format.c

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/*
 * Copyright (C) 2024 Niklas Haas
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
 
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/hdr_dynamic_metadata.h"
#include "libavutil/mastering_display_metadata.h"
#include "libavutil/refstruct.h"
 
#include "format.h"
#include "csputils.h"
#include "ops_internal.h"
#include "config_components.h"
 
#if CONFIG_UNSTABLE
#include "libavutil/hwcontext.h"
#endif
 
#define RET(x)                                                                 \
    do {                                                                       \
        int _ret = (x);                                                        \
        if (_ret  < 0)                                                         \
            return _ret;                                                       \
    } while (0)
 
typedef struct LegacyFormatEntry {
    uint8_t is_supported_in         :1;
    uint8_t is_supported_out        :1;
    uint8_t is_supported_endianness :1;
} LegacyFormatEntry;
 
/* Format support table for legacy swscale */
static const LegacyFormatEntry legacy_format_entries[] = {
    [AV_PIX_FMT_YUV420P]        = { 1, 1 },
    [AV_PIX_FMT_YUYV422]        = { 1, 1 },
    [AV_PIX_FMT_RGB24]          = { 1, 1 },
    [AV_PIX_FMT_BGR24]          = { 1, 1 },
    [AV_PIX_FMT_YUV422P]        = { 1, 1 },
    [AV_PIX_FMT_YUV444P]        = { 1, 1 },
    [AV_PIX_FMT_YUV410P]        = { 1, 1 },
    [AV_PIX_FMT_YUV411P]        = { 1, 1 },
    [AV_PIX_FMT_GRAY8]          = { 1, 1 },
    [AV_PIX_FMT_MONOWHITE]      = { 1, 1 },
    [AV_PIX_FMT_MONOBLACK]      = { 1, 1 },
    [AV_PIX_FMT_PAL8]           = { 1, 0 },
    [AV_PIX_FMT_YUVJ420P]       = { 1, 1 },
    [AV_PIX_FMT_YUVJ411P]       = { 1, 1 },
    [AV_PIX_FMT_YUVJ422P]       = { 1, 1 },
    [AV_PIX_FMT_YUVJ444P]       = { 1, 1 },
    [AV_PIX_FMT_YVYU422]        = { 1, 1 },
    [AV_PIX_FMT_UYVY422]        = { 1, 1 },
    [AV_PIX_FMT_UYYVYY411]      = { 1, 0 },
    [AV_PIX_FMT_BGR8]           = { 1, 1 },
    [AV_PIX_FMT_BGR4]           = { 0, 1 },
    [AV_PIX_FMT_BGR4_BYTE]      = { 1, 1 },
    [AV_PIX_FMT_RGB8]           = { 1, 1 },
    [AV_PIX_FMT_RGB4]           = { 0, 1 },
    [AV_PIX_FMT_RGB4_BYTE]      = { 1, 1 },
    [AV_PIX_FMT_NV12]           = { 1, 1 },
    [AV_PIX_FMT_NV21]           = { 1, 1 },
    [AV_PIX_FMT_ARGB]           = { 1, 1 },
    [AV_PIX_FMT_RGBA]           = { 1, 1 },
    [AV_PIX_FMT_ABGR]           = { 1, 1 },
    [AV_PIX_FMT_BGRA]           = { 1, 1 },
    [AV_PIX_FMT_0RGB]           = { 1, 1 },
    [AV_PIX_FMT_RGB0]           = { 1, 1 },
    [AV_PIX_FMT_0BGR]           = { 1, 1 },
    [AV_PIX_FMT_BGR0]           = { 1, 1 },
    [AV_PIX_FMT_GRAY9BE]        = { 1, 1 },
    [AV_PIX_FMT_GRAY9LE]        = { 1, 1 },
    [AV_PIX_FMT_GRAY10BE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY10LE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY12BE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY12LE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY14BE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY14LE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY16BE]       = { 1, 1 },
    [AV_PIX_FMT_GRAY16LE]       = { 1, 1 },
    [AV_PIX_FMT_YUV440P]        = { 1, 1 },
    [AV_PIX_FMT_YUVJ440P]       = { 1, 1 },
    [AV_PIX_FMT_YUV440P10LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV440P10BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV440P12LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV440P12BE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA420P]       = { 1, 1 },
    [AV_PIX_FMT_YUVA422P]       = { 1, 1 },
    [AV_PIX_FMT_YUVA444P]       = { 1, 1 },
    [AV_PIX_FMT_YUVA420P9BE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA420P9LE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA422P9BE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA422P9LE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA444P9BE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA444P9LE]    = { 1, 1 },
    [AV_PIX_FMT_YUVA420P10BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA420P10LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA422P10BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA422P10LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P10BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P10LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA420P16BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA420P16LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA422P16BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA422P16LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P16BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P16LE]   = { 1, 1 },
    [AV_PIX_FMT_RGB48BE]        = { 1, 1 },
    [AV_PIX_FMT_RGB48LE]        = { 1, 1 },
    [AV_PIX_FMT_RGBA64BE]       = { 1, 1, 1 },
    [AV_PIX_FMT_RGBA64LE]       = { 1, 1, 1 },
    [AV_PIX_FMT_RGB565BE]       = { 1, 1 },
    [AV_PIX_FMT_RGB565LE]       = { 1, 1 },
    [AV_PIX_FMT_RGB555BE]       = { 1, 1 },
    [AV_PIX_FMT_RGB555LE]       = { 1, 1 },
    [AV_PIX_FMT_BGR565BE]       = { 1, 1 },
    [AV_PIX_FMT_BGR565LE]       = { 1, 1 },
    [AV_PIX_FMT_BGR555BE]       = { 1, 1 },
    [AV_PIX_FMT_BGR555LE]       = { 1, 1 },
    [AV_PIX_FMT_YUV420P16LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P16BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P16LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P16BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P16LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P16BE]    = { 1, 1 },
    [AV_PIX_FMT_RGB444LE]       = { 1, 1 },
    [AV_PIX_FMT_RGB444BE]       = { 1, 1 },
    [AV_PIX_FMT_BGR444LE]       = { 1, 1 },
    [AV_PIX_FMT_BGR444BE]       = { 1, 1 },
    [AV_PIX_FMT_YA8]            = { 1, 1 },
    [AV_PIX_FMT_YA16BE]         = { 1, 1 },
    [AV_PIX_FMT_YA16LE]         = { 1, 1 },
    [AV_PIX_FMT_BGR48BE]        = { 1, 1 },
    [AV_PIX_FMT_BGR48LE]        = { 1, 1 },
    [AV_PIX_FMT_BGRA64BE]       = { 1, 1, 1 },
    [AV_PIX_FMT_BGRA64LE]       = { 1, 1, 1 },
    [AV_PIX_FMT_YUV420P9BE]     = { 1, 1 },
    [AV_PIX_FMT_YUV420P9LE]     = { 1, 1 },
    [AV_PIX_FMT_YUV420P10BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P10LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P12BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P12LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P14BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV420P14LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P9BE]     = { 1, 1 },
    [AV_PIX_FMT_YUV422P9LE]     = { 1, 1 },
    [AV_PIX_FMT_YUV422P10BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P10LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P12BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P12LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P14BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV422P14LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P9BE]     = { 1, 1 },
    [AV_PIX_FMT_YUV444P9LE]     = { 1, 1 },
    [AV_PIX_FMT_YUV444P10BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P10LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P12BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P12LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P14BE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P14LE]    = { 1, 1 },
    [AV_PIX_FMT_YUV444P10MSBBE] = { 1, 1 },
    [AV_PIX_FMT_YUV444P10MSBLE] = { 1, 1 },
    [AV_PIX_FMT_YUV444P12MSBBE] = { 1, 1 },
    [AV_PIX_FMT_YUV444P12MSBLE] = { 1, 1 },
    [AV_PIX_FMT_GBRP]           = { 1, 1 },
    [AV_PIX_FMT_GBRP9LE]        = { 1, 1 },
    [AV_PIX_FMT_GBRP9BE]        = { 1, 1 },
    [AV_PIX_FMT_GBRP10LE]       = { 1, 1 },
    [AV_PIX_FMT_GBRP10BE]       = { 1, 1 },
    [AV_PIX_FMT_GBRAP10LE]      = { 1, 1 },
    [AV_PIX_FMT_GBRAP10BE]      = { 1, 1 },
    [AV_PIX_FMT_GBRP10MSBLE]    = { 1, 1 },
    [AV_PIX_FMT_GBRP10MSBBE]    = { 1, 1 },
    [AV_PIX_FMT_GBRP12LE]       = { 1, 1 },
    [AV_PIX_FMT_GBRP12BE]       = { 1, 1 },
    [AV_PIX_FMT_GBRP12MSBLE]    = { 1, 1 },
    [AV_PIX_FMT_GBRP12MSBBE]    = { 1, 1 },
    [AV_PIX_FMT_GBRAP12LE]      = { 1, 1 },
    [AV_PIX_FMT_GBRAP12BE]      = { 1, 1 },
    [AV_PIX_FMT_GBRP14LE]       = { 1, 1 },
    [AV_PIX_FMT_GBRP14BE]       = { 1, 1 },
    [AV_PIX_FMT_GBRAP14LE]      = { 1, 1 },
    [AV_PIX_FMT_GBRAP14BE]      = { 1, 1 },
    [AV_PIX_FMT_GBRP16LE]       = { 1, 1 },
    [AV_PIX_FMT_GBRP16BE]       = { 1, 1 },
    [AV_PIX_FMT_GBRPF32LE]      = { 1, 1 },
    [AV_PIX_FMT_GBRPF32BE]      = { 1, 1 },
    [AV_PIX_FMT_GBRAPF32LE]     = { 1, 1 },
    [AV_PIX_FMT_GBRAPF32BE]     = { 1, 1 },
    [AV_PIX_FMT_GBRPF16LE]      = { 1, 0 },
    [AV_PIX_FMT_GBRPF16BE]      = { 1, 0 },
    [AV_PIX_FMT_GBRAPF16LE]     = { 1, 0 },
    [AV_PIX_FMT_GBRAPF16BE]     = { 1, 0 },
    [AV_PIX_FMT_GBRAP]          = { 1, 1 },
    [AV_PIX_FMT_GBRAP16LE]      = { 1, 1 },
    [AV_PIX_FMT_GBRAP16BE]      = { 1, 1 },
    [AV_PIX_FMT_BAYER_BGGR8]    = { 1, 0 },
    [AV_PIX_FMT_BAYER_RGGB8]    = { 1, 0 },
    [AV_PIX_FMT_BAYER_GBRG8]    = { 1, 0 },
    [AV_PIX_FMT_BAYER_GRBG8]    = { 1, 0 },
    [AV_PIX_FMT_BAYER_BGGR16LE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_BGGR16BE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_RGGB16LE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_RGGB16BE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_GBRG16LE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_GBRG16BE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_GRBG16LE] = { 1, 0 },
    [AV_PIX_FMT_BAYER_GRBG16BE] = { 1, 0 },
    [AV_PIX_FMT_XYZ12BE]        = { 1, 1, 1 },
    [AV_PIX_FMT_XYZ12LE]        = { 1, 1, 1 },
    [AV_PIX_FMT_AYUV64LE]       = { 1, 1},
    [AV_PIX_FMT_AYUV64BE]       = { 1, 1 },
    [AV_PIX_FMT_P010LE]         = { 1, 1 },
    [AV_PIX_FMT_P010BE]         = { 1, 1 },
    [AV_PIX_FMT_P012LE]         = { 1, 1 },
    [AV_PIX_FMT_P012BE]         = { 1, 1 },
    [AV_PIX_FMT_P016LE]         = { 1, 1 },
    [AV_PIX_FMT_P016BE]         = { 1, 1 },
    [AV_PIX_FMT_GRAYF32LE]      = { 1, 1 },
    [AV_PIX_FMT_GRAYF32BE]      = { 1, 1 },
    [AV_PIX_FMT_GRAYF16LE]      = { 1, 0 },
    [AV_PIX_FMT_GRAYF16BE]      = { 1, 0 },
    [AV_PIX_FMT_YAF32LE]        = { 1, 0 },
    [AV_PIX_FMT_YAF32BE]        = { 1, 0 },
    [AV_PIX_FMT_YAF16LE]        = { 1, 0 },
    [AV_PIX_FMT_YAF16BE]        = { 1, 0 },
    [AV_PIX_FMT_YUVA422P12BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA422P12LE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P12BE]   = { 1, 1 },
    [AV_PIX_FMT_YUVA444P12LE]   = { 1, 1 },
    [AV_PIX_FMT_NV24]           = { 1, 1 },
    [AV_PIX_FMT_NV42]           = { 1, 1 },
    [AV_PIX_FMT_Y210LE]         = { 1, 1 },
    [AV_PIX_FMT_Y212LE]         = { 1, 1 },
    [AV_PIX_FMT_Y216LE]         = { 1, 1 },
    [AV_PIX_FMT_X2RGB10LE]      = { 1, 1 },
    [AV_PIX_FMT_X2BGR10LE]      = { 1, 1 },
    [AV_PIX_FMT_NV20BE]         = { 1, 1 },
    [AV_PIX_FMT_NV20LE]         = { 1, 1 },
    [AV_PIX_FMT_P210BE]         = { 1, 1 },
    [AV_PIX_FMT_P210LE]         = { 1, 1 },
    [AV_PIX_FMT_P212BE]         = { 1, 1 },
    [AV_PIX_FMT_P212LE]         = { 1, 1 },
    [AV_PIX_FMT_P410BE]         = { 1, 1 },
    [AV_PIX_FMT_P410LE]         = { 1, 1 },
    [AV_PIX_FMT_P412BE]         = { 1, 1 },
    [AV_PIX_FMT_P412LE]         = { 1, 1 },
    [AV_PIX_FMT_P216BE]         = { 1, 1 },
    [AV_PIX_FMT_P216LE]         = { 1, 1 },
    [AV_PIX_FMT_P416BE]         = { 1, 1 },
    [AV_PIX_FMT_P416LE]         = { 1, 1 },
    [AV_PIX_FMT_NV16]           = { 1, 1 },
    [AV_PIX_FMT_VUYA]           = { 1, 1 },
    [AV_PIX_FMT_VUYX]           = { 1, 1 },
    [AV_PIX_FMT_RGBAF16BE]      = { 1, 0 },
    [AV_PIX_FMT_RGBAF16LE]      = { 1, 0 },
    [AV_PIX_FMT_RGBF16BE]       = { 1, 0 },
    [AV_PIX_FMT_RGBF16LE]       = { 1, 0 },
    [AV_PIX_FMT_RGBF32BE]       = { 1, 0 },
    [AV_PIX_FMT_RGBF32LE]       = { 1, 0 },
    [AV_PIX_FMT_XV30LE]         = { 1, 1 },
    [AV_PIX_FMT_XV36LE]         = { 1, 1 },
    [AV_PIX_FMT_XV36BE]         = { 1, 1 },
    [AV_PIX_FMT_XV48LE]         = { 1, 1 },
    [AV_PIX_FMT_XV48BE]         = { 1, 1 },
    [AV_PIX_FMT_AYUV]           = { 1, 1 },
    [AV_PIX_FMT_UYVA]           = { 1, 1 },
    [AV_PIX_FMT_VYU444]         = { 1, 1 },
    [AV_PIX_FMT_V30XLE]         = { 1, 1 },
};
 
