h264: move mb_{x,y} into the per-slice context

13 files changed, 193 insertions, 188 deletions

diff --git a/libavcodec/dxva2_h264.c b/libavcodec/dxva2_h264.c
index 3de5f1891f..4e8c4ea552 100644
--- a/libavcodec/dxva2_h264.c
+++ b/libavcodec/dxva2_h264.c
@@ -220,7 +220,7 @@ static void fill_slice_long(AVCodecContext *avctx, DXVA_Slice_H264_Long *slice,
     slice->SliceBytesInBuffer    = size;
     slice->wBadSliceChopping     = 0;
 
-    slice->first_mb_in_slice     = (h->mb_y >> FIELD_OR_MBAFF_PICTURE(h)) * h->mb_width + h->mb_x;
+    slice->first_mb_in_slice     = (sl->mb_y >> FIELD_OR_MBAFF_PICTURE(h)) * h->mb_width + sl->mb_x;
     slice->NumMbsForSlice        = 0; /* XXX it is set once we have all slices */
     slice->BitOffsetToSliceData  = get_bits_count(&h->gb);
     slice->slice_type            = ff_h264_get_slice_type(sl);
diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 39d026f225..13f3aa4eca 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -58,8 +58,8 @@ static void h264_er_decode_mb(void *opaque, int ref, int mv_dir, int mv_type,
     H264Context *h = opaque;
     H264SliceContext *sl = &h->slice_ctx[0];
 
-    h->mb_x  = mb_x;
-    h->mb_y  = mb_y;
+    sl->mb_x = mb_x;
+    sl->mb_y = mb_y;
     sl->mb_xy = mb_x + mb_y * h->mb_stride;
     memset(sl->non_zero_count_cache, 0, sizeof(sl->non_zero_count_cache));
     assert(ref >= 0);
@@ -143,7 +143,7 @@ int ff_h264_check_intra4x4_pred_mode(H264Context *h, H264SliceContext *sl)
             if (status < 0) {
                 av_log(h->avctx, AV_LOG_ERROR,
                        "top block unavailable for requested intra4x4 mode %d at %d %d\n",
-                       status, h->mb_x, h->mb_y);
+                       status, sl->mb_x, sl->mb_y);
                 return AVERROR_INVALIDDATA;
             } else if (status) {
                 sl->intra4x4_pred_mode_cache[scan8[0] + i] = status;
@@ -159,7 +159,7 @@ int ff_h264_check_intra4x4_pred_mode(H264Context *h, H264SliceContext *sl)
                 if (status < 0) {
                     av_log(h->avctx, AV_LOG_ERROR,
                            "left block unavailable for requested intra4x4 mode %d at %d %d\n",
-                           status, h->mb_x, h->mb_y);
+                           status, sl->mb_x, sl->mb_y);
                     return AVERROR_INVALIDDATA;
                 } else if (status) {
                     sl->intra4x4_pred_mode_cache[scan8[0] + 8 * i] = status;
@@ -183,7 +183,7 @@ int ff_h264_check_intra_pred_mode(H264Context *h, H264SliceContext *sl,
     if (mode > 3U) {
         av_log(h->avctx, AV_LOG_ERROR,
                "out of range intra chroma pred mode at %d %d\n",
-               h->mb_x, h->mb_y);
+               sl->mb_x, sl->mb_y);
         return AVERROR_INVALIDDATA;
     }
 
@@ -192,7 +192,7 @@ int ff_h264_check_intra_pred_mode(H264Context *h, H264SliceContext *sl,
         if (mode < 0) {
             av_log(h->avctx, AV_LOG_ERROR,
                    "top block unavailable for requested intra mode at %d %d\n",
-                   h->mb_x, h->mb_y);
+                   sl->mb_x, sl->mb_y);
             return AVERROR_INVALIDDATA;
         }
     }
@@ -208,7 +208,7 @@ int ff_h264_check_intra_pred_mode(H264Context *h, H264SliceContext *sl,
         if (mode < 0) {
             av_log(h->avctx, AV_LOG_ERROR,
                    "left block unavailable for requested intra mode at %d %d\n",
-                   h->mb_x, h->mb_y);
+                   sl->mb_x, sl->mb_y);
             return AVERROR_INVALIDDATA;
         }
     }
@@ -1114,7 +1114,7 @@ static void flush_dpb(AVCodecContext *avctx)
     h->cur_pic_ptr = NULL;
     ff_h264_unref_picture(h, &h->cur_pic);
 
-    h->mb_x = h->mb_y = 0;
+    h->mb_y = 0;
 
     ff_h264_free_tables(h, 1);
     h->context_initialized = 0;
diff --git a/libavcodec/h264.h b/libavcodec/h264.h
index ce4e163809..1e0b2327b1 100644
--- a/libavcodec/h264.h
+++ b/libavcodec/h264.h
@@ -356,6 +356,7 @@ typedef struct H264SliceContext {
     ptrdiff_t mb_linesize;  ///< may be equal to s->linesize or s->linesize * 2, for mbaff
     ptrdiff_t mb_uvlinesize;
 
+    int mb_x, mb_y;
     int mb_xy;
     int mb_skip_run;
     int is_complex;
@@ -526,7 +527,7 @@ typedef struct H264Context {
 
     int x264_build;
 
