vc1: use an enum for Frame Coding Mode

Document it a little and possibly fix a bug in dxva2_vc1.

libavcodec/dxva2_vc1.c

@@ -68,7 +68,7 @@ static void fill_picture_parameters(AVCodecContext *avctx,
         pp->bPicStructure      |= 0x01;
     if (s->picture_structure & PICT_BOTTOM_FIELD)
         pp->bPicStructure      |= 0x02;
-    pp->bSecondField            = v->interlace && v->fcm != 0x03 && !s->first_field;
+    pp->bSecondField            = v->interlace && v->fcm != ILACE_FIELD && !s->first_field;
     pp->bPicIntra               = s->pict_type == AV_PICTURE_TYPE_I;
     pp->bPicBackwardPrediction  = s->pict_type == AV_PICTURE_TYPE_B;
     pp->bBidirectionalAveragingMode = (1                                           << 7) |
@@ -100,7 +100,7 @@ static void fill_picture_parameters(AVCodecContext *avctx,
                                   (s->resync_marker  << 4) |
                                   (v->rangered       << 3) |
                                   (s->max_b_frames       );
-    pp->bPicExtrapolation       = (!v->interlace || v->fcm == 0x00) ? 1 : 2;
+    pp->bPicExtrapolation       = (!v->interlace || v->fcm == PROGRESSIVE) ? 1 : 2;
     pp->bPicDeblocked           = ((v->profile != PROFILE_ADVANCED && v->rangeredfrm) << 5) |
                                   (s->loop_filter                                     << 1);
     pp->bPicDeblockConfined     = (v->postprocflag             << 7) |

libavcodec/vc1.c

@@ -836,14 +836,14 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
     if (v->interlace) {
         v->fcm = decode012(gb);
         if (v->fcm) {
-            if (v->fcm == 2)
+            if (v->fcm == ILACE_FIELD)
                 v->field_mode = 1;
             if (!v->warn_interlaced++)
                 av_log(v->s.avctx, AV_LOG_ERROR,
                        "Interlaced frames/fields support is incomplete\n");
         }
     } else {
-        v->fcm = 0;
+        v->fcm = PROGRESSIVE;
     }
 
     if (v->field_mode) {
@@ -957,7 +957,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
     switch (v->s.pict_type) {
     case AV_PICTURE_TYPE_I:
     case AV_PICTURE_TYPE_BI:
-        if (v->fcm == 1) { //interlace frame picture
+        if (v->fcm == ILACE_FRAME) { //interlace frame picture
             status = bitplane_decoding(v->fieldtx_plane, &v->fieldtx_is_raw, v);
             if (status < 0)
                 return -1;
@@ -998,7 +998,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
                 v->dmvrange = get_unary(gb, 0, 3);
             else
                 v->dmvrange = 0;
-            if (v->fcm == 1) { // interlaced frame picture
+            if (v->fcm == ILACE_FRAME) { // interlaced frame picture
                 v->fourmvswitch = get_bits1(gb);
                 v->intcomp      = get_bits1(gb);
                 if (v->intcomp) {
@@ -1038,7 +1038,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
             v->tt_index = 1;
         else
             v->tt_index = 2;
-        if (v->fcm != 1) {
+        if (v->fcm != ILACE_FRAME) {
             int mvmode;
             mvmode     = get_unary(gb, 1, 4);
             lowquant   = (v->pq > 12) ? 0 : 1;
@@ -1073,7 +1073,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
                            || (v->mv_mode == MV_PMODE_INTENSITY_COMP
                                && v->mv_mode2 == MV_PMODE_1MV_HPEL_BILIN));
         }
-        if (v->fcm == 0) { // progressive
+        if (v->fcm == PROGRESSIVE) { // progressive
             if ((v->mv_mode == MV_PMODE_INTENSITY_COMP &&
                  v->mv_mode2 == MV_PMODE_MIXED_MV)
                 || v->mv_mode == MV_PMODE_MIXED_MV) {
@@ -1095,7 +1095,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
             /* 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
+        } else if (v->fcm == ILACE_FRAME) { // frame interlaced
             v->qs_last          = v->s.quarter_sample;
             v->s.quarter_sample = 1;
             v->s.mspel          = 1;
@@ -1135,7 +1135,7 @@ int vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
         break;
     case AV_PICTURE_TYPE_B:
         // TODO: implement interlaced frame B picture decoding
-        if (v->fcm == 1)
+        if (v->fcm == ILACE_FRAME)
             return -1;
         if (v->extended_mv)
             v->mvrange = get_unary(gb, 0, 3);

libavcodec/vc1.h

@@ -161,6 +161,16 @@ enum COTypes {
 };
 //@}
 
+/**
+ * FCM Frame Coding Mode
+ * @note some content might be marked interlaced
+ * but have fcm set to 0 as well (e.g. HD-DVD)
+ */
+enum FrameCodingMode {
+    PROGRESSIVE = 0,    ///<  in the bitstream is reported as 00b
+    ILACE_FRAME,        ///<  in the bitstream is reported as 10b
+    ILACE_FIELD         ///<  in the bitstream is reported as 11b
+};
 
 /** The VC1 Context
  * @todo Change size wherever another size is more efficient
@@ -296,7 +306,7 @@ typedef struct VC1Context{
 
     /** Frame decoding info for Advanced profile */
     //@{
-    uint8_t fcm; ///< 0->Progressive, 2->Frame-Interlace, 3->Field-Interlace
+    enum FrameCodingMode fcm;
     uint8_t numpanscanwin;
     uint8_t tfcntr;
     uint8_t rptfrm, tff, rff;

libavcodec/vc1dec.c

@@ -501,7 +501,8 @@ static void vc1_mc_1mv(VC1Context *v, int dir)
         uvmy = uvmy - 2 + 4 * v->cur_field_type;
     }
 
