vp56.c

mediastreamer2是开源的网络传输媒体流的库

/**
 * @file vp56.c
 * VP5 and VP6 compatible video decoder (common features)
 *
 * Copyright (C) 2006  Aurelien Jacobs <[e-mail]>
 *
 * 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 "avcodec.h"
#include "bytestream.h"

#include "vp56.h"
#include "vp56data.h"


void vp56_init_dequant(vp56_context_t *s, int quantizer)
{
    s->quantizer = quantizer;
    s->dequant_dc = vp56_dc_dequant[quantizer] << 2;
    s->dequant_ac = vp56_ac_dequant[quantizer] << 2;
}

static int vp56_get_vectors_predictors(vp56_context_t *s, int row, int col,
                                       vp56_frame_t ref_frame)
{
    int nb_pred = 0;
    vp56_mv_t vect[2] = {{0,0}, {0,0}};
    int pos, offset;
    vp56_mv_t mvp;

    for (pos=0; pos<12; pos++) {
        mvp.x = col + vp56_candidate_predictor_pos[pos][0];
        mvp.y = row + vp56_candidate_predictor_pos[pos][1];
        if (mvp.x < 0 || mvp.x >= s->mb_width ||
            mvp.y < 0 || mvp.y >= s->mb_height)
            continue;
        offset = mvp.x + s->mb_width*mvp.y;

        if (vp56_reference_frame[s->macroblocks[offset].type] != ref_frame)
            continue;
        if ((s->macroblocks[offset].mv.x == vect[0].x &&
             s->macroblocks[offset].mv.y == vect[0].y) ||
            (s->macroblocks[offset].mv.x == 0 &&
             s->macroblocks[offset].mv.y == 0))
            continue;

        vect[nb_pred++] = s->macroblocks[offset].mv;
        if (nb_pred > 1) {
            nb_pred = -1;
            break;
        }
        s->vector_candidate_pos = pos;
    }

    s->vector_candidate[0] = vect[0];
    s->vector_candidate[1] = vect[1];

    return nb_pred+1;
}

static void vp56_parse_mb_type_models(vp56_context_t *s)
{
    vp56_range_coder_t *c = &s->c;
    vp56_model_t *model = s->modelp;
    int i, ctx, type;

    for (ctx=0; ctx<3; ctx++) {
        if (vp56_rac_get_prob(c, 174)) {
            int idx = vp56_rac_gets(c, 4);
            memcpy(model->mb_types_stats[ctx],
                   vp56_pre_def_mb_type_stats[idx][ctx],
                   sizeof(model->mb_types_stats[ctx]));
        }
        if (vp56_rac_get_prob(c, 254)) {
            for (type=0; type<10; type++) {
                for(i=0; i<2; i++) {
                    if (vp56_rac_get_prob(c, 205)) {
                        int delta, sign = vp56_rac_get(c);

                        delta = vp56_rac_get_tree(c, vp56_pmbtm_tree,
                                                  vp56_mb_type_model_model);
                        if (!delta)
                            delta = 4 * vp56_rac_gets(c, 7);
                        model->mb_types_stats[ctx][type][i] += (delta ^ -sign) + sign;
                    }
                }
            }
        }
    }

    /* compute MB type probability tables based on previous MB type */
    for (ctx=0; ctx<3; ctx++) {
        int p[10];

        for (type=0; type<10; type++)
            p[type] = 100 * model->mb_types_stats[ctx][type][1];

        for (type=0; type<10; type++) {
            int p02, p34, p0234, p17, p56, p89, p5689, p156789;

