/*

 * This file is part of mpv.

 *

 * mpv 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.

 *

 * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.

 */

#include <assert.h>

#include <string.h>

#include <libavcodec/avcodec.h>

#include <libavutil/imgutils.h>

#include <libavutil/pixfmt.h>

#include <libavutil/pixdesc.h>

#include "video/img_format.h"

#include "video/mp_image.h"

#include "video/fmt-conversion.h"

struct mp_imgfmt_entry {

    const char *name;

    // Valid if flags!=0.

    // This can be incomplete, and missing fields are filled in:

    //  - sets num_planes and bpp[], derived from comps[] (rounds to bytes)

    //  - sets MP_IMGFLAG_GRAY, derived from comps[]

    //  - sets MP_IMGFLAG_ALPHA, derived from comps[]

    //  - sets align_x/y if 0, derived from chroma shift

    //  - sets xs[]/ys[] always, derived from num_planes/chroma_shift

    //  - sets MP_IMGFLAG_HAS_COMPS|MP_IMGFLAG_NE if num_planes>0

    //  - sets MP_IMGFLAG_TYPE_UINT if no other type set

    //  - sets id to mp_imgfmt_list[] implied format

    struct mp_imgfmt_desc desc;

};

#define FRINGE_GBRP(def, dname, b)                                          \

    [def - IMGFMT_CUST_BASE] = {                                            \

        .name = dname,                                                      \

        .desc = { .flags = MP_IMGFLAG_COLOR_RGB,                            \

                  .comps = { {2, 0, 8, (b) - 8}, {0, 0, 8, (b) - 8},        \

                             {1, 0, 8, (b) - 8}, }, }}

#define FLOAT_YUV(def, dname, xs, ys, a)                                    \

    [def - IMGFMT_CUST_BASE] = {                                            \

        .name = dname,                                                      \

        .desc = { .flags = MP_IMGFLAG_COLOR_YUV | MP_IMGFLAG_TYPE_FLOAT,    \

                   .chroma_xs = xs, .chroma_ys = ys,                        \

                   .comps = { {0, 0, 32}, {1, 0, 32}, {2, 0, 32},           \

                              {3 * (a), 0, 32 * (a)} }, }}

static const struct mp_imgfmt_entry mp_imgfmt_list[] = {

    // not in ffmpeg

    [IMGFMT_VDPAU_OUTPUT - IMGFMT_CUST_BASE] = {

        .name = "vdpau_output",

        .desc = {

            .flags = MP_IMGFLAG_NE | MP_IMGFLAG_RGB | MP_IMGFLAG_HWACCEL,

        },

    },

    [IMGFMT_YAP8 - IMGFMT_CUST_BASE] = {

        .name = "yap8",

        .desc = {

            .flags = MP_IMGFLAG_COLOR_YUV,

            .comps = { {0, 0, 8}, {0}, {0}, {1, 0, 8} },

        },

    },

    [IMGFMT_YAP16 - IMGFMT_CUST_BASE] = {

        .name = "yap16",

        .desc = {

            .flags = MP_IMGFLAG_COLOR_YUV,

            .comps = { {0, 0, 16}, {0}, {0}, {1, 0, 16} },

        },

    },

    [IMGFMT_Y1 - IMGFMT_CUST_BASE] = {

        .name = "y1",

        .desc = {

            .flags = MP_IMGFLAG_COLOR_RGB,

            .comps = { {0, 0, 8, -7} },

        },

    },

    [IMGFMT_YAPF - IMGFMT_CUST_BASE] = {

        .name = "grayaf32", // try to mimic ffmpeg naming convention

        .desc = {

            .flags = MP_IMGFLAG_COLOR_YUV | MP_IMGFLAG_TYPE_FLOAT,

            .comps = { {0, 0, 32}, {0}, {0}, {1, 0, 32} },

        },

    },

    FLOAT_YUV(IMGFMT_444PF,  "yuv444pf",  0, 0, 0),

    FLOAT_YUV(IMGFMT_444APF, "yuva444pf", 0, 0, 1),

    FLOAT_YUV(IMGFMT_420PF,  "yuv420pf",  1, 1, 0),

    FLOAT_YUV(IMGFMT_420APF, "yuva420pf", 1, 1, 1),

