FFmpeg/libavcodec/svq3.c

/*
 * Copyright (c) 2003 The FFmpeg Project.
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 *
 * How to use this decoder:
 * SVQ3 data is transported within Apple Quicktime files. Quicktime files
 * have stsd atoms to describe media trak properties. A stsd atom for a
 * video trak contains 1 or more ImageDescription atoms. These atoms begin
 * with the 4-byte length of the atom followed by the codec fourcc. Some
 * decoders need information in this atom to operate correctly. Such
 * is the case with SVQ3. In order to get the best use out of this decoder,
 * the calling app must make the SVQ3 ImageDescription atom available
 * via the AVCodecContext's extradata[_size] field:
 *
 * AVCodecContext.extradata = pointer to ImageDescription, first characters
 * are expected to be 'S', 'V', 'Q', and '3', NOT the 4-byte atom length
 * AVCodecContext.extradata_size = size of ImageDescription atom memory
 * buffer (which will be the same as the ImageDescription atom size field
 * from the QT file, minus 4 bytes since the length is missing)
 *
 * You will know you have these parameters passed correctly when the decoder
 * correctly decodes this file:
 *  ftp://ftp.mplayerhq.hu/MPlayer/samples/V-codecs/SVQ3/Vertical400kbit.sorenson3.mov
 *
 */

/**
 * @file svq3.c
 * svq3 decoder.
 */

#define FULLPEL_MODE  1
#define HALFPEL_MODE  2
#define THIRDPEL_MODE 3
#define PREDICT_MODE  4

/* dual scan (from some older h264 draft)
 o-->o-->o   o
         |  /|
 o   o   o / o
 | / |   |/  |
 o   o   o   o
   /
 o-->o-->o-->o
*/
static const uint8_t svq3_scan[16]={
 0+0*4, 1+0*4, 2+0*4, 2+1*4,
 2+2*4, 3+0*4, 3+1*4, 3+2*4,
 0+1*4, 0+2*4, 1+1*4, 1+2*4,
 0+3*4, 1+3*4, 2+3*4, 3+3*4,
};

static const uint8_t svq3_pred_0[25][2] = {
  { 0, 0 },
  { 1, 0 }, { 0, 1 },
  { 0, 2 }, { 1, 1 }, { 2, 0 },
  { 3, 0 }, { 2, 1 }, { 1, 2 }, { 0, 3 },
  { 0, 4 }, { 1, 3 }, { 2, 2 }, { 3, 1 }, { 4, 0 },
  { 4, 1 }, { 3, 2 }, { 2, 3 }, { 1, 4 },
  { 2, 4 }, { 3, 3 }, { 4, 2 },
  { 4, 3 }, { 3, 4 },
  { 4, 4 }
};

static const int8_t svq3_pred_1[6][6][5] = {
  { { 2,-1,-1,-1,-1 }, { 2, 1,-1,-1,-1 }, { 1, 2,-1,-1,-1 },
    { 2, 1,-1,-1,-1 }, { 1, 2,-1,-1,-1 }, { 1, 2,-1,-1,-1 } },
  { { 0, 2,-1,-1,-1 }, { 0, 2, 1, 4, 3 }, { 0, 1, 2, 4, 3 },
    { 0, 2, 1, 4, 3 }, { 2, 0, 1, 3, 4 }, { 0, 4, 2, 1, 3 } },
  { { 2, 0,-1,-1,-1 }, { 2, 1, 0, 4, 3 }, { 1, 2, 4, 0, 3 },
    { 2, 1, 0, 4, 3 }, { 2, 1, 4, 3, 0 }, { 1, 2, 4, 0, 3 } },
  { { 2, 0,-1,-1,-1 }, { 2, 0, 1, 4, 3 }, { 1, 2, 0, 4, 3 },
    { 2, 1, 0, 4, 3 }, { 2, 1, 3, 4, 0 }, { 2, 4, 1, 0, 3 } },
  { { 0, 2,-1,-1,-1 }, { 0, 2, 1, 3, 4 }, { 1, 2, 3, 0, 4 },
    { 2, 0, 1, 3, 4 }, { 2, 1, 3, 0, 4 }, { 2, 0, 4, 3, 1 } },
  { { 0, 2,-1,-1,-1 }, { 0, 2, 4, 1, 3 }, { 1, 4, 2, 0, 3 },
    { 4, 2, 0, 1, 3 }, { 2, 0, 1, 4, 3 }, { 4, 2, 1, 0, 3 } },
};

static const struct { uint8_t run; uint8_t level; } svq3_dct_tables[2][16] = {
  { { 0, 0 }, { 0, 1 }, { 1, 1 }, { 2, 1 }, { 0, 2 }, { 3, 1 }, { 4, 1 }, { 5, 1 },
    { 0, 3 }, { 1, 2 }, { 2, 2 }, { 6, 1 }, { 7, 1 }, { 8, 1 }, { 9, 1 }, { 0, 4 } },
  { { 0, 0 }, { 0, 1 }, { 1, 1 }, { 0, 2 }, { 2, 1 }, { 0, 3 }, { 0, 4 }, { 0, 5 },
    { 3, 1 }, { 4, 1 }, { 1, 2 }, { 1, 3 }, { 0, 6 }, { 0, 7 }, { 0, 8 }, { 0, 9 } }
};

