mjpeg.c

        nb_components > MAX_COMPONENTS)
        return -1;
    s->nb_components = nb_components;
    s->h_max = 1;
    s->v_max = 1;
    for(i=0;i<nb_components;i++) {
        /* component id */
        s->component_id[i] = get_bits(&s->gb, 8) - 1;
        s->h_count[i] = get_bits(&s->gb, 4);
        s->v_count[i] = get_bits(&s->gb, 4);
        /* compute hmax and vmax (only used in interleaved case) */
        if (s->h_count[i] > s->h_max)
            s->h_max = s->h_count[i];
        if (s->v_count[i] > s->v_max)
            s->v_max = s->v_count[i];
        s->quant_index[i] = get_bits(&s->gb, 8);
        if (s->quant_index[i] >= 4)
            return -1;
        dprintf("component %d %d:%d id: %d quant:%d\n", i, s->h_count[i],
	    s->v_count[i], s->component_id[i], s->quant_index[i]);
    }
    
    if(s->v_max==1 && s->h_max==1 && s->lossless==1) s->rgb=1;

    /* if different size, realloc/alloc picture */
    /* XXX: also check h_count and v_count */
    if (width != s->width || height != s->height) {
        for(i=0;i<MAX_COMPONENTS;i++)
            av_freep(&s->current_picture[i]);
        s->width = width;
        s->height = height;
        /* test interlaced mode */
        if (s->first_picture &&
            s->org_height != 0 &&
            s->height < ((s->org_height * 3) / 4)) {
            s->interlaced = 1;
//	    s->bottom_field = (s->interlace_polarity) ? 1 : 0;
	    s->bottom_field = 0;
        }

        if(s->rgb){
            int w, h;
            w = s->width;
            h = s->height;
            if (s->interlaced)
                w *= 2;
            s->linesize[0] = 4*w;
            s->current_picture[0] = av_mallocz(4*w * h);
            s->current_picture[1] = s->current_picture[2] = NULL;
        }else{
          for(i=0;i<nb_components;i++) {
            int w, h;
            w = (s->width  + 8 * s->h_max - 1) / (8 * s->h_max);
            h = (s->height + 8 * s->v_max - 1) / (8 * s->v_max);
            w = w * 8 * s->h_count[i];
            h = h * 8 * s->v_count[i];
            if (s->interlaced)
                w *= 2;
            s->linesize[i] = w;
            s->current_picture[i] = av_mallocz(w * h);
	    if (!s->current_picture[i])
	    {
		dprintf("error: no picture buffers allocated\n");
		return -1;
	    }
          }
        }
        s->first_picture = 0;
    }

    if (len != (8+(3*nb_components)))
    {
	dprintf("decode_sof0: error, len(%d) mismatch\n", len);
    }
    
    return 0;
}

static inline int mjpeg_decode_dc(MJpegDecodeContext *s, int dc_index)
{
    int code;
    code = get_vlc2(&s->gb, s->vlcs[0][dc_index].table, 9, 2);
    if (code < 0)
    {
	dprintf("mjpeg_decode_dc: bad vlc: %d:%d (%p)\n", 0, dc_index,
                &s->vlcs[0][dc_index]);
        return 0xffff;
    }

    if(code)
        return get_xbits(&s->gb, code);
    else
        return 0;
}

/* decode block and dequantize */
static int decode_block(MJpegDecodeContext *s, DCTELEM *block, 
                        int component, int dc_index, int ac_index, int quant_index)
{
    int code, i, j, level, val;
    VLC *ac_vlc;
    int16_t *quant_matrix;

