[FFmpeg-devel] [PATCH] Add vfilters.texi to documentation

[Diego Biurrun]

On Thu, Oct 08, 2009 at 11:54:05PM +0200, Stefano Sabatini wrote:
> 
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ ffmpeg/doc/vfilters.texi	2009-10-08 23:53:29.000000000 +0200
> @@ -0,0 +1,82 @@
> +
> +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.
> +
> +Integrating libavfilter into the main FFmpeg repository is a work in
> +progress. If you wish to try the unfinished development code of
> +libavfilter then download it from the libavfilter SOC repository into
> +some directory of your choice by:

Readers will likely be unfamiliar with the abbreviation SOC.

s/download it/check it out/

> +And then read @url{http://svn.ffmpeg.org/soc/libavfilter/README?view=co}

That's currently non-functional.  Just mention the README.

> +The former video hook modules allowed a list of hooks, that would run
> +in the order that they were specified on the ffmpeg command line.
> +Each filter had one input and one output.

I'm not sure if talking about vhooks is useful.

> + at example
> +input --> split ---> fifo ----------------------> overlay --> output
> +            |                                        ^
> +            |                                        |
> +            +------> fifo --> crop --> vflip --------+
> + at end example

FIFO

> +splits the stream into two streams, sends one stream through the crop filter

splits the stream in two

> +overlaying it on top. You can use the following command to do this filtering:

You can use the following command to achieve this:

The command line is:

> +where input_video.avi has a vertical resolution of 480 pixels, the

s/,/./

> +result should be that in output the top half of the video is mirrored
> +onto the bottom half.

should be? :)

> +Video filters are loaded using the @var{-vfilters} option to ffmpeg or
> +to ffplay.

Options are not "to a program".  They belong to a program or are passed
to it.  A program also has options or can be called with different
options.

> The filters in the same linear chain are separated by

Filters in the

> +The magic labels @var{[in]} and @var{[out]} are respectively the points

s/respectively//

> +After the filter name, you may find the equal sign and a semicolon-separated

May find?  And sometimes may not find?

> +Following, a description of the currently available video filters.

I know it was my own suggestion, but this sounds awkward.  Try

  Below is a description

Diego