mpegvideo_enc.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

        threshold= -threshold;
    }else
        skip_dc=1;

    /* are all which we could set to zero are allready zero? */
    if(last_index<=skip_dc - 1) return;

    for(i=0; i<=last_index; i++){
        const int j = s->intra_scantable.permutated[i];
        const int level = FFABS(block[j]);
        if(level==1){
            if(skip_dc && i==0) continue;
            score+= tab[run];
            run=0;
        }else if(level>1){
            return;
        }else{
            run++;
        }
    }
    if(score >= threshold) return;
    for(i=skip_dc; i<=last_index; i++){
        const int j = s->intra_scantable.permutated[i];
        block[j]=0;
    }
    if(block[0]) s->block_last_index[n]= 0;
    else         s->block_last_index[n]= -1;
}

static inline void clip_coeffs(MpegEncContext *s, DCTELEM *block, int last_index)
{
    int i;
    const int maxlevel= s->max_qcoeff;
    const int minlevel= s->min_qcoeff;
    int overflow=0;

    if(s->mb_intra){
        i=1; //skip clipping of intra dc
    }else
        i=0;

    for(;i<=last_index; i++){
        const int j= s->intra_scantable.permutated[i];
        int level = block[j];

        if     (level>maxlevel){
            level=maxlevel;
            overflow++;
        }else if(level<minlevel){
            level=minlevel;
            overflow++;
        }

        block[j]= level;
    }

    if(overflow && s->avctx->mb_decision == FF_MB_DECISION_SIMPLE)
        av_log(s->avctx, AV_LOG_INFO, "warning, clipping %d dct coefficients to %d..%d\n", overflow, minlevel, maxlevel);
}

static void get_vissual_weight(int16_t *weight, uint8_t *ptr, int stride){
    int x, y;
//FIXME optimize
    for(y=0; y<8; y++){
        for(x=0; x<8; x++){
            int x2, y2;
            int sum=0;
            int sqr=0;
            int count=0;

            for(y2= FFMAX(y-1, 0); y2 < FFMIN(8, y+2); y2++){
                for(x2= FFMAX(x-1, 0); x2 < FFMIN(8, x+2); x2++){
                    int v= ptr[x2 + y2*stride];
                    sum += v;
                    sqr += v*v;
                    count++;
                }
            }
            weight[x + 8*y]= (36*ff_sqrt(count*sqr - sum*sum)) / count;
        }
    }
}

static av_always_inline void encode_mb_internal(MpegEncContext *s, int motion_x, int motion_y, int mb_block_height, int mb_block_count)
{
    int16_t weight[8][64];
    DCTELEM orig[8][64];
    const int mb_x= s->mb_x;
    const int mb_y= s->mb_y;
    int i;
    int skip_dct[8];
    int dct_offset   = s->linesize*8; //default for progressive frames
    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
    int wrap_y, wrap_c;

    for(i=0; i<mb_block_count; i++) skip_dct[i]=s->skipdct;

    if(s->adaptive_quant){
        const int last_qp= s->qscale;
        const int mb_xy= mb_x + mb_y*s->mb_stride;

        s->lambda= s->lambda_table[mb_xy];
        update_qscale(s);

        if(!(s->flags&CODEC_FLAG_QP_RD)){
            s->qscale= s->current_picture_ptr->qscale_table[mb_xy];
            s->dquant= s->qscale - last_qp;

            if(s->out_format==FMT_H263){
                s->dquant= av_clip(s->dquant, -2, 2);

                if(s->codec_id==CODEC_ID_MPEG4){
                    if(!s->mb_intra){
                        if(s->pict_type == B_TYPE){
                            if(s->dquant&1 || s->mv_dir&MV_DIRECT)
                                s->dquant= 0;
                        }
                        if(s->mv_type==MV_TYPE_8X8)
                            s->dquant=0;
                    }
                }
            }
        }
        ff_set_qscale(s, last_qp + s->dquant);
    }else if(s->flags&CODEC_FLAG_QP_RD)
        ff_set_qscale(s, s->qscale + s->dquant);