    /* DC coef */
    val = mjpeg_decode_dc(s, dc_index);
    if (val == 0xffff) {
        dprintf("error dc\n");
        return -1;
    }
    quant_matrix = s->quant_matrixes[quant_index];
    val = val * quant_matrix[0] + s->last_dc[component];
    s->last_dc[component] = val;
    block[0] = val;
    /* AC coefs */
    ac_vlc = &s->vlcs[1][ac_index];
    i = 1;
    for(;;) {
	code = get_vlc2(&s->gb, s->vlcs[1][ac_index].table, 9, 2);

        if (code < 0) {
            dprintf("error ac\n");
            return -1;
        }
        /* EOB */
        if (code == 0)
            break;
        if (code == 0xf0) {
            i += 16;
        } else {
            level = get_xbits(&s->gb, code & 0xf);
            i += code >> 4;
            if (i >= 64) {
                dprintf("error count: %d\n", i);
                return -1;
            }
            j = s->scantable.permutated[i];
            block[j] = level * quant_matrix[j];
            i++;
            if (i >= 64)
                break;
        }
    }
    return 0;
}

static int mjpeg_decode_sos(MJpegDecodeContext *s)
{
    int len, nb_components, i, j, n, h, v, ret, point_transform, predictor;
    int mb_width, mb_height, mb_x, mb_y, vmax, hmax, index, id;
    int comp_index[4];
    int dc_index[4];
    int ac_index[4];
    int nb_blocks[4];
    int h_count[4];
    int v_count[4];
    const int block_size= s->lossless ? 1 : 8;

    /* XXX: verify len field validity */
    len = get_bits(&s->gb, 16);
    nb_components = get_bits(&s->gb, 8);
    if (len != 6+2*nb_components)
    {
	dprintf("decode_sos: invalid len (%d)\n", len);
	return -1;
    }
    /* XXX: only interleaved scan accepted */
    if (nb_components != 3)
    {
	dprintf("decode_sos: components(%d) mismatch\n", nb_components);
        return -1;
    }
    vmax = 0;
    hmax = 0;
    for(i=0;i<nb_components;i++) {
        id = get_bits(&s->gb, 8) - 1;
	dprintf("component: %d\n", id);
        /* find component index */
        for(index=0;index<s->nb_components;index++)
            if (id == s->component_id[index])
                break;
        if (index == s->nb_components)
	{
	    dprintf("decode_sos: index(%d) out of components\n", index);
            return -1;
	}

        comp_index[i] = index;

        nb_blocks[i] = s->h_count[index] * s->v_count[index];
        h_count[i] = s->h_count[index];
        v_count[i] = s->v_count[index];

        dc_index[i] = get_bits(&s->gb, 4);
        ac_index[i] = get_bits(&s->gb, 4);

	if (dc_index[i] < 0 || ac_index[i] < 0 ||
	    dc_index[i] >= 4 || ac_index[i] >= 4)
	    goto out_of_range;
	switch(s->start_code)
	{
	    case SOF0:
		if (dc_index[i] > 1 || ac_index[i] > 1)
		    goto out_of_range;
		break;
	    case SOF1:
	    case SOF2:
		if (dc_index[i] > 3 || ac_index[i] > 3)
		    goto out_of_range;
		break;
	    case SOF3:
		if (dc_index[i] > 3 || ac_index[i] != 0)
		    goto out_of_range;
		break;	
	}
    }

    predictor= get_bits(&s->gb, 8); /* lossless predictor or start of spectral (Ss) */
    skip_bits(&s->gb, 8); /* Se */
    skip_bits(&s->gb, 4); /* Ah */
    point_transform= get_bits(&s->gb, 4); /* Al */

    for(i=0;i<nb_components;i++) 
        s->last_dc[i] = 1024;

    if (nb_components > 1) {
        /* interleaved stream */
        mb_width  = (s->width  + s->h_max * block_size - 1) / (s->h_max * block_size);
        mb_height = (s->height + s->v_max * block_size - 1) / (s->v_max * block_size);
    } else {
        h = s->h_max / s->h_count[comp_index[0]];
        v = s->v_max / s->v_count[comp_index[0]];
        mb_width  = (s->width  + h * block_size - 1) / (h * block_size);
        mb_height = (s->height + v * block_size - 1) / (v * block_size);
        nb_blocks[0] = 1;
        h_count[0] = 1;
        v_count[0] = 1;
    }

    if(s->avctx->debug & FF_DEBUG_PICT_INFO)
        printf("%s %s p:%d >>:%d\n", s->lossless ? "lossless" : "sequencial DCT", s->rgb ? "RGB" : "", predictor, point_transform);
    
    if(s->lossless){
        if(s->rgb){
            uint16_t buffer[2048][4];
            int left[3], top[3], topleft[3];
            const int linesize= s->linesize[0];
            const int mask= (1<<s->bits)-1;
            
