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AddBorders(clip clip, int left, int top, int right, int bottom [, int color])
AddBorders adds black (or specified color) borders around the image, with the specified widths (in pixels). YV12/YUY2 format only stores color information for every two pixels horizontally, so if you're processing in YV12/YUY2 mode, left and right must be even.
The color parameter is optional (added in v2.07), default=0 <black>, and is specified as an RGB value regardless of whether the clip format is RGB or YUV based.
Be aware that many lossy compression algorithms don't deal well with solid-color borders, unless the border width happens to be a multiple of the block size (16 pixels for MPEG).
You can use this filter in combination with Crop to shift an image around without changing the frame size. For example:
# Shift a 352x240 image 2 pixels to the right
Crop(0, 0, 350, 240).AddBorders(2, 0, 0, 0)
