FFmpeg/libavcodec/dv.c

/*
 * DV decoder
 * Copyright (c) 2002 Fabrice Bellard.
 *
 * DV encoder 
 * Copyright (c) 2003 Roman Shaposhnik.
 *
 * Many thanks to Dan Dennedy <dan@dennedy.org> for providing wealth
 * of DV technical info.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * @file dv.c
 * DV codec.
 */
#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"
#include "simple_idct.h"
#include "dvdata.h"

typedef struct DVVideoDecodeContext {
    const DVprofile* sys;
    GetBitContext gb;
    AVFrame picture;
    DCTELEM block[5*6][64] __align8;
    
    /* FIXME: the following is extracted from DSP */
    uint8_t dv_zigzag[2][64];
    uint8_t idct_permutation[64];
    void (*get_pixels)(DCTELEM *block, const uint8_t *pixels, int line_size);
    void (*fdct)(DCTELEM *block);
    
    /* XXX: move it to static storage ? */
    uint8_t dv_shift[2][22][64];
    void (*idct_put[2])(uint8_t *dest, int line_size, DCTELEM *block);
} DVVideoDecodeContext;

#define TEX_VLC_BITS 9
/* XXX: also include quantization */
static RL_VLC_ELEM *dv_rl_vlc[1];
static VLC_TYPE dv_vlc_codes[15][23];

static void dv_build_unquantize_tables(DVVideoDecodeContext *s)
{
    int i, q, j;

    /* NOTE: max left shift is 6 */
    for(q = 0; q < 22; q++) {
        /* 88 unquant */
        for(i = 1; i < 64; i++) {
            /* 88 table */
            j = s->idct_permutation[i];
            s->dv_shift[0][q][j] =
                dv_quant_shifts[q][dv_88_areas[i]] + 1;
        }
        
        /* 248 unquant */
        for(i = 1; i < 64; i++) {
            /* 248 table */
            s->dv_shift[1][q][i] =  
                    dv_quant_shifts[q][dv_248_areas[i]] + 1;
        }
    }
}

static int dvvideo_init(AVCodecContext *avctx)
{
    DVVideoDecodeContext *s = avctx->priv_data;
    MpegEncContext s2;
    static int done=0;

    if (!done) {
        int i;
        VLC dv_vlc;

        done = 1;

        /* NOTE: as a trick, we use the fact the no codes are unused
           to accelerate the parsing of partial codes */
        init_vlc(&dv_vlc, TEX_VLC_BITS, NB_DV_VLC, 
                 dv_vlc_len, 1, 1, dv_vlc_bits, 2, 2);

        dv_rl_vlc[0] = av_malloc(dv_vlc.table_size * sizeof(RL_VLC_ELEM));
        for(i = 0; i < dv_vlc.table_size; i++){
            int code= dv_vlc.table[i][0];
            int len = dv_vlc.table[i][1];
            int level, run;
        
            if(len<0){ //more bits needed
                run= 0;
                level= code;
            } else if (code == (NB_DV_VLC - 1)) {
                /* EOB */
                run = 0;
                level = 256;
            } else {
                run=   dv_vlc_run[code] + 1;
                level= dv_vlc_level[code];
            }
            dv_rl_vlc[0][i].len = len;
            dv_rl_vlc[0][i].level = level;
            dv_rl_vlc[0][i].run = run;
        }

	memset(dv_vlc_codes, 0xff, sizeof(dv_vlc_codes));
	for (i = 0; i < NB_DV_VLC - 1; i++) {
	   if (dv_vlc_run[i] < 15 && dv_vlc_level[i] < 23 && dv_vlc_len[i] < 15)
	       dv_vlc_codes[dv_vlc_run[i]][dv_vlc_level[i]] = i;
	}
    }

    /* ugly way to get the idct & scantable */
    /* XXX: fix it */
    memset(&s2, 0, sizeof(MpegEncContext));
    s2.avctx = avctx;
    dsputil_init(&s2.dsp, avctx);
    if (DCT_common_init(&s2) < 0)
       return -1;

    s->get_pixels = s2.dsp.get_pixels;
    s->fdct = s2.dsp.fdct;
    
    s->idct_put[0] = s2.dsp.idct_put;
    memcpy(s->idct_permutation, s2.dsp.idct_permutation, 64);
    memcpy(s->dv_zigzag[0], s2.intra_scantable.permutated, 64);

