msmpeg4.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

                    }
                } else {
                    /* first escape */
                    put_bits(&s->pb, 1, 1);
                    put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
                    put_bits(&s->pb, 1, sign);
                }
            } else {
                put_bits(&s->pb, 1, sign);
            }
	    last_non_zero = i;
	}
    }
}

/****************************************/
/* decoding stuff */

static VLC mb_non_intra_vlc;
static VLC mb_intra_vlc;
static VLC dc_lum_vlc[2];
static VLC dc_chroma_vlc[2];
static VLC v2_dc_lum_vlc;
static VLC v2_dc_chroma_vlc;
static VLC cbpy_vlc;
static VLC v2_intra_cbpc_vlc;
static VLC v2_mb_type_vlc;
static VLC v2_mv_vlc;
static VLC v1_intra_cbpc_vlc;
static VLC v1_inter_cbpc_vlc;
static VLC inter_intra_vlc;

/* this table is practically identical to the one from h263 except that its inverted */
static void init_h263_dc_for_msmpeg4(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 h263 */
            uni_code= DCtab_lum[size][0];
            uni_len = DCtab_lum[size][1];
            uni_code ^= (1<<uni_len)-1; //M$ doesnt like compatibility

            if (size > 0) {
                uni_code<<=size; uni_code|=l;
                uni_len+=size;
                if (size > 8){
                    uni_code<<=1; uni_code|=1;
                    uni_len++;
                }
            }
            v2_dc_lum_table[level+256][0]= uni_code;
            v2_dc_lum_table[level+256][1]= uni_len;

            /* chrominance h263 */
            uni_code= DCtab_chrom[size][0];
            uni_len = DCtab_chrom[size][1];
            uni_code ^= (1<<uni_len)-1; //M$ doesnt like compatibility
            
            if (size > 0) {
                uni_code<<=size; uni_code|=l;
                uni_len+=size;
                if (size > 8){
                    uni_code<<=1; uni_code|=1;
                    uni_len++;
                }
            }
            v2_dc_chroma_table[level+256][0]= uni_code;
            v2_dc_chroma_table[level+256][1]= uni_len;

        }
}

/* init all vlc decoding tables */
int ff_msmpeg4_decode_init(MpegEncContext *s)
{
    static int done = 0;
    int i;
    MVTable *mv;

    common_init(s);

    if (!done) {
        done = 1;

        for(i=0;i<NB_RL_TABLES;i++) {
            init_rl(&rl_table[i]);
            init_vlc_rl(&rl_table[i]);
        }
        for(i=0;i<2;i++) {
            mv = &mv_tables[i];
            init_vlc(&mv->vlc, MV_VLC_BITS, mv->n + 1, 
                     mv->table_mv_bits, 1, 1,
                     mv->table_mv_code, 2, 2);
        }

        init_vlc(&dc_lum_vlc[0], DC_VLC_BITS, 120, 
                 &table0_dc_lum[0][1], 8, 4,
                 &table0_dc_lum[0][0], 8, 4);
        init_vlc(&dc_chroma_vlc[0], DC_VLC_BITS, 120, 
                 &table0_dc_chroma[0][1], 8, 4,
                 &table0_dc_chroma[0][0], 8, 4);
        init_vlc(&dc_lum_vlc[1], DC_VLC_BITS, 120, 
                 &table1_dc_lum[0][1], 8, 4,
                 &table1_dc_lum[0][0], 8, 4);
        init_vlc(&dc_chroma_vlc[1], DC_VLC_BITS, 120, 
                 &table1_dc_chroma[0][1], 8, 4,
                 &table1_dc_chroma[0][0], 8, 4);
    
        init_vlc(&v2_dc_lum_vlc, DC_VLC_BITS, 512, 
                 &v2_dc_lum_table[0][1], 8, 4,
                 &v2_dc_lum_table[0][0], 8, 4);
        init_vlc(&v2_dc_chroma_vlc, DC_VLC_BITS, 512, 
                 &v2_dc_chroma_table[0][1], 8, 4,
                 &v2_dc_chroma_table[0][0], 8, 4);
    