            for(i=0; i<3; i++){
                buffer[0][i]= 1 << (s->bits + point_transform - 1);
            }
            for(mb_y = 0; mb_y < mb_height; mb_y++) {
                const int modified_predictor= mb_y ? 1 : predictor;
                uint8_t *ptr = s->current_picture[0] + (linesize * mb_y);

                if (s->interlaced && s->bottom_field)
                    ptr += linesize >> 1;

                for(i=0; i<3; i++){
                    top[i]= left[i]= topleft[i]= buffer[0][i];
                }
                for(mb_x = 0; mb_x < mb_width; mb_x++) {
                    if (s->restart_interval && !s->restart_count)
                        s->restart_count = s->restart_interval;

                    for(i=0;i<3;i++) {
                        int pred;

                        topleft[i]= top[i];
                        top[i]= buffer[mb_x][i];

                        PREDICT(pred, topleft[i], top[i], left[i], modified_predictor);
                        
                        left[i]= 
                        buffer[mb_x][i]= mask & (pred + (mjpeg_decode_dc(s, dc_index[i]) << point_transform));
                    }

                    if (s->restart_interval && !--s->restart_count) {
                        align_get_bits(&s->gb);
                        skip_bits(&s->gb, 16); /* skip RSTn */
                    }
                }

                if(s->rct){
                    for(mb_x = 0; mb_x < mb_width; mb_x++) {
                        ptr[4*mb_x+1] = buffer[mb_x][0] - ((buffer[mb_x][1] + buffer[mb_x][2] - 0x200)>>2);
                        ptr[4*mb_x+0] = buffer[mb_x][1] + ptr[4*mb_x+1];
                        ptr[4*mb_x+2] = buffer[mb_x][2] + ptr[4*mb_x+1];
                    }
                }else if(s->pegasus_rct){
                    for(mb_x = 0; mb_x < mb_width; mb_x++) {
                        ptr[4*mb_x+1] = buffer[mb_x][0] - ((buffer[mb_x][1] + buffer[mb_x][2])>>2);
                        ptr[4*mb_x+0] = buffer[mb_x][1] + ptr[4*mb_x+1];
                        ptr[4*mb_x+2] = buffer[mb_x][2] + ptr[4*mb_x+1];
                    }
                }else{
                    for(mb_x = 0; mb_x < mb_width; mb_x++) {
                        ptr[4*mb_x+0] = buffer[mb_x][0];
                        ptr[4*mb_x+1] = buffer[mb_x][1];
                        ptr[4*mb_x+2] = buffer[mb_x][2];
                    }
                }
            }
        }else{
            for(mb_y = 0; mb_y < mb_height; mb_y++) {
                for(mb_x = 0; mb_x < mb_width; mb_x++) {
                    if (s->restart_interval && !s->restart_count)
                        s->restart_count = s->restart_interval;

                    if(mb_x==0 || mb_y==0 || s->interlaced){
                        for(i=0;i<nb_components;i++) {
                            uint8_t *ptr;
                            int x, y, c, linesize;
                            n = nb_blocks[i];
                            c = comp_index[i];
                            h = h_count[i];
                            v = v_count[i];
                            x = 0;
                            y = 0;
                            linesize= s->linesize[c];
                            
                            for(j=0; j<n; j++) {
                                int pred;

                                ptr = s->current_picture[c] + (linesize * (v * mb_y + y)) + (h * mb_x + x); //FIXME optimize this crap
                                if(y==0 && mb_y==0){
                                    if(x==0 && mb_x==0){
                                        pred= 128 << point_transform;
                                    }else{
                                        pred= ptr[-1];
                                    }
                                }else{
                                    if(x==0 && mb_x==0){
                                        pred= ptr[-linesize];
                                    }else{
                                        PREDICT(pred, ptr[-linesize-1], ptr[-linesize], ptr[-1], predictor);
                                    }
                                }
                                
                                if (s->interlaced && s->bottom_field)
                                    ptr += linesize >> 1;
                                *ptr= pred + (mjpeg_decode_dc(s, dc_index[i]) << point_transform);

