vp6.c

mediastreamer2是开源的网络传输媒体流的库

 * Read number of consecutive blocks with null DC or AC.
 * This value is < 74.
 */
static unsigned vp6_get_nb_null(vp56_context_t *s)
{
    unsigned val = get_bits(&s->gb, 2);
    if (val == 2)
        val += get_bits(&s->gb, 2);
    else if (val == 3) {
        val = get_bits1(&s->gb) << 2;
        val = 6+val + get_bits(&s->gb, 2+val);
    }
    return val;
}

static void vp6_parse_coeff_huffman(vp56_context_t *s)
{
    vp56_model_t *model = s->modelp;
    uint8_t *permute = s->scantable.permutated;
    VLC *vlc_coeff;
    int coeff, sign, coeff_idx;
    int b, cg, idx;
    int pt = 0;    /* plane type (0 for Y, 1 for U or V) */

    for (b=0; b<6; b++) {
        int ct = 0;    /* code type */
        if (b > 3) pt = 1;
        vlc_coeff = &s->dccv_vlc[pt];

        for (coeff_idx=0; coeff_idx<64; ) {
            int run = 1;
            if (coeff_idx<2 && s->nb_null[coeff_idx][pt]) {
                s->nb_null[coeff_idx][pt]--;
                if (coeff_idx)
                    break;
            } else {
                coeff = get_vlc2(&s->gb, vlc_coeff->table, 9, 3);
                if (coeff == 0) {
                    if (coeff_idx) {
                        int pt = (coeff_idx >= 6);
                        run += get_vlc2(&s->gb, s->runv_vlc[pt].table, 9, 3);
                        if (run >= 9)
                            run += get_bits(&s->gb, 6);
                    } else
                        s->nb_null[0][pt] = vp6_get_nb_null(s);
                    ct = 0;
                } else if (coeff == 11) {  /* end of block */
                    if (coeff_idx == 1)    /* first AC coeff ? */
                        s->nb_null[1][pt] = vp6_get_nb_null(s);
                    break;
                } else {
                    int coeff2 = vp56_coeff_bias[coeff];
                    if (coeff > 4)
                        coeff2 += get_bits(&s->gb, coeff <= 9 ? coeff - 4 : 11);
                    ct = 1 + (coeff2 > 1);
                    sign = get_bits1(&s->gb);
                    coeff2 = (coeff2 ^ -sign) + sign;
                    if (coeff_idx)
                        coeff2 *= s->dequant_ac;
                    idx = model->coeff_index_to_pos[coeff_idx];
                    s->block_coeff[b][permute[idx]] = coeff2;
                }
            }
            coeff_idx+=run;
            cg = FFMIN(vp6_coeff_groups[coeff_idx], 3);
            vlc_coeff = &s->ract_vlc[pt][ct][cg];
        }
    }
}

static void vp6_parse_coeff(vp56_context_t *s)
{
    vp56_range_coder_t *c = s->ccp;
    vp56_model_t *model = s->modelp;
    uint8_t *permute = s->scantable.permutated;
    uint8_t *model1, *model2, *model3;
    int coeff, sign, coeff_idx;
    int b, i, cg, idx, ctx;
    int pt = 0;    /* plane type (0 for Y, 1 for U or V) */

    for (b=0; b<6; b++) {
        int ct = 1;    /* code type */
        int run = 1;

        if (b > 3) pt = 1;

        ctx = s->left_block[vp56_b6to4[b]].not_null_dc
              + s->above_blocks[s->above_block_idx[b]].not_null_dc;
        model1 = model->coeff_dccv[pt];
        model2 = model->coeff_dcct[pt][ctx];