        init_vlc(&cbpy_vlc, CBPY_VLC_BITS, 16,
                 &cbpy_tab[0][1], 2, 1,
                 &cbpy_tab[0][0], 2, 1);
        init_vlc(&v2_intra_cbpc_vlc, V2_INTRA_CBPC_VLC_BITS, 4,
                 &v2_intra_cbpc[0][1], 2, 1,
                 &v2_intra_cbpc[0][0], 2, 1);
        init_vlc(&v2_mb_type_vlc, V2_MB_TYPE_VLC_BITS, 8,
                 &v2_mb_type[0][1], 2, 1,
                 &v2_mb_type[0][0], 2, 1);
        init_vlc(&v2_mv_vlc, V2_MV_VLC_BITS, 33,
                 &mvtab[0][1], 2, 1,
                 &mvtab[0][0], 2, 1);

        init_vlc(&mb_non_intra_vlc, MB_NON_INTRA_VLC_BITS, 128, 
                 &table_mb_non_intra[0][1], 8, 4,
                 &table_mb_non_intra[0][0], 8, 4);
        init_vlc(&mb_intra_vlc, MB_INTRA_VLC_BITS, 64, 
                 &table_mb_intra[0][1], 4, 2,
                 &table_mb_intra[0][0], 4, 2);
        
        init_vlc(&v1_intra_cbpc_vlc, V1_INTRA_CBPC_VLC_BITS, 8, 
                 intra_MCBPC_bits, 1, 1,
                 intra_MCBPC_code, 1, 1);
        init_vlc(&v1_inter_cbpc_vlc, V1_INTER_CBPC_VLC_BITS, 25, 
                 inter_MCBPC_bits, 1, 1,
                 inter_MCBPC_code, 1, 1);
        
        init_vlc(&inter_intra_vlc, INTER_INTRA_VLC_BITS, 4, 
                 &table_inter_intra[0][1], 2, 1,
                 &table_inter_intra[0][0], 2, 1);
    }
    
    switch(s->msmpeg4_version){
    case 1:
    case 2:
        s->decode_mb= msmpeg4v12_decode_mb;
        break;
    case 3:
    case 4:
        s->decode_mb= msmpeg4v34_decode_mb;
        break;
    }
    
    s->slice_height= s->mb_height; //to avoid 1/0 if the first frame isnt a keyframe
    
    return 0;
}

static int decode012(GetBitContext *gb)
{
    int n;
    n = get_bits1(gb);
    if (n == 0)
        return 0;
    else
        return get_bits1(gb) + 1;
}

int msmpeg4_decode_picture_header(MpegEncContext * s)
{
    int code;

#if 0
{
int i;
for(i=0; i<s->gb.size*8; i++)
    printf("%d", get_bits1(&s->gb));
//    get_bits1(&s->gb);
printf("END\n");
return -1;
}
#endif

    if(s->msmpeg4_version==1){
        int start_code, num;
        start_code = (get_bits(&s->gb, 16)<<16) | get_bits(&s->gb, 16);
        if(start_code!=0x00000100){
            fprintf(stderr, "invalid startcode\n");
            return -1;
        }

        num= get_bits(&s->gb, 5); // frame number */
    }

    s->pict_type = get_bits(&s->gb, 2) + 1;
    if (s->pict_type != I_TYPE &&
        s->pict_type != P_TYPE){
        fprintf(stderr, "invalid picture type\n");
        return -1;
    }
#if 0
{
    static int had_i=0;
    if(s->pict_type == I_TYPE) had_i=1;
    if(!had_i) return -1;
}
#endif
    s->qscale = get_bits(&s->gb, 5);

    if (s->pict_type == I_TYPE) {
        code = get_bits(&s->gb, 5); 
        if(s->msmpeg4_version==1){
            if(code==0 || code>s->mb_height){
                fprintf(stderr, "invalid slice height %d\n", code);
                return -1;
            }