    FLOAT_YUV(IMGFMT_422PF,  "yuv422pf",  1, 0, 0),

    FLOAT_YUV(IMGFMT_422APF, "yuva422pf", 1, 0, 1),

    FLOAT_YUV(IMGFMT_440PF,  "yuv440pf",  0, 1, 0),

    FLOAT_YUV(IMGFMT_440APF, "yuva440pf", 0, 1, 1),

    FLOAT_YUV(IMGFMT_410PF,  "yuv410pf",  2, 2, 0),

    FLOAT_YUV(IMGFMT_410APF, "yuva410pf", 2, 2, 1),

    FLOAT_YUV(IMGFMT_411PF,  "yuv411pf",  2, 0, 0),

    FLOAT_YUV(IMGFMT_411APF, "yuva411pf", 2, 0, 1),

    FRINGE_GBRP(IMGFMT_GBRP1, "gbrp1", 1),

    FRINGE_GBRP(IMGFMT_GBRP2, "gbrp2", 2),

    FRINGE_GBRP(IMGFMT_GBRP3, "gbrp3", 3),

    FRINGE_GBRP(IMGFMT_GBRP4, "gbrp4", 4),

    FRINGE_GBRP(IMGFMT_GBRP5, "gbrp5", 5),

    FRINGE_GBRP(IMGFMT_GBRP6, "gbrp6", 6),

    // in FFmpeg, but FFmpeg names have an annoying "_vld" suffix

    [IMGFMT_VIDEOTOOLBOX - IMGFMT_CUST_BASE] = {

        .name = "videotoolbox",

    },

    [IMGFMT_VAAPI - IMGFMT_CUST_BASE] = {

        .name = "vaapi",

    },

};

static const struct mp_imgfmt_entry *get_mp_desc(int imgfmt)

{

    if (imgfmt < IMGFMT_CUST_BASE)

        return NULL;

    int index = imgfmt - IMGFMT_CUST_BASE;

    if (index >= MP_ARRAY_SIZE(mp_imgfmt_list))

        return NULL;

    const struct mp_imgfmt_entry *e = &mp_imgfmt_list[index];

    return e->name ? e : NULL;

}

char **mp_imgfmt_name_list(void)

{

    int count = IMGFMT_END - IMGFMT_START;

    char **list = talloc_zero_array(NULL, char *, count + 1);

    int num = 0;

    for (int n = IMGFMT_START; n < IMGFMT_END; n++) {

        const char *name = mp_imgfmt_to_name(n);

        if (strcmp(name, "unknown") != 0)

            list[num++] = talloc_strdup(list, name);

    }

    return list;

}

int mp_imgfmt_from_name(bstr name)

{

    if (bstr_equals0(name, "none"))

        return 0;

    static const struct { bstr old, new; } deprecated_fmt_names[] = {

        {bstr0_lit("rgb30"), bstr0_lit("x2rgb10")},

    };

    for (int n = 0; n < MP_ARRAY_SIZE(deprecated_fmt_names); n++) {

        if (bstr_equals(name, deprecated_fmt_names[n].old)) {

            name = deprecated_fmt_names[n].new;

            break;

        }

    }

    for (int n = 0; n < MP_ARRAY_SIZE(mp_imgfmt_list); n++) {

        const struct mp_imgfmt_entry *p = &mp_imgfmt_list[n];

        if (p->name && bstr_equals0(name, p->name))

            return IMGFMT_CUST_BASE + n;

    }

    return pixfmt2imgfmt(av_get_pix_fmt(mp_tprintf(80, "%.*s", BSTR_P(name))));

}

char *mp_imgfmt_to_name_buf(char *buf, size_t buf_size, int fmt)

{

    const struct mp_imgfmt_entry *p = get_mp_desc(fmt);

    const char *name = p ? p->name : NULL;

    if (!name) {

        const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(imgfmt2pixfmt(fmt));

        if (pixdesc)

            name = pixdesc->name;

    }

    if (!name)

        name = "unknown";

    snprintf(buf, buf_size, "%s", name);

    int len = strlen(buf);

    if (len > 2 && buf[len - 2] == MP_SELECT_LE_BE('l', 'b') && buf[len - 1] == 'e')

        buf[len - 2] = '\0';

    return buf;

}

static void fill_pixdesc_layout(struct mp_imgfmt_desc *desc,

                                enum AVPixelFormat fmt,

                                const AVPixFmtDescriptor *pd)

{

    if (pd->flags & AV_PIX_FMT_FLAG_PAL ||

        pd->flags & AV_PIX_FMT_FLAG_HWACCEL)

        goto fail;

    bool has_alpha = pd->flags & AV_PIX_FMT_FLAG_ALPHA;

    if (pd->nb_components != 1 + has_alpha &&

        pd->nb_components != 3 + has_alpha)

        goto fail;