                                if (++x == h) {
                                    x = 0;
                                    y++;
                                }
                            }
                        }
                    }else{
                        for(i=0;i<nb_components;i++) {
                            uint8_t *ptr;
                            int x, y, c, linesize;
                            n = nb_blocks[i];
                            c = comp_index[i];
                            h = h_count[i];
                            v = v_count[i];
                            x = 0;
                            y = 0;
                            linesize= s->linesize[c];
                            
                            for(j=0; j<n; j++) {
                                int pred;

                                ptr = s->current_picture[c] + (linesize * (v * mb_y + y)) + (h * mb_x + x); //FIXME optimize this crap
                                PREDICT(pred, ptr[-linesize-1], ptr[-linesize], ptr[-1], predictor);
                                *ptr= pred + (mjpeg_decode_dc(s, dc_index[i]) << point_transform);
                                if (++x == h) {
                                    x = 0;
                                    y++;
                                }
                            }
                        }
                    }
                    if (s->restart_interval && !--s->restart_count) {
                        align_get_bits(&s->gb);
                        skip_bits(&s->gb, 16); /* skip RSTn */
                    }
                }
            }
        }
    }else{
      for(mb_y = 0; mb_y < mb_height; mb_y++) {
        for(mb_x = 0; mb_x < mb_width; mb_x++) {
            if (s->restart_interval && !s->restart_count)
                s->restart_count = s->restart_interval;

            for(i=0;i<nb_components;i++) {
                uint8_t *ptr;
                int x, y, c;
                n = nb_blocks[i];
                c = comp_index[i];
                h = h_count[i];
                v = v_count[i];
                x = 0;
                y = 0;
                for(j=0;j<n;j++) {
                    memset(s->block, 0, sizeof(s->block));
                    if (decode_block(s, s->block, i, 
                                     dc_index[i], ac_index[i], 
                                     s->quant_index[c]) < 0) {
                        dprintf("error y=%d x=%d\n", mb_y, mb_x);
                        ret = -1;
                        goto the_end;
                    }
//		    dprintf("mb: %d %d processed\n", mb_y, mb_x);
                    ptr = s->current_picture[c] + 
                        (s->linesize[c] * (v * mb_y + y) * 8) + 
                        (h * mb_x + x) * 8;
                    if (s->interlaced && s->bottom_field)
                        ptr += s->linesize[c] >> 1;
                    s->idct_put(ptr, s->linesize[c], s->block);
                    if (++x == h) {
                        x = 0;
                        y++;
                    }
                }
            }
	    /* (< 1350) buggy workaround for Spectralfan.mov, should be fixed */
            if (s->restart_interval && (s->restart_interval < 1350) &&
		!--s->restart_count) {
                align_get_bits(&s->gb);
                skip_bits(&s->gb, 16); /* skip RSTn */
                for (j=0; j<nb_components; j++) /* reset dc */
                    s->last_dc[j] = 1024;
            }
        }
    }
  }
    ret = 0;
 the_end:
    emms_c();
    return ret;
 out_of_range:
    dprintf("decode_sos: ac/dc index out of range\n");
    return -1;
}

static int mjpeg_decode_dri(MJpegDecodeContext *s)
{
    if (get_bits(&s->gb, 16) != 4)
	return -1;
    s->restart_interval = get_bits(&s->gb, 16);
    dprintf("restart interval: %d\n", s->restart_interval);

    return 0;
}

static int mjpeg_decode_app(MJpegDecodeContext *s)
{
    int len, id;

    /* XXX: verify len field validity */
    len = get_bits(&s->gb, 16);
    if (len < 5)
	return -1;

    id = (get_bits(&s->gb, 16) << 16) | get_bits(&s->gb, 16);
    id = be2me_32(id);
    len -= 6;

    if(s->avctx->debug & FF_DEBUG_STARTCODE){
        printf("APPx %8X\n", id); 
    }
    