            s->slice_height = code;
        }else{
            /* 0x17: one slice, 0x18: two slices, ... */
            if (code < 0x17){
                fprintf(stderr, "error, slice code was %X\n", code);
                return -1;
            }

            s->slice_height = s->mb_height / (code - 0x16);
        }

        switch(s->msmpeg4_version){
        case 1:
        case 2:
            s->rl_chroma_table_index = 2;
            s->rl_table_index = 2;

            s->dc_table_index = 0; //not used
            break;
        case 3:
            s->rl_chroma_table_index = decode012(&s->gb);
            s->rl_table_index = decode012(&s->gb);

            s->dc_table_index = get_bits1(&s->gb);
            break;
        case 4:
            msmpeg4_decode_ext_header(s, (2+5+5+17+7)/8);

            if(s->bit_rate > MBAC_BITRATE) s->per_mb_rl_table= get_bits1(&s->gb);
            else                           s->per_mb_rl_table= 0;
            
            if(!s->per_mb_rl_table){
                s->rl_chroma_table_index = decode012(&s->gb);
                s->rl_table_index = decode012(&s->gb);
            }

            s->dc_table_index = get_bits1(&s->gb);
            s->inter_intra_pred= 0;
            break;
        }
        s->no_rounding = 1;
/*	printf("qscale:%d rlc:%d rl:%d dc:%d mbrl:%d slice:%d   \n", 
		s->qscale,
		s->rl_chroma_table_index,
		s->rl_table_index, 
		s->dc_table_index,
                s->per_mb_rl_table,
                s->slice_height);*/
    } else {
        switch(s->msmpeg4_version){
        case 1:
        case 2:
            if(s->msmpeg4_version==1)
                s->use_skip_mb_code = 1;
            else
                s->use_skip_mb_code = get_bits1(&s->gb);
            s->rl_table_index = 2;
            s->rl_chroma_table_index = s->rl_table_index;
            s->dc_table_index = 0; //not used
            s->mv_table_index = 0;
            break;
        case 3:
            s->use_skip_mb_code = get_bits1(&s->gb);
            s->rl_table_index = decode012(&s->gb);
            s->rl_chroma_table_index = s->rl_table_index;

            s->dc_table_index = get_bits1(&s->gb);

            s->mv_table_index = get_bits1(&s->gb);
            break;
        case 4:
            s->use_skip_mb_code = get_bits1(&s->gb);

            if(s->bit_rate > MBAC_BITRATE) s->per_mb_rl_table= get_bits1(&s->gb);
            else                           s->per_mb_rl_table= 0;

            if(!s->per_mb_rl_table){
                s->rl_table_index = decode012(&s->gb);
                s->rl_chroma_table_index = s->rl_table_index;
            }

            s->dc_table_index = get_bits1(&s->gb);

            s->mv_table_index = get_bits1(&s->gb);
            s->inter_intra_pred= (s->width*s->height < 320*240 && s->bit_rate<=II_BITRATE);
            break;
        }
/*	printf("skip:%d rl:%d rlc:%d dc:%d mv:%d mbrl:%d qp:%d   \n", 
		s->use_skip_mb_code, 
		s->rl_table_index, 
		s->rl_chroma_table_index, 
		s->dc_table_index,
		s->mv_table_index,
                s->per_mb_rl_table,
                s->qscale);*/
	if(s->flipflop_rounding){
	    s->no_rounding ^= 1;
	}else{
	    s->no_rounding = 0;
	}
    }

    s->esc3_level_length= 0;
    s->esc3_run_length= 0;

#ifdef DEBUG
    printf("*****frame %d:\n", frame_count++);
#endif
    return 0;
}

int msmpeg4_decode_ext_header(MpegEncContext * s, int buf_size)
{
    int left= buf_size*8 - get_bits_count(&s->gb);
    int length= s->msmpeg4_version>=3 ? 17 : 16;
    /* the alt_bitstream reader could read over the end so we need to check it */
    if(left>=length && left<length+8)
    {
        int fps;

        fps= get_bits(&s->gb, 5);
        s->bit_rate= get_bits(&s->gb, 11)*1024;
        if(s->msmpeg4_version>=3)
            s->flipflop_rounding= get_bits1(&s->gb);
        else
            s->flipflop_rounding= 0;