            /* conservative MB type probability */
            model->mb_type[ctx][type][0] = 255 - (255 * model->mb_types_stats[ctx][type][0]) / (1 + model->mb_types_stats[ctx][type][0] + model->mb_types_stats[ctx][type][1]);

            p[type] = 0;    /* same MB type => weight is null */

            /* binary tree parsing probabilities */
            p02 = p[0] + p[2];
            p34 = p[3] + p[4];
            p0234 = p02 + p34;
            p17 = p[1] + p[7];
            p56 = p[5] + p[6];
            p89 = p[8] + p[9];
            p5689 = p56 + p89;
            p156789 = p17 + p5689;

            model->mb_type[ctx][type][1] = 1 + 255 * p0234/(1+p0234+p156789);
            model->mb_type[ctx][type][2] = 1 + 255 * p02  / (1+p0234);
            model->mb_type[ctx][type][3] = 1 + 255 * p17  / (1+p156789);
            model->mb_type[ctx][type][4] = 1 + 255 * p[0] / (1+p02);
            model->mb_type[ctx][type][5] = 1 + 255 * p[3] / (1+p34);
            model->mb_type[ctx][type][6] = 1 + 255 * p[1] / (1+p17);
            model->mb_type[ctx][type][7] = 1 + 255 * p56  / (1+p5689);
            model->mb_type[ctx][type][8] = 1 + 255 * p[5] / (1+p56);
            model->mb_type[ctx][type][9] = 1 + 255 * p[8] / (1+p89);

            /* restore initial value */
            p[type] = 100 * model->mb_types_stats[ctx][type][1];
        }
    }
}

static vp56_mb_t vp56_parse_mb_type(vp56_context_t *s,
                                    vp56_mb_t prev_type, int ctx)
{
    uint8_t *mb_type_model = s->modelp->mb_type[ctx][prev_type];
    vp56_range_coder_t *c = &s->c;

    if (vp56_rac_get_prob(c, mb_type_model[0]))
        return prev_type;
    else
        return vp56_rac_get_tree(c, vp56_pmbt_tree, mb_type_model);
}

static void vp56_decode_4mv(vp56_context_t *s, int row, int col)
{
    vp56_mv_t mv = {0,0};
    int type[4];
    int b;

    /* parse each block type */
    for (b=0; b<4; b++) {
        type[b] = vp56_rac_gets(&s->c, 2);
        if (type[b])
            type[b]++;  /* only returns 0, 2, 3 or 4 (all INTER_PF) */
    }

    /* get vectors */
    for (b=0; b<4; b++) {
        switch (type[b]) {
            case VP56_MB_INTER_NOVEC_PF:
                s->mv[b] = (vp56_mv_t) {0,0};
                break;
            case VP56_MB_INTER_DELTA_PF:
                s->parse_vector_adjustment(s, &s->mv[b]);
                break;
            case VP56_MB_INTER_V1_PF:
                s->mv[b] = s->vector_candidate[0];
                break;
            case VP56_MB_INTER_V2_PF:
                s->mv[b] = s->vector_candidate[1];
                break;
        }
        mv.x += s->mv[b].x;
        mv.y += s->mv[b].y;
    }

    /* this is the one selected for the whole MB for prediction */
    s->macroblocks[row * s->mb_width + col].mv = s->mv[3];

    /* chroma vectors are average luma vectors */
    if (s->avctx->codec->id == CODEC_ID_VP5) {
        s->mv[4].x = s->mv[5].x = RSHIFT(mv.x,2);
        s->mv[4].y = s->mv[5].y = RSHIFT(mv.y,2);
    } else {
        s->mv[4] = s->mv[5] = (vp56_mv_t) {mv.x/4, mv.y/4};
    }
}

static vp56_mb_t vp56_decode_mv(vp56_context_t *s, int row, int col)
{
    vp56_mv_t *mv, vect = {0,0};
    int ctx, b;

    ctx = vp56_get_vectors_predictors(s, row, col, VP56_FRAME_PREVIOUS);
    s->mb_type = vp56_parse_mb_type(s, s->mb_type, ctx);
    s->macroblocks[row * s->mb_width + col].type = s->mb_type;

    switch (s->mb_type) {
        case VP56_MB_INTER_V1_PF:
            mv = &s->vector_candidate[0];
            break;

        case VP56_MB_INTER_V2_PF:
            mv = &s->vector_candidate[1];
            break;

        case VP56_MB_INTER_V1_GF:
            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
            mv = &s->vector_candidate[0];
            break;

        case VP56_MB_INTER_V2_GF:
            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
            mv = &s->vector_candidate[1];
            break;

        case VP56_MB_INTER_DELTA_PF:
            s->parse_vector_adjustment(s, &vect);
            mv = &vect;
            break;

        case VP56_MB_INTER_DELTA_GF:
            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);
            s->parse_vector_adjustment(s, &vect);
            mv = &vect;
            break;

        case VP56_MB_INTER_4V:
            vp56_decode_4mv(s, row, col);
            return s->mb_type;

        default:
            mv = &vect;
            break;
    }

    s->macroblocks[row*s->mb_width + col].mv = *mv;

