View source for Documentation:Modules/bluescreen

{{Mosaic framework}}
{{Module|name=bluescreen|type=Video filter|first_version=0.9.0|description=Change the video's alpha channel|sc=bluescreen}}

This filter can be used in the mosaic framework to set a video's alpha channel (or transparency) based on a pixel's color. This is also known as [[wikipedia:green screen|green screen]] or chroma key blending and can be used to create effects like on most weather channels.

== Options ==
{{Option
|name=bluescreen-u
|value=integer
|min=0
|max=255
|default=120
|description=U chroma component.
}}
{{Option
|name=bluescreen-v
|value=integer
|min=0
|max=255
|default=90
|description=V chroma component.
}}
{{Option
|name=bluescreen-ut
|value=integer
|min=0
|max=255
|default=17
|description=Tolerance of the bluescreen blender on color variations for the U plane. A value between 10 and 20 seems sensible.
}}
{{Option
|name=bluescreen-vt
|value=integer
|min=0
|max=255
|default=17
|description=Tolerance of the bluescreen blender on color variations for the V plane. A value between 10 and 20 seems sensible.
}}

== Example ==
 % '''vlc -vvv --vlm-conf mosaic.vlm --mosaic-keep-picture --sub-filter mosaic'''

And the vlm config:

 new channel0 broadcast enabled
 setup channel0 input rushfondvert.avi
 setup channel0 output #duplicate{dst=mosaic-bridge{chroma=YUVA,vfilter=bluescreen},select=video}
  
 new background broadcast enabled
 setup background input redefined-nintendo.mpg
 control background play
  
 control channel0 play

Have a look at [https://web.archive.org/web/20060819104251/http://people.videolan.org/~dionoea/bluescreen2.mpg people.videolan.org/~dionoea/bluescreen2.mpg (archived)] for an example of the VLC bluescreen filter. The overlay video is [https://web.archive.org/web/20061205222657/http://people.videolan.org/~dionoea/rushfondvert.avi rushfondvert.avi (archived)] and features someone with a mask in front of a green background. The bluescreen module's default values are adjusted to remove the background from this video. For other videos you should use your favorite color editing tool to find out the appropriate U and V values.

== Another example ==
Tested with VLC 2.0.0

 new channel0 broadcast enabled
 setup channel0 input rushfondvert.avi
 setup channel0 output #duplicate{dst=mosaic-bridge{height=270,width=360,chroma=YUVA,vfilter=bluescreen},select=video}:display
 
 new background broadcast enabled
 setup background input file:///mire.jpg
 
 control background play
 control channel0 play

== Source code ==
* {{VLCSourceFile|modules/video_filter/bluescreen.c}}

== See also ==
* [[YUV]]

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