vc1dec: interlaced stream decoding support 3/3

Cosmetics: break some lines and reformat TODOs

Signed-off-by: Anton Khirnov <anton@khirnov.net>

1 files changed, 291 insertions, 107 deletions

diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index 870feaaa76..11d1d58e44 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -1,5 +1,6 @@
 /*
  * VC-1 and WMV3 decoder common code
+ * Copyright (c) 2011 Mashiat Sarker Shakkhar
  * Copyright (c) 2006-2007 Konstantin Shishkov
  * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
  *
@@ -116,7 +117,7 @@ static int bitplane_decoding(uint8_t* data, int *raw_flag, VC1Context *v)
     int width, height, stride;
 
     width = v->s.mb_width;
-    height = v->s.mb_height;
+    height = v->s.mb_height >> v->field_mode;
     stride = v->s.mb_stride;
     invert = get_bits1(gb);
     imode = get_vlc2(gb, ff_vc1_imode_vlc.table, VC1_IMODE_VLC_BITS, 1);
@@ -682,6 +683,7 @@ int vc1_parse_frame_header(VC1Context *v, GetBitContext* gb)
                 v->lutuv[i] = av_clip_uint8((scale * (i - 128) + 128*64 + 32) >> 6);
             }
         }
+        v->qs_last = v->s.quarter_sample;
         if(v->mv_mode == MV_PMODE_1MV_HPEL || v->mv_mode == MV_PMODE_1MV_HPEL_BILIN)
             v->s.quarter_sample = 0;
         else if(v->mv_mode == MV_PMODE_INTENSITY_COMP) {
@@ -739,6 +741,7 @@ int vc1_parse_frame_header(VC1Context *v, GetBitContext* gb)
         else v->tt_index = 2;
 
         v->mv_mode = get_bits1(gb) ? MV_PMODE_1MV : MV_PMODE_1MV_HPEL_BILIN;
+        v->qs_last = v->s.quarter_sample;
         v->s.quarter_sample = (v->mv_mode == MV_PMODE_1MV);
         v->s.mspel = v->s.quarter_sample;
 
@@ -794,38 +797,78 @@ int vc1_parse_frame_header(VC1Context *v, GetBitContext* gb)
     return 0;
 }
 
+/* fill lookup tables for intensity compensation */
+#define INIT_LUT(lumscale, lumshift, luty, lutuv)   \
+    if (!lumscale) {                                \
+        scale = -64;                                \
+        shift = (255 - lumshift * 2) << 6;          \
+        if (lumshift > 31)                          \
+            shift += 128 << 6;                      \
+    } else {                                        \
+        scale = lumscale + 32;                      \
+        if (lumshift > 31)                          \
+            shift = (lumshift - 64) << 6;           \
+        else                                        \
+            shift = lumshift << 6;                  \
+    }                                               \
+    for (i = 0; i < 256; i++) {                     \
+        luty[i]  = av_clip_uint8((scale * i + shift + 32) >> 6);           \
+        lutuv[i] = av_clip_uint8((scale * (i - 128) + 128*64 + 32) >> 6);  \
+    }
+
 int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
 {
     int pqindex, lowquant;
     int status;
+    int mbmodetab, imvtab, icbptab, twomvbptab, fourmvbptab; /* useful only for debugging */
+    int scale, shift, i; /* for initializing LUT for intensity compensation */
 
     v->p_frame_skipped = 0;
+    if (v->second_field) {
+        v->s.pict_type = (v->fptype & 1) ? AV_PICTURE_TYPE_P : AV_PICTURE_TYPE_I;
+        if (v->fptype & 4)
+            v->s.pict_type = (v->fptype & 1) ? AV_PICTURE_TYPE_BI : AV_PICTURE_TYPE_B;
+        v->s.current_picture_ptr->f.pict_type = v->s.pict_type;
+        if (!v->pic_header_flag)
+            goto parse_common_info;
+    }
 
