This patch enables paletteuse to identify the transparency in incoming
video and tag transparent pixels on outgoing video with the correct
index from the palette.

This requires tracking the transparency index in the palette,
establishing an alpha threshold below which a pixel is considered
transparent and above which the pixel is considered opaque, and
additional changes to track the alpha value throughout the conversion
process.

This change is a partial fix for https://trac.ffmpeg.org/ticket/4443
However, animated GIFs are still output incorrectly due to a bug
in gif optimization which does not correctly handle transparency.
Signed-off-by: Clément Bœsch <u@pkh.me>

Fixes the following warning:
libavfilter/tests/filtfmts.c: In function ‘main’:
libavfilter/tests/filtfmts.c:103:18: warning: assignment discards ‘const’ qualifier from pointer target type

Fixes the following warning:
libavfilter/graphparser.c:122:10: warning: assignment discards 'const' qualifier from pointer target type

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

This is an ABI change in libva2: previously the Intel driver had this
behaviour and it was implemented as a driver quirk, but now it is part
of the specification so all drivers must do it.

Silences several warnings:
main is usually a function

Signed-off-by: Sasi Inguva <isasi@google.com>

Allows to specify the action to be performed when reading the last frame
from the internal FIFO buffer. By default the last frame is written to
filter output depending on the timestamp rounding method. When using
"pass" action the last frame is passed through if input duration
has not been reached yet.

Examples using an input file with 25Hz, 1.4sec duration:
 - "fps=fps=1:round=near" generates an output file of 1sec
 - "fps=fps=1:round=near:eof_action=pass" generates an output file of
   2sec
Signed-off-by: Tobias Rapp <t.rapp@noa-archive.com>

Add missing AV_OPT_FLAG_FILTERING_PARAM flag to "start_time" option.
Fix indent of "round" named constants and clear unused field values.
Signed-off-by: Tobias Rapp <t.rapp@noa-archive.com>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Fixes fate-source
Signed-off-by: James Almer <jamrial@gmail.com>

Signed-off-by: Ashish Singh <ashk43712@gmail.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

Signed-off-by: Tobias Rapp <t.rapp@noa-archive.com>

Signed-off-by: Thomas Mundt <tmundt75@gmail.com>

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

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Thomas Mundt <tmundt75@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Thomas Mundt <tmundt75@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

Eliminate lavc->lavfi dependency. The function isn't big and doesn't
deserve its own file.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

Fixes ticket #6672.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Signed-off-by: Thomas Mundt <tmundt75@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

The complex vertical low-pass filter slightly over-sharpens the picture. This becomes visible when several transcodings are cascaded and the error potentises, e.g. some generations of HD->SD SD->HD.
To prevent this behaviour the destination pixel must not exceed the source pixel when the average of the pixels above and below is less than the source pixel. And the other way around.

Tested and approved in a visual transcoding cascade test by video professionals.
SSIM/PSNR test with the first generation of an HD->SD file as a reference against the 6th generation(3 x SD->HD HD->SD):
Results without the patch:
SSIM Y:0.956508 (13.615881) U:0.991601 (20.757750) V:0.993004 (21.551382) All:0.974405 (15.918463)
PSNR y:31.838009 u:48.424280 v:48.962711 average:34.759466 min:31.699297 max:40.857847
Results with the patch:
SSIM Y:0.970051 (15.236232) U:0.991883 (20.905857) V:0.993174 (21.658049) All:0.981290 (17.279202)
PSNR y:34.412108 u:48.504454 v:48.969496 average:37.264644 min:34.310637 max:42.373392
Signed-off-by: Thomas Mundt <tmundt75@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Fix ticket #2674
Tested with examples from ticket 2674.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Reported-by: Moritz Barsnick
Signed-off-by: Paul B Mahol <onemda@gmail.com>

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

Fix CID 1416960.