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This could arguably also be a vf, but I decided to put it here since decoders are technically required to apply film grain during the output step, and I would rather want to avoid requiring users insert the correct film grain synthesis filter on their own. The code, while in C, is written in a way that unrolls/vectorizes fairly well under -O3, and is reasonably cache friendly. On my CPU, a single thread pushes about 400 FPS at 1080p. Apart from hand-written assembly, one possible avenue of improvement would be to change the access order to compute the grain row-by-row rather than in 8x8 blocks. This requires some redundant PRNG calls, but would make the algorithm more cache-oblivious. The implementation has been written to the wording of SMPTE RDD 5-2006 as faithfully as I can manage. However, apart from passing a visual inspection, no guarantee of correctness can be made due to the lack of any publicly available reference implementation against which to compare it. Signed-off-by: Niklas Haas <git@haasn.dev> Signed-off-by: James Almer <jamrial@gmail.com>
53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
/*
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* H.274 film grain synthesis
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* Copyright (c) 2021 Niklas Haas <ffmpeg@haasn.xyz>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* H.274 film grain synthesis.
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* @author Niklas Haas <ffmpeg@haasn.xyz>
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*/
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#ifndef AVCODEC_H274_H
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#define AVCODEC_H274_H
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#include <libavutil/film_grain_params.h>
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// Must be initialized to {0} prior to first usage
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typedef struct H274FilmGrainDatabase {
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// Database of film grain patterns, lazily computed as-needed
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int8_t db[13 /* h */][13 /* v */][64][64];
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uint16_t residency[13 /* h */]; // bit field of v
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// Temporary buffer for slice generation
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int16_t slice_tmp[64][64];
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} H274FilmGrainDatabase;
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// Synthesizes film grain on top of `in` and stores the result to `out`. `out`
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// must already have been allocated and set to the same size and format as
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// `in`.
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//
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// Returns a negative error code on error, such as invalid params.
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int ff_h274_apply_film_grain(AVFrame *out, const AVFrame *in,
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H274FilmGrainDatabase *db,
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const AVFilmGrainParams *params);
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#endif /* AVCODEC_H274_H */
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