This filter is inspired upon libmpcodecs/vf_framestep.c, by Daniele
Forghieri.

Only-keyframe output is not supported, since that feature can be achieved
through the more versatile select filter.

Signed-off-by: Martin Storsjö <martin@martin.st>

This is a port of the MPlayer hue filter (libmpcodecs/vf_hue.c) by
Michael Niedermayer.

Signed-off-by: Jérémy Tran <tran.jeremy.av@gmail.com>
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

Based on an idea by Andrey Utkin <andrey.krieger.utkin@gmail.com>.

Patch readapted by Stefano Sabatini, color values proposed by Tim
Nicholson <nichot20@yahoo.com>.

Address trac ticket #1462.

See thread:
Subject: [FFmpeg-devel] [PATCH] smptebars filter
Date: Wed, 20 Jun 2012 01:54:58 +0000

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

Since the recent changes, movie and amovie are able to deal with more
than one type of stream, so they should be categorized as "multimedia
sources" rather than audio/video sources.

These filters are designed for storing and transmitting video sequences
with alpha using higher-efficiency codecs such as x264 which don't
natively support an alpha channel. 'alphaextract' takes an input stream
with an alpha channel and returns a video containing just the alpha
component as a grayscale value; 'alphamerge' takes an RGB or YUV stream
and adds an alpha channel recovered from a second grayscale stream.

Signed-off-by: Steven Robertson <steven@strobe.cc>
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

Inspired by MPlayer's af_channels filter and SoX's remix effect.

It joins multiple input streams into one multi-channel output.

Add atempo audio filter for adjusting audio tempo without affecting
pitch. This filter implements WSOLA algorithm with fast cross
correlation calculation in frequency domain.

Signed-off-by: Pavel Koshevoy <pavel@homestead.aragog.com>
Signed-off-by: Stefano Sabatini <stefasab@gmail.com>

This filter changes the number of samples on single output operation.

Based on a patch by Andrey Utkin <andrey.krieger.utkin@gmail.com>.

Based on current version of the asplit filter in FFmpeg written by
Stefano Sabatini and others.

Partially based on a patch by Robert Nagy <ronag89@gmail.com>

Based on a patch by Mina Nagy Zaki <mnzaki@gmail.com>

Also add the public interface libavfilter/buffersink.h.

Based on a commit by Stefano Sabatini.

The scale filter is used for internal colorspace conversions, so it must
always be present.

Partially based on the port by Niel van der Westhuizen
<nielkie@gmail.com>, done for GCI 2010. Same output as the original
filter and as fast.

See thread:
Subject: [FFmpeg-devel] [PATCH] Port MPlayer 2xSaI filter to libavfilter
Date: Thu, 25 Nov 2010 01:31:24 +1000

The code is based on the remove-logo filter in MPlayer/libmpcodecs, by
Robert Edele, relicensed to LGPL with consent of the author.

Address trac issue #249.

Ported by: Baptiste Coudurier
cleanup+fate by ubitux
For detailed authorship of the original code please see avisynth

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Also add bbox.h and bbox.c files, based on the remove-logo filter by
Robert Edele. These files are useful for sharing code with the pending
removelogo port.

Address trac ticket #901.

Port MPlayer tinterlace filter from MPlayer, with some ideas taken
from the FFmbc/libavfilter port, with the following main differences:

* added support for full-scale YUVJ formats
* added support for YUVA420P
* request_frame() on the filter is forced to return a frame
* some code factorization (related to the copy_picture_fields() function)
* fixed black padding values for mode 3

It's a part of public API.