-    int mb_x, mb_y;
+    int mb_y;
     int resync_mb_x;
     int resync_mb_y;
     int mb_height, mb_width;
@@ -1020,7 +1021,7 @@ static av_always_inline void write_back_motion(H264Context *h,
                                                int mb_type)
 {
     const int b_stride      = h->b_stride;
-    const int b_xy  = 4 * h->mb_x + 4 * h->mb_y * h->b_stride; // try mb2b(8)_xy
+    const int b_xy  = 4 * sl->mb_x + 4 * sl->mb_y * h->b_stride; // try mb2b(8)_xy
     const int b8_xy = 4 * sl->mb_xy;
 
     if (USES_LIST(mb_type, 0)) {
diff --git a/libavcodec/h264_cabac.c b/libavcodec/h264_cabac.c
index fb75ff0df5..88f50d6be3 100644
--- a/libavcodec/h264_cabac.c
+++ b/libavcodec/h264_cabac.c
@@ -1288,7 +1288,7 @@ static int decode_cabac_field_decoding_flag(H264Context *h, H264SliceContext *sl
 
     unsigned long ctx = 0;
 
-    ctx += h->mb_field_decoding_flag & !!h->mb_x; //for FMO:(s->current_picture.mb_type[mba_xy] >> 7) & (h->slice_table[mba_xy] == h->slice_num);
+    ctx += h->mb_field_decoding_flag & !!sl->mb_x; //for FMO:(s->current_picture.mb_type[mba_xy] >> 7) & (h->slice_table[mba_xy] == h->slice_num);
     ctx += (h->cur_pic.mb_type[mbb_xy] >> 7) & (h->slice_table[mbb_xy] == sl->slice_num);
 
     return get_cabac_noinline( &sl->cabac, &(sl->cabac_state+70)[ctx] );
@@ -1914,21 +1914,21 @@ int ff_h264_decode_mb_cabac(H264Context *h, H264SliceContext *sl)
     int decode_chroma = h->sps.chroma_format_idc == 1 || h->sps.chroma_format_idc == 2;
     const int pixel_shift = h->pixel_shift;
 
-    mb_xy = sl->mb_xy = h->mb_x + h->mb_y*h->mb_stride;
+    mb_xy = sl->mb_xy = sl->mb_x + sl->mb_y*h->mb_stride;
 
-    tprintf(h->avctx, "pic:%d mb:%d/%d\n", h->frame_num, h->mb_x, h->mb_y);
+    tprintf(h->avctx, "pic:%d mb:%d/%d\n", h->frame_num, sl->mb_x, sl->mb_y);
     if (sl->slice_type_nos != AV_PICTURE_TYPE_I) {
         int skip;
         /* a skipped mb needs the aff flag from the following mb */
-        if (FRAME_MBAFF(h) && (h->mb_y & 1) == 1 && sl->prev_mb_skipped)
+        if (FRAME_MBAFF(h) && (sl->mb_y & 1) == 1 && sl->prev_mb_skipped)
             skip = sl->next_mb_skipped;
         else
-            skip = decode_cabac_mb_skip(h, sl, h->mb_x, h->mb_y );
+            skip = decode_cabac_mb_skip(h, sl, sl->mb_x, sl->mb_y );
         /* read skip flags */
         if( skip ) {
-            if (FRAME_MBAFF(h) && (h->mb_y & 1) == 0) {
+            if (FRAME_MBAFF(h) && (sl->mb_y & 1) == 0) {
                 h->cur_pic.mb_type[mb_xy] = MB_TYPE_SKIP;
-                sl->next_mb_skipped = decode_cabac_mb_skip(h, sl, h->mb_x, h->mb_y+1 );
+                sl->next_mb_skipped = decode_cabac_mb_skip(h, sl, sl->mb_x, sl->mb_y+1 );
                 if(!sl->next_mb_skipped)
                     h->mb_mbaff = h->mb_field_decoding_flag = decode_cabac_field_decoding_flag(h, sl);
             }
@@ -1944,7 +1944,7 @@ int ff_h264_decode_mb_cabac(H264Context *h, H264SliceContext *sl)
         }
     }
     if (FRAME_MBAFF(h)) {
-        if( (h->mb_y&1) == 0 )
+        if ((sl->mb_y & 1) == 0)
             h->mb_mbaff =
             h->mb_field_decoding_flag = decode_cabac_field_decoding_flag(h, sl);
     }
@@ -2367,7 +2367,7 @@ decode_intra_mb:
                 ctx= 3;
                 val++;
                 if(val > 2*max_qp){ //prevent infinite loop
-                    av_log(h->avctx, AV_LOG_ERROR, "cabac decode of qscale diff failed at %d %d\n", h->mb_x, h->mb_y);
+                    av_log(h->avctx, AV_LOG_ERROR, "cabac decode of qscale diff failed at %d %d\n", sl->mb_x, sl->mb_y);
                     return -1;
                 }
             }
diff --git a/libavcodec/h264_cavlc.c b/libavcodec/h264_cavlc.c
index 6b16d2ac31..95b09a9fa4 100644
--- a/libavcodec/h264_cavlc.c
+++ b/libavcodec/h264_cavlc.c
@@ -477,7 +477,7 @@ static int decode_residual(H264Context *h, H264SliceContext *sl,
     if(total_coeff==0)
         return 0;
     if(total_coeff > (unsigned)max_coeff) {
-        av_log(h->avctx, AV_LOG_ERROR, "corrupted macroblock %d %d (total_coeff=%d)\n", h->mb_x, h->mb_y, total_coeff);
+        av_log(h->avctx, AV_LOG_ERROR, "corrupted macroblock %d %d (total_coeff=%d)\n", sl->mb_x, sl->mb_y, total_coeff);
         return -1;
     }
 
