View source for Documentation:Modules/alphamask

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

This filter can be used in the mosaic framework to set a video's alpha channel (or transparency) based on a PNG image's alpha channel. You can thus blend only parts of the mosaic substream on the background.
__TOC__
== Options ==
{{Option
|name=alphamask-mask
|value=string
|default=
|description=PNG file to use as a mask. The alpha channel only will be used to build the mask. This image needs to have the same size as the video it will be used with.
}}

== Example ==
 % '''vlc -I telnet --color -vvv --vlm-conf mosaic.vlm --mosaic-keep-picture \'''
   '''--fake-file ~/images/mire.jpg --fake-width 360 --fake-height 270 \'''
   '''--no-audio --sub-filter mosaic'''

And the vlm config:

 new channel0 broadcast enabled
 setup channel0 input redefined-nintendo.mpg
 setup channel0 output #duplicate{dst=mosaic-bridge{height=270,width=360,chroma=YUVA,vfilter=alphamask{mask=cone_360x270.png}},select=video}
  
 new background broadcast enabled
 setup background input fake:
 control background play
  
 control channel0 play

The files used are available on http://people.videolan.org/~dionoea/mosaic/ if you want to test. (This will blend the redefined nintendo video in a cone like region)

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

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