-    if (v->fastuvmc && (v->fcm != 1)) { // fastuvmc shall be ignored for interlaced frame picture
+    // fastuvmc shall be ignored for interlaced frame picture
+    if (v->fastuvmc && (v->fcm != ILACE_FRAME)) {
         uvmx = uvmx + ((uvmx < 0) ? (uvmx & 1) : -(uvmx & 1));
         uvmy = uvmy + ((uvmy < 0) ? (uvmy & 1) : -(uvmy & 1));
     }
@@ -685,7 +686,7 @@ static void vc1_mc_4mv_luma(VC1Context *v, int n, int dir)
     uint8_t *srcY;
     int dxy, mx, my, src_x, src_y;
     int off;
-    int fieldmv = (v->fcm == 1) ? v->blk_mv_type[s->block_index[n]] : 0;
+    int fieldmv = (v->fcm == ILACE_FRAME) ? v->blk_mv_type[s->block_index[n]] : 0;
     int v_edge_pos = s->v_edge_pos >> v->field_mode;
 
     if (!v->field_mode && !v->s.last_picture.f.data[0])
@@ -744,7 +745,7 @@ static void vc1_mc_4mv_luma(VC1Context *v, int n, int dir)
             v->mv_f[1][s->block_index[k] + v->blocks_off] = f;
     }
 
-    if (v->fcm == 1) {  // not sure if needed for other types of picture
+    if (v->fcm == ILACE_FRAME) {  // not sure if needed for other types of picture
         int qx, qy;
         int width  = s->avctx->coded_width;
         int height = s->avctx->coded_height >> 1;
@@ -761,7 +762,7 @@ static void vc1_mc_4mv_luma(VC1Context *v, int n, int dir)
             my -= 8 * (qy - height - 1);
     }
 
-    if ((v->fcm == 1) && fieldmv)
+    if ((v->fcm == ILACE_FRAME) && fieldmv)
         off = ((n > 1) ? s->linesize : 0) + (n & 1) * 8;
     else
         off = s->linesize * 4 * (n & 2) + (n & 1) * 8;
@@ -779,7 +780,7 @@ static void vc1_mc_4mv_luma(VC1Context *v, int n, int dir)
         src_y = av_clip(src_y, -16, s->mb_height * 16);
     } else {
         src_x = av_clip(src_x, -17, s->avctx->coded_width);
-        if (v->fcm == 1) {
+        if (v->fcm == ILACE_FRAME) {
             if (src_y & 1)
                 src_y = av_clip(src_y, -17, s->avctx->coded_height + 1);
             else
@@ -2917,7 +2918,7 @@ static int vc1_decode_i_block_adv(VC1Context *v, DCTELEM block[64], int n,
         int k;
 
         if (v->s.ac_pred) {
-            if (!use_pred && v->fcm == 1) {
+            if (!use_pred && v->fcm == ILACE_FRAME) {
                 zz_table = v->zzi_8x8;
             } else {
                 if (!dc_pred_dir) // top
@@ -2926,7 +2927,7 @@ static int vc1_decode_i_block_adv(VC1Context *v, DCTELEM block[64], int n,
                     zz_table = v->zz_8x8[3];
             }
         } else {
-            if (v->fcm != 1)
+            if (v->fcm != ILACE_FRAME)
                 zz_table = v->zz_8x8[1];
             else
                 zz_table = v->zzi_8x8;
@@ -3136,10 +3137,10 @@ static int vc1_decode_intra_block(VC1Context *v, DCTELEM block[64], int n,
             i += skip;
             if (i > 63)
                 break;
-            if (v->fcm == 0)
+            if (v->fcm == PROGRESSIVE)
                 block[v->zz_8x8[0][i++]] = value;
             else {
-                if (use_pred && (v->fcm == 1)) {
+                if (use_pred && (v->fcm == ILACE_FRAME)) {
                     if (!dc_pred_dir) // top
                         block[v->zz_8x8[2][i++]] = value;
                     else // left
@@ -4739,12 +4740,12 @@ static void vc1_decode_p_blocks(VC1Context *v)
         for (; s->mb_x < s->mb_width; s->mb_x++) {
             ff_update_block_index(s);
 
-            if (v->fcm == 2)
+            if (v->fcm == ILACE_FIELD)
                 vc1_decode_p_mb_intfi(v);
-            else if (v->fcm == 1)
+            else if (v->fcm == ILACE_FRAME)
                 vc1_decode_p_mb_intfr(v);
             else vc1_decode_p_mb(v);
-            if (s->mb_y != s->start_mb_y && apply_loop_filter && v->fcm == 0)
+            if (s->mb_y != s->start_mb_y && apply_loop_filter && v->fcm == PROGRESSIVE)
                 vc1_apply_p_loop_filter(v);
             if (get_bits_count(&s->gb) > v->bits || get_bits_count(&s->gb) < 0) {
                 // TODO: may need modification to handle slice coding
@@ -4811,7 +4812,7 @@ static void vc1_decode_b_blocks(VC1Context *v)
         for (; s->mb_x < s->mb_width; s->mb_x++) {
             ff_update_block_index(s);
 
-            if (v->fcm == 2)
+            if (v->fcm == ILACE_FIELD)
                 vc1_decode_b_mb_intfi(v);
             else
                 vc1_decode_b_mb(v);