//        printf("fps:%2d bps:%2d roundingType:%1d\n", fps, s->bit_rate/1024, s->flipflop_rounding);
    }
    else if(left<length+8)
    {
        s->flipflop_rounding= 0;
        printf("ext header missing, %d left\n", left);
    }
    else
    {
        fprintf(stderr, "I frame too long, ignoring ext header\n");
    }

    return 0;
}

static inline void msmpeg4_memsetw(short *tab, int val, int n)
{
    int i;
    for(i=0;i<n;i++)
        tab[i] = val;
}

static void msmpeg4v2_encode_motion(MpegEncContext * s, int val)
{
    int range, 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 = s->f_code - 1;
        range = 1 << bit_size;
        if (val <= -64)
            val += 64;
        else if (val >= 64)
            val -= 64;

        if (val >= 0) {
            sign = 0;
        } else {
            val = -val;
            sign = 1;
        }
        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);
        }
    }
}

/* this is identical to h263 except that its range is multiplied by 2 */
static int msmpeg4v2_decode_motion(MpegEncContext * s, int pred, int f_code)
{
    int code, val, sign, shift;

    code = get_vlc2(&s->gb, v2_mv_vlc.table, V2_MV_VLC_BITS, 2);
//     printf("MV code %d at %d %d pred: %d\n", code, s->mb_x,s->mb_y, pred);
    if (code < 0)
        return 0xffff;

    if (code == 0)
        return pred;
    sign = get_bits1(&s->gb);
    shift = f_code - 1;
    val = (code - 1) << shift;
    if (shift > 0)
        val |= get_bits(&s->gb, shift);
    val++;
    if (sign)
        val = -val;

    val += pred;
    if (val <= -64)
        val += 64;
    else if (val >= 64)
        val -= 64;

    return val;
}

static int msmpeg4v12_decode_mb(MpegEncContext *s, DCTELEM block[6][64])
{
    int cbp, code, i;
    
    s->error_status_table[s->mb_x + s->mb_y*s->mb_width]= 0;
    
    if (s->pict_type == P_TYPE) {
        if (s->use_skip_mb_code) {
            if (get_bits1(&s->gb)) {
                /* skip mb */
                s->mb_intra = 0;
                for(i=0;i<6;i++)
                    s->block_last_index[i] = -1;
                s->mv_dir = MV_DIR_FORWARD;
                s->mv_type = MV_TYPE_16X16;
                s->mv[0][0][0] = 0;
                s->mv[0][0][1] = 0;
                s->mb_skiped = 1;
                return 0;
            }
        }

        if(s->msmpeg4_version==2)
            code = get_vlc2(&s->gb, v2_mb_type_vlc.table, V2_MB_TYPE_VLC_BITS, 1);
        else
            code = get_vlc2(&s->gb, v1_inter_cbpc_vlc.table, V1_INTER_CBPC_VLC_BITS, 3);
        if(code<0 || code>7){
            fprintf(stderr, "cbpc %d invalid at %d %d\n", code, s->mb_x, s->mb_y);
            return -1;
        }

        s->mb_intra = code >>2;
    
        cbp = code & 0x3;
    } else {
        s->mb_intra = 1;
        if(s->msmpeg4_version==2)
            cbp= get_vlc2(&s->gb, v2_intra_cbpc_vlc.table, V2_INTRA_CBPC_VLC_BITS, 1);
        else
            cbp= get_vlc2(&s->gb, v1_intra_cbpc_vlc.table, V1_INTRA_CBPC_VLC_BITS, 1);
        if(cbp<0 || cbp>3){
            fprintf(stderr, "cbpc %d invalid at %d %d\n", cbp, s->mb_x, s->mb_y);
            return -1;
        }
    }

    if (!s->mb_intra) {
        int mx, my, cbpy;
        
        cbpy= get_vlc2(&s->gb, cbpy_vlc.table, CBPY_VLC_BITS, 1);