Documentation:Modules/alphamask

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)	alphamask, mask

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.

Options

• 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. default value: NULL

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 people.videolan.org/~dionoea/mosaic (archived) if you want to test. (This will blend the redefined nintendo video in a cone like region)

Source code

• modules/video_filter/alphamask.c

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