@@ -615,7 +615,7 @@ static int decode_residual(H264Context *h, H264SliceContext *sl,
 
     if (zeros_left < 0) {
         av_log(h->avctx, AV_LOG_ERROR,
-               "negative number of zero coeffs at %d %d\n", h->mb_x, h->mb_y);
+               "negative number of zero coeffs at %d %d\n", sl->mb_x, sl->mb_y);
         return AVERROR_INVALIDDATA;
     }
 
@@ -703,9 +703,9 @@ int ff_h264_decode_mb_cavlc(H264Context *h, H264SliceContext *sl)
     int decode_chroma = h->sps.chroma_format_idc == 1 || h->sps.chroma_format_idc == 2;
     const int pixel_shift = h->pixel_shift;
 
-    mb_xy = sl->mb_xy = h->mb_x + h->mb_y*h->mb_stride;
+    mb_xy = sl->mb_xy = sl->mb_x + sl->mb_y*h->mb_stride;
 
-    tprintf(h->avctx, "pic:%d mb:%d/%d\n", h->frame_num, h->mb_x, h->mb_y);
+    tprintf(h->avctx, "pic:%d mb:%d/%d\n", h->frame_num, sl->mb_x, sl->mb_y);
     cbp = 0; /* avoid warning. FIXME: find a solution without slowing
                 down the code */
     if (sl->slice_type_nos != AV_PICTURE_TYPE_I) {
@@ -713,7 +713,7 @@ int ff_h264_decode_mb_cavlc(H264Context *h, H264SliceContext *sl)
             sl->mb_skip_run = get_ue_golomb(&h->gb);
 
         if (sl->mb_skip_run--) {
-            if(FRAME_MBAFF(h) && (h->mb_y&1) == 0){
+            if (FRAME_MBAFF(h) && (sl->mb_y & 1) == 0) {
                 if (sl->mb_skip_run == 0)
                     h->mb_mbaff = h->mb_field_decoding_flag = get_bits1(&h->gb);
             }
@@ -722,7 +722,7 @@ int ff_h264_decode_mb_cavlc(H264Context *h, H264SliceContext *sl)
         }
     }
     if (FRAME_MBAFF(h)) {
-        if( (h->mb_y&1) == 0 )
+        if ((sl->mb_y & 1) == 0)
             h->mb_mbaff = h->mb_field_decoding_flag = get_bits1(&h->gb);
     }
 
@@ -751,7 +751,7 @@ int ff_h264_decode_mb_cavlc(H264Context *h, H264SliceContext *sl)
             mb_type--;
 decode_intra_mb:
         if(mb_type > 25){
-            av_log(h->avctx, AV_LOG_ERROR, "mb_type %d in %c slice too large at %d %d\n", mb_type, av_get_picture_type_char(sl->slice_type), h->mb_x, h->mb_y);
+            av_log(h->avctx, AV_LOG_ERROR, "mb_type %d in %c slice too large at %d %d\n", mb_type, av_get_picture_type_char(sl->slice_type), sl->mb_x, sl->mb_y);
             return -1;
         }
         partition_count=0;
@@ -838,7 +838,7 @@ decode_intra_mb:
             for(i=0; i<4; i++){
                 sl->sub_mb_type[i]= get_ue_golomb_31(&h->gb);
                 if(sl->sub_mb_type[i] >=13){
-                    av_log(h->avctx, AV_LOG_ERROR, "B sub_mb_type %u out of range at %d %d\n", sl->sub_mb_type[i], h->mb_x, h->mb_y);
+                    av_log(h->avctx, AV_LOG_ERROR, "B sub_mb_type %u out of range at %d %d\n", sl->sub_mb_type[i], sl->mb_x, sl->mb_y);
                     return -1;
                 }
                 sub_partition_count[i]= b_sub_mb_type_info[ sl->sub_mb_type[i] ].partition_count;
@@ -856,7 +856,7 @@ decode_intra_mb:
             for(i=0; i<4; i++){
                 sl->sub_mb_type[i]= get_ue_golomb_31(&h->gb);
                 if(sl->sub_mb_type[i] >=4){
-                    av_log(h->avctx, AV_LOG_ERROR, "P sub_mb_type %u out of range at %d %d\n", sl->sub_mb_type[i], h->mb_x, h->mb_y);
+                    av_log(h->avctx, AV_LOG_ERROR, "P sub_mb_type %u out of range at %d %d\n", sl->sub_mb_type[i], sl->mb_x, sl->mb_y);
                     return -1;
                 }
                 sub_partition_count[i]= p_sub_mb_type_info[ sl->sub_mb_type[i] ].partition_count;
@@ -1057,14 +1057,14 @@ decode_intra_mb:
 