static const uint32_t svq3_dequant_coeff[32] = {
   3881,  4351,  4890,  5481,  6154,  6914,  7761,  8718,
   9781, 10987, 12339, 13828, 15523, 17435, 19561, 21873,
  24552, 27656, 30847, 34870, 38807, 43747, 49103, 54683,
  61694, 68745, 77615, 89113,100253,109366,126635,141533
};


static void svq3_luma_dc_dequant_idct_c(DCTELEM *block, int qp){
    const int qmul= svq3_dequant_coeff[qp];
#define stride 16
    int i;
    int temp[16];
    static const int x_offset[4]={0, 1*stride, 4* stride,  5*stride};
    static const int y_offset[4]={0, 2*stride, 8* stride, 10*stride};

    for(i=0; i<4; i++){
        const int offset= y_offset[i];
        const int z0= 13*(block[offset+stride*0] +    block[offset+stride*4]);
        const int z1= 13*(block[offset+stride*0] -    block[offset+stride*4]);
        const int z2=  7* block[offset+stride*1] - 17*block[offset+stride*5];
        const int z3= 17* block[offset+stride*1] +  7*block[offset+stride*5];

        temp[4*i+0]= z0+z3;
        temp[4*i+1]= z1+z2;
        temp[4*i+2]= z1-z2;
        temp[4*i+3]= z0-z3;
    }

    for(i=0; i<4; i++){
        const int offset= x_offset[i];
        const int z0= 13*(temp[4*0+i] +    temp[4*2+i]);
        const int z1= 13*(temp[4*0+i] -    temp[4*2+i]);
        const int z2=  7* temp[4*1+i] - 17*temp[4*3+i];
        const int z3= 17* temp[4*1+i] +  7*temp[4*3+i];

        block[stride*0 +offset]= ((z0 + z3)*qmul + 0x80000)>>20;
        block[stride*2 +offset]= ((z1 + z2)*qmul + 0x80000)>>20;
        block[stride*8 +offset]= ((z1 - z2)*qmul + 0x80000)>>20;
        block[stride*10+offset]= ((z0 - z3)*qmul + 0x80000)>>20;
    }
}
#undef stride

static void svq3_add_idct_c (uint8_t *dst, DCTELEM *block, int stride, int qp, int dc){
    const int qmul= svq3_dequant_coeff[qp];
    int i;
    uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;

    if (dc) {
        dc = 13*13*((dc == 1) ? 1538*block[0] : ((qmul*(block[0] >> 3)) / 2));
        block[0] = 0;
    }

    for (i=0; i < 4; i++) {
        const int z0= 13*(block[0 + 4*i] +    block[2 + 4*i]);
        const int z1= 13*(block[0 + 4*i] -    block[2 + 4*i]);
        const int z2=  7* block[1 + 4*i] - 17*block[3 + 4*i];
        const int z3= 17* block[1 + 4*i] +  7*block[3 + 4*i];

        block[0 + 4*i]= z0 + z3;
        block[1 + 4*i]= z1 + z2;
        block[2 + 4*i]= z1 - z2;
        block[3 + 4*i]= z0 - z3;
    }

    for (i=0; i < 4; i++) {
        const int z0= 13*(block[i + 4*0] +    block[i + 4*2]);
        const int z1= 13*(block[i + 4*0] -    block[i + 4*2]);
        const int z2=  7* block[i + 4*1] - 17*block[i + 4*3];
        const int z3= 17* block[i + 4*1] +  7*block[i + 4*3];
        const int rr= (dc + 0x80000);

        dst[i + stride*0]= cm[ dst[i + stride*0] + (((z0 + z3)*qmul + rr) >> 20) ];
        dst[i + stride*1]= cm[ dst[i + stride*1] + (((z1 + z2)*qmul + rr) >> 20) ];
        dst[i + stride*2]= cm[ dst[i + stride*2] + (((z1 - z2)*qmul + rr) >> 20) ];
        dst[i + stride*3]= cm[ dst[i + stride*3] + (((z0 - z3)*qmul + rr) >> 20) ];
    }
}

static void pred4x4_down_left_svq3_c(uint8_t *src, uint8_t *topright, int stride){
    LOAD_TOP_EDGE
    LOAD_LEFT_EDGE
    const __attribute__((unused)) int unu0= t0;
    const __attribute__((unused)) int unu1= l0;

    src[0+0*stride]=(l1 + t1)>>1;
    src[1+0*stride]=
    src[0+1*stride]=(l2 + t2)>>1;
    src[2+0*stride]=
    src[1+1*stride]=
    src[0+2*stride]=
    src[3+0*stride]=
    src[2+1*stride]=
    src[1+2*stride]=
    src[0+3*stride]=
    src[3+1*stride]=
    src[2+2*stride]=
    src[1+3*stride]=
    src[3+2*stride]=
    src[2+3*stride]=
    src[3+3*stride]=(l3 + t3)>>1;
}

static void pred16x16_plane_svq3_c(uint8_t *src, int stride){
    pred16x16_plane_compat_c(src, stride, 1);
}

static inline int svq3_decode_block (GetBitContext *gb, DCTELEM *block,
                                     int index, const int type) {

  static const uint8_t *const scan_patterns[4] =
  { luma_dc_zigzag_scan, zigzag_scan, svq3_scan, chroma_dc_scan };

  int run, level, sign, vlc, limit;
  const int intra = (3 * type) >> 2;
  const uint8_t *const scan = scan_patterns[type];

  for (limit=(16 >> intra); index < 16; index=limit, limit+=8) {
    for (; (vlc = svq3_get_ue_golomb (gb)) != 0; index++) {

