h263.c

arm平台下的H264编码和解码源代码

            /* left prediction */
            if (a != 1024) {
                ac_val -= 16;
                for(i=1;i<8;i++) {
                    block[s->dsp.idct_permutation[i<<3]] += ac_val[i];
                }
                pred_dc = a;
            }
        } else {
            /* top prediction */
            if (c != 1024) {
                ac_val -= 16 * wrap;
                for(i=1;i<8;i++) {
                    block[s->dsp.idct_permutation[i   ]] += ac_val[i + 8];
                }
                pred_dc = c;
            }
        }
    } else {
        /* just DC prediction */
        if (a != 1024 && c != 1024)
            pred_dc = (a + c) >> 1;
        else if (a != 1024)
            pred_dc = a;
        else
            pred_dc = c;
    }
    
    /* we assume pred is positive */
    block[0]=block[0]*scale + pred_dc;
    
    if (block[0] < 0)
        block[0] = 0;
    else 
        block[0] |= 1;
    
    /* Update AC/DC tables */
    dc_val[(x) + (y) * wrap] = block[0];
    
    /* left copy */
    for(i=1;i<8;i++)
        ac_val1[i    ] = block[s->dsp.idct_permutation[i<<3]];
    /* top copy */
    for(i=1;i<8;i++)
        ac_val1[8 + i] = block[s->dsp.idct_permutation[i   ]];
}

int16_t *h263_pred_motion(MpegEncContext * s, int block, int dir,
                        int *px, int *py)
{
    int wrap;
    int16_t *A, *B, *C, (*mot_val)[2];
    static const int off[4]= {2, 1, 1, -1};

    wrap = s->b8_stride;
    mot_val = s->current_picture.motion_val[dir] + s->block_index[block];

    A = mot_val[ - 1];
    /* special case for first (slice) line */
    if (s->first_slice_line && block<3) {
        // we cant just change some MVs to simulate that as we need them for the B frames (and ME)
        // and if we ever support non rectangular objects than we need to do a few ifs here anyway :(
        if(block==0){ //most common case
            if(s->mb_x  == s->resync_mb_x){ //rare
                *px= *py = 0;
            }else if(s->mb_x + 1 == s->resync_mb_x && s->h263_pred){ //rare
                C = mot_val[off[block] - wrap];
                if(s->mb_x==0){
                    *px = C[0];
                    *py = C[1];
                }else{
                    *px = mid_pred(A[0], 0, C[0]);
                    *py = mid_pred(A[1], 0, C[1]);
                }
            }else{
                *px = A[0];
                *py = A[1];
            }
        }else if(block==1){
            if(s->mb_x + 1 == s->resync_mb_x && s->h263_pred){ //rare
                C = mot_val[off[block] - wrap];
                *px = mid_pred(A[0], 0, C[0]);
                *py = mid_pred(A[1], 0, C[1]);
            }else{
                *px = A[0];
                *py = A[1];
            }
        }else{ /* block==2*/
            B = mot_val[ - wrap];
            C = mot_val[off[block] - wrap];
            if(s->mb_x == s->resync_mb_x) //rare
                A[0]=A[1]=0;
    
            *px = mid_pred(A[0], B[0], C[0]);
            *py = mid_pred(A[1], B[1], C[1]);
        }
    } else {
        B = mot_val[ - wrap];
        C = mot_val[off[block] - wrap];
        *px = mid_pred(A[0], B[0], C[0]);
        *py = mid_pred(A[1], B[1], C[1]);
    }
    return *mot_val;
}

#ifdef CONFIG_ENCODERS
static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
{
    int range, l, bit_size, sign, code, bits;

    if (val == 0) {
        /* zero vector */
        code = 0;
        put_bits(&s->pb, mvtab[code][1], mvtab[code][0]);
    } else {
        bit_size = f_code - 1;
        range = 1 << bit_size;
        /* modulo encoding */
        l = range * 32;
#if 1
        val+= l;
        val&= 2*l-1;
        val-= l;
        sign = val>>31;
        val= (val^sign)-sign;
        sign&=1;
#else
        if (val < -l) {
            val += 2*l;
        } else if (val >= l) {
            val -= 2*l;
        }

        assert(val>=-l && val<l);

        if (val >= 0) {
            sign = 0;
        } else {
            val = -val;
            sign = 1;
        }
#endif
        val--;
        code = (val >> bit_size) + 1;
        bits = val & (range - 1);

        put_bits(&s->pb, mvtab[code][1] + 1, (mvtab[code][0] << 1) | sign); 
        if (bit_size > 0) {
            put_bits(&s->pb, bit_size, bits);
        }
    }

}

/* Encode MV differences on H.263+ with Unrestricted MV mode */
static void h263p_encode_umotion(MpegEncContext * s, int val)
{
    short sval = 0; 
    short i = 0;
    short n_bits = 0;
    short temp_val;
    int code = 0;
    int tcode;
    
    if ( val == 0)
        put_bits(&s->pb, 1, 1);
    else if (val == 1)
        put_bits(&s->pb, 3, 0);
    else if (val == -1)
        put_bits(&s->pb, 3, 2);
    else {
        
        sval = ((val < 0) ? (short)(-val):(short)val);
        temp_val = sval;
        
        while (temp_val != 0) {
            temp_val = temp_val >> 1;
            n_bits++;
        }
        
        i = n_bits - 1;
        while (i > 0) {
            tcode = (sval & (1 << (i-1))) >> (i-1);
            tcode = (tcode << 1) | 1;
            code = (code << 2) | tcode;
            i--;
        }
        code = ((code << 1) | (val < 0)) << 1;
        put_bits(&s->pb, (2*n_bits)+1, code);
        //printf("\nVal = %d\tCode = %d", sval, code);
    }
}