         if(decode_chroma){
             if(cbp > 47){
-                av_log(h->avctx, AV_LOG_ERROR, "cbp too large (%u) at %d %d\n", cbp, h->mb_x, h->mb_y);
+                av_log(h->avctx, AV_LOG_ERROR, "cbp too large (%u) at %d %d\n", cbp, sl->mb_x, sl->mb_y);
                 return -1;
             }
             if(IS_INTRA4x4(mb_type)) cbp= golomb_to_intra4x4_cbp[cbp];
             else                     cbp= golomb_to_inter_cbp   [cbp];
         }else{
             if(cbp > 15){
-                av_log(h->avctx, AV_LOG_ERROR, "cbp too large (%u) at %d %d\n", cbp, h->mb_x, h->mb_y);
+                av_log(h->avctx, AV_LOG_ERROR, "cbp too large (%u) at %d %d\n", cbp, sl->mb_x, sl->mb_y);
                 return -1;
             }
             if(IS_INTRA4x4(mb_type)) cbp= golomb_to_intra4x4_cbp_gray[cbp];
@@ -1103,7 +1103,7 @@ decode_intra_mb:
             if (sl->qscale < 0) sl->qscale += max_qp + 1;
             else                sl->qscale -= max_qp+1;
             if (((unsigned)sl->qscale) > max_qp){
-                av_log(h->avctx, AV_LOG_ERROR, "dquant out of range (%d) at %d %d\n", dquant, h->mb_x, h->mb_y);
+                av_log(h->avctx, AV_LOG_ERROR, "dquant out of range (%d) at %d %d\n", dquant, sl->mb_x, sl->mb_y);
                 return -1;
             }
         }
diff --git a/libavcodec/h264_direct.c b/libavcodec/h264_direct.c
index 136d8fa25e..43ad41de90 100644
--- a/libavcodec/h264_direct.c
+++ b/libavcodec/h264_direct.c
@@ -179,7 +179,7 @@ static void pred_spatial_direct_motion(H264Context *const h, H264SliceContext *s
 {
     int b8_stride = 2;
     int b4_stride = h->b_stride;
-    int mb_xy = sl->mb_xy, mb_y = h->mb_y;
+    int mb_xy = sl->mb_xy, mb_y = sl->mb_y;
     int mb_type_col[2];
     const int16_t (*l1mv0)[2], (*l1mv1)[2];
     const int8_t *l1ref0, *l1ref1;
@@ -193,7 +193,7 @@ static void pred_spatial_direct_motion(H264Context *const h, H264SliceContext *s
     assert(sl->ref_list[1][0].reference & 3);
 
     await_reference_mb_row(h, &sl->ref_list[1][0],
-                           h->mb_y + !!IS_INTERLACED(*mb_type));
+                           sl->mb_y + !!IS_INTERLACED(*mb_type));
 
 #define MB_TYPE_16x16_OR_INTRA (MB_TYPE_16x16 | MB_TYPE_INTRA4x4 | \
                                 MB_TYPE_INTRA16x16 | MB_TYPE_INTRA_PCM)
@@ -262,9 +262,9 @@ static void pred_spatial_direct_motion(H264Context *const h, H264SliceContext *s
 
     if (IS_INTERLACED(sl->ref_list[1][0].mb_type[mb_xy])) { // AFL/AFR/FR/FL -> AFL/FL
         if (!IS_INTERLACED(*mb_type)) {                    //     AFR/FR    -> AFL/FL
-            mb_y  = (h->mb_y & ~1) + sl->col_parity;
-            mb_xy = h->mb_x +
-                    ((h->mb_y & ~1) + sl->col_parity) * h->mb_stride;
+            mb_y  = (sl->mb_y & ~1) + sl->col_parity;
+            mb_xy = sl->mb_x +
+                    ((sl->mb_y & ~1) + sl->col_parity) * h->mb_stride;
             b8_stride = 0;
         } else {
             mb_y  += sl->col_fieldoff;
@@ -273,8 +273,8 @@ static void pred_spatial_direct_motion(H264Context *const h, H264SliceContext *s
         goto single_col;
     } else {                                             // AFL/AFR/FR/FL -> AFR/FR
         if (IS_INTERLACED(*mb_type)) {                   // AFL       /FL -> AFR/FR
-            mb_y           =  h->mb_y & ~1;
-            mb_xy          = (h->mb_y & ~1) * h->mb_stride + h->mb_x;
+            mb_y           =  sl->mb_y & ~1;
+            mb_xy          = (sl->mb_y & ~1) * h->mb_stride + sl->mb_x;
             mb_type_col[0] = sl->ref_list[1][0].mb_type[mb_xy];
             mb_type_col[1] = sl->ref_list[1][0].mb_type[mb_xy + h->mb_stride];
             b8_stride      = 2 + 4 * h->mb_stride;
@@ -323,7 +323,7 @@ single_col:
     l1ref0 = &sl->ref_list[1][0].ref_index[0][4 * mb_xy];
     l1ref1 = &sl->ref_list[1][0].ref_index[1][4 * mb_xy];
     if (!b8_stride) {
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             l1ref0 += 2;
             l1ref1 += 2;
             l1mv0  += 2 * b4_stride;
@@ -465,7 +465,7 @@ static void pred_temp_direct_motion(H264Context *const h, H264SliceContext *sl,
 {
     int b8_stride = 2;
     int b4_stride = h->b_stride;
-    int mb_xy = sl->mb_xy, mb_y = h->mb_y;
+    int mb_xy = sl->mb_xy, mb_y = sl->mb_y;
     int mb_type_col[2];
     const int16_t (*l1mv0)[2], (*l1mv1)[2];
     const int8_t *l1ref0, *l1ref1;
@@ -476,13 +476,13 @@ static void pred_temp_direct_motion(H264Context *const h, H264SliceContext *sl,
     assert(sl->ref_list[1][0].reference & 3);
 