    wrap_y = s->linesize;
    wrap_c = s->uvlinesize;
    ptr_y = s->new_picture.data[0] + (mb_y * 16 * wrap_y) + mb_x * 16;
    ptr_cb = s->new_picture.data[1] + (mb_y * mb_block_height * wrap_c) + mb_x * 8;
    ptr_cr = s->new_picture.data[2] + (mb_y * mb_block_height * wrap_c) + mb_x * 8;

    if(mb_x*16+16 > s->width || mb_y*16+16 > s->height){
        uint8_t *ebuf= s->edge_emu_buffer + 32;
        ff_emulated_edge_mc(ebuf            , ptr_y , wrap_y,16,16,mb_x*16,mb_y*16, s->width   , s->height);
        ptr_y= ebuf;
        ff_emulated_edge_mc(ebuf+18*wrap_y  , ptr_cb, wrap_c, 8, mb_block_height, mb_x*8, mb_y*8, s->width>>1, s->height>>1);
        ptr_cb= ebuf+18*wrap_y;
        ff_emulated_edge_mc(ebuf+18*wrap_y+8, ptr_cr, wrap_c, 8, mb_block_height, mb_x*8, mb_y*8, s->width>>1, s->height>>1);
        ptr_cr= ebuf+18*wrap_y+8;
    }

    if (s->mb_intra) {
        if(s->flags&CODEC_FLAG_INTERLACED_DCT){
            int progressive_score, interlaced_score;

            s->interlaced_dct=0;
            progressive_score= s->dsp.ildct_cmp[4](s, ptr_y           , NULL, wrap_y, 8)
                              +s->dsp.ildct_cmp[4](s, ptr_y + wrap_y*8, NULL, wrap_y, 8) - 400;

            if(progressive_score > 0){
                interlaced_score = s->dsp.ildct_cmp[4](s, ptr_y           , NULL, wrap_y*2, 8)
                                  +s->dsp.ildct_cmp[4](s, ptr_y + wrap_y  , NULL, wrap_y*2, 8);
                if(progressive_score > interlaced_score){
                    s->interlaced_dct=1;

                    dct_offset= wrap_y;
                    wrap_y<<=1;
                    if (s->chroma_format == CHROMA_422)
                        wrap_c<<=1;
                }
            }
        }

        s->dsp.get_pixels(s->block[0], ptr_y                 , wrap_y);
        s->dsp.get_pixels(s->block[1], ptr_y              + 8, wrap_y);
        s->dsp.get_pixels(s->block[2], ptr_y + dct_offset    , wrap_y);
        s->dsp.get_pixels(s->block[3], ptr_y + dct_offset + 8, wrap_y);

        if(s->flags&CODEC_FLAG_GRAY){
            skip_dct[4]= 1;
            skip_dct[5]= 1;
        }else{
            s->dsp.get_pixels(s->block[4], ptr_cb, wrap_c);
            s->dsp.get_pixels(s->block[5], ptr_cr, wrap_c);
            if(!s->chroma_y_shift){ /* 422 */
                s->dsp.get_pixels(s->block[6], ptr_cb + (dct_offset>>1), wrap_c);
                s->dsp.get_pixels(s->block[7], ptr_cr + (dct_offset>>1), wrap_c);
            }
        }
    }else{
        op_pixels_func (*op_pix)[4];
        qpel_mc_func (*op_qpix)[16];
        uint8_t *dest_y, *dest_cb, *dest_cr;

        dest_y  = s->dest[0];
        dest_cb = s->dest[1];
        dest_cr = s->dest[2];

        if ((!s->no_rounding) || s->pict_type==B_TYPE){
            op_pix = s->dsp.put_pixels_tab;
            op_qpix= s->dsp.put_qpel_pixels_tab;
        }else{
            op_pix = s->dsp.put_no_rnd_pixels_tab;
            op_qpix= s->dsp.put_no_rnd_qpel_pixels_tab;
        }