     if(v->interlace){
         v->fcm = decode012(gb);
         if(v->fcm){
-            if(!v->warn_interlaced++)
-                av_log(v->s.avctx, AV_LOG_ERROR, "Interlaced frames/fields support is not implemented\n");
-            return -1;
+            if (v->fcm == 2)
+                v->field_mode = 1;
+            else
+                v->field_mode = 0;
+            if (!v->warn_interlaced++)
+                av_log(v->s.avctx, AV_LOG_ERROR, "Interlaced frames/fields support is incomplete\n");
         }
     }
-    switch(get_unary(gb, 0, 4)) {
-    case 0:
-        v->s.pict_type = AV_PICTURE_TYPE_P;
-        break;
-    case 1:
-        v->s.pict_type = AV_PICTURE_TYPE_B;
-        break;
-    case 2:
-        v->s.pict_type = AV_PICTURE_TYPE_I;
-        break;
-    case 3:
-        v->s.pict_type = AV_PICTURE_TYPE_BI;
-        break;
-    case 4:
-        v->s.pict_type = AV_PICTURE_TYPE_P; // skipped pic
-        v->p_frame_skipped = 1;
-        break;
+
+    if (v->field_mode) {
+        v->fptype = get_bits(gb, 3);
+        v->s.pict_type = (v->fptype & 2) ? AV_PICTURE_TYPE_P : AV_PICTURE_TYPE_I;
+        if (v->fptype & 4) // B-picture
+            v->s.pict_type = (v->fptype & 2) ? AV_PICTURE_TYPE_BI : AV_PICTURE_TYPE_B;
+    } else {
+        switch(get_unary(gb, 0, 4)) {
+        case 0:
+            v->s.pict_type = AV_PICTURE_TYPE_P;
+            break;
+        case 1:
+            v->s.pict_type = AV_PICTURE_TYPE_B;
+            break;
+        case 2:
+            v->s.pict_type = AV_PICTURE_TYPE_I;
+            break;
+        case 3:
+            v->s.pict_type = AV_PICTURE_TYPE_BI;
+            break;
+        case 4:
+            v->s.pict_type = AV_PICTURE_TYPE_P; // skipped pic
+            v->p_frame_skipped = 1;
+            break;
+        }
     }
     if(v->tfcntrflag)
         skip_bits(gb, 8);
@@ -847,6 +890,26 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
     v->rnd = get_bits1(gb);
     if(v->interlace)
         v->uvsamp = get_bits1(gb);
+    if (v->field_mode) {
+        if (!v->refdist_flag)
+            v->refdist = 0;
+        else {
+            if ((v->s.pict_type != AV_PICTURE_TYPE_B)
+                && (v->s.pict_type != AV_PICTURE_TYPE_BI)) {
+                v->refdist = get_bits(gb, 2);
+                if (v->refdist == 3)
+                    v->refdist += get_unary(gb, 0, 16);
+            } else {
+                v->bfraction_lut_index = get_vlc2(gb, ff_vc1_bfraction_vlc.table, VC1_BFRACTION_VLC_BITS, 1);
+                v->bfraction = ff_vc1_bfraction_lut[v->bfraction_lut_index];
+                v->frfd = (v->bfraction * v->refdist) >> 8;
+                v->brfd = v->refdist - v->frfd - 1;
+                if (v->brfd < 0)
+                    v->brfd = 0;
+            }
+        }
+        goto parse_common_info;
+    }
     if(v->finterpflag) v->interpfrm = get_bits1(gb);
     if(v->s.pict_type == AV_PICTURE_TYPE_B) {
         v->bfraction_lut_index = get_vlc2(gb, ff_vc1_bfraction_vlc.table, VC1_BFRACTION_VLC_BITS, 1);
@@ -855,6 +918,10 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
             v->s.pict_type = AV_PICTURE_TYPE_BI; /* XXX: should not happen here */
         }
     }
+
+    parse_common_info:
+    if (v->field_mode)
+        v->cur_field_type = !(v->tff ^ v->second_field);
     pqindex = get_bits(gb, 5);
     if(!pqindex) return -1;
     v->pqindex = pqindex;
@@ -869,23 +936,34 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
     if (v->quantizer_mode == QUANT_NON_UNIFORM)
         v->pquantizer = 0;
     v->pqindex = pqindex;
-    if (pqindex < 9) v->halfpq = get_bits1(gb);
-    else v->halfpq = 0;
+    if (pqindex < 9)
+        v->halfpq = get_bits1(gb);
+    else
+        v->halfpq = 0;
     if (v->quantizer_mode == QUANT_FRAME_EXPLICIT)
         v->pquantizer = get_bits1(gb);
     if(v->postprocflag)
         v->postproc = get_bits(gb, 2);
 