      if (vlc == INVALID_VLC)
        return -1;

      sign = (vlc & 0x1) - 1;
      vlc  = (vlc + 1) >> 1;

      if (type == 3) {
        if (vlc < 3) {
          run   = 0;
          level = vlc;
        } else if (vlc < 4) {
          run   = 1;
          level = 1;
        } else {
          run   = (vlc & 0x3);
          level = ((vlc + 9) >> 2) - run;
        }
      } else {
        if (vlc < 16) {
          run   = svq3_dct_tables[intra][vlc].run;
          level = svq3_dct_tables[intra][vlc].level;
        } else if (intra) {
          run   = (vlc & 0x7);
          level = (vlc >> 3) + ((run == 0) ? 8 : ((run < 2) ? 2 : ((run < 5) ? 0 : -1)));
        } else {
          run   = (vlc & 0xF);
          level = (vlc >> 4) + ((run == 0) ? 4 : ((run < 3) ? 2 : ((run < 10) ? 1 : 0)));
        }
      }

      if ((index += run) >= limit)
        return -1;

      block[scan[index]] = (level ^ sign) - sign;
    }

    if (type != 2) {
      break;
    }
  }

  return 0;
}

static inline void svq3_mc_dir_part (MpegEncContext *s,
                                     int x, int y, int width, int height,
                                     int mx, int my, int dxy,
                                     int thirdpel, int dir, int avg) {

  const Picture *pic = (dir == 0) ? &s->last_picture : &s->next_picture;
  uint8_t *src, *dest;
  int i, emu = 0;
  int blocksize= 2 - (width>>3); //16->0, 8->1, 4->2

  mx += x;
  my += y;

  if (mx < 0 || mx >= (s->h_edge_pos - width  - 1) ||
      my < 0 || my >= (s->v_edge_pos - height - 1)) {

    if ((s->flags & CODEC_FLAG_EMU_EDGE)) {
      emu = 1;
    }

    mx = av_clip (mx, -16, (s->h_edge_pos - width  + 15));
    my = av_clip (my, -16, (s->v_edge_pos - height + 15));
  }

  /* form component predictions */
  dest = s->current_picture.data[0] + x + y*s->linesize;
  src  = pic->data[0] + mx + my*s->linesize;

  if (emu) {
    ff_emulated_edge_mc (s->edge_emu_buffer, src, s->linesize, (width + 1), (height + 1),
                         mx, my, s->h_edge_pos, s->v_edge_pos);
    src = s->edge_emu_buffer;
  }
  if(thirdpel)
    (avg ? s->dsp.avg_tpel_pixels_tab : s->dsp.put_tpel_pixels_tab)[dxy](dest, src, s->linesize, width, height);
  else
    (avg ? s->dsp.avg_pixels_tab : s->dsp.put_pixels_tab)[blocksize][dxy](dest, src, s->linesize, height);

  if (!(s->flags & CODEC_FLAG_GRAY)) {
    mx     = (mx + (mx < (int) x)) >> 1;
    my     = (my + (my < (int) y)) >> 1;
    width  = (width  >> 1);
    height = (height >> 1);
    blocksize++;

    for (i=1; i < 3; i++) {
      dest = s->current_picture.data[i] + (x >> 1) + (y >> 1)*s->uvlinesize;
      src  = pic->data[i] + mx + my*s->uvlinesize;

      if (emu) {
        ff_emulated_edge_mc (s->edge_emu_buffer, src, s->uvlinesize, (width + 1), (height + 1),
                             mx, my, (s->h_edge_pos >> 1), (s->v_edge_pos >> 1));
        src = s->edge_emu_buffer;
      }
      if(thirdpel)
        (avg ? s->dsp.avg_tpel_pixels_tab : s->dsp.put_tpel_pixels_tab)[dxy](dest, src, s->uvlinesize, width, height);
      else
        (avg ? s->dsp.avg_pixels_tab : s->dsp.put_pixels_tab)[blocksize][dxy](dest, src, s->uvlinesize, height);
    }
  }
}

static inline int svq3_mc_dir (H264Context *h, int size, int mode, int dir, int avg) {

  int i, j, k, mx, my, dx, dy, x, y;
  MpegEncContext *const s = (MpegEncContext *) h;
  const int part_width  = ((size & 5) == 4) ? 4 : 16 >> (size & 1);
  const int part_height = 16 >> ((unsigned) (size + 1) / 3);
  const int extra_width = (mode == PREDICT_MODE) ? -16*6 : 0;
  const int h_edge_pos  = 6*(s->h_edge_pos - part_width ) - extra_width;
  const int v_edge_pos  = 6*(s->v_edge_pos - part_height) - extra_width;

  for (i=0; i < 16; i+=part_height) {
    for (j=0; j < 16; j+=part_width) {
      const int b_xy = (4*s->mb_x+(j>>2)) + (4*s->mb_y+(i>>2))*h->b_stride;
      int dxy;
      x = 16*s->mb_x + j;
      y = 16*s->mb_y + i;
      k = ((j>>2)&1) + ((i>>1)&2) + ((j>>1)&4) + (i&8);

      if (mode != PREDICT_MODE) {
        pred_motion (h, k, (part_width >> 2), dir, 1, &mx, &my);
      } else {
        mx = s->next_picture.motion_val[0][b_xy][0]<<1;
        my = s->next_picture.motion_val[0][b_xy][1]<<1;

        if (dir == 0) {
          mx = ((mx * h->frame_num_offset) / h->prev_frame_num_offset + 1)>>1;
          my = ((my * h->frame_num_offset) / h->prev_frame_num_offset + 1)>>1;
        } else {
          mx = ((mx * (h->frame_num_offset - h->prev_frame_num_offset)) / h->prev_frame_num_offset + 1)>>1;
          my = ((my * (h->frame_num_offset - h->prev_frame_num_offset)) / h->prev_frame_num_offset + 1)>>1;
        }
      }