        for (coeff_idx=0; coeff_idx<64; ) {
            if ((coeff_idx>1 && ct==0) || vp56_rac_get_prob(c, model2[0])) {
                /* parse a coeff */
                if (vp56_rac_get_prob(c, model2[2])) {
                    if (vp56_rac_get_prob(c, model2[3])) {
                        idx = vp56_rac_get_tree(c, vp56_pc_tree, model1);
                        coeff = vp56_coeff_bias[idx+5];
                        for (i=vp56_coeff_bit_length[idx]; i>=0; i--)
                            coeff += vp56_rac_get_prob(c, vp56_coeff_parse_table[idx][i]) << i;
                    } else {
                        if (vp56_rac_get_prob(c, model2[4]))
                            coeff = 3 + vp56_rac_get_prob(c, model1[5]);
                        else
                            coeff = 2;
                    }
                    ct = 2;
                } else {
                    ct = 1;
                    coeff = 1;
                }
                sign = vp56_rac_get(c);
                coeff = (coeff ^ -sign) + sign;
                if (coeff_idx)
                    coeff *= s->dequant_ac;
                idx = model->coeff_index_to_pos[coeff_idx];
                s->block_coeff[b][permute[idx]] = coeff;
                run = 1;
            } else {
                /* parse a run */
                ct = 0;
                if (coeff_idx > 0) {
                    if (!vp56_rac_get_prob(c, model2[1]))
                        break;

                    model3 = model->coeff_runv[coeff_idx >= 6];
                    run = vp56_rac_get_tree(c, vp6_pcr_tree, model3);
                    if (!run)
                        for (run=9, i=0; i<6; i++)
                            run += vp56_rac_get_prob(c, model3[i+8]) << i;
                }
            }

            cg = vp6_coeff_groups[coeff_idx+=run];
            model1 = model2 = model->coeff_ract[pt][ct][cg];
        }

        s->left_block[vp56_b6to4[b]].not_null_dc =
        s->above_blocks[s->above_block_idx[b]].not_null_dc = !!s->block_coeff[b][0];
    }
}

static int vp6_adjust(int v, int t)
{
    int V = v, s = v >> 31;
    V ^= s;
    V -= s;
    if (V-t-1 >= (unsigned)(t-1))
        return v;
    V = 2*t - V;
    V += s;
    V ^= s;
    return V;
}

static int vp6_block_variance(uint8_t *src, int stride)
{
    int sum = 0, square_sum = 0;
    int y, x;

    for (y=0; y<8; y+=2) {
        for (x=0; x<8; x+=2) {
            sum += src[x];
            square_sum += src[x]*src[x];
        }
        src += 2*stride;
    }
    return (16*square_sum - sum*sum) >> 8;
}

static void vp6_filter_hv4(uint8_t *dst, uint8_t *src, int stride,
                           int delta, const int16_t *weights)
{
    int x, y;

    for (y=0; y<8; y++) {
        for (x=0; x<8; x++) {
            dst[x] = av_clip_uint8((  src[x-delta  ] * weights[0]
                                 + src[x        ] * weights[1]
                                 + src[x+delta  ] * weights[2]
                                 + src[x+2*delta] * weights[3] + 64) >> 7);
        }
        src += stride;
        dst += stride;
    }
}

static void vp6_filter_diag2(vp56_context_t *s, uint8_t *dst, uint8_t *src,
                             int stride, int h_weight, int v_weight)
{
    uint8_t *tmp = s->edge_emu_buffer+16;
    s->dsp.put_h264_chroma_pixels_tab[0](tmp, src, stride, 9, h_weight, 0);
    s->dsp.put_h264_chroma_pixels_tab[0](dst, tmp, stride, 8, 0, v_weight);
}

static void vp6_filter_diag4(uint8_t *dst, uint8_t *src, int stride,
                             const int16_t *h_weights,const int16_t *v_weights)
{
    int x, y;
    int tmp[8*11];
    int *t = tmp;

    src -= stride;

    for (y=0; y<11; y++) {
        for (x=0; x<8; x++) {
            t[x] = av_clip_uint8((  src[x-1] * h_weights[0]
                               + src[x  ] * h_weights[1]
                               + src[x+1] * h_weights[2]
                               + src[x+2] * h_weights[3] + 64) >> 7);
        }
        src += stride;
        t += 8;
    }

