[FFmpeg-soc] [soc]: r4180 - in libavfilter: README checkout.sh doc doc/vfilters.texi

victor subversion at mplayerhq.hu
Sun Mar 22 17:15:06 CET 2009


Author: victor
Date: Sun Mar 22 17:15:05 2009
New Revision: 4180

Log:
Initial documentation of video filters.

Added:
   libavfilter/doc/
   libavfilter/doc/vfilters.texi
Modified:
   libavfilter/README
   libavfilter/checkout.sh

Modified: libavfilter/README
==============================================================================
--- libavfilter/README	Sun Mar 22 01:05:42 2009	(r4179)
+++ libavfilter/README	Sun Mar 22 17:15:05 2009	(r4180)
@@ -68,22 +68,7 @@ of the filters.
 One of the interesting features of libavfilter is the ability for filters to
 have multiple inputs and multiple outputs.  Unfortunately, ffplay cannot feed
 multiple video streams to the filter system, and cannot handle multiple output
-streams.  To illustrate the sorts of things that are possible, however, we can
-use a complex filter graph.  For example, the following graph:
-
-input --> split ---> fifo ----------------------> overlay --> output
-            |                                        ^
-            |------> fifo --> crop --> vflip --------|
-
-splits the stream into two streams, sends one stream through the crop filter
-and the vflip filter before merging it back with the other stream by overlaying
-it on top. You can use the following command to do this filtering
-
-./ffmpeg -i input_video.avi -s 240x320 -vfilters "[in]split [T1], fifo, [T2]overlay='0:240'[out]; [T1]fifo, crop=0:0:-1:240, vflip[T2]" out.avi
-
-where input_video.avi has a vertical resolution of 480 pixels, the result
-should be that in output the top half of the video is mirroed onto the bottom
-half.
+streams.
 
 KNOWN ISSUES:
 - if for some reason the filter chain cannot be setup (due to an unknown

Modified: libavfilter/checkout.sh
==============================================================================
--- libavfilter/checkout.sh	Sun Mar 22 01:05:42 2009	(r4179)
+++ libavfilter/checkout.sh	Sun Mar 22 17:15:05 2009	(r4180)
@@ -8,3 +8,6 @@ for diff in $(ls $(pwd)/diffs/*.diff); d
 
 echo "copying files to libavfilter"
 find $(pwd) -maxdepth 1 -type f -not -name $(basename $0) -exec cp {} ffmpeg/libavfilter \;
+
+echo "copying libavfilter doc files"
+cp -p $(pwd)/doc/* ffmpeg/doc

