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order that they were specified on the ffmpeg command line.
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Three modules are provided and are described below. They are all intended to
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be used as a base for your own modules.
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be used as a base for your own modules.
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Modules are loaded using the -vhook option to ffmpeg. The value of this parameter
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is a space seperated list of arguments. The first is the module name, and the rest
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is a space separated list of arguments. The first is the module name, and the rest
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are passed as arguments to the Configure function of the module.
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This allows a caption to be placed onto each frame. It supports inserting the
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time and date. By using the imlib functions, it would be easy to add your own
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graphical logo, add a frame/border, etc.
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This module implements a text overlay for a video image. Currently it
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supports a fixed overlay or reading the text from a file. The string
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is passed through strftime so that it is easy to imprint the date and
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You may also overlay an image (even semi-transparent) like TV stations do.
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You may move either the text or the image around your video to create
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scrolling credits, for example.
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Text fonts are being looked for in a FONTPATH environment variable.
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@multitable @columnfractions .2 .8
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@item @option{-c <color>} @tab The color of the text
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@item @option{-F <fontname>} @tab The font face and size
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@item @option{-t <text>} @tab The text
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@item @option{-f <filename>} @tab The filename to read text from
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@item @option{-x <expresion>} @tab X coordinate of text or image
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@item @option{-y <expresion>} @tab Y coordinate of text or image
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@item @option{-i <filename>} @tab The filename to read a image from
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Expresions are functions of these variables:
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@multitable @columnfractions .2 .8
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@item @var{N} @tab frame number (starting at zero)
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@item @var{H} @tab frame height
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@item @var{W} @tab frame width
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@item @var{h} @tab image height
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@item @var{w} @tab image width
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@item @var{X} @tab previous x coordinate of text or image
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@item @var{Y} @tab previous y coordinate of text or image
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You may also use the constants @var{PI}, @var{E}, and the math functions available at the
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FFmpeg formula evaluator at (@url{ffmpeg-doc.html#SEC13}), except @var{bits2qp(bits)}
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and @var{qp2bits(qp)}.
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# Remember to set the path to your fonts
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FONTPATH="/cygdrive/c/WINDOWS/Fonts/"
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FONTPATH="$FONTPATH:/usr/share/imlib2/data/fonts/"
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FONTPATH="$FONTPATH:/usr/X11R6/lib/X11/fonts/TTF/"
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# Bulb dancing in a Lissajous pattern
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ffmpeg -i input.avi -vhook \
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'vhook/imlib2.dll -x W*(0.5+0.25*sin(N/47*PI))-w/2 -y H*(0.5+0.50*cos(N/97*PI))-h/2 -i /usr/share/imlib2/data/images/bulb.png' \
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-acodec copy -sameq output.avi
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ffmpeg -i input.avi -vhook \
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'vhook/imlib2.dll -c red -F Vera.ttf/20 -x 150+0.5*N -y 70+0.25*N -t Hello' \
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-acodec copy -sameq output.avi
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It's basically a launch point for a PPM pipe, so you can use any
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executable (or script) which consumes a PPM on stdin and produces a PPM
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on stdout (and flushes each frame).
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ffmpeg -i input -vhook "/path/to/ppm.so some-ppm-filter args" output
added
removed
ffmpeg/doc/hooks.texi