    /* buggy AVID, it puts EOI only at every 10th frame */
    /* also this fourcc is used by non-avid files too, it holds some
       informations, but it's always present in AVID creates files */
    if (id == ff_get_fourcc("AVI1"))
    {
	/* structure:
	    4bytes	AVI1
	    1bytes	polarity
	    1bytes	always zero
	    4bytes	field_size
	    4bytes	field_size_less_padding
	*/
    	s->buggy_avid = 1;
//	if (s->first_picture)
//	    printf("mjpeg: workarounding buggy AVID\n");
	s->interlace_polarity = get_bits(&s->gb, 8);
#if 0
	skip_bits(&s->gb, 8);
	skip_bits(&s->gb, 32);
	skip_bits(&s->gb, 32);
	len -= 10;
#endif
//	if (s->interlace_polarity)
//	    printf("mjpeg: interlace polarity: %d\n", s->interlace_polarity);
	goto out;
    }
    
//    len -= 2;
    
    if (id == ff_get_fourcc("JFIF"))
    {
	int t_w, t_h;
	skip_bits(&s->gb, 8); /* the trailing zero-byte */
	printf("mjpeg: JFIF header found (version: %x.%x)\n",
	    get_bits(&s->gb, 8), get_bits(&s->gb, 8));
	if (get_bits(&s->gb, 8) == 0)
	{
	    int x_density, y_density; 
	    x_density = get_bits(&s->gb, 16);
	    y_density = get_bits(&s->gb, 16);

	    dprintf("x/y density: %d (%f), %d (%f)\n", x_density,
		(float)x_density, y_density, (float)y_density);
#if 0
            //MN: needs to be checked
            if(x_density)
//                s->avctx->aspect_ratio= s->width*y_density/((float)s->height*x_density);
		s->avctx->aspect_ratio = (float)x_density/y_density;
		/* it's better, but every JFIF I have seen stores 1:1 */
            else
                s->avctx->aspect_ratio= 0.0;
#endif
	}
	else
	{
	    skip_bits(&s->gb, 16);
	    skip_bits(&s->gb, 16);
	}

	t_w = get_bits(&s->gb, 8);
	t_h = get_bits(&s->gb, 8);
	if (t_w && t_h)
	{
	    /* skip thumbnail */
	    if (len-10-(t_w*t_h*3) > 0)
		len -= t_w*t_h*3;
	}
	len -= 10;
	goto out;
    }
    
    if (id == ff_get_fourcc("Adob") && (get_bits(&s->gb, 8) == 'e'))
    {
	printf("mjpeg: Adobe header found\n");
	skip_bits(&s->gb, 16); /* version */
	skip_bits(&s->gb, 16); /* flags0 */
	skip_bits(&s->gb, 16); /* flags1 */
	skip_bits(&s->gb, 8); /* transform */
	len -= 7;
	goto out;
    }

    if (id == ff_get_fourcc("LJIF")){
        printf("Pegasus lossless jpeg header found\n");
	skip_bits(&s->gb, 16); /* version ? */
	skip_bits(&s->gb, 16); /* unknwon always 0? */
	skip_bits(&s->gb, 16); /* unknwon always 0? */
	skip_bits(&s->gb, 16); /* unknwon always 0? */
        switch( get_bits(&s->gb, 8)){
        case 1:
            s->rgb= 1;
            s->pegasus_rct=0;
            break;
        case 2:
            s->rgb= 1;
            s->pegasus_rct=1;
            break;
        default:
            printf("unknown colorspace\n");
        }
        len -= 9;
        goto out;
    }
    
    /* Apple MJPEG-A */
    if ((s->start_code == APP1) && (len > (0x28 - 8)))
    {
	id = (get_bits(&s->gb, 16) << 16) | get_bits(&s->gb, 16);
	id = be2me_32(id);
	len -= 4;
	if (id == ff_get_fourcc("mjpg")) /* Apple MJPEG-A */
	{
#if 0
	    skip_bits(&s->gb, 32); /* field size */
	    skip_bits(&s->gb, 32); /* pad field size */
	    skip_bits(&s->gb, 32); /* next off */
	    skip_bits(&s->gb, 32); /* quant off */
	    skip_bits(&s->gb, 32); /* huff off */
	    skip_bits(&s->gb, 32); /* image off */
	    skip_bits(&s->gb, 32); /* scan off */
	    skip_bits(&s->gb, 32); /* data off */
#endif
	    if (s->first_picture)
		printf("mjpeg: Apple MJPEG-A header found\n");
	}
    }

