Letterbox
(→Syntax and Parameters) |
(letterbox, crop and addborders don't change the (pixel) aspect ratio) |
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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: | 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: | ||
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* Black out video noise from the existing black bands in an image that's already letterboxed | * 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 [[Wikipedia:VHS|VHS]] tape sources. | * Black out the video noise at the bottom of the frame in [[Wikipedia:VHS|VHS]] tape sources. | ||
Revision as of 19:11, 26 March 2016
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.
The functionality of Letterbox can be duplicated with a combination of Crop and AddBorders, but Letterbox is faster and easier.
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)
- Fill color; specified as an RGB value. See this page for more information on specifying colors.
- For YUV clips, colors are converted from full-range (0–255) to tv-range (16–235).
- Fill color; specified as an RGB value. See this page for more information on specifying colors.
Changes
| v2.07 | Added color option. |
| v2.06 | Added optional left and right parameters (x1 and x2). |