    /* XXX: use MMX also for idct248 */
    s->idct_put[1] = simple_idct248_put;
    memcpy(s->dv_zigzag[1], dv_248_zigzag, 64);

    /* XXX: do it only for constant case */
    dv_build_unquantize_tables(s);

    /* FIXME: I really don't think this should be here */
    if (dv_codec_profile(avctx))
	avctx->pix_fmt = dv_codec_profile(avctx)->pix_fmt; 
    avctx->coded_frame = &s->picture;
    
    return 0;
}

// #define VLC_DEBUG

typedef struct BlockInfo {
    const uint8_t *shift_table;
    const uint8_t *scan_table;
    uint8_t pos; /* position in block */
    uint8_t eob_reached; /* true if EOB has been reached */
    uint8_t dct_mode;
    uint8_t partial_bit_count;
    uint16_t partial_bit_buffer;
    int shift_offset;
} BlockInfo;

/* block size in bits */
static const uint16_t block_sizes[6] = {
    112, 112, 112, 112, 80, 80
};

#ifndef ALT_BITSTREAM_READER
#warning only works with ALT_BITSTREAM_READER
#endif

/* decode ac coefs */
static void dv_decode_ac(DVVideoDecodeContext *s, 
                         BlockInfo *mb, DCTELEM *block, int last_index)
{
    int last_re_index;
    int shift_offset = mb->shift_offset;
    const uint8_t *scan_table = mb->scan_table;
    const uint8_t *shift_table = mb->shift_table;
    int pos = mb->pos;
    int level, pos1, sign, run;
    int partial_bit_count;
#ifndef ALT_BITSTREAM_READER //FIXME
    int re_index=0; 
    int re1_index=0;
#endif
    OPEN_READER(re, &s->gb);
    
#ifdef VLC_DEBUG
    printf("start\n");
#endif

    /* if we must parse a partial vlc, we do it here */
    partial_bit_count = mb->partial_bit_count;
    if (partial_bit_count > 0) {
        uint8_t buf[4];
        uint32_t v;
        int l, l1;
        GetBitContext gb1;

        /* build the dummy bit buffer */
        l = 16 - partial_bit_count;
        UPDATE_CACHE(re, &s->gb);
#ifdef VLC_DEBUG
        printf("show=%04x\n", SHOW_UBITS(re, &s->gb, 16));
#endif
        v = (mb->partial_bit_buffer << l) | SHOW_UBITS(re, &s->gb, l);
        buf[0] = v >> 8;
        buf[1] = v;
#ifdef VLC_DEBUG
        printf("v=%04x cnt=%d %04x\n", 
               v, partial_bit_count, (mb->partial_bit_buffer << l));
#endif
        /* try to read the codeword */
        init_get_bits(&gb1, buf, 4*8);
        {
            OPEN_READER(re1, &gb1);
            UPDATE_CACHE(re1, &gb1);
            GET_RL_VLC(level, run, re1, &gb1, dv_rl_vlc[0], 
                       TEX_VLC_BITS, 2);
            l = re1_index;
            CLOSE_READER(re1, &gb1);
        }
#ifdef VLC_DEBUG
        printf("****run=%d level=%d size=%d\n", run, level, l);
#endif
        /* compute codeword length */
        l1 = (level != 256 && level != 0);
        /* if too long, we cannot parse */
        l -= partial_bit_count;
        if ((re_index + l + l1) > last_index)
            return;
        /* skip read bits */
        last_re_index = 0; /* avoid warning */
        re_index += l;
        /* by definition, if we can read the vlc, all partial bits
           will be read (otherwise we could have read the vlc before) */
        mb->partial_bit_count = 0;
        UPDATE_CACHE(re, &s->gb);
        goto handle_vlc;
    }