    // Very convenient: we assume we're always on little endian, and FFmpeg

    // explicitly marks big endian formats => don't need to guess whether a

    // format is little endian, or not affected by byte order.

    bool is_be = pd->flags & AV_PIX_FMT_FLAG_BE;

    bool is_ne = MP_SELECT_LE_BE(false, true) == is_be;

    // Packed sub-sampled YUV is very... special.

    bool is_packed_ss_yuv = pd->log2_chroma_w && !pd->log2_chroma_h &&

        pd->comp[1].plane == 0 && pd->comp[2].plane == 0 &&

        pd->nb_components == 3;

    if (is_packed_ss_yuv)

        desc->bpp[0] = pd->comp[1].step * 8;

    // Determine if there are any byte overlaps => relevant for determining

    // access unit for endian, since pixdesc does not expose this, and assumes

    // a weird model where you do separate memory fetches for each component.

    bool any_shared_bytes = !!(pd->flags & AV_PIX_FMT_FLAG_BITSTREAM);

    for (int c = 0; c < pd->nb_components; c++) {

        for (int i = 0; i < c; i++) {

            const AVComponentDescriptor *d1 = &pd->comp[c];

            const AVComponentDescriptor *d2 = &pd->comp[i];

            if (d1->plane == d2->plane) {

                if (d1->offset + (d1->depth + 7) / 8u > d2->offset &&

                    d2->offset + (d2->depth + 7) / 8u > d1->offset)

                    any_shared_bytes = true;

            }

        }

    }

    int el_bits = (pd->flags & AV_PIX_FMT_FLAG_BITSTREAM) ? 1 : 8;

    for (int c = 0; c < pd->nb_components; c++) {

        const AVComponentDescriptor *d = &pd->comp[c];

        if (d->plane >= MP_MAX_PLANES)

            goto fail;

        desc->num_planes = MPMAX(desc->num_planes, d->plane + 1);

        int plane_bits = desc->bpp[d->plane];

        int c_bits = d->step * el_bits;

        // The first component wins, because either all components result in

        // the same value, or luma wins (luma always comes before chroma).

        if (plane_bits) {

            if (c_bits > plane_bits)

                goto fail; // inconsistent

        } else {

            desc->bpp[d->plane] = plane_bits = c_bits;

        }

        int shift = d->shift;

        // What the fuck: for some inexplicable reason, MONOB uses shift=7

        // in pixdesc, which is basically out of bounds. Pixdesc bug?

        // Make it behave like MONOW. (No, the bit-order is not different.)

        if (fmt == AV_PIX_FMT_MONOBLACK)

            shift = 0;

        int offset = d->offset * el_bits;

        // The pixdesc logic for reading and endian swapping is as follows

        // (reverse engineered from av_read_image_line2()):

        // - determine a word size that will include the component fully;

        //   this includes the "active" bits and the amount "shifted" away

        //   (for example shift=7/depth=18 => 32 bit word reading [31:0])

        // - the same format can use different word sizes (e.g. bgr565: the R

        //   component at offset 0 is read as 8 bit; BG is read as 16 bits)

        // - if BE flag is set, swap the word before proceeding

        // - extract via shift and mask derived by depth

        int word = mp_round_next_power_of_2(MPMAX(d->depth + shift, 8));

        // The purpose of this is unknown. It's an absurdity fished out of

        // av_read_image_line2()'s implementation. It seems technically

        // unnecessary, and provides no information. On the other hand, it

        // compensates for seemingly bogus packed integer pixdescs; this

        // is "why" some formats use d->offset = -1.

        if (is_be && el_bits == 8 && word == 8)

            offset += 8;

        // Pixdesc's model sometimes requires accesses with varying word-sizes,

        // as seen in bgr565 and other formats. Also, it makes you read some

        // formats with multiple endian-dependent accesses, where accessing a

        // larger unit would make more sense. (Consider X2RGB10BE, for which

        // pixdesc wants you to perform 3 * 2 byte accesses, and swap each of

        // the read 16 bit words. What you really want is to swap the entire 4

        // byte thing, and then extract the components with bit shifts).

        // This is complete bullshit, so we transform it into word swaps before

        // further processing. Care needs to be taken to not change formats like

        // P010 or YA16 (prefer component accesses for them; P010 isn't even

        // representable, because endian_shift is for all planes).