static void init_mv_penalty_and_fcode(MpegEncContext *s)
{
    int f_code;
    int mv;
    
    if(mv_penalty==NULL)
        mv_penalty= av_mallocz( sizeof(uint8_t)*(MAX_FCODE+1)*(2*MAX_MV+1) );
    
    for(f_code=1; f_code<=MAX_FCODE; f_code++){
        for(mv=-MAX_MV; mv<=MAX_MV; mv++){
            int len;

            if(mv==0) len= mvtab[0][1];
            else{
                int val, bit_size, range, code;

                bit_size = f_code - 1;
                range = 1 << bit_size;

                val=mv;
                if (val < 0) 
                    val = -val;
                val--;
                code = (val >> bit_size) + 1;
                if(code<33){
                    len= mvtab[code][1] + 1 + bit_size;
                }else{
                    len= mvtab[32][1] + 2 + bit_size;
                }
            }

            mv_penalty[f_code][mv+MAX_MV]= len;
        }
    }

    for(f_code=MAX_FCODE; f_code>0; f_code--){
        for(mv=-(16<<f_code); mv<(16<<f_code); mv++){
            fcode_tab[mv+MAX_MV]= f_code;
        }
    }

    for(mv=0; mv<MAX_MV*2+1; mv++){
        umv_fcode_tab[mv]= 1;
    }
}
#endif

#ifdef CONFIG_ENCODERS

static void init_uni_dc_tab(void)
{
    int level, uni_code, uni_len;

    for(level=-256; level<256; level++){
        int size, v, l;
        /* find number of bits */
        size = 0;
        v = abs(level);
        while (v) {
            v >>= 1;
	    size++;
        }

        if (level < 0)
            l= (-level) ^ ((1 << size) - 1);
        else
            l= level;

        /* luminance */
        uni_code= DCtab_lum[size][0];
        uni_len = DCtab_lum[size][1];

        if (size > 0) {
            uni_code<<=size; uni_code|=l;
            uni_len+=size;
            if (size > 8){
                uni_code<<=1; uni_code|=1;
                uni_len++;
            }
        }
        uni_DCtab_lum_bits[level+256]= uni_code;
        uni_DCtab_lum_len [level+256]= uni_len;

        /* chrominance */
        uni_code= DCtab_chrom[size][0];
        uni_len = DCtab_chrom[size][1];
        
        if (size > 0) {
            uni_code<<=size; uni_code|=l;
            uni_len+=size;
            if (size > 8){
                uni_code<<=1; uni_code|=1;
                uni_len++;
            }
        }
        uni_DCtab_chrom_bits[level+256]= uni_code;
        uni_DCtab_chrom_len [level+256]= uni_len;

    }
}

#endif //CONFIG_ENCODERS

#ifdef CONFIG_ENCODERS
static void init_uni_mpeg4_rl_tab(RLTable *rl, uint32_t *bits_tab, uint8_t *len_tab){
    int slevel, run, last;
    
    assert(MAX_LEVEL >= 64);
    assert(MAX_RUN   >= 63);

    for(slevel=-64; slevel<64; slevel++){
        if(slevel==0) continue;
        for(run=0; run<64; run++){
            for(last=0; last<=1; last++){
                const int index= UNI_MPEG4_ENC_INDEX(last, run, slevel+64);
                int level= slevel < 0 ? -slevel : slevel;
                int sign= slevel < 0 ? 1 : 0;
                int bits, len, code;
                int level1, run1;
                
                len_tab[index]= 100;
                     
                /* ESC0 */
                code= get_rl_index(rl, last, run, level);
                bits= rl->table_vlc[code][0];
                len=  rl->table_vlc[code][1];
                bits=bits*2+sign; len++;
                
                if(code!=rl->n && len < len_tab[index]){
                    bits_tab[index]= bits;
                    len_tab [index]= len;
                }
#if 1
                /* ESC1 */
                bits= rl->table_vlc[rl->n][0];
                len=  rl->table_vlc[rl->n][1];
                bits=bits*2;    len++; //esc1
                level1= level - rl->max_level[last][run];
                if(level1>0){
                    code= get_rl_index(rl, last, run, level1);
                    bits<<= rl->table_vlc[code][1];
                    len  += rl->table_vlc[code][1];
                    bits += rl->table_vlc[code][0];
                    bits=bits*2+sign; len++;
                
                    if(code!=rl->n && len < len_tab[index]){
                        bits_tab[index]= bits;
                        len_tab [index]= len;
                    }
                }
#endif 
#if 1
                /* ESC2 */
                bits= rl->table_vlc[rl->n][0];
                len=  rl->table_vlc[rl->n][1];
                bits=bits*4+2;    len+=2; //esc2
                run1 = run - rl->max_run[last][level] - 1;
                if(run1>=0){
                    code= get_rl_index(rl, last, run1, level);
                    bits<<= rl->table_vlc[code][1];
                    len  += rl->table_vlc[code][1];
                    bits += rl->table_vlc[code][0];
                    bits=bits*2+sign; len++;
                
                    if(code!=rl->n && len < len_tab[index]){
                        bits_tab[index]= bits;
                        len_tab [index]= len;
                    }
                }
#endif           
                /* ESC3 */        
                bits= rl->table_vlc[rl->n][0];
                len = rl->table_vlc[rl->n][1];
                bits=bits*4+3;    len+=2; //esc3
                bits=bits*2+last; len++;
                bits=bits*64+run; len+=6;
                bits=bits*2+1;    len++;  //marker
                bits=bits*4096+(slevel&0xfff); len+=12;
                bits=bits*2+1;    len++;  //marker
                
                if(len < len_tab[index]){
                    bits_tab[index]= bits;
                    len_tab [index]= len;
                }
            }