     await_reference_mb_row(h, &sl->ref_list[1][0],
-                           h->mb_y + !!IS_INTERLACED(*mb_type));
+                           sl->mb_y + !!IS_INTERLACED(*mb_type));
 
     if (IS_INTERLACED(sl->ref_list[1][0].mb_type[mb_xy])) { // AFL/AFR/FR/FL -> AFL/FL
         if (!IS_INTERLACED(*mb_type)) {                    //     AFR/FR    -> AFL/FL
-            mb_y  = (h->mb_y & ~1) + sl->col_parity;
-            mb_xy = h->mb_x +
-                    ((h->mb_y & ~1) + sl->col_parity) * h->mb_stride;
+            mb_y  = (sl->mb_y & ~1) + sl->col_parity;
+            mb_xy = sl->mb_x +
+                    ((sl->mb_y & ~1) + sl->col_parity) * h->mb_stride;
             b8_stride = 0;
         } else {
             mb_y  += sl->col_fieldoff;
@@ -491,8 +491,8 @@ static void pred_temp_direct_motion(H264Context *const h, H264SliceContext *sl,
         goto single_col;
     } else {                                        // AFL/AFR/FR/FL -> AFR/FR
         if (IS_INTERLACED(*mb_type)) {              // AFL       /FL -> AFR/FR
-            mb_y           = h->mb_y & ~1;
-            mb_xy          = h->mb_x + (h->mb_y & ~1) * h->mb_stride;
+            mb_y           = sl->mb_y & ~1;
+            mb_xy          = sl->mb_x + (sl->mb_y & ~1) * h->mb_stride;
             mb_type_col[0] = sl->ref_list[1][0].mb_type[mb_xy];
             mb_type_col[1] = sl->ref_list[1][0].mb_type[mb_xy + h->mb_stride];
             b8_stride      = 2 + 4 * h->mb_stride;
@@ -547,7 +547,7 @@ single_col:
     l1ref0 = &sl->ref_list[1][0].ref_index[0][4 * mb_xy];
     l1ref1 = &sl->ref_list[1][0].ref_index[1][4 * mb_xy];
     if (!b8_stride) {
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             l1ref0 += 2;
             l1ref1 += 2;
             l1mv0  += 2 * b4_stride;
@@ -562,9 +562,9 @@ single_col:
         int ref_offset;
 
         if (FRAME_MBAFF(h) && IS_INTERLACED(*mb_type)) {
-            map_col_to_list0[0] = sl->map_col_to_list0_field[h->mb_y & 1][0];
-            map_col_to_list0[1] = sl->map_col_to_list0_field[h->mb_y & 1][1];
-            dist_scale_factor   = sl->dist_scale_factor_field[h->mb_y & 1];
+            map_col_to_list0[0] = sl->map_col_to_list0_field[sl->mb_y & 1][0];
+            map_col_to_list0[1] = sl->map_col_to_list0_field[sl->mb_y & 1][1];
+            dist_scale_factor   = sl->dist_scale_factor_field[sl->mb_y & 1];
         }
         ref_offset = (sl->ref_list[1][0].mbaff << 4) & (mb_type_col[0] >> 3);
 
diff --git a/libavcodec/h264_mb.c b/libavcodec/h264_mb.c
index 6410bcb684..a9ea97c73a 100644
--- a/libavcodec/h264_mb.c
+++ b/libavcodec/h264_mb.c
@@ -57,7 +57,7 @@ static inline void get_lowest_part_y(H264Context *h, H264SliceContext *sl,
 {
     int my;
 
-    y_offset += 16 * (h->mb_y >> MB_FIELD(h));
+    y_offset += 16 * (sl->mb_y >> MB_FIELD(h));
 
     if (list0) {
         int ref_n = sl->ref_cache[0][scan8[n]];
@@ -287,7 +287,7 @@ static av_always_inline void mc_dir_part(H264Context *h, H264SliceContext *sl,
     ysh = 3 - (chroma_idc == 2 /* yuv422 */);
     if (chroma_idc == 1 /* yuv420 */ && MB_FIELD(h)) {
         // chroma offset when predicting from a field of opposite parity
-        my  += 2 * ((h->mb_y & 1) - (pic->reference - 1));
+        my  += 2 * ((sl->mb_y & 1) - (pic->reference - 1));
         emu |= (my >> 3) < 0 || (my >> 3) + 8 >= (pic_height >> 1);
     }
 
@@ -345,8 +345,8 @@ static av_always_inline void mc_part_std(H264Context *h, H264SliceContext *sl,
         dest_cb += (x_offset << pixel_shift) + y_offset * sl->mb_uvlinesize;
         dest_cr += (x_offset << pixel_shift) + y_offset * sl->mb_uvlinesize;
     }
-    x_offset += 8 * h->mb_x;
-    y_offset += 8 * (h->mb_y >> MB_FIELD(h));
+    x_offset += 8 * sl->mb_x;
+    y_offset += 8 * (sl->mb_y >> MB_FIELD(h));
 
     if (list0) {
         H264Picture *ref = &sl->ref_list[0][sl->ref_cache[0][scan8[n]]];
@@ -399,8 +399,8 @@ static av_always_inline void mc_part_weighted(H264Context *h, H264SliceContext *
         dest_cb      += (x_offset << pixel_shift) + y_offset * sl->mb_uvlinesize;
         dest_cr      += (x_offset << pixel_shift) + y_offset * sl->mb_uvlinesize;
     }
-    x_offset += 8 * h->mb_x;
-    y_offset += 8 * (h->mb_y >> MB_FIELD(h));
+    x_offset += 8 * sl->mb_x;
+    y_offset += 8 * (sl->mb_y >> MB_FIELD(h));
 