      /* clip motion vector prediction to frame border */
      mx = av_clip (mx, extra_width - 6*x, h_edge_pos - 6*x);
      my = av_clip (my, extra_width - 6*y, v_edge_pos - 6*y);

      /* get (optional) motion vector differential */
      if (mode == PREDICT_MODE) {
        dx = dy = 0;
      } else {
        dy = svq3_get_se_golomb (&s->gb);
        dx = svq3_get_se_golomb (&s->gb);

        if (dx == INVALID_VLC || dy == INVALID_VLC) {
          av_log(h->s.avctx, AV_LOG_ERROR, "invalid MV vlc\n");
          return -1;
        }
      }

      /* compute motion vector */
      if (mode == THIRDPEL_MODE) {
        int fx, fy;
        mx = ((mx + 1)>>1) + dx;
        my = ((my + 1)>>1) + dy;
        fx= ((unsigned)(mx + 0x3000))/3 - 0x1000;
        fy= ((unsigned)(my + 0x3000))/3 - 0x1000;
        dxy= (mx - 3*fx) + 4*(my - 3*fy);

        svq3_mc_dir_part (s, x, y, part_width, part_height, fx, fy, dxy, 1, dir, avg);
        mx += mx;
        my += my;
      } else if (mode == HALFPEL_MODE || mode == PREDICT_MODE) {
        mx = ((unsigned)(mx + 1 + 0x3000))/3 + dx - 0x1000;
        my = ((unsigned)(my + 1 + 0x3000))/3 + dy - 0x1000;
        dxy= (mx&1) + 2*(my&1);

        svq3_mc_dir_part (s, x, y, part_width, part_height, mx>>1, my>>1, dxy, 0, dir, avg);
        mx *= 3;
        my *= 3;
      } else {
        mx = ((unsigned)(mx + 3 + 0x6000))/6 + dx - 0x1000;
        my = ((unsigned)(my + 3 + 0x6000))/6 + dy - 0x1000;

        svq3_mc_dir_part (s, x, y, part_width, part_height, mx, my, 0, 0, dir, avg);
        mx *= 6;
        my *= 6;
      }

      /* update mv_cache */
      if (mode != PREDICT_MODE) {
        int32_t mv = pack16to32(mx,my);

        if (part_height == 8 && i < 8) {
          *(int32_t *) h->mv_cache[dir][scan8[k] + 1*8] = mv;

          if (part_width == 8 && j < 8) {
            *(int32_t *) h->mv_cache[dir][scan8[k] + 1 + 1*8] = mv;
          }
        }
        if (part_width == 8 && j < 8) {
          *(int32_t *) h->mv_cache[dir][scan8[k] + 1] = mv;
        }
        if (part_width == 4 || part_height == 4) {
          *(int32_t *) h->mv_cache[dir][scan8[k]] = mv;
        }
      }

      /* write back motion vectors */
      fill_rectangle(s->current_picture.motion_val[dir][b_xy], part_width>>2, part_height>>2, h->b_stride, pack16to32(mx,my), 4);
    }
  }

  return 0;
}

static int svq3_decode_mb (H264Context *h, unsigned int mb_type) {
  int i, j, k, m, dir, mode;
  int cbp = 0;
  uint32_t vlc;
  int8_t *top, *left;
  MpegEncContext *const s = (MpegEncContext *) h;
  const int mb_xy = s->mb_x + s->mb_y*s->mb_stride;
  const int b_xy = 4*s->mb_x + 4*s->mb_y*h->b_stride;

  h->top_samples_available        = (s->mb_y == 0) ? 0x33FF : 0xFFFF;
  h->left_samples_available        = (s->mb_x == 0) ? 0x5F5F : 0xFFFF;
  h->topright_samples_available        = 0xFFFF;

  if (mb_type == 0) {           /* SKIP */
    if (s->pict_type == P_TYPE || s->next_picture.mb_type[mb_xy] == -1) {
      svq3_mc_dir_part (s, 16*s->mb_x, 16*s->mb_y, 16, 16, 0, 0, 0, 0, 0, 0);

      if (s->pict_type == B_TYPE) {
        svq3_mc_dir_part (s, 16*s->mb_x, 16*s->mb_y, 16, 16, 0, 0, 0, 0, 1, 1);
      }

      mb_type = MB_TYPE_SKIP;
    } else {
      mb_type= FFMIN(s->next_picture.mb_type[mb_xy], 6);
      if(svq3_mc_dir (h, mb_type, PREDICT_MODE, 0, 0) < 0)
        return -1;
      if(svq3_mc_dir (h, mb_type, PREDICT_MODE, 1, 1) < 0)
        return -1;

      mb_type = MB_TYPE_16x16;
    }
  } else if (mb_type < 8) {     /* INTER */
    if (h->thirdpel_flag && h->halfpel_flag == !get_bits (&s->gb, 1)) {
      mode = THIRDPEL_MODE;
    } else if (h->halfpel_flag && h->thirdpel_flag == !get_bits (&s->gb, 1)) {
      mode = HALFPEL_MODE;
    } else {
      mode = FULLPEL_MODE;
    }