int sws_isSupportedInput(enum AVPixelFormat pix_fmt)
{
    return (unsigned)pix_fmt < FF_ARRAY_ELEMS(legacy_format_entries) ?
    legacy_format_entries[pix_fmt].is_supported_in : 0;
}
 
int sws_isSupportedOutput(enum AVPixelFormat pix_fmt)
{
    return (unsigned)pix_fmt < FF_ARRAY_ELEMS(legacy_format_entries) ?
    legacy_format_entries[pix_fmt].is_supported_out : 0;
}
 
int sws_isSupportedEndiannessConversion(enum AVPixelFormat pix_fmt)
{
    return (unsigned)pix_fmt < FF_ARRAY_ELEMS(legacy_format_entries) ?
    legacy_format_entries[pix_fmt].is_supported_endianness : 0;
}
 
static void sanitize_fmt(SwsFormat *fmt, const AVPixFmtDescriptor *desc)
{
    if (desc->flags & (AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PAL | AV_PIX_FMT_FLAG_BAYER)) {
        /* RGB-like family */
        fmt->csp   = AVCOL_SPC_RGB;
        fmt->range = AVCOL_RANGE_JPEG;
    } else if (desc->flags & AV_PIX_FMT_FLAG_XYZ) {
        fmt->csp   = AVCOL_SPC_UNSPECIFIED;
        fmt->color = (SwsColor) {
            .prim = AVCOL_PRI_BT709, /* swscale currently hard-codes this XYZ matrix */
            .trc  = AVCOL_TRC_SMPTE428,
        };
    } else if (desc->nb_components < 3) {
        /* Grayscale formats */
        fmt->color.prim = AVCOL_PRI_UNSPECIFIED;
        fmt->csp        = AVCOL_SPC_UNSPECIFIED;
        if (desc->flags & AV_PIX_FMT_FLAG_FLOAT)
            fmt->range = AVCOL_RANGE_UNSPECIFIED;
        else
            fmt->range = AVCOL_RANGE_JPEG; // FIXME: this restriction should be lifted
    }
 
    switch (av_pix_fmt_desc_get_id(desc)) {
    case AV_PIX_FMT_YUVJ420P:
    case AV_PIX_FMT_YUVJ411P:
    case AV_PIX_FMT_YUVJ422P:
    case AV_PIX_FMT_YUVJ444P:
    case AV_PIX_FMT_YUVJ440P:
        fmt->range = AVCOL_RANGE_JPEG;
        break;
    }
 
    if (!desc->log2_chroma_w && !desc->log2_chroma_h)
        fmt->loc = AVCHROMA_LOC_UNSPECIFIED;
}
 
/**
 * This function also sanitizes and strips the input data, removing irrelevant
 * fields for certain formats.
 */
SwsFormat ff_fmt_from_frame(const AVFrame *frame, int field)
{
    const AVColorPrimariesDesc *primaries;
    AVFrameSideData *sd;
 
    enum AVPixelFormat format = frame->format;
    enum AVPixelFormat hw_format = AV_PIX_FMT_NONE;
 
#if CONFIG_UNSTABLE
    const AVPixFmtDescriptor *hw_desc = av_pix_fmt_desc_get(frame->format);
    av_assert0(hw_desc);
 
    if (hw_desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
        av_assert0(frame->hw_frames_ctx);
 
        AVHWFramesContext *hwfc = (AVHWFramesContext *)frame->hw_frames_ctx->data;
        hw_format = frame->format;
        format = hwfc->sw_format;
    }
#endif
 