out:
    /* slow but needed for extreme adobe jpegs */
    if (len < 0)
	printf("mjpeg: error, decode_app parser read over the end\n");
    while(--len > 0)
	skip_bits(&s->gb, 8);

    return 0;
}

static int mjpeg_decode_com(MJpegDecodeContext *s)
{
    /* XXX: verify len field validity */
    int len = get_bits(&s->gb, 16);
    if (len >= 2 && len < 32768) {
	/* XXX: any better upper bound */
	uint8_t *cbuf = av_malloc(len - 1);
	if (cbuf) {
	    int i;
	    for (i = 0; i < len - 2; i++)
		cbuf[i] = get_bits(&s->gb, 8);
	    if (i > 0 && cbuf[i-1] == '\n')
		cbuf[i-1] = 0;
	    else
		cbuf[i] = 0;

	    printf("mjpeg comment: '%s'\n", cbuf);

	    /* buggy avid, it puts EOI only at every 10th frame */
	    if (!strcmp(cbuf, "AVID"))
	    {
		s->buggy_avid = 1;
		//	if (s->first_picture)
		//	    printf("mjpeg: workarounding buggy AVID\n");
	    }

	    av_free(cbuf);
	}
    }

    return 0;
}

#if 0
static int valid_marker_list[] =
{
        /* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f */
/* 0 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 1 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 2 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 3 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 4 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 5 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 6 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 7 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 8 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* 9 */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* a */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* b */    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
/* c */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* d */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* e */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* f */    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
}
#endif

/* return the 8 bit start code value and update the search
   state. Return -1 if no start code found */
static int find_marker(uint8_t **pbuf_ptr, uint8_t *buf_end)
{
    uint8_t *buf_ptr;
    unsigned int v, v2;
    int val;
#ifdef DEBUG
    int skipped=0;
#endif

    buf_ptr = *pbuf_ptr;
    while (buf_ptr < buf_end) {
        v = *buf_ptr++;
	v2 = *buf_ptr;
        if ((v == 0xff) && (v2 >= 0xc0) && (v2 <= 0xfe)) {
	    val = *buf_ptr++;
	    goto found;
        }
#ifdef DEBUG
	skipped++;
#endif
    }
    val = -1;
found:
#ifdef DEBUG
    dprintf("find_marker skipped %d bytes\n", skipped);
#endif
    *pbuf_ptr = buf_ptr;
    return val;
}

static int mjpeg_decode_frame(AVCodecContext *avctx, 
                              void *data, int *data_size,
                              uint8_t *buf, int buf_size)
{
    MJpegDecodeContext *s = avctx->priv_data;
    uint8_t *buf_end, *buf_ptr;
    int i, start_code;
    AVPicture *picture = data;

    *data_size = 0;

    /* no supplementary picture */
    if (buf_size == 0)
        return 0;

    buf_ptr = buf;
    buf_end = buf + buf_size;
    while (buf_ptr < buf_end) {
        /* find start next marker */
        start_code = find_marker(&buf_ptr, buf_end);
	{
	    /* EOF */
            if (start_code < 0) {
		goto the_end;
            } else {
                dprintf("marker=%x avail_size_in_buf=%d\n", start_code, buf_end - buf_ptr);
		
		if ((buf_end - buf_ptr) > s->buffer_size)
		{
		    av_free(s->buffer);
		    s->buffer_size = buf_end-buf_ptr;
		    s->buffer = av_malloc(s->buffer_size);
		    dprintf("buffer too small, expanding to %d bytes\n",
			s->buffer_size);
		}
		
		/* unescape buffer of SOS */
		if (start_code == SOS)
		{
		    uint8_t *src = buf_ptr;
		    uint8_t *dst = s->buffer;

		    while (src<buf_end)
		    {
			uint8_t x = *(src++);