    /* fill caches */
    /* note ref_cache should contain here:
        ????????
        ???11111
        N??11111
        N??11111
        N??11111
        N
    */

    for (m=0; m < 2; m++) {
      if (s->mb_x > 0 && h->intra4x4_pred_mode[mb_xy - 1][0] != -1) {
        for (i=0; i < 4; i++) {
          *(uint32_t *) h->mv_cache[m][scan8[0] - 1 + i*8] = *(uint32_t *) s->current_picture.motion_val[m][b_xy - 1 + i*h->b_stride];
        }
      } else {
        for (i=0; i < 4; i++) {
          *(uint32_t *) h->mv_cache[m][scan8[0] - 1 + i*8] = 0;
        }
      }
      if (s->mb_y > 0) {
        memcpy (h->mv_cache[m][scan8[0] - 1*8], s->current_picture.motion_val[m][b_xy - h->b_stride], 4*2*sizeof(int16_t));
        memset (&h->ref_cache[m][scan8[0] - 1*8], (h->intra4x4_pred_mode[mb_xy - s->mb_stride][4] == -1) ? PART_NOT_AVAILABLE : 1, 4);

        if (s->mb_x < (s->mb_width - 1)) {
          *(uint32_t *) h->mv_cache[m][scan8[0] + 4 - 1*8] = *(uint32_t *) s->current_picture.motion_val[m][b_xy - h->b_stride + 4];
          h->ref_cache[m][scan8[0] + 4 - 1*8] =
                  (h->intra4x4_pred_mode[mb_xy - s->mb_stride + 1][0] == -1 ||
                   h->intra4x4_pred_mode[mb_xy - s->mb_stride][4] == -1) ? PART_NOT_AVAILABLE : 1;
        }else
          h->ref_cache[m][scan8[0] + 4 - 1*8] = PART_NOT_AVAILABLE;
        if (s->mb_x > 0) {
          *(uint32_t *) h->mv_cache[m][scan8[0] - 1 - 1*8] = *(uint32_t *) s->current_picture.motion_val[m][b_xy - h->b_stride - 1];
          h->ref_cache[m][scan8[0] - 1 - 1*8] = (h->intra4x4_pred_mode[mb_xy - s->mb_stride - 1][3] == -1) ? PART_NOT_AVAILABLE : 1;
        }else
          h->ref_cache[m][scan8[0] - 1 - 1*8] = PART_NOT_AVAILABLE;
      }else
        memset (&h->ref_cache[m][scan8[0] - 1*8 - 1], PART_NOT_AVAILABLE, 8);

      if (s->pict_type != B_TYPE)
        break;
    }

    /* decode motion vector(s) and form prediction(s) */
    if (s->pict_type == P_TYPE) {
      if(svq3_mc_dir (h, (mb_type - 1), mode, 0, 0) < 0)
        return -1;
    } else {        /* B_TYPE */
      if (mb_type != 2) {
        if(svq3_mc_dir (h, 0, mode, 0, 0) < 0)
          return -1;
      } else {
        for (i=0; i < 4; i++) {
          memset (s->current_picture.motion_val[0][b_xy + i*h->b_stride], 0, 4*2*sizeof(int16_t));
        }
      }
      if (mb_type != 1) {
        if(svq3_mc_dir (h, 0, mode, 1, (mb_type == 3)) < 0)
          return -1;
      } else {
        for (i=0; i < 4; i++) {
          memset (s->current_picture.motion_val[1][b_xy + i*h->b_stride], 0, 4*2*sizeof(int16_t));
        }
      }
    }

    mb_type = MB_TYPE_16x16;
  } else if (mb_type == 8 || mb_type == 33) {   /* INTRA4x4 */
    memset (h->intra4x4_pred_mode_cache, -1, 8*5*sizeof(int8_t));

    if (mb_type == 8) {
      if (s->mb_x > 0) {
        for (i=0; i < 4; i++) {
          h->intra4x4_pred_mode_cache[scan8[0] - 1 + i*8] = h->intra4x4_pred_mode[mb_xy - 1][i];
        }
        if (h->intra4x4_pred_mode_cache[scan8[0] - 1] == -1) {
          h->left_samples_available = 0x5F5F;
        }
      }
      if (s->mb_y > 0) {
        h->intra4x4_pred_mode_cache[4+8*0] = h->intra4x4_pred_mode[mb_xy - s->mb_stride][4];
        h->intra4x4_pred_mode_cache[5+8*0] = h->intra4x4_pred_mode[mb_xy - s->mb_stride][5];
        h->intra4x4_pred_mode_cache[6+8*0] = h->intra4x4_pred_mode[mb_xy - s->mb_stride][6];
        h->intra4x4_pred_mode_cache[7+8*0] = h->intra4x4_pred_mode[mb_xy - s->mb_stride][3];

        if (h->intra4x4_pred_mode_cache[4+8*0] == -1) {
          h->top_samples_available = 0x33FF;
        }
      }