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
 
    SwsFormat fmt = {
        .width     = frame->width,
        .height    = frame->height,
        .format    = format,
        .hw_format = hw_format,
        .range     = frame->color_range,
        .csp       = frame->colorspace,
        .loc       = frame->chroma_location,
        .desc      = desc,
        .color = {
            .prim = frame->color_primaries,
            .trc  = frame->color_trc,
        },
    };
 
    av_assert1(fmt.width > 0);
    av_assert1(fmt.height > 0);
    av_assert1(fmt.format != AV_PIX_FMT_NONE);
    av_assert0(desc);
    sanitize_fmt(&fmt, desc);
 
    if (frame->flags & AV_FRAME_FLAG_INTERLACED) {
        fmt.height = (fmt.height + (field == FIELD_TOP)) >> 1;
        fmt.interlaced = 1;
        fmt.field = field;
    }
 
    /* Set luminance and gamut information */
    fmt.color.min_luma = av_make_q(0, 1);
    switch (fmt.color.trc) {
    case AVCOL_TRC_SMPTE2084:
        fmt.color.max_luma = av_make_q(10000, 1); break;
    case AVCOL_TRC_ARIB_STD_B67:
        fmt.color.max_luma = av_make_q( 1000, 1); break; /* HLG reference display */
    default:
        fmt.color.max_luma = av_make_q(  203, 1); break; /* SDR reference brightness */
    }
 
    primaries = av_csp_primaries_desc_from_id(fmt.color.prim);
    if (primaries)
        fmt.color.gamut = primaries->prim;
 
    if ((sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MASTERING_DISPLAY_METADATA))) {
        const AVMasteringDisplayMetadata *mdm = (const AVMasteringDisplayMetadata *) sd->data;
        if (mdm->has_luminance) {
            fmt.color.min_luma = mdm->min_luminance;
            fmt.color.max_luma = mdm->max_luminance;
        }
 
        if (mdm->has_primaries) {
            /* Ignore mastering display white point as it has no bearance on
             * the underlying content */
            fmt.color.gamut.r.x = mdm->display_primaries[0][0];
            fmt.color.gamut.r.y = mdm->display_primaries[0][1];
            fmt.color.gamut.g.x = mdm->display_primaries[1][0];
            fmt.color.gamut.g.y = mdm->display_primaries[1][1];
            fmt.color.gamut.b.x = mdm->display_primaries[2][0];
            fmt.color.gamut.b.y = mdm->display_primaries[2][1];
        }
    }
 
    if ((sd = av_frame_get_side_data(frame, AV_FRAME_DATA_DYNAMIC_HDR_PLUS))) {
        const AVDynamicHDRPlus *dhp = (const AVDynamicHDRPlus *) sd->data;
        const AVHDRPlusColorTransformParams *pars = &dhp->params[0];
        const AVRational nits = av_make_q(10000, 1);
        AVRational maxrgb = pars->maxscl[0];
 
        if (!dhp->num_windows || dhp->application_version > 1)
            goto skip_hdr10;
 
        /* Maximum of MaxSCL components */
        if (av_cmp_q(pars->maxscl[1], maxrgb) > 0)
            maxrgb = pars->maxscl[1];
        if (av_cmp_q(pars->maxscl[2], maxrgb) > 0)
            maxrgb = pars->maxscl[2];
 
        if (maxrgb.num > 0) {
            /* Estimate true luminance from MaxSCL */
            const AVLumaCoefficients *luma = av_csp_luma_coeffs_from_avcsp(fmt.csp);
            if (!luma)
                goto skip_hdr10;
            fmt.color.frame_peak = av_add_q(av_mul_q(luma->cr, pars->maxscl[0]),
                                   av_add_q(av_mul_q(luma->cg, pars->maxscl[1]),
                                            av_mul_q(luma->cb, pars->maxscl[2])));
            /* Scale the scene average brightness by the ratio between the
             * maximum luminance and the MaxRGB values */
            fmt.color.frame_avg = av_mul_q(pars->average_maxrgb,
                                           av_div_q(fmt.color.frame_peak, maxrgb));
        } else {
            /**
             * Calculate largest value from histogram to use as fallback for
             * clips with missing MaxSCL information. Note that this may end
             * up picking the "reserved" value at the 5% percentile, which in
             * practice appears to track the brightest pixel in the scene.
             */
            for (int i = 0; i < pars->num_distribution_maxrgb_percentiles; i++) {
                const AVRational pct = pars->distribution_maxrgb[i].percentile;
                if (av_cmp_q(pct, maxrgb) > 0)
                    maxrgb = pct;
                fmt.color.frame_peak = maxrgb;
                fmt.color.frame_avg  = pars->average_maxrgb;
            }
        }
 
        /* Rescale to nits */
        fmt.color.frame_peak = av_mul_q(nits, fmt.color.frame_peak);
        fmt.color.frame_avg  = av_mul_q(nits, fmt.color.frame_avg);
    }
skip_hdr10:
 
    /* PQ is always scaled down to absolute zero, so ignore mastering metadata */
    if (fmt.color.trc == AVCOL_TRC_SMPTE2084)
        fmt.color.min_luma = av_make_q(0, 1);
 
    return fmt;
}
 
void ff_fmt_from_pixfmt(enum AVPixelFormat pixfmt, SwsFormat *fmt)
{
    ff_fmt_clear(fmt);
    fmt->format = pixfmt;
    fmt->desc = av_pix_fmt_desc_get(pixfmt);
    sanitize_fmt(fmt, fmt->desc);
}
 
static int infer_prim_ref(SwsColor *csp, const SwsColor *ref)
{
    if (csp->prim != AVCOL_PRI_UNSPECIFIED)
        return 0;
 
    /* Reuse the reference gamut only for "safe", similar primaries */
    switch (ref->prim) {
    case AVCOL_PRI_BT709:
    case AVCOL_PRI_BT470M:
    case AVCOL_PRI_BT470BG:
    case AVCOL_PRI_SMPTE170M:
    case AVCOL_PRI_SMPTE240M:
        csp->prim  = ref->prim;
        csp->gamut = ref->gamut;
        break;
    default:
        csp->prim  = AVCOL_PRI_BT709;
        csp->gamut = av_csp_primaries_desc_from_id(csp->prim)->prim;
        break;
    }
 
    return 1;
}
 
static int infer_trc_ref(SwsColor *csp, const SwsColor *ref)
{
    if (csp->trc != AVCOL_TRC_UNSPECIFIED)
        return 0;
 
    /* Pick a suitable SDR transfer function, to try and minimize conversions */
    switch (ref->trc) {
    case AVCOL_TRC_UNSPECIFIED:
    /* HDR curves, never default to these */
    case AVCOL_TRC_SMPTE2084:
    case AVCOL_TRC_ARIB_STD_B67:
        csp->trc = AVCOL_TRC_BT709;
        csp->min_luma = av_make_q(0, 1);
        csp->max_luma = av_make_q(203, 1);
        break;
    default:
        csp->trc = ref->trc;
        csp->min_luma = ref->min_luma;
        csp->max_luma = ref->max_luma;
        break;
    }
 
    return 1;
}
 
bool ff_infer_colors(SwsColor *src, SwsColor *dst)
{
    int incomplete = 0;
 
    incomplete |= infer_prim_ref(dst, src);
    incomplete |= infer_prim_ref(src, dst);
    av_assert0(src->prim != AVCOL_PRI_UNSPECIFIED);
    av_assert0(dst->prim != AVCOL_PRI_UNSPECIFIED);
 
    incomplete |= infer_trc_ref(dst, src);
    incomplete |= infer_trc_ref(src, dst);
    av_assert0(src->trc != AVCOL_TRC_UNSPECIFIED);
    av_assert0(dst->trc != AVCOL_TRC_UNSPECIFIED);
 
    return incomplete;
}
 
void ff_sws_chroma_pos(const SwsFormat *fmt, bool *incomplete,
                       int *out_x_pos, int *out_y_pos)
{
    enum AVChromaLocation chroma_loc = fmt->loc;
    const int sub_x = fmt->desc->log2_chroma_w;
    const int sub_y = fmt->desc->log2_chroma_h;
    int x_pos, y_pos;
 
    /* Explicitly default to center siting for compatibility with swscale */
    if (chroma_loc == AVCHROMA_LOC_UNSPECIFIED) {
        chroma_loc = AVCHROMA_LOC_CENTER;
        *incomplete |= sub_x || sub_y;
    }
 
    /* av_chroma_location_enum_to_pos() always gives us values in the range from
     * 0 to 256, but we need to adjust this to the true value range of the
     * subsampling grid, which may be larger for h/v_sub > 1 */
    av_chroma_location_enum_to_pos(&x_pos, &y_pos, chroma_loc);
    x_pos *= (1 << sub_x) - 1;
    y_pos *= (1 << sub_y) - 1;
 
    /* Fix vertical chroma position for interlaced frames */
    if (sub_y && fmt->interlaced) {
        /* When vertically subsampling, chroma samples are effectively only
         * placed next to even rows. To access them from the odd field, we need
         * to account for this shift by offsetting the distance of one luma row.
         *
         * For 4x vertical subsampling (v_sub == 2), they are only placed
         * next to every *other* even row, so we need to shift by three luma
         * rows to get to the chroma sample. */
        if (fmt->field == FIELD_BOTTOM)
            y_pos += (256 << sub_y) - 256;
 
        /* Luma row distance is doubled for fields, so halve offsets */
        y_pos >>= 1;
    }
 
