intra_utils.c

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/*
 * VVC intra prediction utils
 *
 * Copyright (C) 2021 Nuo Mi
 *
 * 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 <stdint.h>
#include <stdlib.h>
#include "libavutil/avassert.h"
#include "libavutil/macros.h"
#include "libavutil/common.h"
#include "ctu.h"
#include "intra.h"
#include "ps.h"
#include "dec.h"
 
int ff_vvc_get_mip_size_id(const int w, const int h)
{
    if (w == 4 && h == 4)
        return 0;
    if ((w == 4 || h == 4) || (w == 8 && h == 8))
        return 1;
    return 2;
}
 
int ff_vvc_nscale_derive(const int w, const int h, const int mode)
{
    int side_size, nscale;
    av_assert0(mode < INTRA_LT_CCLM && !(mode > INTRA_HORZ && mode < INTRA_VERT));
    if (mode == INTRA_PLANAR || mode == INTRA_DC ||
        mode == INTRA_HORZ || mode == INTRA_VERT) {
        nscale = (av_log2(w) + av_log2(h) - 2) >> 2;
    } else {
        const int intra_pred_angle = ff_vvc_intra_pred_angle_derive(mode);
        const int inv_angle        = ff_vvc_intra_inv_angle_derive(intra_pred_angle);
        if (mode >= INTRA_VERT)
            side_size = h;
        if (mode <= INTRA_HORZ)
            side_size = w;
        nscale = FFMIN(2, av_log2(side_size) - av_log2(3 * inv_angle - 2) + 8);
    }
    return nscale;
}
 
int ff_vvc_need_pdpc(const int w, const int h, const uint8_t bdpcm_flag, const int mode, const int ref_idx)
{
    av_assert0(mode < INTRA_LT_CCLM);
    if ((w >= 4 && h >= 4) && !ref_idx && !bdpcm_flag) {
        int nscale;
        if (mode == INTRA_PLANAR || mode == INTRA_DC ||
            mode == INTRA_HORZ || mode == INTRA_VERT)
            return 1;
        if (mode > INTRA_HORZ && mode < INTRA_VERT)
            return 0;
        nscale = ff_vvc_nscale_derive(w, h, mode);
        return nscale >= 0;
 
    }
    return 0;
}
 
static const ReconstructedArea* get_reconstructed_area(const VVCLocalContext *lc, const int x, const int y, const int c_idx)
{
    const int ch_type = c_idx > 0;
    for (int i = lc->num_ras[ch_type] - 1; i >= 0; i--) {
        const ReconstructedArea* a = &lc->ras[ch_type][i];
        const int r = (a->x + a->w);
        const int b = (a->y + a->h);
        if (a->x <= x && x < r && a->y <= y && y < b)
            return a;
 
        //it's too far away, no need check it;
        if (x >= r && y >= b)
            break;
    }
    return NULL;
}
 
int ff_vvc_get_top_available(const VVCLocalContext *lc, const int x, const int y, int target_size, const int c_idx)
{
    const VVCFrameContext *fc = lc->fc;
    const VVCSPS *sps = fc->ps.sps;
    const int hs = sps->hshift[c_idx];
    const int vs = sps->vshift[c_idx];
    const int log2_ctb_size_v   = sps->ctb_log2_size_y - vs;
    const int end_of_ctb_x      = ((lc->cu->x0 >> sps->ctb_log2_size_y) + 1) << sps->ctb_log2_size_y;
    const int y0b               = av_zero_extend(y, log2_ctb_size_v);
    const int max_x             = FFMIN(fc->ps.pps->width, end_of_ctb_x) >> hs;
    const ReconstructedArea *a;
    int px = x;
 
    if (!y0b) {
        if (!lc->ctb_up_flag)
            return 0;
        target_size = FFMIN(target_size, (lc->end_of_tiles_x >> hs) - x);
        if (sps->r->sps_entropy_coding_sync_enabled_flag)
            target_size = FFMIN(target_size, (end_of_ctb_x >> hs) - x);
        return target_size;
    }
 
