Letterbox

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* Black out [[Wikipedia:Overscan#Overscan_amounts|overscan]] areas in [[Wikipedia:Video_CD|VCD]] or [[Wikipedia:Super_Video_CD|SVCD]] sources.  
 
* Black out [[Wikipedia:Overscan#Overscan_amounts|overscan]] areas in [[Wikipedia:Video_CD|VCD]] or [[Wikipedia:Super_Video_CD|SVCD]] sources.  
 
* Create a quick rectangular [[Mask|mask]] for other filters – a so-called "[[Wikipedia:Matte_(filmmaking)#Garbage_matte|garbage matte]]"
 
* Create a quick rectangular [[Mask|mask]] for other filters – a so-called "[[Wikipedia:Matte_(filmmaking)#Garbage_matte|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.  
 
The functionality of '''Letterbox''' can be duplicated with a combination of [[Crop]] and [[AddBorders]], but '''Letterbox''' is faster and easier.  

Revision as of 18:39, 30 January 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:

  • Adjust the aspect ratio (letterboxing's traditional purpose)
  • 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)
Number of top and bottom rows to blank out.
int  x1, x2 = 0
Number of left (x1) and right (x2) columns to blank out.
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).


Changes

v2.07 Added color option.
v2.06 Added optional left and right parameters (x1 and x2).
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