    *out_x_pos = x_pos;
    *out_y_pos = y_pos;
}
 
/* Variant of sws_test_format() for the ops-based code */
static int test_format_ops(enum AVPixelFormat format, int output);
static int test_format_legacy(enum AVPixelFormat format, int output)
{
    return output ? sws_isSupportedOutput(format) : sws_isSupportedInput(format);
}
 
int ff_sws_test_pixfmt_backend(const SwsBackend backends,
                               enum AVPixelFormat format, int output)
{
    /* The only non-ops backend is the legacy backend */
    const SwsBackend backends_ops = SWS_BACKEND_ALL ^ SWS_BACKEND_LEGACY;
    return ((backends & SWS_BACKEND_LEGACY) && test_format_legacy(format, output)) ||
           ((backends & backends_ops)       && test_format_ops(format, output));
}
 
int sws_test_format(enum AVPixelFormat format, int output)
{
    return ff_sws_test_pixfmt_backend(SWS_BACKEND_STABLE, format, output);
}
 
int sws_test_hw_format(enum AVPixelFormat format)
{
    switch (format) {
    case AV_PIX_FMT_NONE: return 1;
#if CONFIG_VULKAN
    case AV_PIX_FMT_VULKAN: return 1;
#endif
    default: return 0;
    }
}
 
int sws_test_colorspace(enum AVColorSpace csp, int output)
{
    switch (csp) {
    case AVCOL_SPC_UNSPECIFIED:
    case AVCOL_SPC_RGB:
    case AVCOL_SPC_BT709:
    case AVCOL_SPC_BT470BG:
    case AVCOL_SPC_SMPTE170M:
    case AVCOL_SPC_FCC:
    case AVCOL_SPC_SMPTE240M:
    case AVCOL_SPC_BT2020_NCL:
        return 1;
    default:
        return 0;
    }
}
 
int sws_test_primaries(enum AVColorPrimaries prim, int output)
{
    return ((prim > AVCOL_PRI_RESERVED0 && prim < AVCOL_PRI_NB) ||
            (prim >= AVCOL_PRI_EXT_BASE && prim < AVCOL_PRI_EXT_NB)) &&
           prim != AVCOL_PRI_RESERVED;
}
 
int sws_test_transfer(enum AVColorTransferCharacteristic trc, int output)
{
    av_csp_eotf_function eotf = output ? av_csp_itu_eotf_inv(trc)
                                       : av_csp_itu_eotf(trc);
    return trc == AVCOL_TRC_UNSPECIFIED || eotf != NULL;
}
 
static int test_range(enum AVColorRange range)
{
    return (unsigned)range < AVCOL_RANGE_NB;
}
 
static int test_loc(enum AVChromaLocation loc)
{
    return (unsigned)loc < AVCHROMA_LOC_NB;
}
 
int ff_test_fmt(const SwsBackend backends, const SwsFormat *fmt, int output)
{
    return fmt->width > 0 && fmt->height > 0            &&
           ff_sws_test_pixfmt_backend(backends, fmt->format, output) &&
           sws_test_colorspace(fmt->csp,        output) &&
           sws_test_primaries (fmt->color.prim, output) &&
           sws_test_transfer  (fmt->color.trc,  output) &&
           sws_test_hw_format (fmt->hw_format)          &&
           test_range         (fmt->range)              &&
           test_loc           (fmt->loc);
}
 
int sws_test_frame(const AVFrame *frame, int output)
{
    for (int field = 0; field < 2; field++) {
        const SwsFormat fmt = ff_fmt_from_frame(frame, field);
        if (!ff_test_fmt(SWS_BACKEND_STABLE, &fmt, output))
            return 0;
        if (!fmt.interlaced)
            break;
    }
 
    return 1;
}
 
int sws_is_noop(const AVFrame *dst, const AVFrame *src)
{
    for (int field = 0; field < 2; field++) {
        SwsFormat dst_fmt = ff_fmt_from_frame(dst, field);
        SwsFormat src_fmt = ff_fmt_from_frame(src, field);
        if (!ff_fmt_equal(&dst_fmt, &src_fmt))
            return 0;
        if (!dst_fmt.interlaced)
            break;
    }
 
    return 1;
}
 
void ff_sws_frame_from_avframe(SwsFrame *dst, const AVFrame *src)
{
    dst->format  = src->format;
    dst->width   = src->width;
    dst->height  = src->height;
    dst->avframe = src;
    for (int i = 0; i < FF_ARRAY_ELEMS(dst->data); i++) {
        dst->data[i]     = src->data[i];
        dst->linesize[i] = src->linesize[i];
    }
}
 
#if CONFIG_UNSTABLE
 
/**
 * Returns the underlying descriptor for fake formats like PAL8 whose
 * descriptors alone do not fully describe the pixel data.
 */
static inline const AVPixFmtDescriptor *fmt_desc_decoded(enum AVPixelFormat fmt)
{
    if (fmt == AV_PIX_FMT_PAL8)
        return av_pix_fmt_desc_get(AV_PIX_FMT_RGB32);
 
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
    av_assert0(!(desc->flags & AV_PIX_FMT_FLAG_PAL));
    return desc;
}
 
/* Returns the type suitable for a pixel after fully decoding/unpacking it */
static SwsPixelType fmt_pixel_type(enum AVPixelFormat fmt)
{
    const AVPixFmtDescriptor *desc = fmt_desc_decoded(fmt);
    const int bits = FFALIGN(desc->comp[0].depth, 8);
    if (desc->flags & AV_PIX_FMT_FLAG_FLOAT) {
        switch (bits) {
        case 32: return SWS_PIXEL_F32;
        /* TODO: no support for 16-bit float yet */
        }
    } else {
        switch (bits) {
        case  8: return SWS_PIXEL_U8;
        case 16: return SWS_PIXEL_U16;
        /* TODO: AVRational cannot represent UINT32_MAX */
        }
    }
 
    return SWS_PIXEL_NONE;
}
 
/* A regular format is defined as any format that contains only a single
 * component per elementary data type (i.e. no sub-byte pack/unpack needed),
 * and whose components map 1:1 onto elementary data units */
static int is_regular_fmt(enum AVPixelFormat fmt)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
    if (desc->flags & (AV_PIX_FMT_FLAG_PAL | AV_PIX_FMT_FLAG_BAYER))
        return 0; /* no 1:1 correspondence between components and data units */
    if (desc->flags & (AV_PIX_FMT_FLAG_BITSTREAM))
        return 0; /* bitstream formats are packed by definition */
    if ((desc->flags & AV_PIX_FMT_FLAG_PLANAR) || desc->nb_components == 1)
        return 1; /* planar formats are regular by definition */
 
    const int step = desc->comp[0].step;
    int total_bits = 0;
 
    for (int i = 0; i < desc->nb_components; i++) {
        if (desc->comp[i].shift || desc->comp[i].step != step)
            return 0; /* irregular/packed format */
        total_bits += desc->comp[i].depth;
    }
 
    /* Exclude formats with missing components like RGB0, 0RGB, etc. */
    return total_bits == step * 8;
}
 
typedef struct FmtInfo {
    SwsReadWriteOp rw;
    SwsSwizzleOp   swizzle;
    SwsPackOp      pack;
    int            shift;
} FmtInfo;
 
#define BITSTREAM_FMT(SWIZ, FRAC, MODE, ...) (FmtInfo) {        \
    .rw = { .elems = 1, .frac = FRAC, .mode = MODE },           \
    .swizzle = SWIZ,                                            \
    __VA_ARGS__                                                 \
}
 
#define SUBPACKED_FMT(SWIZ, ...) (FmtInfo) {                    \
    .rw = { .elems = 1, .mode = SWS_RW_PACKED },                \
    .swizzle = SWIZ,                                            \
    .pack.pattern = {__VA_ARGS__},                              \
}
 
#define PACKED_FMT(SWIZ, N, ...) (FmtInfo) {                    \
    .rw = { .elems = N, .mode = SWS_RW_PACKED },                \
    .swizzle = SWIZ,                                            \
    __VA_ARGS__                                                 \
}
 
#define RGBA SWS_SWIZZLE(0, 1, 2, 3)
#define BGRA SWS_SWIZZLE(2, 1, 0, 3)
#define ARGB SWS_SWIZZLE(3, 0, 1, 2)
#define ABGR SWS_SWIZZLE(3, 2, 1, 0)
#define AVYU SWS_SWIZZLE(3, 2, 0, 1)
#define VYUA SWS_SWIZZLE(2, 0, 1, 3)
#define UYVA SWS_SWIZZLE(1, 0, 2, 3)
#define VUYA BGRA
 
static FmtInfo fmt_info_irregular(enum AVPixelFormat fmt)
{
    switch (fmt) {
    /* Bitstream formats */
    case AV_PIX_FMT_MONOWHITE:
    case AV_PIX_FMT_MONOBLACK:
        return BITSTREAM_FMT(RGBA, 3, SWS_RW_PLANAR);
    case AV_PIX_FMT_RGB4: return BITSTREAM_FMT(RGBA, 1, SWS_RW_PACKED, .pack = {{ 1, 2, 1 }});
    case AV_PIX_FMT_BGR4: return BITSTREAM_FMT(BGRA, 1, SWS_RW_PACKED, .pack = {{ 1, 2, 1 }});
 
    /* Sub-packed 8-bit aligned formats */
    case AV_PIX_FMT_RGB4_BYTE:  return SUBPACKED_FMT(RGBA, 1, 2, 1);
    case AV_PIX_FMT_BGR4_BYTE:  return SUBPACKED_FMT(BGRA, 1, 2, 1);
    case AV_PIX_FMT_RGB8:       return SUBPACKED_FMT(RGBA, 3, 3, 2);
    case AV_PIX_FMT_BGR8:       return SUBPACKED_FMT(BGRA, 2, 3, 3);
 