        // As a heuristic, assume that if any components share a byte, the whole

        // pixel is read as a single memory access and endian swapped at once.

        int access_size = 8;

        if (plane_bits > 8) {

            if (any_shared_bytes) {

                access_size = plane_bits;

                if (is_be && word != access_size) {

                    // Before: offset = 8*byte_offset (with word bits of data)

                    // After: offset = bit_offset into swapped endian_size word

                    offset = access_size - word - offset;

                }

            } else {

                access_size = word;

            }

        }

        int endian_size = (access_size && !is_ne) ? access_size : 8;

        int endian_shift = mp_log2(endian_size) - 3;

        if (!MP_IS_POWER_OF_2(endian_size) || endian_shift < 0 || endian_shift > 3)

            goto fail;

        if (desc->endian_shift && desc->endian_shift != endian_shift)

            goto fail;

        desc->endian_shift = endian_shift;

        // We always use bit offsets; this doesn't lose any information,

        // and pixdesc is merely more redundant.

        offset += shift;

        if (offset < 0 || offset >= (1 << 6))

            goto fail;

        if (offset + d->depth > plane_bits)

            goto fail;

        if (d->depth < 0 || d->depth >= (1 << 6))

            goto fail;

        desc->comps[c] = (struct mp_imgfmt_comp_desc){

            .plane = d->plane,

            .offset = offset,

            .size = d->depth,

        };

    }

    for (int p = 0; p < desc->num_planes; p++) {

        if (!desc->bpp[p])

            goto fail; // plane doesn't exist

    }

    // What the fuck: this is probably a pixdesc bug, so fix it.

    if (fmt == AV_PIX_FMT_RGB8) {

        desc->comps[2] = (struct mp_imgfmt_comp_desc){0, 0, 2};

        desc->comps[1] = (struct mp_imgfmt_comp_desc){0, 2, 3};

        desc->comps[0] = (struct mp_imgfmt_comp_desc){0, 5, 3};

    }

    // Overlap test. If any shared bits are happening, this is not a format we

    // can represent (or it's something like Bayer: components in the same bits,

    // but different alternating lines).

    bool any_shared_bits = false;

    for (int c = 0; c < pd->nb_components; c++) {

        for (int i = 0; i < c; i++) {

            struct mp_imgfmt_comp_desc *c1 = &desc->comps[c];

            struct mp_imgfmt_comp_desc *c2 = &desc->comps[i];

            if (c1->plane == c2->plane) {

                if (c1->offset + c1->size > c2->offset &&

                    c2->offset + c2->size > c1->offset)

                    any_shared_bits = true;

            }

        }

    }

    if (any_shared_bits) {

        for (int c = 0; c < pd->nb_components; c++)

            desc->comps[c] = (struct mp_imgfmt_comp_desc){0};

    }

    // Many important formats have padding within an access word. For example

    // yuv420p10 has the upper 6 bit cleared to 0; P010 has the lower 6 bits

    // cleared to 0. Pixdesc cannot represent that these bits are 0. There are

    // other formats where padding is not guaranteed to be 0, but they are

    // described in the same way.

    // Apply a heuristic that is supposed to identify formats which use

    // guaranteed 0 padding. This could fail, but nobody said this pixdesc crap

    // is robust.

    for (int c = 0; c < pd->nb_components; c++) {

        struct mp_imgfmt_comp_desc *cd = &desc->comps[c];

        // Note: rgb444 would defeat our heuristic if we checked only per comp.

        //       also, exclude "bitstream" formats due to monow/monob

        int fsize = MP_ALIGN_UP(cd->size, 8);

        if (!any_shared_bytes && el_bits == 8 && fsize != cd->size &&

            fsize - cd->size <= (1 << 3))

        {

            if (!(cd->offset % 8u)) {

                cd->pad = -(fsize - cd->size);

                cd->size = fsize;

            } else if (!((cd->offset + cd->size) % 8u)) {

                cd->pad = fsize - cd->size;

                cd->size = fsize;

                cd->offset = MP_ALIGN_DOWN(cd->offset, 8);

            }

        }

    }

    // The alpha component always has ID 4 (index 3) in our representation, so

    // move the alpha component to there.

    if (has_alpha && pd->nb_components < 4) {

        desc->comps[3] = desc->comps[pd->nb_components - 1];

        desc->comps[pd->nb_components - 1] = (struct mp_imgfmt_comp_desc){0};