     if (list0 && list1) {
         /* don't optimize for luma-only case, since B-frames usually
@@ -421,7 +421,7 @@ static av_always_inline void mc_part_weighted(H264Context *h, H264SliceContext *
                     pixel_shift, chroma_idc);
 
         if (sl->use_weight == 2) {
-            int weight0 = sl->implicit_weight[refn0][refn1][h->mb_y & 1];
+            int weight0 = sl->implicit_weight[refn0][refn1][sl->mb_y & 1];
             int weight1 = 64 - weight0;
             luma_weight_avg(dest_y, tmp_y, sl->mb_linesize,
                             height, 5, weight0, weight1, 0);
@@ -482,11 +482,11 @@ static av_always_inline void prefetch_motion(H264Context *h, H264SliceContext *s
      * optimized for 64byte cache lines */
     const int refn = sl->ref_cache[list][scan8[0]];
     if (refn >= 0) {
-        const int mx  = (sl->mv_cache[list][scan8[0]][0] >> 2) + 16 * h->mb_x + 8;
-        const int my  = (sl->mv_cache[list][scan8[0]][1] >> 2) + 16 * h->mb_y;
+        const int mx  = (sl->mv_cache[list][scan8[0]][0] >> 2) + 16 * sl->mb_x + 8;
+        const int my  = (sl->mv_cache[list][scan8[0]][1] >> 2) + 16 * sl->mb_y;
         uint8_t **src = sl->ref_list[list][refn].f.data;
         int off       = (mx << pixel_shift) +
-                        (my + (h->mb_x & 3) * 4) * sl->mb_linesize +
+                        (my + (sl->mb_x & 3) * 4) * sl->mb_linesize +
                         (64 << pixel_shift);
         h->vdsp.prefetch(src[0] + off, h->linesize, 4);
         if (chroma_idc == 3 /* yuv444 */) {
@@ -494,7 +494,7 @@ static av_always_inline void prefetch_motion(H264Context *h, H264SliceContext *s
             h->vdsp.prefetch(src[2] + off, h->linesize, 4);
         } else {
             off = ((mx >> 1) << pixel_shift) +
-                  ((my >> 1) + (h->mb_x & 7)) * h->uvlinesize +
+                  ((my >> 1) + (sl->mb_x & 7)) * h->uvlinesize +
                   (64 << pixel_shift);
             h->vdsp.prefetch(src[1] + off, src[2] - src[1], 2);
         }
@@ -515,7 +515,7 @@ static av_always_inline void xchg_mb_border(H264Context *h, H264SliceContext *sl
     uint8_t *top_border;
 
     if (!simple && FRAME_MBAFF(h)) {
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             if (!MB_MBAFF(h))
                 return;
         } else {
@@ -527,16 +527,16 @@ static av_always_inline void xchg_mb_border(H264Context *h, H264SliceContext *sl
         deblock_topleft = h->slice_table[sl->mb_xy - 1 - h->mb_stride] == sl->slice_num;
         deblock_top     = sl->top_type;
     } else {
-        deblock_topleft = (h->mb_x > 0);
-        deblock_top     = (h->mb_y > !!MB_FIELD(h));
+        deblock_topleft = (sl->mb_x > 0);
+        deblock_top     = (sl->mb_y > !!MB_FIELD(h));
     }
 
     src_y  -= linesize   + 1 + pixel_shift;
     src_cb -= uvlinesize + 1 + pixel_shift;
     src_cr -= uvlinesize + 1 + pixel_shift;
 
-    top_border_m1 = h->top_borders[top_idx][h->mb_x - 1];
-    top_border    = h->top_borders[top_idx][h->mb_x];
+    top_border_m1 = h->top_borders[top_idx][sl->mb_x - 1];
+    top_border    = h->top_borders[top_idx][sl->mb_x];
 