    /* get the AC coefficients until last_index is reached */
    for(;;) {
        UPDATE_CACHE(re, &s->gb);
#ifdef VLC_DEBUG
        printf("%2d: bits=%04x index=%d\n", 
               pos, SHOW_UBITS(re, &s->gb, 16), re_index);
#endif
        last_re_index = re_index;
        GET_RL_VLC(level, run, re, &s->gb, dv_rl_vlc[0], 
                   TEX_VLC_BITS, 2);
    handle_vlc:
#ifdef VLC_DEBUG
        printf("run=%d level=%d\n", run, level);
#endif
        if (level == 256) {
            if (re_index > last_index) {
            cannot_read:
                /* put position before read code */
                re_index = last_re_index;
                mb->eob_reached = 0;
                break;
            }
            /* EOB */
            mb->eob_reached = 1;
            break;
        } else if (level != 0) {
            if ((re_index + 1) > last_index)
                goto cannot_read;
            sign = SHOW_SBITS(re, &s->gb, 1);
            level = (level ^ sign) - sign;
            LAST_SKIP_BITS(re, &s->gb, 1);
            pos += run;
            /* error */
            if (pos >= 64) {
                goto read_error;
            }
            pos1 = scan_table[pos];
            level = level << (shift_table[pos1] + shift_offset);
            block[pos1] = level;
            //            printf("run=%d level=%d shift=%d\n", run, level, shift_table[pos1]);
        } else {
            if (re_index > last_index)
                goto cannot_read;
            /* level is zero: means run without coding. No
               sign is coded */
            pos += run;
            /* error */
            if (pos >= 64) {
            read_error:
#if defined(VLC_DEBUG) || 1
                fprintf(stderr, "error pos=%d\n", pos);
#endif
                /* for errors, we consider the eob is reached */
                mb->eob_reached = 1;
                break;
            }
        }
    }
    CLOSE_READER(re, &s->gb);
    mb->pos = pos;
}

static inline void bit_copy(PutBitContext *pb, GetBitContext *gb, int bits_left)
{
    while (bits_left >= 16) {
        put_bits(pb, 16, get_bits(gb, 16));
        bits_left -= 16;
    }
    if (bits_left > 0) {
        put_bits(pb, bits_left, get_bits(gb, bits_left));
    }
}

/* mb_x and mb_y are in units of 8 pixels */
static inline void dv_decode_video_segment(DVVideoDecodeContext *s, 
                                           uint8_t *buf_ptr1, 
                                           const uint16_t *mb_pos_ptr)
{
    int quant, dc, dct_mode, class1, j;
    int mb_index, mb_x, mb_y, v, last_index;
    DCTELEM *block, *block1;
    int c_offset, bits_left;
    uint8_t *y_ptr;
    BlockInfo mb_data[5 * 6], *mb, *mb1;
    void (*idct_put)(uint8_t *dest, int line_size, DCTELEM *block);
    uint8_t *buf_ptr;
    PutBitContext pb, vs_pb;
    uint8_t mb_bit_buffer[80 + 4]; /* allow some slack */
    int mb_bit_count;
    uint8_t vs_bit_buffer[5 * 80 + 4]; /* allow some slack */
    int vs_bit_count;
    
    memset(s->block, 0, sizeof(s->block));

    /* pass 1 : read DC and AC coefficients in blocks */
    buf_ptr = buf_ptr1;
    block1 = &s->block[0][0];
    mb1 = mb_data;
    init_put_bits(&vs_pb, vs_bit_buffer, 5 * 80);
    vs_bit_count = 0;
    for(mb_index = 0; mb_index < 5; mb_index++) {
        /* skip header */
        quant = buf_ptr[3] & 0x0f;
        buf_ptr += 4;
        init_put_bits(&pb, mb_bit_buffer, 80);
        mb_bit_count = 0;
        mb = mb1;
        block = block1;
        for(j = 0;j < 6; j++) {
            /* NOTE: size is not important here */
            init_get_bits(&s->gb, buf_ptr, 14*8);
            