    }

    if (is_packed_ss_yuv) {

        desc->flags |= MP_IMGFLAG_PACKED_SS_YUV;

        desc->bpp[0] /= 1 << pd->log2_chroma_w;

    } else if (!any_shared_bits) {

        desc->flags |= MP_IMGFLAG_HAS_COMPS;

    }

    return;

fail:

    for (int n = 0; n < 4; n++)

        desc->comps[n] = (struct mp_imgfmt_comp_desc){0};

    // Average bit size fallback.

    int num_planes = av_pix_fmt_count_planes(fmt);

    desc->num_planes = MPCLAMP(num_planes, 0, MP_MAX_PLANES);

    for (int p = 0; p < desc->num_planes; p++) {

        int ls = av_image_get_linesize(fmt, 256, p);

        desc->bpp[p] = ls > 0 ? ls * 8 / 256 : 0;

    }

}

static bool mp_imgfmt_get_desc_from_pixdesc(int mpfmt, struct mp_imgfmt_desc *out)

{

    enum AVPixelFormat fmt = imgfmt2pixfmt(mpfmt);

    const AVPixFmtDescriptor *pd = av_pix_fmt_desc_get(fmt);

    if (!pd || pd->nb_components > 4)

        return false;

    struct mp_imgfmt_desc desc = {

        .id = mpfmt,

        .chroma_xs = pd->log2_chroma_w,

        .chroma_ys = pd->log2_chroma_h,

    };

    if (pd->flags & AV_PIX_FMT_FLAG_ALPHA)

        desc.flags |= MP_IMGFLAG_ALPHA;

    if (pd->flags & AV_PIX_FMT_FLAG_HWACCEL)

        desc.flags |= MP_IMGFLAG_TYPE_HW;

    // Pixdesc does not provide a flag for XYZ, so this is the best we can do.

    if (strncmp(pd->name, "xyz", 3) == 0) {

        desc.flags |= MP_IMGFLAG_COLOR_XYZ;

    } else if (pd->flags & AV_PIX_FMT_FLAG_RGB) {

        desc.flags |= MP_IMGFLAG_COLOR_RGB;

    } else if (fmt == AV_PIX_FMT_MONOBLACK || fmt == AV_PIX_FMT_MONOWHITE) {

        desc.flags |= MP_IMGFLAG_COLOR_RGB;

    } else if (fmt == AV_PIX_FMT_PAL8) {

        desc.flags |= MP_IMGFLAG_COLOR_RGB | MP_IMGFLAG_TYPE_PAL8;

    }

    if (pd->flags & AV_PIX_FMT_FLAG_FLOAT)

        desc.flags |= MP_IMGFLAG_TYPE_FLOAT;

    // Educated guess.

    if (!(desc.flags & MP_IMGFLAG_COLOR_MASK) &&

        !(desc.flags & MP_IMGFLAG_TYPE_HW))

        desc.flags |= MP_IMGFLAG_COLOR_YUV;

    desc.align_x = 1 << desc.chroma_xs;

    desc.align_y = 1 << desc.chroma_ys;

    fill_pixdesc_layout(&desc, fmt, pd);

    if (desc.flags & (MP_IMGFLAG_HAS_COMPS | MP_IMGFLAG_PACKED_SS_YUV)) {

        if (!(desc.flags & MP_IMGFLAG_TYPE_MASK))

            desc.flags |= MP_IMGFLAG_TYPE_UINT;

    }

    if (desc.bpp[0] % 8u && (pd->flags & AV_PIX_FMT_FLAG_BITSTREAM))

        desc.align_x = 8 / desc.bpp[0]; // expect power of 2

    // Very heuristical.

    bool is_ne = !desc.endian_shift;

    bool need_endian = (desc.comps[0].size % 8u && desc.bpp[0] > 8) ||

                       desc.comps[0].size > 8;

    if (need_endian) {

        bool is_le = MP_SELECT_LE_BE(is_ne, !is_ne);

        desc.flags |= is_le ? MP_IMGFLAG_LE : MP_IMGFLAG_BE;

    } else {

        desc.flags |= MP_IMGFLAG_LE | MP_IMGFLAG_BE;

    }

    *out = desc;

    return true;

}

bool mp_imgfmt_get_packed_yuv_locations(int imgfmt, uint8_t *luma_offsets)

{

    struct mp_imgfmt_desc desc = mp_imgfmt_get_desc(imgfmt);

    if (!(desc.flags & MP_IMGFLAG_PACKED_SS_YUV))

        return false;

    mp_assert(desc.num_planes == 1);

    // Guess at which positions the additional luma samples are. We iterate

    // starting with the first byte, and then put a luma sample at places

    // not covered by other luma/chroma.