			*(dst++) = x;
			if (x == 0xff)
			{
			    while(*src == 0xff) src++;

			    x = *(src++);
			    if (x >= 0xd0 && x <= 0xd7)
				*(dst++) = x;
			    else if (x)
				break;
			}
		    }
		    init_get_bits(&s->gb, s->buffer, (dst - s->buffer)*8);
		    
		    dprintf("escaping removed %d bytes\n",
			(buf_end - buf_ptr) - (dst - s->buffer));
		}
		else
		    init_get_bits(&s->gb, buf_ptr, (buf_end - buf_ptr)*8);
		
		s->start_code = start_code;
                if(s->avctx->debug & FF_DEBUG_STARTCODE){
                    printf("startcode: %X\n", start_code);
                }

		/* process markers */
		if (start_code >= 0xd0 && start_code <= 0xd7) {
		    dprintf("restart marker: %d\n", start_code&0x0f);
		} else if (s->first_picture) {
		    /* APP fields */
		    if (start_code >= 0xe0 && start_code <= 0xef)
			mjpeg_decode_app(s);
		    /* Comment */
		    else if (start_code == COM)
			mjpeg_decode_com(s);
		}

                switch(start_code) {
                case SOI:
		    s->restart_interval = 0;
                    /* nothing to do on SOI */
                    break;
                case DQT:
                    mjpeg_decode_dqt(s);
                    break;
                case DHT:
                    if(mjpeg_decode_dht(s) < 0){
                        fprintf(stderr, "huffman table decode error\n");
                        return -1;
                    }
                    break;
                case SOF0:
                    s->lossless=0;
                    if (mjpeg_decode_sof(s) < 0) 
			return -1;
                    break;
                case SOF3:
                    s->lossless=1;
                    if (mjpeg_decode_sof(s) < 0) 
			return -1;
                    break;
		case EOI:
eoi_parser:
		    {
                        if (s->interlaced) {
                            s->bottom_field ^= 1;
                            /* if not bottom field, do not output image yet */
                            if (s->bottom_field)
                                goto not_the_end;
                        }
                        for(i=0;i<3;i++) {
                            picture->data[i] = s->current_picture[i];
			    picture->linesize[i] = (s->interlaced) ?
				s->linesize[i] >> 1 : s->linesize[i];
                        }
                        *data_size = sizeof(AVPicture);
                        avctx->height = s->height;
                        if (s->interlaced)
                            avctx->height *= 2;
                        avctx->width = s->width;
                        /* XXX: not complete test ! */
                        switch((s->h_count[0] << 4) | s->v_count[0]) {
                        case 0x11:
                            if(s->rgb){
                                avctx->pix_fmt = PIX_FMT_RGBA32;
                            }else
                                avctx->pix_fmt = PIX_FMT_YUV444P;
                            break;
                        case 0x21:
                            avctx->pix_fmt = PIX_FMT_YUV422P;
                            break;
                        default:
                        case 0x22:
                            avctx->pix_fmt = PIX_FMT_YUV420P;
                            break;
                        }
                        /* dummy quality */
                        /* XXX: infer it with matrix */
//                    	avctx->quality = 3; 
                        goto the_end;
                    }
		    break;
                case SOS:
                    mjpeg_decode_sos(s);
		    /* buggy avid puts EOI every 10-20th frame */
		    /* if restart period is over process EOI */
		    if ((s->buggy_avid && !s->interlaced) || s->restart_interval)
			goto eoi_parser;
                    break;
		case DRI:
		    mjpeg_decode_dri(s);
		    break;
		case SOF1:
		case SOF2:
		case SOF5:
		case SOF6:
		case SOF7:
		case SOF9:
		case SOF10:
		case SOF11:
		case SOF13:
		case SOF14:
		case SOF15:
		case JPG:
		    printf("mjpeg: unsupported coding type (%x)\n", start_code);
		    break;
//		default:
//		    printf("mjpeg: unsupported marker (%x)\n", start_code);
//		    break;
                }

not_the_end:
		/* eof process start code */
		buf_ptr += (get_bits_count(&s->gb)+7)/8;
		dprintf("marker parser used %d bytes (%d bits)\n",
		    (get_bits_count(&s->gb)+7)/8, get_bits_count(&s->gb));
            }
        }
    }
the_end:
    dprintf("mjpeg decode frame unused %d bytes\n", buf_end - buf_ptr);
//    return buf_end - buf_ptr;
    return buf_ptr - buf;
}

static int mjpegb_decode_frame(AVCodecContext *avctx, 
                              void *data, int *data_size,
                              uint8_t *buf, int buf_size)
{
    MJpegDecodeContext *s = avctx->priv_data;
    uint8_t *buf_end, *buf_ptr;
    int i;
    AVPicture *picture = data;
    GetBitContext hgb; /* for the header */
    uint32_t dqt_offs, dht_offs, sof_offs, sos_offs, second_field_offs;
    uint32_t field_size;