 #define XCHG(a, b, xchg)                        \
     if (pixel_shift) {                          \
@@ -558,8 +558,8 @@ static av_always_inline void xchg_mb_border(H264Context *h, H264SliceContext *sl
         }
         XCHG(top_border + (0 << pixel_shift), src_y + (1 << pixel_shift), xchg);
         XCHG(top_border + (8 << pixel_shift), src_y + (9 << pixel_shift), 1);
-        if (h->mb_x + 1 < h->mb_width) {
-            XCHG(h->top_borders[top_idx][h->mb_x + 1],
+        if (sl->mb_x + 1 < h->mb_width) {
+            XCHG(h->top_borders[top_idx][sl->mb_x + 1],
                  src_y + (17 << pixel_shift), 1);
         }
     }
@@ -574,9 +574,9 @@ static av_always_inline void xchg_mb_border(H264Context *h, H264SliceContext *sl
                 XCHG(top_border + (24 << pixel_shift), src_cb + (9 << pixel_shift), 1);
                 XCHG(top_border + (32 << pixel_shift), src_cr + (1 << pixel_shift), xchg);
                 XCHG(top_border + (40 << pixel_shift), src_cr + (9 << pixel_shift), 1);
-                if (h->mb_x + 1 < h->mb_width) {
-                    XCHG(h->top_borders[top_idx][h->mb_x + 1] + (16 << pixel_shift), src_cb + (17 << pixel_shift), 1);
-                    XCHG(h->top_borders[top_idx][h->mb_x + 1] + (32 << pixel_shift), src_cr + (17 << pixel_shift), 1);
+                if (sl->mb_x + 1 < h->mb_width) {
+                    XCHG(h->top_borders[top_idx][sl->mb_x + 1] + (16 << pixel_shift), src_cb + (17 << pixel_shift), 1);
+                    XCHG(h->top_borders[top_idx][sl->mb_x + 1] + (32 << pixel_shift), src_cr + (17 << pixel_shift), 1);
                 }
             }
         } else {
@@ -671,7 +671,7 @@ static av_always_inline void hl_decode_mb_predict_luma(H264Context *h,
                     uint64_t tr_high;
                     if (dir == DIAG_DOWN_LEFT_PRED || dir == VERT_LEFT_PRED) {
                         const int topright_avail = (sl->topright_samples_available << i) & 0x8000;
-                        assert(h->mb_y || linesize <= block_offset[i]);
+                        assert(sl->mb_y || linesize <= block_offset[i]);
                         if (!topright_avail) {
                             if (pixel_shift) {
                                 tr_high  = ((uint16_t *)ptr)[3 - linesize / 2] * 0x0001000100010001ULL;
diff --git a/libavcodec/h264_mb_template.c b/libavcodec/h264_mb_template.c
index 4eca679357..556a2b5dd3 100644
--- a/libavcodec/h264_mb_template.c
+++ b/libavcodec/h264_mb_template.c
@@ -42,8 +42,8 @@
 
 static av_noinline void FUNC(hl_decode_mb)(H264Context *h, H264SliceContext *sl)
 {
-    const int mb_x    = h->mb_x;
-    const int mb_y    = h->mb_y;
+    const int mb_x    = sl->mb_x;
+    const int mb_y    = sl->mb_y;
     const int mb_xy   = sl->mb_xy;
     const int mb_type = h->cur_pic.mb_type[mb_xy];
     uint8_t *dest_y, *dest_cb, *dest_cr;
@@ -61,8 +61,8 @@ static av_noinline void FUNC(hl_decode_mb)(H264Context *h, H264SliceContext *sl)
     dest_cb = h->cur_pic.f.data[1] +  (mb_x << PIXEL_SHIFT) * 8 + mb_y * h->uvlinesize * block_h;
     dest_cr = h->cur_pic.f.data[2] +  (mb_x << PIXEL_SHIFT) * 8 + mb_y * h->uvlinesize * block_h;
 
-    h->vdsp.prefetch(dest_y  + (h->mb_x & 3) * 4 * h->linesize   + (64 << PIXEL_SHIFT), h->linesize,       4);
-    h->vdsp.prefetch(dest_cb + (h->mb_x & 7)     * h->uvlinesize + (64 << PIXEL_SHIFT), dest_cr - dest_cb, 2);
+    h->vdsp.prefetch(dest_y  + (sl->mb_x & 3) * 4 * h->linesize   + (64 << PIXEL_SHIFT), h->linesize,       4);
+    h->vdsp.prefetch(dest_cb + (sl->mb_x & 7)     * h->uvlinesize + (64 << PIXEL_SHIFT), dest_cr - dest_cb, 2);
 
     h->list_counts[mb_xy] = sl->list_count;
 
@@ -82,13 +82,13 @@ static av_noinline void FUNC(hl_decode_mb)(H264Context *h, H264SliceContext *sl)
                     continue;
                 if (IS_16X16(mb_type)) {
                     int8_t *ref = &sl->ref_cache[list][scan8[0]];
-                    fill_rectangle(ref, 4, 4, 8, (16 + *ref) ^ (h->mb_y & 1), 1);
+                    fill_rectangle(ref, 4, 4, 8, (16 + *ref) ^ (sl->mb_y & 1), 1);
                 } else {
                     for (i = 0; i < 16; i += 4) {
                         int ref = sl->ref_cache[list][scan8[i]];
                         if (ref >= 0)
                             fill_rectangle(&sl->ref_cache[list][scan8[i]], 2, 2,
-                                           8, (16 + ref) ^ (h->mb_y & 1), 1);
+                                           8, (16 + ref) ^ (sl->mb_y & 1), 1);
                     }
                 }
             }
@@ -274,8 +274,8 @@ static av_noinline void FUNC(hl_decode_mb)(H264Context *h, H264SliceContext *sl)
 
 static av_noinline void FUNC(hl_decode_mb_444)(H264Context *h, H264SliceContext *sl)
 {
-    const int mb_x    = h->mb_x;
-    const int mb_y    = h->mb_y;
+    const int mb_x    = sl->mb_x;
+    const int mb_y    = sl->mb_y;
     const int mb_xy   = sl->mb_xy;
     const int mb_type = h->cur_pic.mb_type[mb_xy];
     uint8_t *dest[3];
@@ -288,7 +288,7 @@ static av_noinline void FUNC(hl_decode_mb_444)(H264Context *h, H264SliceContext
     for (p = 0; p < plane_count; p++) {
         dest[p] = h->cur_pic.f.data[p] +
                   ((mb_x << PIXEL_SHIFT) + mb_y * h->linesize) * 16;
-        h->vdsp.prefetch(dest[p] + (h->mb_x & 3) * 4 * h->linesize + (64 << PIXEL_SHIFT),
+        h->vdsp.prefetch(dest[p] + (sl->mb_x & 3) * 4 * h->linesize + (64 << PIXEL_SHIFT),
                          h->linesize, 4);
     }
 