    // Pixdesc does not and can not provide this information. This heuristic

    // may fail in certain cases. What a load of bullshit, right?

    int lsize = desc.comps[0].size;

    int cur_offset = 0;

    for (int lsample = 1; lsample < (1 << desc.chroma_xs); lsample++) {

        while (1) {

            if (cur_offset + lsize > desc.bpp[0] * desc.align_x)

                return false;

            bool free = true;

            for (int c = 0; c < 3; c++) {

                struct mp_imgfmt_comp_desc *cd = &desc.comps[c];

                if (!cd->size)

                    continue;

                if (cd->offset + cd->size > cur_offset &&

                    cur_offset + lsize > cd->offset)

                {

                    free = false;

                    break;

                }

            }

            if (free)

                break;

            cur_offset += lsize;

        }

        luma_offsets[lsample] = cur_offset;

        cur_offset += lsize;

    }

    luma_offsets[0] = desc.comps[0].offset;

    return true;

}

static bool get_native_desc(int mpfmt, struct mp_imgfmt_desc *desc)

{

    const struct mp_imgfmt_entry *p = get_mp_desc(mpfmt);

    if (!p || !p->desc.flags)

        return false;

    *desc = p->desc;

    // Fill in some fields mp_imgfmt_entry.desc is not required to set.

    desc->id = mpfmt;

    for (int n = 0; n < MP_NUM_COMPONENTS; n++) {

        struct mp_imgfmt_comp_desc *cd = &desc->comps[n];

        if (cd->size)

            desc->num_planes = MPMAX(desc->num_planes, cd->plane + 1);

        desc->bpp[cd->plane] =

            MPMAX(desc->bpp[cd->plane], MP_ALIGN_UP(cd->offset + cd->size, 8));

    }

    if (!desc->align_x && !desc->align_y) {

        desc->align_x = 1 << desc->chroma_xs;

        desc->align_y = 1 << desc->chroma_ys;

    }

    if (desc->num_planes)

        desc->flags |= MP_IMGFLAG_HAS_COMPS | MP_IMGFLAG_NE;

    if (!(desc->flags & MP_IMGFLAG_TYPE_MASK))

        desc->flags |= MP_IMGFLAG_TYPE_UINT;

    return true;

}

int mp_imgfmt_desc_get_num_comps(const struct mp_imgfmt_desc *desc)

{

    int flags = desc->flags;

    if (!(flags & MP_IMGFLAG_COLOR_MASK))

        return 0;

    return 3 + (flags & MP_IMGFLAG_GRAY ? -2 : 0) + !!(flags & MP_IMGFLAG_ALPHA);

}

struct mp_imgfmt_desc mp_imgfmt_get_desc(int mpfmt)

{

    struct mp_imgfmt_desc desc;

    if (!get_native_desc(mpfmt, &desc) &&

        !mp_imgfmt_get_desc_from_pixdesc(mpfmt, &desc))

        return (struct mp_imgfmt_desc){0};

    for (int p = 0; p < desc.num_planes; p++) {

        desc.xs[p] = (p == 1 || p == 2) ? desc.chroma_xs : 0;

        desc.ys[p] = (p == 1 || p == 2) ? desc.chroma_ys : 0;

    }

    bool is_ba = desc.num_planes > 0;

    for (int p = 0; p < desc.num_planes; p++)

        is_ba = !(desc.bpp[p] % 8u);

    if (is_ba)

        desc.flags |= MP_IMGFLAG_BYTE_ALIGNED;

    if (desc.flags & MP_IMGFLAG_HAS_COMPS) {

        if (desc.comps[3].size)

            desc.flags |= MP_IMGFLAG_ALPHA;

        // Assuming all colors are (CCC+[A]) or (C+[A]), the latter being gray.

        if (!desc.comps[1].size)

            desc.flags |= MP_IMGFLAG_GRAY;

        bool bb = true;

        for (int n = 0; n < MP_NUM_COMPONENTS; n++) {

            if (desc.comps[n].offset % 8u || desc.comps[n].size % 8u)

                bb = false;

        }

        if (bb)

            desc.flags |= MP_IMGFLAG_BYTES;