-    if(v->s.pict_type == AV_PICTURE_TYPE_I || v->s.pict_type == AV_PICTURE_TYPE_P) v->use_ic = 0;
+    if(v->s.pict_type == AV_PICTURE_TYPE_I || v->s.pict_type == AV_PICTURE_TYPE_P)
+        v->use_ic = 0;
 
-    if(v->parse_only)
+    if (v->parse_only)
         return 0;
 
     switch(v->s.pict_type) {
     case AV_PICTURE_TYPE_I:
     case AV_PICTURE_TYPE_BI:
+        if (v->fcm == 1) { //interlace frame picture
+            status = bitplane_decoding(v->fieldtx_plane, &v->fieldtx_is_raw, v);
+            if (status < 0)
+                return -1;
+            av_log(v->s.avctx, AV_LOG_DEBUG, "FIELDTX plane encoding: "
+                   "Imode: %i, Invert: %i\n", status>>1, status&1);
+        }
         status = bitplane_decoding(v->acpred_plane, &v->acpred_is_raw, v);
-        if (status < 0) return -1;
+        if (status < 0)
+            return -1;
         av_log(v->s.avctx, AV_LOG_DEBUG, "ACPRED plane encoding: "
                 "Imode: %i, Invert: %i\n", status>>1, status&1);
         v->condover = CONDOVER_NONE;
@@ -893,82 +971,148 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
             v->condover = decode012(gb);
             if(v->condover == CONDOVER_SELECT) {
                 status = bitplane_decoding(v->over_flags_plane, &v->overflg_is_raw, v);
-                if (status < 0) return -1;
+                if (status < 0)
+                    return -1;
                 av_log(v->s.avctx, AV_LOG_DEBUG, "CONDOVER plane encoding: "
                         "Imode: %i, Invert: %i\n", status>>1, status&1);
             }
         }
         break;
     case AV_PICTURE_TYPE_P:
-        if (v->extended_mv) v->mvrange = get_unary(gb, 0, 3);
-        else v->mvrange = 0;
+        if (v->field_mode) {
+            v->numref = get_bits1(gb);
+            if (!v->numref) {
+                v->reffield = get_bits1(gb);
+                v->ref_field_type[0] = v->reffield ^ !v->cur_field_type;
+            }
+        }
+        if (v->extended_mv)
+            v->mvrange = get_unary(gb, 0, 3);
+        else
+            v->mvrange = 0;
+        if (v->interlace) {
+            if (v->extended_dmv)
+                v->dmvrange = get_unary(gb, 0, 3);
+            else
+                v->dmvrange = 0;
+            if (v->fcm == 1) { // interlaced frame picture
+                v->fourmvswitch = get_bits1(gb);
+                v->intcomp = get_bits1(gb);
+                if (v->intcomp) {
+                    v->lumscale = get_bits(gb, 6);
+                    v->lumshift = get_bits(gb, 6);
+                    INIT_LUT(v->lumscale, v->lumshift, v->luty, v->lutuv);
+                }
+                status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
+                av_log(v->s.avctx, AV_LOG_DEBUG, "SKIPMB plane encoding: "
+                    "Imode: %i, Invert: %i\n", status>>1, status&1);
+                mbmodetab = get_bits(gb, 2);
+                if (v->fourmvswitch)
+                    v->mbmode_vlc = &ff_vc1_intfr_4mv_mbmode_vlc[mbmodetab];
+                else
+                    v->mbmode_vlc = &ff_vc1_intfr_non4mv_mbmode_vlc[mbmodetab];
+                imvtab = get_bits(gb, 2);
+                v->imv_vlc = &ff_vc1_1ref_mvdata_vlc[imvtab];
+                // interlaced p-picture cbpcy range is [1, 63]
+                icbptab = get_bits(gb, 3);
+                v->cbpcy_vlc = &ff_vc1_icbpcy_vlc[icbptab];
+                twomvbptab = get_bits(gb, 2);
+                v->twomvbp_vlc = &ff_vc1_2mv_block_pattern_vlc[twomvbptab];
+                if (v->fourmvswitch) {
+                    fourmvbptab = get_bits(gb, 2);
+                    v->fourmvbp_vlc = &ff_vc1_4mv_block_pattern_vlc[fourmvbptab];
+                }
+            }
+        }
         v->k_x = v->mvrange + 9 + (v->mvrange >> 1); //k_x can be 9 10 12 13
         v->k_y = v->mvrange + 8; //k_y can be 8 9 10 11
         v->range_x = 1 << (v->k_x - 1);
         v->range_y = 1 << (v->k_y - 1);
 