      /* decode prediction codes for luma blocks */
      for (i=0; i < 16; i+=2) {
        vlc = svq3_get_ue_golomb (&s->gb);

        if (vlc >= 25){
          av_log(h->s.avctx, AV_LOG_ERROR, "luma prediction:%d\n", vlc);
          return -1;
        }

        left    = &h->intra4x4_pred_mode_cache[scan8[i] - 1];
        top     = &h->intra4x4_pred_mode_cache[scan8[i] - 8];

        left[1] = svq3_pred_1[top[0] + 1][left[0] + 1][svq3_pred_0[vlc][0]];
        left[2] = svq3_pred_1[top[1] + 1][left[1] + 1][svq3_pred_0[vlc][1]];

        if (left[1] == -1 || left[2] == -1){
          av_log(h->s.avctx, AV_LOG_ERROR, "weird prediction\n");
          return -1;
        }
      }
    } else {    /* mb_type == 33, DC_128_PRED block type */
      for (i=0; i < 4; i++) {
        memset (&h->intra4x4_pred_mode_cache[scan8[0] + 8*i], DC_PRED, 4);
      }
    }

    write_back_intra_pred_mode (h);

    if (mb_type == 8) {
      check_intra4x4_pred_mode (h);

      h->top_samples_available  = (s->mb_y == 0) ? 0x33FF : 0xFFFF;
      h->left_samples_available = (s->mb_x == 0) ? 0x5F5F : 0xFFFF;
    } else {
      for (i=0; i < 4; i++) {
        memset (&h->intra4x4_pred_mode_cache[scan8[0] + 8*i], DC_128_PRED, 4);
      }

      h->top_samples_available  = 0x33FF;
      h->left_samples_available = 0x5F5F;
    }

    mb_type = MB_TYPE_INTRA4x4;
  } else {                      /* INTRA16x16 */
    dir = i_mb_type_info[mb_type - 8].pred_mode;
    dir = (dir >> 1) ^ 3*(dir & 1) ^ 1;

    if ((h->intra16x16_pred_mode = check_intra_pred_mode (h, dir)) == -1){
      av_log(h->s.avctx, AV_LOG_ERROR, "check_intra_pred_mode = -1\n");
      return -1;
    }

    cbp = i_mb_type_info[mb_type - 8].cbp;
    mb_type = MB_TYPE_INTRA16x16;
  }

  if (!IS_INTER(mb_type) && s->pict_type != I_TYPE) {
    for (i=0; i < 4; i++) {
      memset (s->current_picture.motion_val[0][b_xy + i*h->b_stride], 0, 4*2*sizeof(int16_t));
    }
    if (s->pict_type == B_TYPE) {
      for (i=0; i < 4; i++) {
        memset (s->current_picture.motion_val[1][b_xy + i*h->b_stride], 0, 4*2*sizeof(int16_t));
      }
    }
  }
  if (!IS_INTRA4x4(mb_type)) {
    memset (h->intra4x4_pred_mode[mb_xy], DC_PRED, 8);
  }
  if (!IS_SKIP(mb_type) || s->pict_type == B_TYPE) {
    memset (h->non_zero_count_cache + 8, 0, 4*9*sizeof(uint8_t));
    s->dsp.clear_blocks(h->mb);
  }

  if (!IS_INTRA16x16(mb_type) && (!IS_SKIP(mb_type) || s->pict_type == B_TYPE)) {
    if ((vlc = svq3_get_ue_golomb (&s->gb)) >= 48){
      av_log(h->s.avctx, AV_LOG_ERROR, "cbp_vlc=%d\n", vlc);
      return -1;
    }

    cbp = IS_INTRA(mb_type) ? golomb_to_intra4x4_cbp[vlc] : golomb_to_inter_cbp[vlc];
  }
  if (IS_INTRA16x16(mb_type) || (s->pict_type != I_TYPE && s->adaptive_quant && cbp)) {
    s->qscale += svq3_get_se_golomb (&s->gb);

    if (s->qscale > 31){
      av_log(h->s.avctx, AV_LOG_ERROR, "qscale:%d\n", s->qscale);
      return -1;
    }
  }
  if (IS_INTRA16x16(mb_type)) {
    if (svq3_decode_block (&s->gb, h->mb, 0, 0)){
      av_log(h->s.avctx, AV_LOG_ERROR, "error while decoding intra luma dc\n");
      return -1;
    }
  }

  if (cbp) {
    const int index = IS_INTRA16x16(mb_type) ? 1 : 0;
    const int type = ((s->qscale < 24 && IS_INTRA4x4(mb_type)) ? 2 : 1);

    for (i=0; i < 4; i++) {
      if ((cbp & (1 << i))) {
        for (j=0; j < 4; j++) {
          k = index ? ((j&1) + 2*(i&1) + 2*(j&2) + 4*(i&2)) : (4*i + j);
          h->non_zero_count_cache[ scan8[k] ] = 1;

          if (svq3_decode_block (&s->gb, &h->mb[16*k], index, type)){
            av_log(h->s.avctx, AV_LOG_ERROR, "error while decoding block\n");
            return -1;
          }
        }
      }
    }

    if ((cbp & 0x30)) {
      for (i=0; i < 2; ++i) {
        if (svq3_decode_block (&s->gb, &h->mb[16*(16 + 4*i)], 0, 3)){
          av_log(h->s.avctx, AV_LOG_ERROR, "error while decoding chroma dc block\n");
          return -1;
        }
      }

      if ((cbp & 0x20)) {
        for (i=0; i < 8; i++) {
          h->non_zero_count_cache[ scan8[16+i] ] = 1;

          if (svq3_decode_block (&s->gb, &h->mb[16*(16 + i)], 1, 1)){
            av_log(h->s.avctx, AV_LOG_ERROR, "error while decoding chroma ac block\n");
            return -1;
          }
        }
      }
    }
  }