    t = tmp + 8;
    for (y=0; y<8; y++) {
        for (x=0; x<8; x++) {
            dst[x] = av_clip_uint8((  t[x-8 ] * v_weights[0]
                                 + t[x   ] * v_weights[1]
                                 + t[x+8 ] * v_weights[2]
                                 + t[x+16] * v_weights[3] + 64) >> 7);
        }
        dst += stride;
        t += 8;
    }
}

static void vp6_filter(vp56_context_t *s, uint8_t *dst, uint8_t *src,
                       int offset1, int offset2, int stride,
                       vp56_mv_t mv, int mask, int select, int luma)
{
    int filter4 = 0;
    int x8 = mv.x & mask;
    int y8 = mv.y & mask;

    if (luma) {
        x8 *= 2;
        y8 *= 2;
        filter4 = s->filter_mode;
        if (filter4 == 2) {
            if (s->max_vector_length &&
                (FFABS(mv.x) > s->max_vector_length ||
                 FFABS(mv.y) > s->max_vector_length)) {
                filter4 = 0;
            } else if (s->sample_variance_threshold
                       && (vp6_block_variance(src+offset1, stride)
                           < s->sample_variance_threshold)) {
                filter4 = 0;
            }
        }
    }

    if ((y8 && (offset2-offset1)*s->flip<0) || (!y8 && offset1 > offset2)) {
        offset1 = offset2;
    }

    if (filter4) {
        if (!y8) {                      /* left or right combine */
            vp6_filter_hv4(dst, src+offset1, stride, 1,
                           vp6_block_copy_filter[select][x8]);
        } else if (!x8) {               /* above or below combine */
            vp6_filter_hv4(dst, src+offset1, stride, stride,
                           vp6_block_copy_filter[select][y8]);
        } else {
            vp6_filter_diag4(dst, src+offset1 + ((mv.x^mv.y)>>31), stride,
                             vp6_block_copy_filter[select][x8],
                             vp6_block_copy_filter[select][y8]);
        }
    } else {
        if (!x8 || !y8) {
            s->dsp.put_h264_chroma_pixels_tab[0](dst, src+offset1, stride, 8, x8, y8);
        } else {
            vp6_filter_diag2(s, dst, src+offset1 + ((mv.x^mv.y)>>31), stride, x8, y8);
        }
    }
}

static int vp6_decode_init(AVCodecContext *avctx)
{
    vp56_context_t *s = avctx->priv_data;

    vp56_init(avctx, avctx->codec->id == CODEC_ID_VP6,
                     avctx->codec->id == CODEC_ID_VP6A);
    s->vp56_coord_div = vp6_coord_div;
    s->parse_vector_adjustment = vp6_parse_vector_adjustment;
    s->adjust = vp6_adjust;
    s->filter = vp6_filter;
    s->default_models_init = vp6_default_models_init;
    s->parse_vector_models = vp6_parse_vector_models;
    s->parse_coeff_models = vp6_parse_coeff_models;
    s->parse_header = vp6_parse_header;

    return 0;
}

AVCodec vp6_decoder = {
    "vp6",
    CODEC_TYPE_VIDEO,
    CODEC_ID_VP6,
    sizeof(vp56_context_t),
    vp6_decode_init,
    NULL,
    vp56_free,
    vp56_decode_frame,
    CODEC_CAP_DR1,
};

/* flash version, not flipped upside-down */
AVCodec vp6f_decoder = {
    "vp6f",
    CODEC_TYPE_VIDEO,
    CODEC_ID_VP6F,
    sizeof(vp56_context_t),
    vp6_decode_init,
    NULL,
    vp56_free,
    vp56_decode_frame,
    CODEC_CAP_DR1,
};

/* flash version, not flipped upside-down, with alpha channel */
AVCodec vp6a_decoder = {
    "vp6a",
    CODEC_TYPE_VIDEO,
    CODEC_ID_VP6A,
    sizeof(vp56_context_t),
    vp6_decode_init,
    NULL,
    vp56_free,
    vp56_decode_frame,
    CODEC_CAP_DR1,
};