    /* Sub-packed 16-bit aligned formats */
    case AV_PIX_FMT_RGB565LE:
    case AV_PIX_FMT_RGB565BE:
        return SUBPACKED_FMT(RGBA, 5, 6, 5);
    case AV_PIX_FMT_BGR565LE:
    case AV_PIX_FMT_BGR565BE:
        return SUBPACKED_FMT(BGRA, 5, 6, 5);
    case AV_PIX_FMT_RGB555LE:
    case AV_PIX_FMT_RGB555BE:
        return SUBPACKED_FMT(RGBA, 5, 5, 5);
    case AV_PIX_FMT_BGR555LE:
    case AV_PIX_FMT_BGR555BE:
        return SUBPACKED_FMT(BGRA, 5, 5, 5);
    case AV_PIX_FMT_RGB444LE:
    case AV_PIX_FMT_RGB444BE:
        return SUBPACKED_FMT(RGBA, 4, 4, 4);
    case AV_PIX_FMT_BGR444LE:
    case AV_PIX_FMT_BGR444BE:
        return SUBPACKED_FMT(BGRA, 4, 4, 4);
 
    /* Sub-packed 32-bit aligned formats */
    case AV_PIX_FMT_X2RGB10LE:
    case AV_PIX_FMT_X2RGB10BE:
        return SUBPACKED_FMT(ARGB, 2, 10, 10, 10);
    case AV_PIX_FMT_X2BGR10LE:
    case AV_PIX_FMT_X2BGR10BE:
        return SUBPACKED_FMT(ABGR, 2, 10, 10, 10);
    case AV_PIX_FMT_XV30LE:
    case AV_PIX_FMT_XV30BE:
        return SUBPACKED_FMT(AVYU, 2, 10, 10, 10);
    case AV_PIX_FMT_V30XLE:
    case AV_PIX_FMT_V30XBE:
        return SUBPACKED_FMT(VYUA, 10, 10, 10, 2);
 
    /* 3-component formats with extra padding */
    case AV_PIX_FMT_RGB0:   return PACKED_FMT(RGBA, 4);
    case AV_PIX_FMT_BGR0:   return PACKED_FMT(BGRA, 4);
    case AV_PIX_FMT_0RGB:   return PACKED_FMT(ARGB, 4);
    case AV_PIX_FMT_0BGR:   return PACKED_FMT(ABGR, 4);
    case AV_PIX_FMT_VUYX:   return PACKED_FMT(VUYA, 4);
    case AV_PIX_FMT_XV36LE:
    case AV_PIX_FMT_XV36BE:
        return PACKED_FMT(UYVA, 4, .shift = 4);
    case AV_PIX_FMT_XV48LE:
    case AV_PIX_FMT_XV48BE:
        return PACKED_FMT(UYVA, 4);
 
    /* Miscellaneous irregular formats */
    case AV_PIX_FMT_PAL8:
        return (FmtInfo) {
            .rw = { .elems = 4, .mode = SWS_RW_PALETTE },
            /* PAL8 is explicitly defined as endian-dependent */
        #if AV_HAVE_BIGENDIAN
            .swizzle = ARGB,
        #else
            .swizzle = BGRA,
        #endif
        };
    }
 
    return (FmtInfo) {0};
}
 
struct comp {
    int index;
    int plane;
    int offset;
};
 
/* Compare by (plane, offset) */
static int cmp_comp(const void *a, const void *b) {
    const struct comp *ca = a;
    const struct comp *cb = b;
    if (ca->plane != cb->plane)
        return ca->plane - cb->plane;
    return ca->offset - cb->offset;
}
 
static int fmt_analyze_regular(const AVPixFmtDescriptor *desc, SwsReadWriteOp *rw_op,
                               SwsSwizzleOp *swizzle, SwsShiftOp *shift)
{
    if (desc->nb_components == 2) {
        /* YA formats */
        *swizzle = SWS_SWIZZLE(0, 3, 1, 2);
    } else {
        /* Sort by increasing component order */
        struct comp sorted[4] = { {0}, {1}, {2}, {3} };
        for (int i = 0; i < desc->nb_components; i++) {
            sorted[i].plane  = desc->comp[i].plane;
            sorted[i].offset = desc->comp[i].offset;
        }
 
        qsort(sorted, desc->nb_components, sizeof(struct comp), cmp_comp);
 
        SwsSwizzleOp swiz = SWS_SWIZZLE(0, 1, 2, 3);
        for (int i = 0; i < desc->nb_components; i++)
            swiz.in[i] = sorted[i].index;
        *swizzle = swiz;
    }
 
    SwsReadWriteMode mode = SWS_RW_PLANAR;
    if (desc->nb_components > 1 && !(desc->flags & AV_PIX_FMT_FLAG_PLANAR))
        mode = SWS_RW_PACKED;
 
    *shift = (SwsShiftOp) { desc->comp[0].shift };
    *rw_op = (SwsReadWriteOp) {
        .elems = desc->nb_components,
        .mode  = mode,
    };
    return 0;
}
 
static int fmt_analyze(enum AVPixelFormat fmt, SwsReadWriteOp *rw_op,
                       SwsPackOp *pack_op, SwsSwizzleOp *swizzle,
                       SwsShiftOp *shift, SwsPixelType *pixel_type,
                       SwsPixelType *raw_type)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
    if (!desc)
        return AVERROR(EINVAL);
 
    /* No support for subsampled formats at the moment */
    if (desc->log2_chroma_w || desc->log2_chroma_h)
        return AVERROR(ENOTSUP);
 
    /* No support for semi-planar formats at the moment */
    if (desc->flags & AV_PIX_FMT_FLAG_PLANAR &&
        av_pix_fmt_count_planes(fmt) < desc->nb_components)
        return AVERROR(ENOTSUP);
 
    *pixel_type = *raw_type = fmt_pixel_type(fmt);
    if (!*pixel_type)
        return AVERROR(ENOTSUP);
 
    if (is_regular_fmt(fmt)) {
        *pack_op = (SwsPackOp) {0};
        return fmt_analyze_regular(desc, rw_op, swizzle, shift);
    }
 
    FmtInfo info = fmt_info_irregular(fmt);
    if (!info.rw.elems)
        return AVERROR(ENOTSUP);
 
    *rw_op   = info.rw;
    *pack_op = info.pack;
    *swizzle = info.swizzle;
    *shift   = (SwsShiftOp) { info.shift };
 
    if (info.pack.pattern[0]) {
        const int sum = info.pack.pattern[0] + info.pack.pattern[1] +
                        info.pack.pattern[2] + info.pack.pattern[3];
        if (sum > 16)
            *raw_type = SWS_PIXEL_U32;
        else if (sum > 8)
            *raw_type = SWS_PIXEL_U16;
        else
            *raw_type = SWS_PIXEL_U8;
    }
 
    return 0;
}
 
static int test_format_ops(enum AVPixelFormat format, int output)
{
    SwsReadWriteOp rw;
    SwsSwizzleOp swizzle;
    SwsPackOp pack;
    SwsShiftOp shift;
    SwsPixelType pixel_type, raw_type;
    int ret = fmt_analyze(format, &rw, &pack, &swizzle, &shift,
                          &pixel_type, &raw_type);
    if (ret < 0)
        return 0;
    if (rw.mode == SWS_RW_PALETTE && output)
        return 0; /* palettes are currently only supported as input */
    return 1;
}
 
static void swizzle_inv(SwsSwizzleOp *swiz)
{
    /* Input[x] =: Output[swizzle.x] */
    unsigned tmp[4];
    tmp[swiz->x] = 0;
    tmp[swiz->y] = 1;
    tmp[swiz->z] = 2;
    tmp[swiz->w] = 3;
    *swiz = (SwsSwizzleOp) {{ .x = tmp[0], tmp[1], tmp[2], tmp[3] }};
}
 
/**
 * This initializes all absent components explicitly to zero. There is no
 * need to worry about the correct neutral value as fmt_decode() will
 * implicitly ignore and overwrite absent components in any case. This function
 * is just to ensure that we don't operate on undefined memory. In most cases,
 * it will end up getting pushed towards the output or optimized away entirely
 * by the optimization pass.
 */
static SwsClearOp fmt_clear(const SwsFormat *fmt)
{
    const AVPixFmtDescriptor *desc = fmt_desc_decoded(fmt->format);
    const bool has_chroma = desc->nb_components >= 3;
    const bool has_alpha  = desc->flags & AV_PIX_FMT_FLAG_ALPHA;
 
    SwsClearOp c = {0};
    if (!has_chroma) {
        c.mask |= SWS_COMP(1) | SWS_COMP(2);
        c.value[1] = c.value[2] = Q(0);
    }
 
    if (!has_alpha) {
        c.mask |= SWS_COMP(3);
        c.value[3] = Q(0);
    }
 
    return c;
}
 
#if HAVE_BIGENDIAN
#  define NATIVE_ENDIAN_FLAG AV_PIX_FMT_FLAG_BE
#else
#  define NATIVE_ENDIAN_FLAG 0
#endif
 
static inline AVRational64 intmax_q64(int bits)
{
    av_assert1(bits >= 0 && bits < 64);
    return Q(UINT64_MAX >> (64 - bits));
}
 
int ff_sws_decode_pixfmt(SwsOpList *ops, const SwsFormat *fmt)
{
    const AVPixFmtDescriptor *desc = fmt_desc_decoded(fmt->format);
    SwsPixelType pixel_type, raw_type;
    SwsReadWriteOp rw_op;
    SwsSwizzleOp swizzle;
    SwsPackOp unpack;
    SwsComps *comps = &ops->comps_src;
    SwsShiftOp shift;
 
