)
+
+  yuv_file.close()
+  output_file.close()
+
+
+def _parse_args():
+  """Registers the command-line options."""
+  usage = "usage: %prog [options]"
+  parser = optparse.OptionParser(usage=usage)
+
+  parser.add_option('--width', type='int',
+                    default=352,
+                    help=('Width of the YUV file\'s frames. '
+                          'Default: %default'))
+  parser.add_option('--height', type='int', default=288,
+                    help=('Height of the YUV file\'s frames. '
+                          'Default: %default'))
+  parser.add_option('--crop_height', type='int', default=32,
+                    help=('How much of the top of the YUV file to crop. '
+                          'Has to be module of 2. Default: %default'))
+  parser.add_option('--yuv_file', type='string',
+                    help=('The YUV file to be cropped.'))
+  parser.add_option('--output_file', type='string', default='output.yuv',
+                    help=('The output YUV file containing the cropped YUV. '
+                          'Default: %default'))
+  options = parser.parse_args()[0]
+  if not options.yuv_file:
+    parser.error('yuv_file argument missing. Please specify input YUV file!')
+  return options
+
+
+def _main():
+  """A tool to crop rows of pixels from the top part of a YUV file.
+
+  A simple invocation will be:
+  ./yuv_cropper.py --width=640 --height=480 --crop_height=32
+  --yuv_file=<path_and_name_of_yuv_file>
+  --output_yuv=<path and name_of_output_file>
+  """
+  options = _parse_args()
+
+  if os.path.getsize(options.yuv_file) == 0:
+    sys.stderr.write('Error: The YUV file you have passed has size 0. The '
+                     'produced output will also have size 0.\n')
+    return -1
+
+  crop_frames(options.yuv_file, options.output_file, options.width,
+              options.height, options.crop_height)
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(_main())