1#!/usr/bin/env python
2# Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3#
4# Use of this source code is governed by a BSD-style license
5# that can be found in the LICENSE file in the root of the source
6# tree. An additional intellectual property rights grant can be found
7# in the file PATENTS.  All contributing project authors may
8# be found in the AUTHORS file in the root of the source tree.
9
10import optparse
11import os
12import sys
13
14
15def _crop_one_frame(yuv_file, output_file, component_sizes):
16  """Crops one frame.
17
18  This function crops one frame going through all the YUV planes and cropping
19  respective amount of rows.
20
21  Args:
22    yuv_file(file): The opened (for binary reading) YUV file.
23    output_file(file): The opened (for binary writing) file.
24    component_sizes(list of 3 3-ples): The list contains the sizes for all the
25      planes (Y, U, V) of the YUV file plus the crop_height scaled for every
26      plane. The sizes equal width, height and crop_height for the Y plane,
27      and are equal to width/2, height/2 and crop_height/2 for the U and V
28      planes.
29  Return:
30    (bool): True if there are more frames to crop, False otherwise.
31  """
32  for comp_width, comp_height, comp_crop_height in component_sizes:
33    for row in range(comp_height):
34      # Read the plane data for this row.
35      yuv_plane = yuv_file.read(comp_width)
36
37      # If the plane is empty, we have reached the end of the file.
38      if yuv_plane == "":
39        return False
40
41      # Only write the plane data for the rows bigger than crop_height.
42      if row >= comp_crop_height:
43        output_file.write(yuv_plane)
44  return True
45
46
47def crop_frames(yuv_file_name, output_file_name, width, height, crop_height):
48  """Crops rows of pixels from the top of the YUV frames.
49
50  This function goes through all the frames in a video and crops the crop_height
51  top pixel rows of every frame.
52
53  Args:
54    yuv_file_name(string): The name of the YUV file to be cropped.
55    output_file_name(string): The name of the output file where the result will
56      be written.
57    width(int): The width of the original YUV file.
58    height(int): The height of the original YUV file.
59    crop_height(int): The height (the number of pixel rows) to be cropped from
60      the frames.
61  """
62  # Component sizes = [Y_sizes, U_sizes, V_sizes].
63  component_sizes = [(width, height, crop_height),
64                     (width/2, height/2, crop_height/2),
65                     (width/2, height/2, crop_height/2)]
66
67  yuv_file = open(yuv_file_name, 'rb')
68  output_file = open(output_file_name, 'wb')
69
70  data_left = True
71  while data_left:
72    data_left = _crop_one_frame(yuv_file, output_file, component_sizes)
73
74  yuv_file.close()
75  output_file.close()
76
77
78def _parse_args():
79  """Registers the command-line options."""
80  usage = "usage: %prog [options]"
81  parser = optparse.OptionParser(usage=usage)
82
83  parser.add_option('--width', type='int',
84                    default=352,
85                    help=('Width of the YUV file\'s frames. '
86                          'Default: %default'))
87  parser.add_option('--height', type='int', default=288,
88                    help=('Height of the YUV file\'s frames. '
89                          'Default: %default'))
90  parser.add_option('--crop_height', type='int', default=32,
91                    help=('How much of the top of the YUV file to crop. '
92                          'Has to be module of 2. Default: %default'))
93  parser.add_option('--yuv_file', type='string',
94                    help=('The YUV file to be cropped.'))
95  parser.add_option('--output_file', type='string', default='output.yuv',
96                    help=('The output YUV file containing the cropped YUV. '
97                          'Default: %default'))
98  options = parser.parse_args()[0]
99  if not options.yuv_file:
100    parser.error('yuv_file argument missing. Please specify input YUV file!')
101  return options
102
103
104def _main():
105  """A tool to crop rows of pixels from the top part of a YUV file.
106
107  A simple invocation will be:
108  ./yuv_cropper.py --width=640 --height=480 --crop_height=32
109  --yuv_file=<path_and_name_of_yuv_file>
110  --output_yuv=<path and name_of_output_file>
111  """
112  options = _parse_args()
113
114  if os.path.getsize(options.yuv_file) == 0:
115    sys.stderr.write('Error: The YUV file you have passed has size 0. The '
116                     'produced output will also have size 0.\n')
117    return -1
118
119  crop_frames(options.yuv_file, options.output_file, options.width,
120              options.height, options.crop_height)
121  return 0
122
123
124if __name__ == '__main__':
125  sys.exit(_main())
126