Based on the 2007 GSoC project from Kamil Nowosad <k.nowosad@students.mimuw.edu.pl>
Updated to current programming standards, style and many more small
fixes by Diego Biurrun <diego@biurrun.de>.
Signed-off-by: Diego Biurrun <diego@biurrun.de>

Based on a patch by Vittorio Giovara <vittorio.giovara@gmail.com>

Fixes Bug 378.

Signed-off-by: Anton Khirnov <anton@khirnov.net>

Removes an arbitrary hardcoded limit on the number of filters.

The caller needs to know what valid indices can be passed to
avfilter_pad_get_name/type.

This will be useful in avtools in the following commits.
Any other caller might also want to know this information.

Drop the unused opaque parameter from its signature.

It will be useful in the following commits.

Since this function adds a standalone filter to a filter graph and we do
not support creating such filters, there is no reason for this function
to exist.

Since we do not support "standalone" filters not attached to an
AVFilterGraph, we should not have a public function to create such
filters. In addition that function is horribly named, the action it does
cannot be possibly described as "opening" a filter.

We do not support using filters without AVFilterGraph in practice
anyway, so there is no point in pretending we do.

Adapted from the author's blag.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

Based on a patch by Michael Niedermayer <michaelni@gmx.at>.

Change the mappings separator from comma to '|' to avoid excessive
escaping, since comma is already used for separating filters in the
filtergraph description.