static int encode_block(SVQ1Context *s, uint8_t *src, uint8_t *ref, uint8_t *decoded, int stride, int level, int threshold, int lambda, int intra){

    int count, y, x, i, j, split, best_mean, best_score, best_count;

    int best_vector[6];

    int block_sum[7]= {0, 0, 0, 0, 0, 0};

    int w= 2<<((level+2)>>1);

    int h= 2<<((level+1)>>1);

    int size=w*h;

    int16_t block[7][256];

    const int8_t *codebook_sum, *codebook;

    const uint16_t (*mean_vlc)[2];

    const uint8_t (*multistage_vlc)[2];



    best_score=0;

    

    if(intra){

        codebook_sum= svq1_intra_codebook_sum[level];

        codebook= svq1_intra_codebooks[level];

        mean_vlc= svq1_intra_mean_vlc;

        multistage_vlc= svq1_intra_multistage_vlc[level];

        for(y=0; y<h; y++){

            for(x=0; x<w; x++){

                int v= src[x + y*stride];

                block[0][x + w*y]= v;

                best_score += v*v;

                block_sum[0] += v;

            }

        }

    }else{

        codebook_sum= svq1_inter_codebook_sum[level];

        codebook= svq1_inter_codebooks[level];

        mean_vlc= svq1_inter_mean_vlc + 256;

        multistage_vlc= svq1_inter_multistage_vlc[level];

        for(y=0; y<h; y++){

            for(x=0; x<w; x++){

                int v= src[x + y*stride] - ref[x + y*stride];

                block[0][x + w*y]= v;

                best_score += v*v;

                block_sum[0] += v;

            }

        }

    }



    best_count=0;

    best_score -= ((block_sum[0]*block_sum[0])>>(level+3));

    best_mean= (block_sum[0] + (size>>1)) >> (level+3);



    if(level<4){

        for(count=1; count<7; count++){

            int best_vector_score= INT_MAX;

            int best_vector_sum=-999, best_vector_mean=-999;

            const int stage= count-1;

            const int8_t *vector;



            for(i=0; i<16; i++){

                int sum= codebook_sum[stage*16 + i];

                int sqr, diff, mean, score;



                vector = codebook + stage*size*16 + i*size;

                sqr = s->dsp.ssd_int8_vs_int16(vector, block[stage], size);

                diff= block_sum[stage] - sum;

                mean= (diff + (size>>1)) >> (level+3);

                assert(mean >-300 && mean<300);

                if(intra) mean= av_clip(mean, 0, 255);

                else      mean= av_clip(mean, -256, 255);

                score= sqr - ((diff*(int64_t)diff)>>(level+3)); 

                if(score < best_vector_score){

                    best_vector_score= score;

                    best_vector[stage]= i;

                    best_vector_sum= sum;

                    best_vector_mean= mean;

                }

            }

            assert(best_vector_mean != -999);

            vector= codebook + stage*size*16 + best_vector[stage]*size;

            for(j=0; j<size; j++){

                block[stage+1][j] = block[stage][j] - vector[j];

            }

            block_sum[stage+1]= block_sum[stage] - best_vector_sum;

            best_vector_score +=

                lambda*(+ 1 + 4*count

                        + multistage_vlc[1+count][1]

                        + mean_vlc[best_vector_mean][1]);



            if(best_vector_score < best_score){

                best_score= best_vector_score;

                best_count= count;

                best_mean= best_vector_mean;

            }

        }

    }



    split=0;

    if(best_score > threshold && level){

        int score=0;

        int offset= (level&1) ? stride*h/2 : w/2;

        PutBitContext backup[6];



        for(i=level-1; i>=0; i--){

            backup[i]= s->reorder_pb[i];

        }

        score += encode_block(s, src         , ref         , decoded         , stride, level-1, threshold>>1, lambda, intra);

        score += encode_block(s, src + offset, ref + offset, decoded + offset, stride, level-1, threshold>>1, lambda, intra);

        score += lambda;



        if(score < best_score){

            best_score= score;

            split=1;

        }else{

            for(i=level-1; i>=0; i--){

                s->reorder_pb[i]= backup[i];

            }

        }

    }

    if (level > 0)

        put_bits(&s->reorder_pb[level], 1, split);



    if(!split){

        assert((best_mean >= 0 && best_mean<256) || !intra);

        assert(best_mean >= -256 && best_mean<256);

        assert(best_count >=0 && best_count<7);

        assert(level<4 || best_count==0);



        

        put_bits(&s->reorder_pb[level],

            multistage_vlc[1 + best_count][1],

            multistage_vlc[1 + best_count][0]);

        put_bits(&s->reorder_pb[level], mean_vlc[best_mean][1],

            mean_vlc[best_mean][0]);



        for (i = 0; i < best_count; i++){

            assert(best_vector[i]>=0 && best_vector[i]<16);

            put_bits(&s->reorder_pb[level], 4, best_vector[i]);

        }



        for(y=0; y<h; y++){

            for(x=0; x<w; x++){

                decoded[x + y*stride]= src[x + y*stride] - block[best_count][x + w*y] + best_mean;

            }

        }

    }



    return best_score;

}