-        if (v->pq < 5) v->tt_index = 0;
-        else if(v->pq < 13) v->tt_index = 1;
-        else v->tt_index = 2;
-
-        lowquant = (v->pq > 12) ? 0 : 1;
-        v->mv_mode = ff_vc1_mv_pmode_table[lowquant][get_unary(gb, 1, 4)];
-        if (v->mv_mode == MV_PMODE_INTENSITY_COMP)
-        {
-            int scale, shift, i;
-            v->mv_mode2 = ff_vc1_mv_pmode_table2[lowquant][get_unary(gb, 1, 3)];
-            v->lumscale = get_bits(gb, 6);
-            v->lumshift = get_bits(gb, 6);
-            /* fill lookup tables for intensity compensation */
-            if(!v->lumscale) {
-                scale = -64;
-                shift = (255 - v->lumshift * 2) << 6;
-                if(v->lumshift > 31)
-                    shift += 128 << 6;
-            } else {
-                scale = v->lumscale + 32;
-                if(v->lumshift > 31)
-                    shift = (v->lumshift - 64) << 6;
-                else
-                    shift = v->lumshift << 6;
-            }
-            for(i = 0; i < 256; i++) {
-                v->luty[i] = av_clip_uint8((scale * i + shift + 32) >> 6);
-                v->lutuv[i] = av_clip_uint8((scale * (i - 128) + 128*64 + 32) >> 6);
+        if (v->pq < 5)
+            v->tt_index = 0;
+        else if(v->pq < 13)
+            v->tt_index = 1;
+        else
+            v->tt_index = 2;
+        if (v->fcm != 1) {
+            int mvmode;
+            mvmode = get_unary(gb, 1, 4);
+            lowquant = (v->pq > 12) ? 0 : 1;
+            v->mv_mode = ff_vc1_mv_pmode_table[lowquant][mvmode];
+            if (v->mv_mode == MV_PMODE_INTENSITY_COMP) {
+                int mvmode2;
+                mvmode2 = get_unary(gb, 1, 3);
+                v->mv_mode2 = ff_vc1_mv_pmode_table2[lowquant][mvmode2];
+                if (v->field_mode)
+                    v->intcompfield = decode210(gb);
+                v->lumscale = get_bits(gb, 6);
+                v->lumshift = get_bits(gb, 6);
+                INIT_LUT(v->lumscale, v->lumshift, v->luty, v->lutuv);
+                if ((v->field_mode) && !v->intcompfield) {
+                    v->lumscale2 = get_bits(gb, 6);
+                    v->lumshift2 = get_bits(gb, 6);
+                    INIT_LUT(v->lumscale2, v->lumshift2, v->luty2, v->lutuv2);
+                }
+                v->use_ic = 1;
             }
-            v->use_ic = 1;
-        }
-        if(v->mv_mode == MV_PMODE_1MV_HPEL || v->mv_mode == MV_PMODE_1MV_HPEL_BILIN)
-            v->s.quarter_sample = 0;
-        else if(v->mv_mode == MV_PMODE_INTENSITY_COMP) {
-            if(v->mv_mode2 == MV_PMODE_1MV_HPEL || v->mv_mode2 == MV_PMODE_1MV_HPEL_BILIN)
+            v->qs_last = v->s.quarter_sample;
+            if(v->mv_mode == MV_PMODE_1MV_HPEL || v->mv_mode == MV_PMODE_1MV_HPEL_BILIN)
                 v->s.quarter_sample = 0;
-            else
+            else if(v->mv_mode == MV_PMODE_INTENSITY_COMP) {
+                if(v->mv_mode2 == MV_PMODE_1MV_HPEL || v->mv_mode2 == MV_PMODE_1MV_HPEL_BILIN)
+                    v->s.quarter_sample = 0;
+                else
+                    v->s.quarter_sample = 1;
+            } else
                 v->s.quarter_sample = 1;
-        } else
-            v->s.quarter_sample = 1;
-        v->s.mspel = !(v->mv_mode == MV_PMODE_1MV_HPEL_BILIN || (v->mv_mode == MV_PMODE_INTENSITY_COMP && v->mv_mode2 == MV_PMODE_1MV_HPEL_BILIN));
-
-        if ((v->mv_mode == MV_PMODE_INTENSITY_COMP &&
-                 v->mv_mode2 == MV_PMODE_MIXED_MV)
+            v->s.mspel = !(v->mv_mode == MV_PMODE_1MV_HPEL_BILIN || (v->mv_mode == MV_PMODE_INTENSITY_COMP && v->mv_mode2 == MV_PMODE_1MV_HPEL_BILIN));
+        }
+        if (v->fcm == 0) { // progressive
+            if ((v->mv_mode == MV_PMODE_INTENSITY_COMP &&