        if (s->mv_dir & MV_DIR_FORWARD) {
            MPV_motion(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.data, op_pix, op_qpix);
            op_pix = s->dsp.avg_pixels_tab;
            op_qpix= s->dsp.avg_qpel_pixels_tab;
        }
        if (s->mv_dir & MV_DIR_BACKWARD) {
            MPV_motion(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.data, op_pix, op_qpix);
        }

        if(s->flags&CODEC_FLAG_INTERLACED_DCT){
            int progressive_score, interlaced_score;

            s->interlaced_dct=0;
            progressive_score= s->dsp.ildct_cmp[0](s, dest_y           , ptr_y           , wrap_y, 8)
                              +s->dsp.ildct_cmp[0](s, dest_y + wrap_y*8, ptr_y + wrap_y*8, wrap_y, 8) - 400;

            if(s->avctx->ildct_cmp == FF_CMP_VSSE) progressive_score -= 400;

            if(progressive_score>0){
                interlaced_score = s->dsp.ildct_cmp[0](s, dest_y           , ptr_y           , wrap_y*2, 8)
                                  +s->dsp.ildct_cmp[0](s, dest_y + wrap_y  , ptr_y + wrap_y  , wrap_y*2, 8);

                if(progressive_score > interlaced_score){
                    s->interlaced_dct=1;

                    dct_offset= wrap_y;
                    wrap_y<<=1;
                    if (s->chroma_format == CHROMA_422)
                        wrap_c<<=1;
                }
            }
        }

        s->dsp.diff_pixels(s->block[0], ptr_y                 , dest_y                 , wrap_y);
        s->dsp.diff_pixels(s->block[1], ptr_y              + 8, dest_y              + 8, wrap_y);
        s->dsp.diff_pixels(s->block[2], ptr_y + dct_offset    , dest_y + dct_offset    , wrap_y);
        s->dsp.diff_pixels(s->block[3], ptr_y + dct_offset + 8, dest_y + dct_offset + 8, wrap_y);

        if(s->flags&CODEC_FLAG_GRAY){
            skip_dct[4]= 1;
            skip_dct[5]= 1;
        }else{
            s->dsp.diff_pixels(s->block[4], ptr_cb, dest_cb, wrap_c);
            s->dsp.diff_pixels(s->block[5], ptr_cr, dest_cr, wrap_c);
            if(!s->chroma_y_shift){ /* 422 */
                s->dsp.diff_pixels(s->block[6], ptr_cb + (dct_offset>>1), dest_cb + (dct_offset>>1), wrap_c);
                s->dsp.diff_pixels(s->block[7], ptr_cr + (dct_offset>>1), dest_cr + (dct_offset>>1), wrap_c);
            }
        }
        /* pre quantization */
        if(s->current_picture.mc_mb_var[s->mb_stride*mb_y+ mb_x]<2*s->qscale*s->qscale){
            //FIXME optimize
            if(s->dsp.sad[1](NULL, ptr_y               , dest_y               , wrap_y, 8) < 20*s->qscale) skip_dct[0]= 1;
            if(s->dsp.sad[1](NULL, ptr_y            + 8, dest_y            + 8, wrap_y, 8) < 20*s->qscale) skip_dct[1]= 1;
            if(s->dsp.sad[1](NULL, ptr_y +dct_offset   , dest_y +dct_offset   , wrap_y, 8) < 20*s->qscale) skip_dct[2]= 1;
            if(s->dsp.sad[1](NULL, ptr_y +dct_offset+ 8, dest_y +dct_offset+ 8, wrap_y, 8) < 20*s->qscale) skip_dct[3]= 1;
            if(s->dsp.sad[1](NULL, ptr_cb              , dest_cb              , wrap_c, 8) < 20*s->qscale) skip_dct[4]= 1;
            if(s->dsp.sad[1](NULL, ptr_cr              , dest_cr              , wrap_c, 8) < 20*s->qscale) skip_dct[5]= 1;
            if(!s->chroma_y_shift){ /* 422 */
                if(s->dsp.sad[1](NULL, ptr_cb +(dct_offset>>1), dest_cb +(dct_offset>>1), wrap_c, 8) < 20*s->qscale) skip_dct[6]= 1;
                if(s->dsp.sad[1](NULL, ptr_cr +(dct_offset>>1), dest_cr +(dct_offset>>1), wrap_c, 8) < 20*s->qscale) skip_dct[7]= 1;
            }
        }
    }

