vc1: implement vc1 field interlaced dxva2 decoding

Tested-by: Gwenole Beauchesne <gb.devel@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

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 != ILACE_FIELD && !s->first_field;
+    pp->bSecondField            = v->interlace && v->fcm == ILACE_FIELD && v->second_field;
     pp->bPicIntra               = s->pict_type == AV_PICTURE_TYPE_I || v->bi_type;
     pp->bPicBackwardPrediction  = s->pict_type == AV_PICTURE_TYPE_B && !v->bi_type;
     pp->bBidirectionalAveragingMode = (1                                           << 7) |
@@ -183,8 +183,11 @@ static int commit_bitstream_and_slice_buffer(AVCodecContext *avctx,
 
     result = data_size <= dxva_size ? 0 : -1;
     if (!result) {
-        if (start_code_size > 0)
+        if (start_code_size > 0) {
             memcpy(dxva_data, start_code, start_code_size);
+            if (v->second_field)
+                dxva_data[3] = 0x0c;
+        }
         memcpy(dxva_data + start_code_size,
                ctx_pic->bitstream + slice->dwSliceDataLocation, slice_size);
         if (padding > 0)

libavcodec/vc1dec.c

@@ -5318,7 +5318,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
     MpegEncContext *s = &v->s;
     AVFrame *pict = data;
     uint8_t *buf2 = NULL;
-    const uint8_t *buf_start = buf;
+    const uint8_t *buf_start = buf, *buf_start_second_field = NULL;
     int mb_height, n_slices1=-1;
     struct {
         uint8_t *buf;
@@ -5326,6 +5326,8 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
         int mby_start;
     } *slices = NULL, *tmp;
 
+    v->second_field = 0;
+
     if(s->flags & CODEC_FLAG_LOW_DELAY)
         s->low_delay = 1;
 
@@ -5372,6 +5374,9 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                     break;
                 case VC1_CODE_FIELD: {
                     int buf_size3;
+                    if (avctx->hwaccel ||
+                        s->avctx->codec->capabilities&CODEC_CAP_HWACCEL_VDPAU)
+                        buf_start_second_field = start;
                     tmp = av_realloc(slices, sizeof(*slices) * (n_slices+1));
                     if (!tmp)
                         goto err;
@@ -5423,6 +5428,9 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
                 av_log(avctx, AV_LOG_ERROR, "Error in WVC1 interlaced frame\n");
                 goto err;
             } else { // found field marker, unescape second field
+                if (avctx->hwaccel ||
+                    s->avctx->codec->capabilities&CODEC_CAP_HWACCEL_VDPAU)
+                    buf_start_second_field = divider;
                 tmp = av_realloc(slices, sizeof(*slices) * (n_slices+1));
                 if (!tmp)
                     goto err;
@@ -5558,12 +5566,42 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
         &&s->avctx->codec->capabilities&CODEC_CAP_HWACCEL_VDPAU)
         ff_vdpau_vc1_decode_picture(s, buf_start, (buf + buf_size) - buf_start);
     else if (avctx->hwaccel) {
-        if (avctx->hwaccel->start_frame(avctx, buf, buf_size) < 0)
-            goto err;
-        if (avctx->hwaccel->decode_slice(avctx, buf_start, (buf + buf_size) - buf_start) < 0)
-            goto err;
-        if (avctx->hwaccel->end_frame(avctx) < 0)
-            goto err;
+        if (v->field_mode && buf_start_second_field) {
+            // decode first field
+            s->picture_structure = PICT_BOTTOM_FIELD - v->tff;
+            if (avctx->hwaccel->start_frame(avctx, buf_start, buf_start_second_field - buf_start) < 0)
+                goto err;
+            if (avctx->hwaccel->decode_slice(avctx, buf_start, buf_start_second_field - buf_start) < 0)
+                goto err;
+            if (avctx->hwaccel->end_frame(avctx) < 0)
+                goto err;
+
+            // decode second field
+            s->gb = slices[n_slices1 + 1].gb;
+            s->picture_structure = PICT_TOP_FIELD + v->tff;
+            v->second_field = 1;
+            v->pic_header_flag = 0;
+            if (ff_vc1_parse_frame_header_adv(v, &s->gb) < 0) {
+                av_log(avctx, AV_LOG_ERROR, "parsing header for second field failed");
+                goto err;
+            }
+            v->s.current_picture_ptr->f.pict_type = v->s.pict_type;
+
+            if (avctx->hwaccel->start_frame(avctx, buf_start_second_field, (buf + buf_size) - buf_start_second_field) < 0)
+                goto err;
+            if (avctx->hwaccel->decode_slice(avctx, buf_start_second_field, (buf + buf_size) - buf_start_second_field) < 0)
+                goto err;
+            if (avctx->hwaccel->end_frame(avctx) < 0)
+                goto err;
+        } else {
+            s->picture_structure = PICT_FRAME;
+            if (avctx->hwaccel->start_frame(avctx, buf_start, (buf + buf_size) - buf_start) < 0)
+                goto err;
+            if (avctx->hwaccel->decode_slice(avctx, buf_start, (buf + buf_size) - buf_start) < 0)
+                goto err;
+            if (avctx->hwaccel->end_frame(avctx) < 0)
+                goto err;
+        }
     } else {
         ff_er_frame_start(s);