    RET(fmt_analyze(fmt->format, &rw_op, &unpack, &swizzle, &shift,
                    &pixel_type, &raw_type));
 
    swizzle_inv(&swizzle);
 
    /* Set baseline pixel content flags */
    const int integer = ff_sws_pixel_type_is_int(raw_type);
    const int swapped = ff_sws_pixel_type_size(raw_type) > 1 &&
                        (desc->flags & AV_PIX_FMT_FLAG_BE) != NATIVE_ENDIAN_FLAG;
    for (int i = 0; i < rw_op.elems; i++) {
        comps->flags[i] = (integer ? SWS_COMP_EXACT   : 0) |
                          (swapped ? SWS_COMP_SWAPPED : 0);
    }
 
    /* Generate value range information for simple unpacked formats */
    if (integer && !unpack.pattern[0]) {
        /* YA formats have desc->comp[] in the order {Y, A} instead of the
         * canonical order {Y, U, V, A} */
        const int is_ya = desc->nb_components == 2;
        for (int c = 0; c < desc->nb_components; c++) {
            const int bits  = desc->comp[c].depth + shift.amount;
            const int idx   = swizzle.in[is_ya ? 3 * c : c];
            comps->min[idx] = Q(0);
            comps->max[idx] = intmax_q64(bits);
        }
    }
 
    /* TODO: handle subsampled or semipacked input formats */
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op    = SWS_OP_READ,
        .type  = raw_type,
        .rw    = rw_op,
    }));
 
    if (swapped) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_SWAP_BYTES,
            .type = raw_type,
        }));
    }
 
    if (unpack.pattern[0]) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_UNPACK,
            .type = raw_type,
            .pack = unpack,
        }));
 
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_CONVERT,
            .type = raw_type,
            .convert.to = pixel_type,
        }));
    }
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op      = SWS_OP_SWIZZLE,
        .type    = pixel_type,
        .swizzle = swizzle,
    }));
 
    if (shift.amount) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op    = SWS_OP_RSHIFT,
            .type  = pixel_type,
            .shift = shift,
        }));
    }
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op    = SWS_OP_CLEAR,
        .type  = pixel_type,
        .clear = fmt_clear(fmt),
    }));
 
    return 0;
}
 
int ff_sws_encode_pixfmt(SwsOpList *ops, const SwsFormat *fmt)
{
    const AVPixFmtDescriptor *desc = fmt_desc_decoded(fmt->format);
    SwsPixelType pixel_type, raw_type;
    SwsReadWriteOp rw_op;
    SwsSwizzleOp swizzle;
    SwsPackOp pack;
    SwsShiftOp shift;
 
    RET(fmt_analyze(fmt->format, &rw_op, &pack, &swizzle, &shift,
                    &pixel_type, &raw_type));
 
    if (rw_op.mode == SWS_RW_PALETTE)
        return AVERROR(ENOTSUP);
 
    if (shift.amount) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op    = SWS_OP_LSHIFT,
            .type  = pixel_type,
            .shift = shift,
        }));
    }
 
    if (rw_op.elems > desc->nb_components) {
        /* Format writes unused alpha channel, clear it explicitly for sanity */
        av_assert1(!(desc->flags & AV_PIX_FMT_FLAG_ALPHA));
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_CLEAR,
            .type = pixel_type,
            .clear.mask = SWS_COMP(3),
            .clear.value[3] = Q(0),
        }));
    }
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op      = SWS_OP_SWIZZLE,
        .type    = pixel_type,
        .swizzle = swizzle,
    }));
 
    if (pack.pattern[0]) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_CONVERT,
            .type = pixel_type,
            .convert.to = raw_type,
        }));
 
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_PACK,
            .type = raw_type,
            .pack = pack,
        }));
    }
 
    if (ff_sws_pixel_type_size(raw_type) > 1 &&
        (desc->flags & AV_PIX_FMT_FLAG_BE) != NATIVE_ENDIAN_FLAG) {
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op   = SWS_OP_SWAP_BYTES,
            .type = raw_type,
        }));
    }
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op   = SWS_OP_WRITE,
        .type = raw_type,
        .rw   = rw_op,
    }));
 
    return 0;
}
 
static inline AVRational64 av_neg_q64(AVRational64 x)
{
    return (AVRational64) { -x.num, x.den };
}
 
static SwsLinearOp fmt_encode_range(const SwsFormat *fmt, bool *incomplete)
{
    const AVRational64 q0 = Q(0);
    const AVRational64 q1 = Q(1);
 
    SwsLinearOp c = { .m = {
        { q1, q0, q0, q0, q0 },
        { q0, q1, q0, q0, q0 },
        { q0, q0, q1, q0, q0 },
        { q0, q0, q0, q1, q0 },
    }};
 
    const AVPixFmtDescriptor *desc = fmt_desc_decoded(fmt->format);
    const int depth0 = desc->comp[0].depth;
    const int depth1 = desc->comp[1].depth;
    const int depth2 = desc->comp[2].depth;
    const int depth3 = desc->comp[3].depth;
 
    if (desc->flags & AV_PIX_FMT_FLAG_FLOAT)
        return c; /* floats are directly output as-is */
 
    if (fmt->csp == AVCOL_SPC_RGB || (desc->flags & AV_PIX_FMT_FLAG_XYZ)) {
        c.m[0][0] = intmax_q64(depth0);
        c.m[1][1] = intmax_q64(depth1);
        c.m[2][2] = intmax_q64(depth2);
    } else if (fmt->range == AVCOL_RANGE_JPEG) {
        /* Full range YUV */
        c.m[0][0] = intmax_q64(depth0);
        if (desc->nb_components >= 3) {
            /* This follows the ITU-R convention, which is slightly different
             * from the JFIF convention. */
            c.m[1][1] = intmax_q64(depth1);
            c.m[2][2] = intmax_q64(depth2);
            c.m[1][4] = Q(1 << (depth1 - 1));
            c.m[2][4] = Q(1 << (depth2 - 1));
        }
    } else {
        /* Limited range YUV */
        if (fmt->range == AVCOL_RANGE_UNSPECIFIED)
            *incomplete = true;
        c.m[0][0] = Q(219 << (depth0 - 8));
        c.m[0][4] = Q( 16 << (depth0 - 8));
        if (desc->nb_components >= 3) {
            c.m[1][1] = Q(224 << (depth1 - 8));
            c.m[2][2] = Q(224 << (depth2 - 8));
            c.m[1][4] = Q(128 << (depth1 - 8));
            c.m[2][4] = Q(128 << (depth2 - 8));
        }
    }
 
    if (desc->flags & AV_PIX_FMT_FLAG_ALPHA) {
        const bool is_ya = desc->nb_components == 2;
        c.m[3][3] = intmax_q64(is_ya ? depth1 : depth3);
    }
 
    if (fmt->format == AV_PIX_FMT_MONOWHITE) {
        /* This format is inverted, 0 = white, 1 = black */
        c.m[0][4] = ff_add_q64(c.m[0][4], c.m[0][0]);
        c.m[0][0] = av_neg_q64(c.m[0][0]);
    }
 
    return c;
}
 
static SwsLinearOp fmt_decode_range(const SwsFormat *fmt, bool *incomplete)
{
    SwsLinearOp c = fmt_encode_range(fmt, incomplete);
 
    /* Invert main diagonal + offset: x = s * y + k  ==>  y = (x - k) / s */
    for (int i = 0; i < 4; i++) {
        av_assert1(c.m[i][i].num);
        c.m[i][i] = ff_inv_q64(c.m[i][i]);
        c.m[i][4] = ff_mul_q64(c.m[i][4], av_neg_q64(c.m[i][i]));
    }
 
    /* Explicitly initialize alpha for sanity */
    if (!(fmt->desc->flags & AV_PIX_FMT_FLAG_ALPHA))
        c.m[3][4] = Q(1);
 
    return c;
}
 
static AVRational64 *generate_bayer_matrix(const int size_log2)
{
    const int size = 1 << size_log2;
    const int num_entries = size * size;
    AVRational64 *m = av_refstruct_allocz(sizeof(*m) * num_entries);
    av_assert1(size_log2 < 16);
    if (!m)
        return NULL;
 
    /* Start with a 1x1 matrix */
    m[0] = Q(0);
 
    /* Generate three copies of the current, appropriately scaled and offset */
    for (int sz = 1; sz < size; sz <<= 1) {
        const int den = 4 * sz * sz;
        for (int y = 0; y < sz; y++) {
            for (int x = 0; x < sz; x++) {
                const AVRational64 cur = m[y * size + x];
                m[(y + sz) * size + x + sz] = ff_add_q64(cur, ff_make_q64(1, den));
                m[(y     ) * size + x + sz] = ff_add_q64(cur, ff_make_q64(2, den));
                m[(y + sz) * size + x     ] = ff_add_q64(cur, ff_make_q64(3, den));
            }
        }
    }
 
