理解“/dev/video”输出

/开发/视频 设备。就像 motion 做。

我怎样才能把这些数据解释成一个可以理解的像素矩阵呢?

参考程序代码:

#!/usr/bin/ruby

# calculates a percentage difference between two array's
def percentage_difference( arrayA, arrayB )
  top_size = arrayA.size > arrayB.size ? arrayA.size : arrayB.size
  diff_elements = 0;
  0.upto( top_size - 1 ) do |i|
    diff_elements += 1 unless arrayA[i] == arrayB[i]
  end
  ( 1.0 * diffelements ) / top_size
end


cam = File.open( '/dev/video' );

lastframe = [];

while( true ) do
  # reads a frame from the open video device ( cam ) and converts to bytes;
  newframe = cam.readpartial( num_of_bytes_per_frame ).bytes.map { |b| b }

  # prints the percentage difference between the two frames
  puts percentage_difference( lastframe, newframe );

  lastframe = newframe;
end