  s->current_picture.mb_type[mb_xy] = mb_type;

  if (IS_INTRA(mb_type)) {
    h->chroma_pred_mode = check_intra_pred_mode (h, DC_PRED8x8);
  }

  return 0;
}

static int svq3_decode_slice_header (H264Context *h) {
  MpegEncContext *const s = (MpegEncContext *) h;
  const int mb_xy = s->mb_x + s->mb_y*s->mb_stride;
  int i, header;

  header = get_bits (&s->gb, 8);

  if (((header & 0x9F) != 1 && (header & 0x9F) != 2) || (header & 0x60) == 0) {
    /* TODO: what? */
    av_log(h->s.avctx, AV_LOG_ERROR, "unsupported slice header (%02X)\n", header);
    return -1;
  } else {
    int length = (header >> 5) & 3;

    h->next_slice_index = get_bits_count(&s->gb) + 8*show_bits (&s->gb, 8*length) + 8*length;

    if (h->next_slice_index > s->gb.size_in_bits){
      av_log(h->s.avctx, AV_LOG_ERROR, "slice after bitstream end\n");
      return -1;
    }

    s->gb.size_in_bits = h->next_slice_index - 8*(length - 1);
    skip_bits(&s->gb, 8);

    if (length > 0) {
      memcpy ((uint8_t *) &s->gb.buffer[get_bits_count(&s->gb) >> 3],
             &s->gb.buffer[s->gb.size_in_bits >> 3], (length - 1));
    }
  }

  if ((i = svq3_get_ue_golomb (&s->gb)) == INVALID_VLC || i >= 3){
    av_log(h->s.avctx, AV_LOG_ERROR, "illegal slice type %d \n", i);
    return -1;
  }

  h->slice_type = golomb_to_pict_type[i];

  if ((header & 0x9F) == 2) {
    i = (s->mb_num < 64) ? 6 : (1 + av_log2 (s->mb_num - 1));
    s->mb_skip_run = get_bits (&s->gb, i) - (s->mb_x + (s->mb_y * s->mb_width));
  } else {
    get_bits1 (&s->gb);
    s->mb_skip_run = 0;
  }

  h->slice_num = get_bits (&s->gb, 8);
  s->qscale = get_bits (&s->gb, 5);
  s->adaptive_quant = get_bits1 (&s->gb);

  /* unknown fields */
  get_bits1 (&s->gb);

  if (h->unknown_svq3_flag) {
    get_bits1 (&s->gb);
  }

  get_bits1 (&s->gb);
  get_bits (&s->gb, 2);

  while (get_bits1 (&s->gb)) {
    get_bits (&s->gb, 8);
  }

  /* reset intra predictors and invalidate motion vector references */
  if (s->mb_x > 0) {
    memset (h->intra4x4_pred_mode[mb_xy - 1], -1, 4*sizeof(int8_t));
    memset (h->intra4x4_pred_mode[mb_xy - s->mb_x], -1, 8*sizeof(int8_t)*s->mb_x);
  }
  if (s->mb_y > 0) {
    memset (h->intra4x4_pred_mode[mb_xy - s->mb_stride], -1, 8*sizeof(int8_t)*(s->mb_width - s->mb_x));

    if (s->mb_x > 0) {
      h->intra4x4_pred_mode[mb_xy - s->mb_stride - 1][3] = -1;
    }
  }

  return 0;
}

static int svq3_decode_frame (AVCodecContext *avctx,
                              void *data, int *data_size,
                              uint8_t *buf, int buf_size) {
  MpegEncContext *const s = avctx->priv_data;
  H264Context *const h = avctx->priv_data;
  int m, mb_type;
  unsigned char *extradata;
  unsigned int size;

  s->flags = avctx->flags;
  s->flags2 = avctx->flags2;
  s->unrestricted_mv = 1;

  if (!s->context_initialized) {
    s->width = avctx->width;
    s->height = avctx->height;
    h->pred4x4[DIAG_DOWN_LEFT_PRED] = pred4x4_down_left_svq3_c;
    h->pred16x16[PLANE_PRED8x8] = pred16x16_plane_svq3_c;
    h->halfpel_flag = 1;
    h->thirdpel_flag = 1;
    h->unknown_svq3_flag = 0;
    h->chroma_qp = 4;

    if (MPV_common_init (s) < 0)
      return -1;

    h->b_stride = 4*s->mb_width;

    alloc_tables (h);

    /* prowl for the "SEQH" marker in the extradata */
    extradata = (unsigned char *)avctx->extradata;
    for (m = 0; m < avctx->extradata_size; m++) {
      if (!memcmp (extradata, "SEQH", 4))
        break;
      extradata++;
    }

    /* if a match was found, parse the extra data */
    if (extradata && !memcmp (extradata, "SEQH", 4)) {

      GetBitContext gb;

      size = AV_RB32(&extradata[4]);
      init_get_bits (&gb, extradata + 8, size*8);

      /* 'frame size code' and optional 'width, height' */
      if (get_bits (&gb, 3) == 7) {
        get_bits (&gb, 12);
        get_bits (&gb, 12);
      }

      h->halfpel_flag = get_bits1 (&gb);
      h->thirdpel_flag = get_bits1 (&gb);

      /* unknown fields */
      get_bits1 (&gb);
      get_bits1 (&gb);
      get_bits1 (&gb);
      get_bits1 (&gb);

      s->low_delay = get_bits1 (&gb);

