<HTML> <HEAD> <!-- Created by texi2html 1.56k from hooks.texi on 28 December 2002 --> <TITLE>Video Hook Documentation</TITLE> </HEAD> <BODY> <H1>Video Hook Documentation</H1> <P> <P><HR><P> <H1>Table of Contents</H1> <UL> <LI><A NAME="TOC1" HREF="hooks.html#SEC1">1. Introduction</A> <UL> <LI><A NAME="TOC2" HREF="hooks.html#SEC2">1.1 null.c</A> <LI><A NAME="TOC3" HREF="hooks.html#SEC3">1.2 fish.c</A> <LI><A NAME="TOC4" HREF="hooks.html#SEC4">1.3 imlib2.c</A> </UL> </UL> <P><HR><P> <P> Video Hook Documentation <H1><A NAME="SEC1" HREF="hooks.html#TOC1">1. Introduction</A></H1> <P> 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. <P> 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. <P> Three modules are provided and are described below. They are all intended to be used as a base for your own modules. <P> Modules are loaded using the -vhook option to ffmpeg. The value of this parameter is a space seperated list of arguments. The first is the module name, and the rest are passed as arguments to the Configure function of the module. <H2><A NAME="SEC2" HREF="hooks.html#TOC2">1.1 null.c</A></H2> <P> 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. <H2><A NAME="SEC3" HREF="hooks.html#TOC3">1.2 fish.c</A></H2> <P> 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. <P> Why use HSV? It turns out that HSV cuboids represent a more compact range of colors than would an RGB cuboid. <H2><A NAME="SEC4" HREF="hooks.html#TOC4">1.3 imlib2.c</A></H2> <P> 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. <P><HR><P> This document was generated on 28 December 2002 using <A HREF="http://wwwinfo.cern.ch/dis/texi2html/">texi2html</A> 1.56k. </BODY> </HTML>