    }

    if ((desc.flags & (MP_IMGFLAG_YUV | MP_IMGFLAG_RGB))

        && (desc.flags & MP_IMGFLAG_HAS_COMPS)

        && (desc.flags & MP_IMGFLAG_BYTES)

        && ((desc.flags & MP_IMGFLAG_TYPE_MASK) == MP_IMGFLAG_TYPE_UINT))

    {

        int cnt = mp_imgfmt_desc_get_num_comps(&desc);

        bool same_depth = true;

        for (int p = 0; p < desc.num_planes; p++)

            same_depth &= desc.bpp[p] == desc.bpp[0];

        if (same_depth && cnt == desc.num_planes) {

            if (desc.flags & MP_IMGFLAG_YUV) {

                desc.flags |= MP_IMGFLAG_YUV_P;

            } else {

                desc.flags |= MP_IMGFLAG_RGB_P;

            }

        }

        if (cnt == 3 && desc.num_planes == 2 &&

            desc.bpp[1] == desc.bpp[0] * 2 &&

            (desc.flags & MP_IMGFLAG_YUV))

        {

            desc.flags |= MP_IMGFLAG_YUV_NV;

        }

    }

    return desc;

}

static bool validate_regular_imgfmt(const struct mp_regular_imgfmt *fmt)

{

    bool present[MP_NUM_COMPONENTS] = {0};

    int n_comp = 0;

    for (int n = 0; n < fmt->num_planes; n++) {

        const struct mp_regular_imgfmt_plane *plane = &fmt->planes[n];

        n_comp += plane->num_components;

        if (n_comp > MP_NUM_COMPONENTS)

            return false;

        if (!plane->num_components)

            return false; // no empty planes in between allowed

        bool pad_only = true;

        int chroma_luma = 0; // luma: 1, chroma: 2, both: 3

        for (int i = 0; i < plane->num_components; i++) {

            int comp = plane->components[i];

            if (comp > MP_NUM_COMPONENTS)

                return false;

            if (comp == 0)

                continue;

            pad_only = false;

            if (present[comp - 1])

                return false; // no duplicates

            present[comp - 1] = true;

            chroma_luma |= (comp == 2 || comp == 3) ? 2 : 1;

        }

        if (pad_only)

            return false; // no planes with only padding allowed

        if ((fmt->chroma_xs > 0 || fmt->chroma_ys > 0) && chroma_luma == 3)

            return false; // separate chroma/luma planes required

    }

    if (!(present[0] || present[3]) ||  // at least component 1 or alpha needed

        (present[1] && !present[0]) ||  // component 2 requires component 1

        (present[2] && !present[1]))    // component 3 requires component 2

        return false;

    return true;

}

static enum pl_color_system get_forced_csp_from_flags(int flags)

{

    if (flags & MP_IMGFLAG_COLOR_XYZ)

        return PL_COLOR_SYSTEM_XYZ;

    if (flags & MP_IMGFLAG_COLOR_RGB)

        return PL_COLOR_SYSTEM_RGB;

    return PL_COLOR_SYSTEM_UNKNOWN;

}

enum pl_color_system mp_imgfmt_get_forced_csp(int imgfmt)

{

    return get_forced_csp_from_flags(mp_imgfmt_get_desc(imgfmt).flags);

}

static enum mp_component_type get_component_type_from_flags(int flags)

{

    if (flags & MP_IMGFLAG_TYPE_UINT)

        return MP_COMPONENT_TYPE_UINT;

    if (flags & MP_IMGFLAG_TYPE_FLOAT)

        return MP_COMPONENT_TYPE_FLOAT;

    return MP_COMPONENT_TYPE_UNKNOWN;

}

enum mp_component_type mp_imgfmt_get_component_type(int imgfmt)

{

    return get_component_type_from_flags(mp_imgfmt_get_desc(imgfmt).flags);

}

int mp_find_other_endian(int imgfmt)

{

    return pixfmt2imgfmt(av_pix_fmt_swap_endianness(imgfmt2pixfmt(imgfmt)));

}

bool mp_get_regular_imgfmt(struct mp_regular_imgfmt *dst, int imgfmt)

