[Bug 710810] New: [geometrictransform] add a matrix plugin for a 2D perspective transform

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=710810
  GStreamer | gst-plugins-bad | 1.2.0

           Summary: [geometrictransform] add a matrix plugin for a 2D
                    perspective transform
    Classification: Platform
           Product: GStreamer
           Version: 1.2.0
        OS/Version: All
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: Normal
         Component: gst-plugins-bad
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: ospite at studenti.unina.it
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


Created an attachment (id=258024)
 View: https://bugzilla.gnome.org/attachment.cgi?id=258024
 Review: https://bugzilla.gnome.org/review?bug=710810&attachment=258024

add a matrix plugin for a 2D perspective transform

Hi,

in the attached patch I am proposing a "matrix" plugin which applies a 2D
perspective (also called projective) transform to the frame buffer.

A perspective transform can be used for instance to perform keystone correction
when playing the content with a video projector.

It is a little and nice generic plugin, but it is my first one, so I could use
some review, in particular I am concerned about the gst_matrix_get_property()
implementation, I am using a new allocated GValueArray (allocated in
get_array_from_matrix()), is that OK?

A test program for the plugin can be found here:
http://git.ao2.it/experiments/gstreamer.git/tree/HEAD:/c/gst-matrix-example

The plugin is based on the "rotate" one, the "semantic diff" can be seen with
this script:

#!/bin/bash

set -e

filter()
{
  cat $1 | sed -e 's/ROTATE/MATRIX/g' -e 's/Rotate/Matrix/g' -e
's/rotate/matrix/g'
}

diff -pu <(filter gstrotate.h) gstmatrix.h | cat
diff -pu <(filter gstrotate.c) gstmatrix.c

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