+                v->mv_mode2 == MV_PMODE_MIXED_MV)
                 || v->mv_mode == MV_PMODE_MIXED_MV)
-        {
-            status = bitplane_decoding(v->mv_type_mb_plane, &v->mv_type_is_raw, v);
-            if (status < 0) return -1;
-            av_log(v->s.avctx, AV_LOG_DEBUG, "MB MV Type plane encoding: "
-                   "Imode: %i, Invert: %i\n", status>>1, status&1);
-        } else {
-            v->mv_type_is_raw = 0;
-            memset(v->mv_type_mb_plane, 0, v->s.mb_stride * v->s.mb_height);
+            {
+                status = bitplane_decoding(v->mv_type_mb_plane, &v->mv_type_is_raw, v);
+                if (status < 0)
+                    return -1;
+                av_log(v->s.avctx, AV_LOG_DEBUG, "MB MV Type plane encoding: "
+                    "Imode: %i, Invert: %i\n", status>>1, status&1);
+            } else {
+                v->mv_type_is_raw = 0;
+                memset(v->mv_type_mb_plane, 0, v->s.mb_stride * v->s.mb_height);
+            }
+            status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
+            if (status < 0)
+                return -1;
+            av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
+                    "Imode: %i, Invert: %i\n", status>>1, status&1);
+
+            /* Hopefully this is correct for P frames */
+            v->s.mv_table_index = get_bits(gb, 2); //but using ff_vc1_ tables
+            v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];
+        } else if (v->fcm == 1) { // frame interlaced
+            v->qs_last = v->s.quarter_sample;
+            v->s.quarter_sample = 1;
+            v->s.mspel = 1;
+        } else {    // field interlaced
+            mbmodetab = get_bits(gb, 3);
+            imvtab = get_bits(gb, 2 + v->numref);
+            if (!v->numref)
+                v->imv_vlc = &ff_vc1_1ref_mvdata_vlc[imvtab];
+            else
+                v->imv_vlc = &ff_vc1_2ref_mvdata_vlc[imvtab];
+            icbptab = get_bits(gb, 3);
+            v->cbpcy_vlc = &ff_vc1_icbpcy_vlc[icbptab];
+            if ((v->mv_mode == MV_PMODE_INTENSITY_COMP &&
+                v->mv_mode2 == MV_PMODE_MIXED_MV) || v->mv_mode == MV_PMODE_MIXED_MV) {
+                fourmvbptab = get_bits(gb, 2);
+                v->fourmvbp_vlc = &ff_vc1_4mv_block_pattern_vlc[fourmvbptab];
+                v->mbmode_vlc = &ff_vc1_if_mmv_mbmode_vlc[mbmodetab];
+            } else {
+                v->mbmode_vlc = &ff_vc1_if_1mv_mbmode_vlc[mbmodetab];
+            }
         }
-        status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
-        if (status < 0) return -1;
-        av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
-               "Imode: %i, Invert: %i\n", status>>1, status&1);
-
-        /* Hopefully this is correct for P frames */
-        v->s.mv_table_index = get_bits(gb, 2); //but using ff_vc1_ tables
-        v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];
         if (v->dquant)
         {
             av_log(v->s.avctx, AV_LOG_DEBUG, "VOP DQuant info\n");
@@ -989,32 +1133,72 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
         }
         break;
     case AV_PICTURE_TYPE_B:
-        if (v->extended_mv) v->mvrange = get_unary(gb, 0, 3);
-        else v->mvrange = 0;
+        // TODO: implement interlaced frame B picture decoding
+        if (v->fcm == 1)
+            return -1;
+        if (v->extended_mv)
+            v->mvrange = get_unary(gb, 0, 3);
+        else
+            v->mvrange = 0;
         v->k_x = v->mvrange + 9 + (v->mvrange >> 1); //k_x can be 9 10 12 13
         v->k_y = v->mvrange + 8; //k_y can be 8 9 10 11
         v->range_x = 1 << (v->k_x - 1);
         v->range_y = 1 << (v->k_y - 1);
 
