The licence was changed from GPL to LGPL with explicit approval from
the original author.
See thread:
Subject: [FFmpeg-devel] [PATCH] lavfi: add rgbtestsrc source,
ported from MPlayer libmpcodecs
Date: Mon, 11 Jul 2011 16:32:41 +0200
Signed-off-by: Anton Khirnov <anton@khirnov.net>