    /**
     * To correctly round, we need to evenly distribute the result on [0, 1),
     * giving an average value of 1/2.
     *
     * After the above construction, we have a matrix with average value:
     *   [ 0/N + 1/N + 2/N + ... (N-1)/N ] / N = (N-1)/(2N)
     * where N = size * size is the total number of entries.
     *
     * To make the average value equal to 1/2 = N/(2N), add a bias of 1/(2N).
     */
    for (int i = 0; i < num_entries; i++)
        m[i] = ff_add_q64(m[i], ff_make_q64(1, 2 * num_entries));
 
    return m;
}
 
static bool trc_is_hdr(enum AVColorTransferCharacteristic trc)
{
    static_assert(AVCOL_TRC_NB == 19, "Update this list when adding TRCs");
    static_assert(AVCOL_TRC_EXT_NB == 257, "Update this list when adding TRCs");
    switch (trc) {
    case AVCOL_TRC_LOG:
    case AVCOL_TRC_LOG_SQRT:
    case AVCOL_TRC_V_LOG:
    case AVCOL_TRC_SMPTEST2084:
    case AVCOL_TRC_ARIB_STD_B67:
        return true;
    default:
        return false;
    }
}
 
static int fmt_dither(SwsContext *ctx, SwsOpList *ops,
                      const SwsPixelType type,
                      const SwsFormat *src, const SwsFormat *dst)
{
    SwsDither mode = ctx->dither;
    SwsDitherOp dither;
    const int bpc = dst->desc->comp[0].depth;
 
    if (mode == SWS_DITHER_AUTO) {
        /* Visual threshold of perception: 12 bits for SDR, 14 bits for HDR */
        const int jnd_bits = trc_is_hdr(dst->color.trc) ? 14 : 12;
        mode = bpc >= jnd_bits ? SWS_DITHER_NONE : SWS_DITHER_BAYER;
    }
 
    switch (mode) {
    case SWS_DITHER_NONE:
        if (ctx->flags & SWS_ACCURATE_RND) {
            /* Add constant 0.5 for correct rounding */
            AVRational64 *bias = av_refstruct_allocz(sizeof(*bias));
            if (!bias)
                return AVERROR(ENOMEM);
            *bias = (AVRational64) {1, 2};
            return ff_sws_op_list_append(ops, &(SwsOp) {
                .op   = SWS_OP_DITHER,
                .type = type,
                .dither.matrix = bias,
                .dither.min = *bias,
                .dither.max = *bias,
            });
        } else {
            return 0; /* No-op */
        }
    case SWS_DITHER_BAYER:
        /* Hardcode 16x16 matrix for now; in theory we could adjust this
         * based on the expected level of precision in the output, since lower
         * bit depth outputs can suffice with smaller dither matrices; however
         * in practice we probably want to use error diffusion for such low bit
         * depths anyway */
        dither.size_log2 = 4;
        dither.matrix = generate_bayer_matrix(dither.size_log2);
        if (!dither.matrix)
            return AVERROR(ENOMEM);
 
        const int size = 1 << dither.size_log2;
        dither.min = dither.max = dither.matrix[0];
        for (int i = 1; i < size * size; i++) {
            if (ff_cmp_q64(dither.min, dither.matrix[i]) > 0)
                dither.min = dither.matrix[i];
            if (ff_cmp_q64(dither.matrix[i], dither.max) > 0)
                dither.max = dither.matrix[i];
        }
 
        /* Brute-forced offsets; minimizes quantization error across a 16x16
         * bayer dither pattern for standard RGBA and YUVA pixel formats */
        const int offsets_16x16[4] = {0, 3, 2, 5};
        for (int i = 0; i < 4; i++) {
            av_assert0(offsets_16x16[i] <= INT8_MAX);
            dither.y_offset[i] = offsets_16x16[i];
        }
 
        const AVPixFmtDescriptor *src_desc = fmt_desc_decoded(src->format);
        if (src_desc->nb_components < 3 && bpc >= 8) {
            /**
             * For high-bit-depth sources without chroma, use same matrix
             * offset for all color channels. This prevents introducing color
             * noise in grayscale images; and also allows optimizing the dither
             * operation. Skipped for low bit depth (<8 bpc) as the loss in
             * PSNR, from the inability to diffuse error among all three
             * channels, can be substantial.
             *
             * This shifts: { X, Y, Z, W } -> { X, X, X, Y }
             */
            dither.y_offset[3] = dither.y_offset[1];
            dither.y_offset[1] = dither.y_offset[2] = dither.y_offset[0];
        }
 
        return ff_sws_op_list_append(ops, &(SwsOp) {
            .op     = SWS_OP_DITHER,
            .type   = type,
            .dither = dither,
        });
    case SWS_DITHER_ED:
    case SWS_DITHER_A_DITHER:
    case SWS_DITHER_X_DITHER:
        return AVERROR(ENOTSUP);
 
    case SWS_DITHER_NB:
        break;
    }
 
    av_unreachable("Invalid dither mode");
    return AVERROR(EINVAL);
}
 
#define Q64(x) ff_make_q64((x).num, (x).den)
 
static inline SwsLinearOp
linear_mat3(const AVRational m00, const AVRational m01, const AVRational m02,
            const AVRational m10, const AVRational m11, const AVRational m12,
            const AVRational m20, const AVRational m21, const AVRational m22)
{
    return (SwsLinearOp) {{
        { Q64(m00), Q64(m01), Q64(m02), Q(0), Q(0) },
        { Q64(m10), Q64(m11), Q64(m12), Q(0), Q(0) },
        { Q64(m20), Q64(m21), Q64(m22), Q(0), Q(0) },
        {     Q(0),     Q(0),     Q(0), Q(1), Q(0) },
    }};
}
 
int ff_sws_decode_colors(SwsContext *ctx, SwsPixelType type,
                         SwsOpList *ops, const SwsFormat *fmt, bool *incomplete)
{
    const AVLumaCoefficients *c = av_csp_luma_coeffs_from_avcsp(fmt->csp);
    const SwsPixelType pixel_type = fmt_pixel_type(fmt->format);
    if (!pixel_type)
         return AVERROR(ENOTSUP);
 
    const AVRational q0 = av_make_q(0, 1);
    const AVRational q1 = av_make_q(1, 1);
    const AVRational q2 = av_make_q(2, 1);
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op         = SWS_OP_CONVERT,
        .type       = pixel_type,
        .convert.to = type,
    }));
 
    /* Decode pixel format into standardized range */
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .type = type,
        .op   = SWS_OP_LINEAR,
        .lin  = fmt_decode_range(fmt, incomplete),
    }));
 
    /* Final step, decode colorspace */
    switch (fmt->csp) {
    case AVCOL_SPC_RGB:
        return 0;
    case AVCOL_SPC_UNSPECIFIED:
        c = av_csp_luma_coeffs_from_avcsp(AVCOL_SPC_BT470BG);
        *incomplete = true;
        av_fallthrough;
    case AVCOL_SPC_FCC:
    case AVCOL_SPC_BT470BG:
    case AVCOL_SPC_SMPTE170M:
    case AVCOL_SPC_BT709:
    case AVCOL_SPC_SMPTE240M:
    case AVCOL_SPC_BT2020_NCL: {
        AVRational crg = av_sub_q(q0, av_div_q(c->cr, c->cg));
        AVRational cbg = av_sub_q(q0, av_div_q(c->cb, c->cg));
        AVRational m02 = av_mul_q(q2, av_sub_q(q1, c->cr));
        AVRational m21 = av_mul_q(q2, av_sub_q(q1, c->cb));
        AVRational m11 = av_mul_q(cbg, m21);
        AVRational m12 = av_mul_q(crg, m02);
 
        return ff_sws_op_list_append(ops, &(SwsOp) {
            .type = type,
            .op   = SWS_OP_LINEAR,
            .lin  = linear_mat3(
                q1,  q0, m02,
                q1, m11, m12,
                q1, m21,  q0
            ),
        });
    }
 
    case AVCOL_SPC_YCGCO:
        return ff_sws_op_list_append(ops, &(SwsOp) {
            .type = type,
            .op   = SWS_OP_LINEAR,
            .lin  = linear_mat3(
                q1, av_make_q(-1, 1), av_make_q( 1, 1),
                q1, av_make_q( 1, 1), av_make_q( 0, 1),
                q1, av_make_q(-1, 1), av_make_q(-1, 1)
            ),
        });
 
    case AVCOL_SPC_BT2020_CL:
    case AVCOL_SPC_SMPTE2085:
    case AVCOL_SPC_CHROMA_DERIVED_NCL:
    case AVCOL_SPC_CHROMA_DERIVED_CL:
    case AVCOL_SPC_ICTCP:
    case AVCOL_SPC_IPT_C2:
    case AVCOL_SPC_YCGCO_RE:
    case AVCOL_SPC_YCGCO_RO:
        return AVERROR(ENOTSUP);
 
    case AVCOL_SPC_RESERVED:
        return AVERROR(EINVAL);
 
    case AVCOL_SPC_NB:
        break;
    }
 
    av_unreachable("Corrupt AVColorSpace value?");
    return AVERROR(EINVAL);
}
 
int ff_sws_encode_colors(SwsContext *ctx, SwsPixelType type,
                         SwsOpList *ops, const SwsFormat *src,
                         const SwsFormat *dst, bool *incomplete)
{
    const AVLumaCoefficients *c = av_csp_luma_coeffs_from_avcsp(dst->csp);
    const SwsPixelType pixel_type = fmt_pixel_type(dst->format);
    if (!pixel_type)
         return AVERROR(ENOTSUP);
 
    switch (dst->csp) {
    case AVCOL_SPC_RGB:
        break;
    case AVCOL_SPC_UNSPECIFIED:
        c = av_csp_luma_coeffs_from_avcsp(AVCOL_SPC_BT470BG);
        *incomplete = true;
        av_fallthrough;
    case AVCOL_SPC_FCC:
    case AVCOL_SPC_BT470BG:
    case AVCOL_SPC_SMPTE170M:
    case AVCOL_SPC_BT709:
    case AVCOL_SPC_SMPTE240M:
    case AVCOL_SPC_BT2020_NCL: {
        AVRational cb1 = av_sub_q(c->cb, av_make_q(1, 1));
        AVRational cr1 = av_sub_q(c->cr, av_make_q(1, 1));
        AVRational m20 = av_make_q(1,2);
        AVRational m10 = av_mul_q(m20, av_div_q(c->cr, cb1));
        AVRational m11 = av_mul_q(m20, av_div_q(c->cg, cb1));
        AVRational m21 = av_mul_q(m20, av_div_q(c->cg, cr1));
        AVRational m22 = av_mul_q(m20, av_div_q(c->cb, cr1));
 