            /* get the dc */
            dc = get_bits(&s->gb, 9);
            dc = (dc << (32 - 9)) >> (32 - 9);
            dct_mode = get_bits1(&s->gb);
            mb->dct_mode = dct_mode;
            mb->scan_table = s->dv_zigzag[dct_mode];
            class1 = get_bits(&s->gb, 2);
            mb->shift_offset = (class1 == 3);
            mb->shift_table = s->dv_shift[dct_mode]
                [quant + dv_quant_offset[class1]];
            dc = dc << 2;
            /* convert to unsigned because 128 is not added in the
               standard IDCT */
            dc += 1024;
            block[0] = dc;
            last_index = block_sizes[j];
            buf_ptr += last_index >> 3;
            mb->pos = 0;
            mb->partial_bit_count = 0;

#ifdef VLC_DEBUG
            printf("MB block: %d, %d ", mb_index, j);
#endif
            dv_decode_ac(s, mb, block, last_index);

            /* write the remaining bits  in a new buffer only if the
               block is finished */
            bits_left = last_index - get_bits_count(&s->gb);
            if (mb->eob_reached) {
                mb->partial_bit_count = 0;
                mb_bit_count += bits_left;
                bit_copy(&pb, &s->gb, bits_left);
            } else {
                /* should be < 16 bits otherwise a codeword could have
                   been parsed */
                mb->partial_bit_count = bits_left;
                mb->partial_bit_buffer = get_bits(&s->gb, bits_left);
            }
            block += 64;
            mb++;
        }
        
        flush_put_bits(&pb);

        /* pass 2 : we can do it just after */
#ifdef VLC_DEBUG
        printf("***pass 2 size=%d MB#=%d\n", mb_bit_count, mb_index);
#endif
        block = block1;
        mb = mb1;
        init_get_bits(&s->gb, mb_bit_buffer, 80*8);
        for(j = 0;j < 6; j++) {
            if (!mb->eob_reached && get_bits_count(&s->gb) < mb_bit_count) {
                dv_decode_ac(s, mb, block, mb_bit_count);
                /* if still not finished, no need to parse other blocks */
                if (!mb->eob_reached) {
                    /* we could not parse the current AC coefficient,
                       so we add the remaining bytes */
                    bits_left = mb_bit_count - get_bits_count(&s->gb);
                    if (bits_left > 0) {
                        mb->partial_bit_count += bits_left;
                        mb->partial_bit_buffer = 
                            (mb->partial_bit_buffer << bits_left) | 
                            get_bits(&s->gb, bits_left);
                    }
                    goto next_mb;
                }
            }
            block += 64;
            mb++;
        }
        /* all blocks are finished, so the extra bytes can be used at
           the video segment level */
        bits_left = mb_bit_count - get_bits_count(&s->gb);
        vs_bit_count += bits_left;
        bit_copy(&vs_pb, &s->gb, bits_left);
    next_mb:
        mb1 += 6;
        block1 += 6 * 64;
    }

    /* we need a pass other the whole video segment */
    flush_put_bits(&vs_pb);
        
#ifdef VLC_DEBUG
    printf("***pass 3 size=%d\n", vs_bit_count);
#endif
    block = &s->block[0][0];
    mb = mb_data;
    init_get_bits(&s->gb, vs_bit_buffer, 5 * 80*8);
    for(mb_index = 0; mb_index < 5; mb_index++) {
        for(j = 0;j < 6; j++) {
            if (!mb->eob_reached) {
#ifdef VLC_DEBUG
                printf("start %d:%d\n", mb_index, j);
#endif
                dv_decode_ac(s, mb, block, vs_bit_count);
            }
            block += 64;
            mb++;
        }
    }
    