    /* same vector for all blocks */
    for (b=0; b<6; b++)
        s->mv[b] = *mv;

    return s->mb_type;
}

static void vp56_add_predictors_dc(vp56_context_t *s, vp56_frame_t ref_frame)
{
    int idx = s->scantable.permutated[0];
    int b;

    for (b=0; b<6; b++) {
        vp56_ref_dc_t *ab = &s->above_blocks[s->above_block_idx[b]];
        vp56_ref_dc_t *lb = &s->left_block[vp56_b6to4[b]];
        int count = 0;
        int dc = 0;
        int i;

        if (ref_frame == lb->ref_frame) {
            dc += lb->dc_coeff;
            count++;
        }
        if (ref_frame == ab->ref_frame) {
            dc += ab->dc_coeff;
            count++;
        }
        if (s->avctx->codec->id == CODEC_ID_VP5)
            for (i=0; i<2; i++)
                if (count < 2 && ref_frame == ab[-1+2*i].ref_frame) {
                    dc += ab[-1+2*i].dc_coeff;
                    count++;
                }
        if (count == 0)
            dc = s->prev_dc[vp56_b2p[b]][ref_frame];
        else if (count == 2)
            dc /= 2;

        s->block_coeff[b][idx] += dc;
        s->prev_dc[vp56_b2p[b]][ref_frame] = s->block_coeff[b][idx];
        ab->dc_coeff = s->block_coeff[b][idx];
        ab->ref_frame = ref_frame;
        lb->dc_coeff = s->block_coeff[b][idx];
        lb->ref_frame = ref_frame;
        s->block_coeff[b][idx] *= s->dequant_dc;
    }
}

static void vp56_edge_filter(vp56_context_t *s, uint8_t *yuv,
                             int pix_inc, int line_inc, int t)
{
    int pix2_inc = 2 * pix_inc;
    int i, v;

    for (i=0; i<12; i++) {
        v = (yuv[-pix2_inc] + 3*(yuv[0]-yuv[-pix_inc]) - yuv[pix_inc] + 4) >>3;
        v = s->adjust(v, t);
        yuv[-pix_inc] = av_clip_uint8(yuv[-pix_inc] + v);
        yuv[0] = av_clip_uint8(yuv[0] - v);
        yuv += line_inc;
    }
}

static void vp56_deblock_filter(vp56_context_t *s, uint8_t *yuv,
                                int stride, int dx, int dy)
{
    int t = vp56_filter_threshold[s->quantizer];
    if (dx)  vp56_edge_filter(s, yuv +         10-dx ,      1, stride, t);
    if (dy)  vp56_edge_filter(s, yuv + stride*(10-dy), stride,      1, t);
}

static void vp56_mc(vp56_context_t *s, int b, int plane, uint8_t *src,
                    int stride, int x, int y)
{
    uint8_t *dst=s->framep[VP56_FRAME_CURRENT]->data[plane]+s->block_offset[b];
    uint8_t *src_block;
    int src_offset;
    int overlap_offset = 0;
    int mask = s->vp56_coord_div[b] - 1;
    int deblock_filtering = s->deblock_filtering;
    int dx;
    int dy;

    if (s->avctx->skip_loop_filter >= AVDISCARD_ALL ||
        (s->avctx->skip_loop_filter >= AVDISCARD_NONKEY
         && !s->framep[VP56_FRAME_CURRENT]->key_frame))
        deblock_filtering = 0;

    dx = s->mv[b].x / s->vp56_coord_div[b];
    dy = s->mv[b].y / s->vp56_coord_div[b];

    if (b >= 4) {
        x /= 2;
        y /= 2;
    }
    x += dx - 2;
    y += dy - 2;