From 2d9385aebc2f7f19ac6b4637ff8bd72a17c91be5 Mon Sep 17 00:00:00 2001
From: gpoirier <gpoirier@b3059339-0415-0410-9bf9-f77b7e298cf2>
Date: Sun, 24 Jul 2005 21:58:34 +0000
Subject: [PATCH] General note about filtering from Rich's encoding guide

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@16088 b3059339-0415-0410-9bf9-f77b7e298cf2
---
 DOCS/xml/en/encoding-guide.xml | 43 ++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/DOCS/xml/en/encoding-guide.xml b/DOCS/xml/en/encoding-guide.xml
index 67ff6bf637..1aa21d8182 100644
--- a/DOCS/xml/en/encoding-guide.xml
+++ b/DOCS/xml/en/encoding-guide.xml
@@ -1085,6 +1085,49 @@
 <sect2 id="menc-feat-dvd-mpeg4-filtering">
 <title>Filtering</title>
 
+<para>
+  Learning how to use <application>MEncoder</application>'s video filters
+  is essential to producing good encodes.
+  All video processing is performed through the filters -- cropping,
+  scaling, color adjustment, noise removal, sharpening, deinterlacing,
+  telecine, inverse telecine, and deblocking, just to name a few.
+  Along with the vast number of supported input formats, the variety of
+  filters available in <application>MEncoder</application> is one of its
+  main advantages over other similar programs.
+</para>
+
+<para>
+  Filters are loaded in a chain using the -vf option:
+
+  <screen>-vf filter1=options,filter2=options,...</screen>
+
+  Most filters take several numeric options separated by colons, but
+  the syntax for options varies from filter to filter, so read the man
+  page for details on the filters you wish to use.
+</para>
+
+<para>
+  Filters operate on the video in the order they are loaded.
+  For example, the following chain:
+
+  <screen>-vf crop=688:464:12:4,scale=640:464</screen>
+
+  will first crop the 688x464 region of the picture with upper-left
+  corner at (12,4), and then scale the result down to 640x464.
+</para>
+
+<para>
+  Certain filters need to be loaded at or near the beginning of the
+  filter chain, in order to take advantage of information from the
+  video decoder that will be lost or invalidated by other filters.
+  The principal examples are <option>pp</option> (postprocessing, only
+  when it is performing deblock or dering operations),
+  <option>spp</option> (another postprocessor to remove MPEG artifacts),
+  <option>pullup</option> (inverse telecine), and
+  <option>softpulldown</option> (for converting soft telecine to hard
+  telecine).
+</para>
+
 <para>
   In general, you want to do as little filtering as possible to the movie
   in order to remain close to the original DVD source. Cropping is often