    /* compute idct and place blocks */
    block = &s->block[0][0];
    mb = mb_data;
    for(mb_index = 0; mb_index < 5; mb_index++) {
        v = *mb_pos_ptr++;
        mb_x = v & 0xff;
        mb_y = v >> 8;
        y_ptr = s->picture.data[0] + (mb_y * s->picture.linesize[0] * 8) + (mb_x * 8);
        if (s->sys->pix_fmt == PIX_FMT_YUV411P)
            c_offset = (mb_y * s->picture.linesize[1] * 8) + ((mb_x >> 2) * 8);
        else
            c_offset = ((mb_y >> 1) * s->picture.linesize[1] * 8) + ((mb_x >> 1) * 8);
        for(j = 0;j < 6; j++) {
            idct_put = s->idct_put[mb->dct_mode];
            if (j < 4) {
                if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x < (704 / 8)) {
                    /* NOTE: at end of line, the macroblock is handled as 420 */
                    idct_put(y_ptr + (j * 8), s->picture.linesize[0], block);
                } else {
                    idct_put(y_ptr + ((j & 1) * 8) + ((j >> 1) * 8 * s->picture.linesize[0]),
                             s->picture.linesize[0], block);
                }
            } else {
                if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x >= (704 / 8)) {
                    uint64_t aligned_pixels[64/8];
                    uint8_t *pixels= (uint8_t*)aligned_pixels;
		    uint8_t *c_ptr, *c_ptr1, *ptr;
                    int y, linesize;
                    /* NOTE: at end of line, the macroblock is handled as 420 */
                    idct_put(pixels, 8, block);
                    linesize = s->picture.linesize[6 - j];
                    c_ptr = s->picture.data[6 - j] + c_offset;
                    ptr = pixels;
                    for(y = 0;y < 8; y++) {
                        /* convert to 411P */
                        c_ptr1 = c_ptr + 8*linesize;
                        c_ptr[0]= ptr[0]; c_ptr1[0]= ptr[4];
                        c_ptr[1]= ptr[1]; c_ptr1[1]= ptr[5];
                        c_ptr[2]= ptr[2]; c_ptr1[2]= ptr[6];
                        c_ptr[3]= ptr[3]; c_ptr1[3]= ptr[7];
                        c_ptr += linesize;
                        ptr += 8;
                    }
                } else {
                    /* don't ask me why they inverted Cb and Cr ! */
                    idct_put(s->picture.data[6 - j] + c_offset, 
                             s->picture.linesize[6 - j], block);
                }
            }
            block += 64;
            mb++;
        }
    }
}

/* Converts run and level (where level != 0) pair into vlc, returning bit size */
static inline int dv_rl2vlc(int run, int l, uint32_t* vlc)
{
    int sign = l >> 8;
    int level = (l ^ sign) - sign;
    int size;
    
    sign = (sign & 1);

    if (run < 15 && level < 23 && dv_vlc_codes[run][level] != -1) {
        *vlc = (dv_vlc_bits[dv_vlc_codes[run][level]] << 1) | sign; 
	size = dv_vlc_len[dv_vlc_codes[run][level]] + 1;
    }
    else { 
	if (level < 23) {
	    *vlc = (dv_vlc_bits[dv_vlc_codes[0][level]] << 1) | sign; 
	    size = dv_vlc_len[dv_vlc_codes[0][level]] + 1;
	} else {
	    *vlc = 0xfe00 | (level << 1) | sign;
	    size = 16;
	}

	switch(run) {
	case 0:
	    break;
	case 1:
	case 2:
	    *vlc |= ((0x7ce | (run - 1)) << size);
	    size += 11;
	    break;
	case 3:
	case 4:
	case 5:
	case 6:
	    *vlc |= ((0xfac | (run - 3)) << size);
	    size += 12;
	    break;
	default:
	    *vlc |= ((0x1f80 | (run - 1)) << size);
	    size += 13;
	    break;
	}
    }
    
    return size;
}

typedef struct EncBlockInfo {
    int qno;
    int cno;
    int dct_mode;
    int block_size;
    DCTELEM *mb;
    PutBitContext pb;
} EncBlockInfo;

static inline int dv_bits_left(EncBlockInfo* bi)
{
    return (bi->block_size - get_bit_count(&bi->pb));
}

static inline void dv_encode_ac(EncBlockInfo* bi, PutBitContext* heap)
{
    int i, level, size, run = 0;
    uint32_t vlc;
    PutBitContext* cpb = &bi->pb;
    
    for (i=1; i<64; i++) {
       level = bi->mb[ff_zigzag_direct[i]] / 
               (1<<(dv_quant_shifts[bi->qno + dv_quant_offset[bi->cno]]
			       [dv_88_areas[ff_zigzag_direct[i]]] + 4 + (bi->cno == 3)));
       if (level != 0) {
	   size = dv_rl2vlc(run, level, &vlc);
put_vlc:

