Difference between revisions of "Documentation:Modules/alphamask"

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[[Category:Video Filters]]

Revision as of 02:55, 13 March 2019

Module: alphamask
Type Video filter
First VLC version 0.9.0
Last VLC version -
Operating system(s) all
Description change the video's alpha channel
Shortcut(s) -

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.


  • alphamask-mask <string> : 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.


% 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)

See also

This page is part of official VLC media player Documentation (User GuideStreaming HowToHacker GuideModules)
Please read the Documentation Editing Guidelines before you edit the documentation
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.