Added: libavfilter/doc/vfilters.texi
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ libavfilter/doc/vfilters.texi	Sun Mar 22 17:15:05 2009	(r4180)
@@ -0,0 +1,242 @@
+\input texinfo @c -*- texinfo -*-
+
+ at settitle Video Filters Documentation
+ at titlepage
+ at sp 7
+ at center @titlefont{Video Filters Documentation}
+ at sp 3
+ at end titlepage
+
+
+ at chapter Introduction
+
+Libavfilter is the filtering API of FFmpeg. It is the substitute of the
+now deprecated 'vhooks' and started as a Google Summer of Code project.
+To get libavfilter you must download it into some directory of your choice by:
+ at example
+   svn checkout svn://svn.mplayerhq.hu/soc/libavfilter
+ at end example
+
+And then read @url{http://svn.mplayerhq.hu/soc/libavfilter/README?view=co}
+to learn how to integrate it into ffmpeg and ffplay.
+
+The former video hook modules allowed a list of filters, that would run in the
+order that they were specified on the ffmpeg command line.
+Each filter had one input and one output.
+
+In libavfilter, it is possible for filters to have multiple inputs and
+multiple outputs.
+To illustrate the sorts of things that are possible, we can
+use a complex filter graph.  For example, the following one:
+
+ at example
+input --> split ---> fifo ----------------------> overlay --> output
+            |                                        ^
+            |------> fifo --> crop --> vflip --------|
+ at end example
+
+splits the stream into two streams, sends one stream through the crop filter
+and the vflip filter before merging it back with the other stream by
+overlaying it on top. You can use the following command to do this filtering
+
+ at example
+./ffmpeg -i in.avi -s 240x320 -vfilters "[in]split [T1], fifo, [T2]overlay='0:240'[out]; [T1]fifo, crop=0:0:-1:240, vflip[T2]" out.avi
+ at end example
+
+where input_video.avi has a vertical resolution of 480 pixels, the result
+should be that in output the top half of the video is mirrored onto the bottom
+half.
+
+Video filters are loaded using the @var{-vfilters} option to ffmpeg. The
+filters in the same linear chain are separated by commas. In our example,
+ at var{split, fifo, overlay} are in one linear chain, and @var{fifo, crop, vflip}
+are in another.
+The points where the linear chains join are labeled by names enclosed in
+square brackets. In our example, that is @var{[T1]} and @var{[T2]}.
+The magic labels @var{[in]} and @var{[out]} are respectively the points
+where video is input and output.
+After the filter name, you may find the equal sign and a semicolon separated
+parameter list.
+
+There are also the so called @var{source filters} that do not have a video input,
+and we expect in future some @var{sink filters} that will not have video output.
+
+ at chapter Available video filters
+
+When you configure your ffmpeg build, you can disable any of the existing video
+filters.
+The configure output will show the video filters included in your build.
+
+These are the currently available video filters:
+
+ at section crop
+
+ at example
+./ffmpeg -i in.avi -vfilters "crop=0:0:-1:240" out.avi
+ at end example
+
+Crop the input video to x:y:width:height.
+The -1 in width or height means that dimension in the input video.
+
+ at section drawbox
+
+ at example
+./ffmpeg -i in.avi -vfilters "drawbox=10:20:200:60:red" out.avi
+ at end example
+
+Draw a box with x:y:width:height dimensions in a chosen color.
+
+ at section fifo
+
+ at example
+./ffmpeg -i in.avi -vfilters "fifo" out.avi
+ at end example
+
+ at section format
+
+ at example
+./ffmpeg -i in.avi -vfilters "format=yuv420p" out.avi
+ at end example
+
+Convert video to one of the specified filters formats (libavfilter will
+try to pick one that is supported as an input to the next filter).
+
+ at section fps
+
+ at example
+./ffmpeg -i in.avi -vfilters "fps=30000:1001" out.avi
+ at end example
+
+Modifies the framerate of the input video to a chosen one.
+
+ at section hflip
+
+ at example
+./ffmpeg -i in.avi -vfilters "hflip" out.avi
+ at end example
+
+Flip the video horizontally.
+
+ at section negate
+
+ at example
+./ffmpeg -i in.avi -vfilters "negate" out.avi
+ at end example
+
+Convert a video to its negative.
+
+ at section noformat
+
+ at example
+./ffmpeg -i in.avi -vfilters "noformat=yuv420p" out.avi
+ at end example
+
+Force libavfilter not to send any of the specified pixel formats to the
+next filter.
+
+ at section overlay
+
+Overlay one video on top of another (see the example in the introduction
+section).
+Be aware that frames are taken
+from each input video in timestamp order, hence, if their initial
+timestamps differ, it is a a good idea to pass the two
+inputs through a @var{setpts=PTS-STARTPTS} filter to have them
+begin in the same zero timestamp, as it does the example for
+the @var{movie} filter.
+
+ at section rotate
+
+ at example
+./ffmpeg -i in.avi -vfilters "rotate=30" out.avi
+ at end example
+
+Rotate video by a chosen amount in degrees. By default, 45 degrees.
+
+ at section scale
+
+ at example
+./ffmpeg -i in.avi -vfilters "scale=200:100:sws_flags=bicubic" out.avi
+ at end example
+
+Scale to new width/height and/or convert pixel format.
+The two first parameter are the desired width and height.
+If the third parameter @var{sws_flags} is absent, then @var{bilinear} is assumed.
+
+ at section setpts
+
+ at example
+# Start counting PTS from zero
+ffmpeg -i input.avi -vfilters setpts=PTS-STARTPTS output.avi
+
+# Fast motion
+ffmpeg -i input.avi -vfilters setpts=0.5*PTS output.avi
+
+# Fixed rate 25 fps
+ffmpeg -i input.avi -vfilters setpts=N*AVTB/25 output.avi
+
+# Fixed rate 25 fps with some jitter
+ffmpeg -i input.avi -vfilters 'setpts=AVTB/25*(N+0.05*sin(N*2*PI/25))' output.avi
+ at end example
+
+Modifies the presentation timestamp (PTS) of the input video.
+
+ at section slicify
+
+ at example
+./ffmpeg -i in.avi -vfilters "slicify=32" out.avi
+ at end example
+
+Pass on input video to next video filter as multiple slices.
+The parameter is the slice height (16 if not specified).
+Adding this in the beginning of filter chains should make filtering
+faster due to the better use of the memory cache.
+
+ at section split
+
+See the example in the introduction section.
+The input video is passed on to two outputs.
+
+ at section transpose
+
+ at example
+./ffmpeg -i in.avi -vfilters "transpose" out.avi
+ at end example
+
+Transpose (line => column) input video to next video filter.
+
+ at section vflip
+
+ at example
+./ffmpeg -i in.avi -vfilters "vflip" out.avi
+ at end example
+
+Flip the video vertically.
+
+ at section buffer
+
+This input filter is used by the client application to feed pictures to
+the filter chain. See ffmpeg.c for an usage example.
+
+ at section movie
+
+The parameters of the movie filter are
+ at example
+ seekpoint in microseconds : string format : string filename
+ at end example
+
+We can overlay a second movie on top of a main one as in this graph:
+
+ at example
+ input -----------> deltapts0 --> overlay --> output
+                                    ^
+ movie --> scale--> deltapts1 ------|
+ at end example
+
+To do that
+
+ at example
+ffmpeg -i in.avi -s 240x320 -vfilters "[in]setpts=PTS-STARTPTS, [T1]overlay=16:16[out]; movie=3200000:avi:in.avi, scale=180:144, setpts=PTS-STARTPTS[T1]" -y out.avi
+ at end example
+
+ at bye


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