#ifdef VLC_DEBUG
           printf(" %3d:%3d", run, level);
#endif
	   if (cpb == &bi->pb && size > dv_bits_left(bi)) {
	       size -= dv_bits_left(bi);
	       put_bits(cpb, dv_bits_left(bi), vlc >> size);
	       vlc = vlc & ((1<<size)-1);
	       cpb = heap;
	   }
	   put_bits(cpb, size, vlc);
	   run = 0;
       } else
	   run++;
    }
   
    if (i == 64) {
        size = 4; vlc = 6; /* End Of Block stamp */
	goto put_vlc;
    }
}

static inline void dv_redistr_bits(EncBlockInfo* bi, int count, uint8_t* extra_data, int extra_bits, PutBitContext* heap)
{
    int i;
    GetBitContext gb;
    
    init_get_bits(&gb, extra_data, extra_bits);
    
    for (i=0; i<count; i++) {
       int bits_left = dv_bits_left(bi);
#ifdef VLC_DEBUG
       if (bits_left)
           printf("------------> inserting %d bytes in %d:%d\n", bits_left, i/6, i%6);
#endif
       if (bits_left > extra_bits) {
           bit_copy(&bi->pb, &gb, extra_bits); 
	   extra_bits = 0;
	   break;
       } else
           bit_copy(&bi->pb, &gb, bits_left);
	   
       extra_bits -= bits_left;
       bi++;
    }
    
    if (extra_bits > 0 && heap)
	bit_copy(heap, &gb, extra_bits);
}

static inline void dv_set_class_number(EncBlockInfo* bi, int j)
{
    int i, max_ac = 0;

    for (i=1; i<64; i++) {
       int ac = abs(bi->mb[ff_zigzag_direct[i]]) / 4;
       if (max_ac < ac)
           max_ac = ac;
    }
    if (max_ac < 12)
        bi->cno = j;
    else if (max_ac < 24)
        bi->cno = j + 1;
    else if (max_ac < 36)
        bi->cno = j + 2;
    else
        bi->cno = j + 3;
    
    if (bi->cno > 3)
        bi->cno = 3;
}

/*
 * This is a very rough initial implementaion. The performance is
 * horrible and some features are missing, mainly 2-4-8 DCT encoding.
 * The weighting is missing as well, but it's missing from the decoding
 * step also -- so at least we're on the same page with decoder ;-)
 */
static inline void dv_encode_video_segment(DVVideoDecodeContext *s, 
                                           uint8_t *dif, 
                                           const uint16_t *mb_pos_ptr)
{
    int mb_index, i, j, v;
    int mb_x, mb_y, c_offset, linesize; 
    uint8_t*  y_ptr;
    uint8_t*  data;
    int       do_edge_wrap;
    DCTELEM  *block;
    EncBlockInfo  enc_blks[5*6];
    EncBlockInfo* enc_blk;
    int       free_vs_bits;
    int extra_bits;
    PutBitContext extra_vs;
    uint8_t   extra_vs_data[5*6*128];
    uint8_t   extra_mb_data[6*128];

    int       QNO = 15;
   
    /* Stage 1 -- doing DCT on 5 MBs */
    block = &s->block[0][0];
    for(mb_index = 0; mb_index < 5; mb_index++) {
        v = *mb_pos_ptr++;
        mb_x = v & 0xff;
        mb_y = v >> 8;
        y_ptr = s->picture.data[0] + (mb_y * s->picture.linesize[0] * 8) + (mb_x * 8);
	c_offset = (s->sys->pix_fmt == PIX_FMT_YUV411P) ?
	           ((mb_y * s->picture.linesize[1] * 8) + ((mb_x >> 2) * 8)) :
		   (((mb_y >> 1) * s->picture.linesize[1] * 8) + ((mb_x >> 1) * 8));
	do_edge_wrap = 0;
        for(j = 0;j < 6; j++) {
            if (j < 4) {  /* Four Y blocks */
		/* NOTE: at end of line, the macroblock is handled as 420 */
		if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x < (704 / 8)) {
                    data = y_ptr + (j * 8);
                } else {
                    data = y_ptr + ((j & 1) * 8) + ((j >> 1) * 8 * s->picture.linesize[0]);
                }
		linesize = s->picture.linesize[0];
            } else {      /* Cr and Cb blocks */
	        /* don't ask Fabrice why they inverted Cb and Cr ! */
	        data = s->picture.data[6 - j] + c_offset;
		linesize = s->picture.linesize[6 - j];
		if (s->sys->pix_fmt == PIX_FMT_YUV411P && mb_x >= (704 / 8))
		    do_edge_wrap = 1;
	    }	
            