    target_size = FFMAX(0, FFMIN(target_size, max_x - x));
    while (target_size > 0 && (a = get_reconstructed_area(lc, px, y - 1, c_idx))) {
        const int sz = FFMIN(target_size, a->x + a->w - px);
        px += sz;
        target_size -= sz;
    }
    return px - x;
}
 
int ff_vvc_get_left_available(const VVCLocalContext *lc, const int x, const int y, int target_size, const int c_idx)
{
    const VVCFrameContext *fc = lc->fc;
    const VVCSPS *sps = fc->ps.sps;
    const int hs = sps->hshift[c_idx];
    const int vs = sps->vshift[c_idx];
    const int log2_ctb_size_h   =  sps->ctb_log2_size_y - hs;
    const int x0b               = av_zero_extend(x, log2_ctb_size_h);
    const int end_of_ctb_y      = ((lc->cu->y0 >> sps->ctb_log2_size_y) + 1) << sps->ctb_log2_size_y;
    const int max_y             = FFMIN(fc->ps.pps->height, end_of_ctb_y) >> vs;
    const ReconstructedArea *a;
    int  py = y;
 
    if (!x0b && !lc->ctb_left_flag)
        return 0;
 
    target_size = FFMAX(0, FFMIN(target_size, max_y - y));
    if (!x0b)
        return target_size;
 
    while (target_size > 0 && (a = get_reconstructed_area(lc, x - 1, py, c_idx))) {
        const int sz = FFMIN(target_size, a->y + a->h - py);
        py += sz;
        target_size -= sz;
    }
    return py - y;
}
 
static int less(const void *a, const void *b)
{
    return *(const int*)a - *(const int*)b;
}
 
int ff_vvc_ref_filter_flag_derive(const int mode)
{
    static const int modes[] = { -14, -12, -10, -6, INTRA_PLANAR, 2, 34, 66, 72, 76, 78, 80};
    return bsearch(&mode, modes, FF_ARRAY_ELEMS(modes), sizeof(int), less) != NULL;
}
 
int ff_vvc_intra_pred_angle_derive(const int pred_mode)
{
    static const int angles[] = {
          0,   1,   2,   3,   4,   6,   8,  10,  12,  14,  16,  18,  20,  23,  26, 29,
         32,  35,  39,  45,  51,  57,  64,  73,  86, 102, 128, 171, 256, 341, 512
    };
    int sign = 1, idx, intra_pred_angle;
    if (pred_mode > INTRA_DIAG) {
        idx = pred_mode - INTRA_VERT;
    } else if (pred_mode > 0) {
        idx = INTRA_HORZ - pred_mode;
    } else {
        idx = INTRA_HORZ - 2 - pred_mode;
    }
    if (idx < 0) {
        idx = -idx;
        sign = -1;
    }
    intra_pred_angle = sign * angles[idx];
    return intra_pred_angle;
}
 
int ff_vvc_intra_inv_angle_derive(const int intra_pred_angle)
{
    av_assert2(intra_pred_angle != 0);
    if (intra_pred_angle > 0)
        return ROUNDED_DIV(32*512, intra_pred_angle);
    else
        return -ROUNDED_DIV(32*512, -intra_pred_angle);
}
 
//8.4.5.2.7 Wide angle intra prediction mode mapping process
int ff_vvc_wide_angle_mode_mapping(const CodingUnit *cu,
    const int tb_width, const int tb_height, const int c_idx, int pred_mode_intra)
{
    int nw, nh, wh_ratio, min, max;
 
    if (cu->isp_split_type == ISP_NO_SPLIT || c_idx) {
        nw = tb_width;
        nh = tb_height;
    } else {
        nw = cu->cb_width;
        nh = cu->cb_height;
    }
    wh_ratio    = FFABS(ff_log2(nw) - ff_log2(nh));
    max         = (wh_ratio > 1) ? (8  + 2 * wh_ratio) : 8;
    min         = (wh_ratio > 1) ? (60 - 2 * wh_ratio) : 60;
 
    if (nw > nh && pred_mode_intra >=2 && pred_mode_intra < max)
        pred_mode_intra += 65;
    else if (nh > nw && pred_mode_intra <= 66 && pred_mode_intra > min)
        pred_mode_intra -= 67;
    return pred_mode_intra;
}