    if(s->avctx->quantizer_noise_shaping){
        if(!skip_dct[0]) get_vissual_weight(weight[0], ptr_y                 , wrap_y);
        if(!skip_dct[1]) get_vissual_weight(weight[1], ptr_y              + 8, wrap_y);
        if(!skip_dct[2]) get_vissual_weight(weight[2], ptr_y + dct_offset    , wrap_y);
        if(!skip_dct[3]) get_vissual_weight(weight[3], ptr_y + dct_offset + 8, wrap_y);
        if(!skip_dct[4]) get_vissual_weight(weight[4], ptr_cb                , wrap_c);
        if(!skip_dct[5]) get_vissual_weight(weight[5], ptr_cr                , wrap_c);
        if(!s->chroma_y_shift){ /* 422 */
            if(!skip_dct[6]) get_vissual_weight(weight[6], ptr_cb + (dct_offset>>1), wrap_c);
            if(!skip_dct[7]) get_vissual_weight(weight[7], ptr_cr + (dct_offset>>1), wrap_c);
        }
        memcpy(orig[0], s->block[0], sizeof(DCTELEM)*64*mb_block_count);
    }

    /* DCT & quantize */
    assert(s->out_format!=FMT_MJPEG || s->qscale==8);
    {
        for(i=0;i<mb_block_count;i++) {
            if(!skip_dct[i]){
                int overflow;
                s->block_last_index[i] = s->dct_quantize(s, s->block[i], i, s->qscale, &overflow);
            // FIXME we could decide to change to quantizer instead of clipping
            // JS: I don't think that would be a good idea it could lower quality instead
            //     of improve it. Just INTRADC clipping deserves changes in quantizer
                if (overflow) clip_coeffs(s, s->block[i], s->block_last_index[i]);
            }else
                s->block_last_index[i]= -1;
        }
        if(s->avctx->quantizer_noise_shaping){
            for(i=0;i<mb_block_count;i++) {
                if(!skip_dct[i]){
                    s->block_last_index[i] = dct_quantize_refine(s, s->block[i], weight[i], orig[i], i, s->qscale);
                }
            }
        }

        if(s->luma_elim_threshold && !s->mb_intra)
            for(i=0; i<4; i++)
                dct_single_coeff_elimination(s, i, s->luma_elim_threshold);
        if(s->chroma_elim_threshold && !s->mb_intra)
            for(i=4; i<mb_block_count; i++)
                dct_single_coeff_elimination(s, i, s->chroma_elim_threshold);

        if(s->flags & CODEC_FLAG_CBP_RD){
            for(i=0;i<mb_block_count;i++) {
                if(s->block_last_index[i] == -1)
                    s->coded_score[i]= INT_MAX/256;
            }
        }
    }

    if((s->flags&CODEC_FLAG_GRAY) && s->mb_intra){
        s->block_last_index[4]=
        s->block_last_index[5]= 0;
        s->block[4][0]=
        s->block[5][0]= (1024 + s->c_dc_scale/2)/ s->c_dc_scale;
    }

    //non c quantize code returns incorrect block_last_index FIXME
    if(s->alternate_scan && s->dct_quantize != dct_quantize_c){
        for(i=0; i<mb_block_count; i++){
            int j;
            if(s->block_last_index[i]>0){
                for(j=63; j>0; j--){
                    if(s->block[i][ s->intra_scantable.permutated[j] ]) break;
                }
                s->block_last_index[i]= j;
            }
        }
    }

    /* huffman encode */
    switch(s->codec_id){ //FIXME funct ptr could be slightly faster
    case CODEC_ID_MPEG1VIDEO:
    case CODEC_ID_MPEG2VIDEO:
        if (ENABLE_MPEG1VIDEO_ENCODER || ENABLE_MP