	    /* Everything is set up -- now just copy data -> DCT block */
	    if (do_edge_wrap) {  /* Edge wrap copy: 4x16 -> 8x8 */
		uint8_t* d;
		DCTELEM *b = block;
	        for (i=0;i<8;i++) {
		   d = data + 8 * linesize;
		   b[0] = data[0]; b[1] = data[1]; b[2] = data[2]; b[3] = data[3];
                   b[4] =    d[0]; b[5] =    d[1]; b[6] =    d[2]; b[7] =    d[3];
		   data += linesize;
		   b += 8;
		}
	    } else {             /* Simple copy: 8x8 -> 8x8 */
	        s->get_pixels(block, data, linesize);
	    }
            
	    s->fdct(block);
	    
	    block += 64;
        }
    }

    /* Stage 2 -- setup for encoding phase */
    enc_blk = &enc_blks[0];
    block = &s->block[0][0];
    for (i=0; i<5; i++) {
       for (j=0; j<6; j++) {
	  enc_blk->mb = block;
	  enc_blk->dct_mode = 0;
	  enc_blk->block_size = block_sizes[j];
	  
	  dv_set_class_number(enc_blk, j/4*(j%2));
	  
	  block += 64;
	  enc_blk++;
       }
    }
   
    /* Stage 3 -- encoding by trial-and-error */
encode_vs:
    enc_blk = &enc_blks[0];
    for (i=0; i<5; i++) {
       uint8_t* p = dif + i*80 + 4;
       for (j=0; j<6; j++) {
          enc_blk->qno = QNO;
	  init_put_bits(&enc_blk->pb, p, block_sizes[j]/8);
	  enc_blk++;
	  p += block_sizes[j]/8;
       }
    }

    init_put_bits(&extra_vs, extra_vs_data, sizeof(extra_vs_data));
    free_vs_bits = 0;
    enc_blk = &enc_blks[0];
    for (i=0; i<5; i++) {
       PutBitContext extra_mb;
       EncBlockInfo* enc_blk2 = enc_blk;
       int free_mb_bits = 0;

       init_put_bits(&extra_mb, extra_mb_data, sizeof(extra_mb_data));
       dif[i*80 + 3] = enc_blk->qno;
       
       for (j=0; j<6; j++) {
	  uint16_t dc = ((enc_blk->mb[0] >> 3) - 1024) >> 2;

	  put_bits(&enc_blk->pb, 9, dc);
	  put_bits(&enc_blk->pb, 1, enc_blk->dct_mode);
	  put_bits(&enc_blk->pb, 2, enc_blk->cno);

#ifdef VLC_DEBUG
          printf("[%d, %d]: ", i, j);
#endif
	  dv_encode_ac(enc_blk, &extra_mb);
#ifdef VLC_DEBUG
          printf("\n");
#endif
	  
	  free_mb_bits += dv_bits_left(enc_blk);
	  enc_blk++;
       }
       
       /* We can't flush extra_mb just yet -- since it'll round up bit number */
       extra_bits = get_bit_count(&extra_mb);
       if (free_mb_bits > extra_bits)
           free_vs_bits += free_mb_bits - extra_bits;
    
       if (extra_bits) {  /* FIXME: speed up things when free_mb_bits == 0 */
           flush_put_bits(&extra_mb);
           dv_redistr_bits(enc_blk2, 6, extra_mb_data, extra_bits, &extra_vs);
       }
    }
    