{

    struct mp_regular_imgfmt res = {0};

    struct mp_imgfmt_desc desc = mp_imgfmt_get_desc(imgfmt);

    if (!desc.num_planes)

        return false;

    res.num_planes = desc.num_planes;

    if (desc.endian_shift || !(desc.flags & MP_IMGFLAG_HAS_COMPS))

        return false;

    res.component_type = get_component_type_from_flags(desc.flags);

    if (!res.component_type)

        return false;

    struct mp_imgfmt_comp_desc *comp0 = &desc.comps[0];

    if (comp0->size < 1 || comp0->size > 64 || (comp0->size % 8u))

        return false;

    res.component_size = comp0->size / 8u;

    res.component_pad = comp0->pad;

    for (int n = 0; n < res.num_planes; n++) {

        if (desc.bpp[n] % comp0->size)

            return false;

        res.planes[n].num_components = desc.bpp[n] / comp0->size;

    }

    for (int n = 0; n < MP_NUM_COMPONENTS; n++) {

        struct mp_imgfmt_comp_desc *comp = &desc.comps[n];

        if (!comp->size)

            continue;

        struct mp_regular_imgfmt_plane *plane = &res.planes[comp->plane];

        res.num_planes = MPMAX(res.num_planes, comp->plane + 1);

        // We support uniform depth only.

        if (comp->size != comp0->size || comp->pad != comp0->pad)

            return false;

        // Size-aligned only.

        int pos = comp->offset / comp->size;

        if (comp->offset != pos * comp->size || pos >= MP_NUM_COMPONENTS)

            return false;

        if (plane->components[pos])

            return false;

        plane->components[pos] = n + 1;

    }

    res.chroma_xs = desc.chroma_xs;

    res.chroma_ys = desc.chroma_ys;

    res.forced_csp = get_forced_csp_from_flags(desc.flags);

    if (!validate_regular_imgfmt(&res))

        return false;

    *dst = res;

    return true;

}

static bool regular_imgfmt_equals(struct mp_regular_imgfmt *a,

                                  struct mp_regular_imgfmt *b)

{

    if (a->component_type != b->component_type ||

        a->component_size != b->component_size ||

        a->num_planes     != b->num_planes ||

        a->component_pad  != b->component_pad ||

        a->forced_csp     != b->forced_csp ||

        a->chroma_xs      != b->chroma_xs ||

        a->chroma_ys      != b->chroma_ys)

        return false;

    for (int n = 0; n < a->num_planes; n++) {

        int num_comps = a->planes[n].num_components;

        if (num_comps != b->planes[n].num_components)

            return false;

        for (int i = 0; i < num_comps; i++) {

            if (a->planes[n].components[i] != b->planes[n].components[i])

                return false;

        }

    }

    return true;

}

// Find a format that matches this one exactly.

int mp_find_regular_imgfmt(struct mp_regular_imgfmt *src)

{

    for (int n = IMGFMT_START + 1; n < IMGFMT_END; n++) {

        struct mp_regular_imgfmt f;

        if (mp_get_regular_imgfmt(&f, n) && regular_imgfmt_equals(src, &f))

            return n;

    }

    return 0;

}

// Compare the dst image formats, and return the one which can carry more data

// (e.g. higher depth, more color components, lower chroma subsampling, etc.),

// with respect to what is required to keep most of the src format.

// Returns the imgfmt, or 0 on error.

int mp_imgfmt_select_best(int dst1, int dst2, int src)

{

    enum AVPixelFormat dst1pxf = imgfmt2pixfmt(dst1);

    enum AVPixelFormat dst2pxf = imgfmt2pixfmt(dst2);

    enum AVPixelFormat srcpxf = imgfmt2pixfmt(src);

    enum AVPixelFormat dstlist[] = {dst1pxf, dst2pxf, AV_PIX_FMT_NONE};

    return pixfmt2imgfmt(avcodec_find_best_pix_fmt_of_list(dstlist, srcpxf, 1, 0));

}

// Same as mp_imgfmt_select_best(), but with a list of dst formats.

int mp_imgfmt_select_best_list(int *dst, int num_dst, int src)

{

    int best = 0;

    for (int n = 0; n < num_dst; n++)

        best = best ? mp_imgfmt_select_best(best, dst[n], src) : dst[n];

    return best;

}

bool mp_imgfmt_is_subsampled(enum mp_imgfmt fmt)

{

    struct mp_imgfmt_desc desc = mp_imgfmt_get_desc(fmt);

    return desc.chroma_xs || desc.chroma_ys;

}

bool mp_imgfmt_is_420_subsampled(enum mp_imgfmt fmt)

{

    struct mp_imgfmt_desc desc = mp_imgfmt_get_desc(fmt);

    return desc.chroma_xs == 1 && desc.chroma_ys == 1;

}