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- \input texinfo @c -*- texinfo -*-
-
- @settitle Video Hook Documentation
- @titlepage
- @sp 7
- @center @titlefont{Video Hook Documentation}
- @sp 3
- @end titlepage
-
-
- @chapter Introduction
-
-
- The video hook functionality is designed (mostly) for live video. It allows
- the video to be modified or examined between the decoder and the encoder.
-
- Any number of hook modules can be placed inline, and they are run in the
- order that they were specified on the ffmpeg command line.
-
- Three modules are provided and are described below. They are all intended to
- be used as a base for your own modules.
-
- Modules are loaded using the -vhook option to ffmpeg. The value of this parameter
- is a space separated list of arguments. The first is the module name, and the rest
- are passed as arguments to the Configure function of the module.
-
- @section null.c
-
- This does nothing. Actually it converts the input image to RGB24 and then converts
- it back again. This is meant as a sample that you can use to test your setup.
-
- @section fish.c
-
- This implements a 'fish detector'. Essentially it converts the image into HSV
- space and tests whether more than a certain percentage of the pixels fall into
- a specific HSV cuboid. If so, then the image is saved into a file for processing
- by other bits of code.
-
- Why use HSV? It turns out that HSV cuboids represent a more compact range of
- colors than would an RGB cuboid.
-
- @section imlib2.c
-
- This allows a caption to be placed onto each frame. It supports inserting the
- time and date. By using the imlib functions, it would be easy to add your own
- graphical logo, add a frame/border, etc.
-
- @section ppm.c
-
- It's basically a launch point for a PPM pipe, so you can use any
- executable (or script) which consumes a PPM on stdin and produces a PPM
- on stdout (and flushes each frame).
-
- Usage example:
-
- @example
- ffmpeg -i input -vhook "/path/to/ppm.so some-ppm-filter args" output
- @end example
-
- @bye
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