    *data_size = 0;

    /* no supplementary picture */
    if (buf_size == 0)
        return 0;

    buf_ptr = buf;
    buf_end = buf + buf_size;
    
read_header:
    /* reset on every SOI */
    s->restart_interval = 0;

    init_get_bits(&hgb, buf_ptr, /*buf_size*/(buf_end - buf_ptr)*8);

    skip_bits(&hgb, 32); /* reserved zeros */
    
    if (get_bits(&hgb, 32) != be2me_32(ff_get_fourcc("mjpg")))
    {
	dprintf("not mjpeg-b (bad fourcc)\n");
	return 0;
    }

    field_size = get_bits(&hgb, 32); /* field size */
    dprintf("field size: 0x%x\n", field_size);
    skip_bits(&hgb, 32); /* padded field size */
    second_field_offs = get_bits(&hgb, 32);
    dprintf("second field offs: 0x%x\n", second_field_offs);
    if (second_field_offs)
	s->interlaced = 1;

    dqt_offs = get_bits(&hgb, 32);
    dprintf("dqt offs: 0x%x\n", dqt_offs);
    if (dqt_offs)
    {
	init_get_bits(&s->gb, buf+dqt_offs, (buf_end - (buf+dqt_offs))*8);
	s->start_code = DQT;
	mjpeg_decode_dqt(s);
    }
    
    dht_offs = get_bits(&hgb, 32);
    dprintf("dht offs: 0x%x\n", dht_offs);
    if (dht_offs)
    {
	init_get_bits(&s->gb, buf+dht_offs, (buf_end - (buf+dht_offs))*8);
	s->start_code = DHT;
	mjpeg_decode_dht(s);
    }

    sof_offs = get_bits(&hgb, 32);
    dprintf("sof offs: 0x%x\n", sof_offs);
    if (sof_offs)
    {
	init_get_bits(&s->gb, buf+sof_offs, (buf_end - (buf+sof_offs))*8);
	s->start_code = SOF0;
	if (mjpeg_decode_sof(s) < 0)
	    return -1;
    }

    sos_offs = get_bits(&hgb, 32);
    dprintf("sos offs: 0x%x\n", sos_offs);
    if (sos_offs)
    {
//	init_get_bits(&s->gb, buf+sos_offs, (buf_end - (buf+sos_offs))*8);
	init_get_bits(&s->gb, buf+sos_offs, field_size*8);
	s->start_code = SOS;
	mjpeg_decode_sos(s);
    }

    skip_bits(&hgb, 32); /* start of data offset */

    if (s->interlaced) {
        s->bottom_field ^= 1;
        /* if not bottom field, do not output image yet */
        if (s->bottom_field && second_field_offs)
	{
	    buf_ptr = buf + second_field_offs;
	    second_field_offs = 0;
	    goto read_header;
    	}
    }

    for(i=0;i<3;i++) {
        picture->data[i] = s->current_picture[i];
        picture->linesize[i] = (s->interlaced) ?
    	    s->linesize[i] >> 1 : s->linesize[i];
    }
    *data_size = sizeof(AVPicture);
    avctx->height = s->height;
    if (s->interlaced)
        avctx->height *= 2;
    avctx->width = s->width;
    /* XXX: not complete test ! */
    switch((s->h_count[0] << 4) | s->v_count[0]) {
        case 0x11:
    	    avctx->pix_fmt = PIX_FMT_YUV444P;
            break;
        case 0x21:
            avctx->pix_fmt = PIX_FMT_YUV422P;
            break;
        default:
	case 0x22:
            avctx->pix_fmt = PIX_FMT_YUV420P;
            break;
    }
    /* dummy quality */
    /* XXX: infer it with matrix */