-        if (v->pq < 5) v->tt_index = 0;
-        else if(v->pq < 13) v->tt_index = 1;
-        else v->tt_index = 2;
-
-        v->mv_mode = get_bits1(gb) ? MV_PMODE_1MV : MV_PMODE_1MV_HPEL_BILIN;
-        v->s.quarter_sample = (v->mv_mode == MV_PMODE_1MV);
-        v->s.mspel = v->s.quarter_sample;
-
-        status = bitplane_decoding(v->direct_mb_plane, &v->dmb_is_raw, v);
-        if (status < 0) return -1;
-        av_log(v->s.avctx, AV_LOG_DEBUG, "MB Direct Type plane encoding: "
-               "Imode: %i, Invert: %i\n", status>>1, status&1);
-        status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
-        if (status < 0) return -1;
-        av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
-               "Imode: %i, Invert: %i\n", status>>1, status&1);
-
-        v->s.mv_table_index = get_bits(gb, 2);
-        v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];
+        if (v->pq < 5)
+            v->tt_index = 0;
+        else if(v->pq < 13)
+            v->tt_index = 1;
+        else
+            v->tt_index = 2;
+
+        if (v->field_mode) {
+            int mvmode;
+            if (v->extended_dmv)
+                v->dmvrange = get_unary(gb, 0, 3);
+            mvmode = get_unary(gb, 1, 3);
+            lowquant = (v->pq > 12) ? 0 : 1;
+            v->mv_mode = ff_vc1_mv_pmode_table2[lowquant][mvmode];
+            v->qs_last = v->s.quarter_sample;
+            v->s.quarter_sample = (v->mv_mode == MV_PMODE_1MV || v->mv_mode == MV_PMODE_MIXED_MV);
+            v->s.mspel = !(v->mv_mode == MV_PMODE_1MV_HPEL_BILIN || v->mv_mode == MV_PMODE_1MV_HPEL);
+            status = bitplane_decoding(v->forward_mb_plane, &v->fmb_is_raw, v);
+            if (status < 0)
+                return -1;
+            av_log(v->s.avctx, AV_LOG_DEBUG, "MB Forward Type plane encoding: "
+                   "Imode: %i, Invert: %i\n", status>>1, status&1);
+            mbmodetab = get_bits(gb, 3);
+            if (v->mv_mode == MV_PMODE_MIXED_MV)
+                v->mbmode_vlc = &ff_vc1_if_mmv_mbmode_vlc[mbmodetab];
+            else
+                v->mbmode_vlc = &ff_vc1_if_1mv_mbmode_vlc[mbmodetab];
+            imvtab = get_bits(gb, 3);
+            v->imv_vlc = &ff_vc1_2ref_mvdata_vlc[imvtab];
+            icbptab = get_bits(gb, 3);
+            v->cbpcy_vlc = &ff_vc1_icbpcy_vlc[icbptab];
+            if (v->mv_mode == MV_PMODE_MIXED_MV) {
+                fourmvbptab = get_bits(gb, 2);
+                v->fourmvbp_vlc = &ff_vc1_4mv_block_pattern_vlc[fourmvbptab];
+            }
+            v->numref = 1; // interlaced field B pictures are always 2-ref
+        } else {
+            v->mv_mode = get_bits1(gb) ? MV_PMODE_1MV : MV_PMODE_1MV_HPEL_BILIN;
+            v->qs_last = v->s.quarter_sample;
+            v->s.quarter_sample = (v->mv_mode == MV_PMODE_1MV);
+            v->s.mspel = v->s.quarter_sample;
+            status = bitplane_decoding(v->direct_mb_plane, &v->dmb_is_raw, v);
+            if (status < 0)
+                return -1;
+            av_log(v->s.avctx, AV_LOG_DEBUG, "MB Direct Type plane encoding: "
+                   "Imode: %i, Invert: %i\n", status>>1, status&1);
+            status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
+            if (status < 0)
+                return -1;
+            av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
+                   "Imode: %i, Invert: %i\n", status>>1, status&1);
+            v->s.mv_table_index = get_bits(gb, 2);
+            v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];
+        }
 
         if (v->dquant)
         {