      /* unknown field */
      get_bits1 (&gb);

      while (get_bits1 (&gb)) {
        get_bits (&gb, 8);
      }

      h->unknown_svq3_flag = get_bits1 (&gb);
      avctx->has_b_frames = !s->low_delay;
    }
  }

  /* special case for last picture */
  if (buf_size == 0) {
    if (s->next_picture_ptr && !s->low_delay) {
      *(AVFrame *) data = *(AVFrame *) &s->next_picture;
      *data_size = sizeof(AVFrame);
    }
    return 0;
  }

  init_get_bits (&s->gb, buf, 8*buf_size);

  s->mb_x = s->mb_y = 0;

  if (svq3_decode_slice_header (h))
    return -1;

  s->pict_type = h->slice_type;
  s->picture_number = h->slice_num;

  if(avctx->debug&FF_DEBUG_PICT_INFO){
      av_log(h->s.avctx, AV_LOG_DEBUG, "%c hpel:%d, tpel:%d aqp:%d qp:%d\n",
      av_get_pict_type_char(s->pict_type), h->halfpel_flag, h->thirdpel_flag,
      s->adaptive_quant, s->qscale
      );
  }

  /* for hurry_up==5 */
  s->current_picture.pict_type = s->pict_type;
  s->current_picture.key_frame = (s->pict_type == I_TYPE);

  /* skip b frames if we dont have reference frames */
  if (s->last_picture_ptr == NULL && s->pict_type == B_TYPE) return 0;
  /* skip b frames if we are in a hurry */
  if (avctx->hurry_up && s->pict_type == B_TYPE) return 0;
  /* skip everything if we are in a hurry >= 5 */
  if (avctx->hurry_up >= 5) return 0;
  if(  (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==B_TYPE)
     ||(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=I_TYPE)
     || avctx->skip_frame >= AVDISCARD_ALL)
      return 0;

  if (s->next_p_frame_damaged) {
    if (s->pict_type == B_TYPE)
      return 0;
    else
      s->next_p_frame_damaged = 0;
  }

  if (frame_start (h) < 0)
    return -1;

  if (s->pict_type == B_TYPE) {
    h->frame_num_offset = (h->slice_num - h->prev_frame_num);

    if (h->frame_num_offset < 0) {
      h->frame_num_offset += 256;
    }
    if (h->frame_num_offset == 0 || h->frame_num_offset >= h->prev_frame_num_offset) {
      av_log(h->s.avctx, AV_LOG_ERROR, "error in B-frame picture id\n");
      return -1;
    }
  } else {
    h->prev_frame_num = h->frame_num;
    h->frame_num = h->slice_num;
    h->prev_frame_num_offset = (h->frame_num - h->prev_frame_num);

    if (h->prev_frame_num_offset < 0) {
      h->prev_frame_num_offset += 256;
    }
  }

  for(m=0; m<2; m++){
    int i;
    for(i=0; i<4; i++){
      int j;
      for(j=-1; j<4; j++)
        h->ref_cache[m][scan8[0] + 8*i + j]= 1;
      h->ref_cache[m][scan8[0] + 8*i + j]= PART_NOT_AVAILABLE;
    }
  }

  for (s->mb_y=0; s->mb_y < s->mb_height; s->mb_y++) {
    for (s->mb_x=0; s->mb_x < s->mb_width; s->mb_x++) {

      if ( (get_bits_count(&s->gb) + 7) >= s->gb.size_in_bits &&
          ((get_bits_count(&s->gb) & 7) == 0 || show_bits (&s->gb, (-get_bits_count(&s->gb) & 7)) == 0)) {

        skip_bits(&s->gb, h->next_slice_index - get_bits_count(&s->gb));
        s->gb.size_in_bits = 8*buf_size;

        if (svq3_decode_slice_header (h))
          return -1;

        /* TODO: support s->mb_skip_run */
      }

      mb_type = svq3_get_ue_golomb (&s->gb);

      if (s->pict_type == I_TYPE) {
        mb_type += 8;
      } else if (s->pict_type == B_TYPE && mb_type >= 4) {
        mb_type += 4;
      }
      if (mb_type > 33 || svq3_decode_mb (h, mb_type)) {
        av_log(h->s.avctx, AV_LOG_ERROR, "error while decoding MB %d %d\n", s->mb_x, s->mb_y);
        return -1;
      }

      if (mb_type != 0) {
        hl_decode_mb (h);
      }

      if (s->pict_type != B_TYPE && !s->low_delay) {
        s->current_picture.mb_type[s->mb_x + s->mb_y*s->mb_stride] =
                        (s->pict_type == P_TYPE && mb_type < 8) ? (mb_type - 1) : -1;
      }
    }

    ff_draw_horiz_band(s, 16*s->mb_y, 16);
  }

  MPV_frame_end(s);

  if (s->pict_type == B_TYPE || s->low_delay) {
    *(AVFrame *) data = *(AVFrame *) &s->current_picture;
  } else {
    *(AVFrame *) data = *(AVFrame *) &s->last_picture;
  }

  avctx->frame_number = s->picture_number - 1;

  /* dont output the last pic after seeking */
  if (s->last_picture_ptr || s->low_delay) {
    *data_size = sizeof(AVFrame);
  }

  return buf_size;
}


AVCodec svq3_decoder = {
    "svq3",
    CODEC_TYPE_VIDEO,
    CODEC_ID_SVQ3,
    sizeof(H264Context),
    decode_init,
    NULL,
    decode_end,
    svq3_decode_frame,
    CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_DELAY,
};