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .type = type,
            .op   = SWS_OP_LINEAR,
            .lin  = linear_mat3(
                c->cr, c->cg, c->cb,
                m10,     m11,   m20,
                m20,     m21,   m22
            ),
        }));
        break;
    }
 
    case AVCOL_SPC_YCGCO:
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .type = type,
            .op   = SWS_OP_LINEAR,
            .lin  = linear_mat3(
                av_make_q( 1, 4), av_make_q(1, 2), av_make_q( 1, 4),
                av_make_q( 1, 2), av_make_q(0, 1), av_make_q(-1, 2),
                av_make_q(-1, 4), av_make_q(1, 2), av_make_q(-1, 4)
            ),
        }));
        break;
 
    case AVCOL_SPC_BT2020_CL:
    case AVCOL_SPC_SMPTE2085:
    case AVCOL_SPC_CHROMA_DERIVED_NCL:
    case AVCOL_SPC_CHROMA_DERIVED_CL:
    case AVCOL_SPC_ICTCP:
    case AVCOL_SPC_IPT_C2:
    case AVCOL_SPC_YCGCO_RE:
    case AVCOL_SPC_YCGCO_RO:
        return AVERROR(ENOTSUP);
 
    case AVCOL_SPC_RESERVED:
    case AVCOL_SPC_NB:
        return AVERROR(EINVAL);
    }
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .type = type,
        .op   = SWS_OP_LINEAR,
        .lin  = fmt_encode_range(dst, incomplete),
    }));
 
    if (!(dst->desc->flags & AV_PIX_FMT_FLAG_FLOAT)) {
        SwsClampOp range = {0};
 
        const bool is_ya = dst->desc->nb_components == 2;
        for (int i = 0; i < dst->desc->nb_components; i++) {
            /* Clamp to legal pixel range */
            const int idx = i * (is_ya ? 3 : 1);
            range.limit[idx] = intmax_q64(dst->desc->comp[i].depth);
        }
 
        RET(fmt_dither(ctx, ops, type, src, dst));
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op    = SWS_OP_MAX,
            .type  = type,
            .clamp = {{ Q(0), Q(0), Q(0), Q(0) }},
        }));
 
        RET(ff_sws_op_list_append(ops, &(SwsOp) {
            .op    = SWS_OP_MIN,
            .type  = type,
            .clamp = range,
        }));
    }
 
    return ff_sws_op_list_append(ops, &(SwsOp) {
        .type       = type,
        .op         = SWS_OP_CONVERT,
        .convert.to = pixel_type,
    });
}
 
static SwsScaler get_scaler_fallback(SwsContext *ctx)
{
    if (ctx->scaler != SWS_SCALE_AUTO)
        return ctx->scaler;
 
    /* Backwards compatibility with legacy flags API */
    if (ctx->flags & SWS_BILINEAR) {
        return SWS_SCALE_BILINEAR;
    } else if (ctx->flags & (SWS_BICUBIC | SWS_BICUBLIN)) {
        return SWS_SCALE_BICUBIC;
    } else if (ctx->flags & SWS_POINT) {
        return SWS_SCALE_POINT;
    } else if (ctx->flags & SWS_AREA) {
        return SWS_SCALE_AREA;
    } else if (ctx->flags & SWS_GAUSS) {
        return SWS_SCALE_GAUSSIAN;
    } else if (ctx->flags & SWS_SINC) {
        return SWS_SCALE_SINC;
    } else if (ctx->flags & SWS_LANCZOS) {
        return SWS_SCALE_LANCZOS;
    } else if (ctx->flags & SWS_SPLINE) {
        return SWS_SCALE_SPLINE;
    } else {
        return SWS_SCALE_AUTO;
    }
}
 
static int add_filter(SwsContext *ctx, SwsPixelType type, SwsOpList *ops,
                      SwsOpType filter, int src_size, int dst_size)
{
    if (src_size == dst_size)
        return 0; /* no-op */
 
    SwsFilterParams params = {
        .scaler   = get_scaler_fallback(ctx),
        .src_size = src_size,
        .dst_size = dst_size,
    };
 
    for (int i = 0; i < SWS_NUM_SCALER_PARAMS; i++)
        params.scaler_params[i] = ctx->scaler_params[i];
 
    SwsFilterWeights *kernel;
    int ret = ff_sws_filter_generate(ctx, &params, &kernel);
    if (ret == AVERROR(ENOTSUP)) {
        /* Filter size exceeds limit; cascade with geometric mean size */
        int mean = sqrt((int64_t) src_size * dst_size);
        if (mean == src_size || mean == dst_size)
            return AVERROR_BUG; /* sanity, prevent infinite loop */
        ret = add_filter(ctx, type, ops, filter, src_size, mean);
        if (ret < 0)
            return ret;
        return add_filter(ctx, type, ops, filter, mean, dst_size);
    } else if (ret < 0) {
        return ret;
    }
 
    return ff_sws_op_list_append(ops, &(SwsOp) {
        .type = type,
        .op   = filter,
        .filter.kernel = kernel,
        .filter.type   = type,
    });
}
 
int ff_sws_add_filters(SwsContext *ctx, SwsPixelType type, SwsOpList *ops,
                       const SwsFormat *src, const SwsFormat *dst)
{
    /**
     * Always perform horizontal scaling first, since it's much more likely to
     * benefit from small integer optimizations; we should maybe flip the order
     * here if we're downscaling the vertical resolution by a lot, though.
     */
    int ret = add_filter(ctx, type, ops, SWS_OP_FILTER_H, src->width, dst->width);
    if (ret < 0)
        return ret;
 
    return add_filter(ctx, type, ops, SWS_OP_FILTER_V, src->height, dst->height);
}
 
int ff_sws_apply_lut3d(SwsContext *ctx, SwsPixelType type, SwsOpList *ops,
                       const SwsLut3D *lut3d)
{
    /* Unnormalize to LUT input domain and clamp */
    const AVRational64 domain = Q(INPUT_LUT_SIZE - 1);
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .type   = type,
        .op     = SWS_OP_LINEAR,
        .lin    = {{
            { domain,   Q(0),   Q(0), Q(0), Q(0) },
            {   Q(0), domain,   Q(0), Q(0), Q(0) },
            {   Q(0),   Q(0), domain, Q(0), Q(0) },
            {   Q(0),   Q(0),   Q(0), Q(1), Q(0) },
        }},
    }));
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op     = SWS_OP_MAX,
        .type   = type,
        .clamp  = {{ Q(0), Q(0), Q(0) }},
    }));
 
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op     = SWS_OP_MIN,
        .type   = type,
        .clamp  = {{ domain, domain, domain }},
    }));
 
    /* Apply the 3DLUT itself */
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .op     = SWS_OP_LUT_3D,
        .type   = type,
        .lut3d.lut     = av_refstruct_ref_c(lut3d),
        .lut3d.dynamic = lut3d->dynamic,
    }));
 
    /* Normalize back to [0, 1] */
    const AVRational64 inv = ff_inv_q64(Q(UINT16_MAX));
    RET(ff_sws_op_list_append(ops, &(SwsOp) {
        .type   = type,
        .op     = SWS_OP_LINEAR,
        .lin    = {{
            {  inv, Q(0), Q(0), Q(0), Q(0) },
            { Q(0),  inv, Q(0), Q(0), Q(0) },
            { Q(0), Q(0),  inv, Q(0), Q(0) },
            { Q(0), Q(0), Q(0), Q(1), Q(0) },
        }},
    }));
 
    return 0;
}
 
int ff_sws_op_list_generate(SwsContext *ctx, const SwsFormat *src,
                            const SwsFormat *dst, const SwsLut3D *lut3d,
                            SwsOpList **out_ops, bool *incomplete)
{
    /* The new code does not yet support alpha blending */
    if (src->desc->flags & AV_PIX_FMT_FLAG_ALPHA &&
        ctx->alpha_blend != SWS_ALPHA_BLEND_NONE)
        return AVERROR(ENOTSUP);
 
    SwsOpList *ops = ff_sws_op_list_alloc();
    if (!ops)
        return AVERROR(ENOMEM);
    ops->src = *src;
    ops->dst = *dst;
 
    const SwsPixelType type = SWS_PIXEL_F32;
    int ret = ff_sws_decode_pixfmt(ops, src);
    if (ret < 0)
        goto fail;
    ret = ff_sws_decode_colors(ctx, type, ops, src, incomplete);
    if (ret < 0)
        goto fail;
    ret = ff_sws_add_filters(ctx, type, ops, src, dst);
    if (ret < 0)
        goto fail;
    if (lut3d) {
        ret = ff_sws_apply_lut3d(ctx, type, ops, lut3d);
        if (ret < 0)
            goto fail;
    }
    ret = ff_sws_encode_colors(ctx, type, ops, src, dst, incomplete);
    if (ret < 0)
        goto fail;
    ret = ff_sws_encode_pixfmt(ops, dst);
    if (ret < 0)
        goto fail;
 
    *out_ops = ops;
    return 0;
 
fail:
    ff_sws_op_list_free(&ops);
    return ret;
}
 
#else /* !CONFIG_UNSTABLE */
 
static int test_format_ops(enum AVPixelFormat format, int output)
{
    return 0;
}
 
#endif