    /* We can't flush extra_mb just yet -- since it'll round up bit number */
    extra_bits = get_bit_count(&extra_vs);
    if (extra_bits > free_vs_bits && QNO) { /* FIXME: very crude trial-and-error */
        QNO--;
	goto encode_vs;
    }
    
    if (extra_bits) {
        flush_put_bits(&extra_vs);
        dv_redistr_bits(&enc_blks[0], 5*6, extra_vs_data, extra_bits, NULL);
    }

    for (i=0; i<6*5; i++) {
       flush_put_bits(&enc_blks[i].pb);
#ifdef VLC_DEBUG
       printf("[%d:%d] qno=%d cno=%d\n", i/6, i%6, enc_blks[i].qno, enc_blks[i].cno);
#endif
    }
}

/* NOTE: exactly one frame must be given (120000 bytes for NTSC,
   144000 bytes for PAL) */
static int dvvideo_decode_frame(AVCodecContext *avctx, 
                                 void *data, int *data_size,
                                 uint8_t *buf, int buf_size)
{
    DVVideoDecodeContext *s = avctx->priv_data;
    int ds, vs;
    const uint16_t *mb_pos_ptr;
    
    s->sys = dv_frame_profile(buf);
    if (!s->sys || buf_size < s->sys->frame_size)
        return -1; /* NOTE: we only accept several full frames */

	
    if(s->picture.data[0])
        avctx->release_buffer(avctx, &s->picture);
    
    s->picture.reference = 0;
    avctx->pix_fmt = s->sys->pix_fmt;
    avctx->width = s->sys->width;
    avctx->height = s->sys->height;
    if(avctx->get_buffer(avctx, &s->picture) < 0) {
        fprintf(stderr, "get_buffer() failed\n");
        return -1;
    }
    s->picture.interlaced_frame = 1;
    s->picture.top_field_first = 0;

    /* for each DIF segment */
    mb_pos_ptr = s->sys->video_place;
    for (ds = 0; ds < s->sys->difseg_size; ds++) {
        buf += 6 * 80; /* skip DIF segment header */
        
        for(vs = 0; vs < 27; vs++) {
            if ((vs % 3) == 0)
	        buf += 80; /* skip audio block */
            
#ifdef VLC_DEBUG
            printf("********************* %d, %d **********************\n", ds, vs);
#endif
	    dv_decode_video_segment(s, buf, mb_pos_ptr);
            buf += 5 * 80;
            mb_pos_ptr += 5;
        }
    }

    emms_c();

    /* return image */
    *data_size = sizeof(AVFrame);
    *(AVFrame*)data= s->picture;
    
    return s->sys->frame_size;
}

static int dvvideo_encode_frame(AVCodecContext *c, uint8_t *buf, int buf_size, 
                                void *data)
{
    DVVideoDecodeContext *s = c->priv_data;
    const uint16_t *mb_pos_ptr;
    int ds, vs;

    s->sys = dv_codec_profile(c);
    if (!s->sys)
	return -1;
    
    c->pix_fmt = s->sys->pix_fmt;
    s->picture = *((AVFrame *)data);

    /* for each DIF segment */
    mb_pos_ptr = s->sys->video_place;
    for (ds = 0; ds < s->sys->difseg_size; ds++) {
        buf += 6 * 80; /* skip DIF segment header */
        
        for(vs = 0; vs < 27; vs++) {
            if ((vs % 3) == 0)
	        buf += 80; /* skip audio block */

#ifdef VLC_DEBUG
            printf("********************* %d, %d **********************\n", ds, vs);
#endif
	    dv_encode_video_segment(s, buf, mb_pos_ptr);
            buf += 5 * 80;
            mb_pos_ptr += 5;
        }
    }

    emms_c();
    return s->sys->frame_size;
}

static int dvvideo_end(AVCodecContext *avctx)
{
    avcodec_default_free_buffers(avctx);    
    return 0;
}

AVCodec dvvideo_decoder = {
    "dvvideo",
    CODEC_TYPE_VIDEO,
    CODEC_ID_DVVIDEO,
    sizeof(DVVideoDecodeContext),
    dvvideo_init,
    dvvideo_encode_frame,
    dvvideo_end,
    dvvideo_decode_frame,
    CODEC_CAP_DR1,
    NULL
};