Fills the top and bottom rows of each frame, and optionally the left and right columns, with black or color. This has several common uses:
- Black out video noise from the existing black bands in an image that's already letterboxed
- Black out the video noise at the bottom of the frame in VHS tape sources.
- Black out overscan areas in VCD or SVCD sources.
- Create a quick rectangular mask for other filters – a so-called "garbage matte"
See also: AddBorders, which increases frame size. Letterbox does not change frame size.
Generally, it's better to Crop video noise off than to black it out; many older lossy compression algorithms don't deal well with solid-color borders, unless the border happens to fall on a macroblock boundary (16 pixels for MPEG). However, in some cases, particularly for certain hardware players, it's better to use Letterbox because it lets you keep a standard frame size.
Syntax and Parameters
Letterbox(clip clip, int top, int bottom [, int x1 , int x2 , int color ] )
- int top, bottom = (required)
- int x1, x2 = 0
- int color = (black)
|v2.07||Added color option.|
|v2.06||Added optional left and right parameters (x1 and x2).|