@@ -307,13 +307,13 @@ static av_noinline void FUNC(hl_decode_mb_444)(H264Context *h, H264SliceContext
                     continue;
                 if (IS_16X16(mb_type)) {
                     int8_t *ref = &sl->ref_cache[list][scan8[0]];
-                    fill_rectangle(ref, 4, 4, 8, (16 + *ref) ^ (h->mb_y & 1), 1);
+                    fill_rectangle(ref, 4, 4, 8, (16 + *ref) ^ (sl->mb_y & 1), 1);
                 } else {
                     for (i = 0; i < 16; i += 4) {
                         int ref = sl->ref_cache[list][scan8[i]];
                         if (ref >= 0)
                             fill_rectangle(&sl->ref_cache[list][scan8[i]], 2, 2,
-                                           8, (16 + ref) ^ (h->mb_y & 1), 1);
+                                           8, (16 + ref) ^ (sl->mb_y & 1), 1);
                     }
                 }
             }
diff --git a/libavcodec/h264_mc_template.c b/libavcodec/h264_mc_template.c
index 575320a301..f1f906f729 100644
--- a/libavcodec/h264_mc_template.c
+++ b/libavcodec/h264_mc_template.c
@@ -49,7 +49,7 @@ static void mc_part(H264Context *h, H264SliceContext *sl,
                     int list0, int list1)
 {
     if ((sl->use_weight == 2 && list0 && list1 &&
-         (sl->implicit_weight[sl->ref_cache[0][scan8[n]]][sl->ref_cache[1][scan8[n]]][h->mb_y & 1] != 32)) ||
+         (sl->implicit_weight[sl->ref_cache[0][scan8[n]]][sl->ref_cache[1][scan8[n]]][sl->mb_y & 1] != 32)) ||
         sl->use_weight == 1)
         mc_part_weighted(h, sl, n, square, height, delta, dest_y, dest_cb, dest_cr,
                          x_offset, y_offset, qpix_put, chroma_put,
diff --git a/libavcodec/h264_mvpred.h b/libavcodec/h264_mvpred.h
index ca6323726f..a3616796ba 100644
--- a/libavcodec/h264_mvpred.h
+++ b/libavcodec/h264_mvpred.h
@@ -64,7 +64,7 @@ static av_always_inline int fetch_diagonal_mv(H264Context *h, H264SliceContext *
 
             if (!MB_FIELD(h) && IS_INTERLACED(sl->left_type[0])) {
                 SET_DIAG_MV(* 2, >> 1, sl->left_mb_xy[0] + h->mb_stride,
-                            (h->mb_y & 1) * 2 + (i >> 5));
+                            (sl->mb_y & 1) * 2 + (i >> 5));
             }
             if (MB_FIELD(h) && !IS_INTERLACED(sl->left_type[0])) {
                 // left shift will turn LIST_NOT_USED into PART_NOT_AVAILABLE, but that's OK.
@@ -148,7 +148,7 @@ static av_always_inline void pred_motion(H264Context *const h,
     tprintf(h->avctx,
             "pred_motion (%2d %2d %2d) (%2d %2d %2d) (%2d %2d %2d) -> (%2d %2d %2d) at %2d %2d %d list %d\n",
             top_ref, B[0], B[1], diagonal_ref, C[0], C[1], left_ref,
-            A[0], A[1], ref, *mx, *my, h->mb_x, h->mb_y, n, list);
+            A[0], A[1], ref, *mx, *my, sl->mb_x, sl->mb_y, n, list);
 }
 
 /**
@@ -167,7 +167,7 @@ static av_always_inline void pred_16x8_motion(H264Context *const h,
         const int16_t *const B = sl->mv_cache[list][scan8[0] - 8];
 
         tprintf(h->avctx, "pred_16x8: (%2d %2d %2d) at %2d %2d %d list %d\n",
-                top_ref, B[0], B[1], h->mb_x, h->mb_y, n, list);
+                top_ref, B[0], B[1], sl->mb_x, sl->mb_y, n, list);
 
         if (top_ref == ref) {
             *mx = B[0];
@@ -179,7 +179,7 @@ static av_always_inline void pred_16x8_motion(H264Context *const h,
         const int16_t *const A = sl->mv_cache[list][scan8[8] - 1];
 
         tprintf(h->avctx, "pred_16x8: (%2d %2d %2d) at %2d %2d %d list %d\n",
-                left_ref, A[0], A[1], h->mb_x, h->mb_y, n, list);
+                left_ref, A[0], A[1], sl->mb_x, sl->mb_y, n, list);
 
         if (left_ref == ref) {
             *mx = A[0];
@@ -208,7 +208,7 @@ static av_always_inline void pred_8x16_motion(H264Context *const h,
         const int16_t *const A = sl->mv_cache[list][scan8[0] - 1];
 
         tprintf(h->avctx, "pred_8x16: (%2d %2d %2d) at %2d %2d %d list %d\n",
-                left_ref, A[0], A[1], h->mb_x, h->mb_y, n, list);
+                left_ref, A[0], A[1], sl->mb_x, sl->mb_y, n, list);
 
         if (left_ref == ref) {
             *mx = A[0];
@@ -222,7 +222,7 @@ static av_always_inline void pred_8x16_motion(H264Context *const h,
         diagonal_ref = fetch_diagonal_mv(h, sl, &C, scan8[4], list, 2);
 
         tprintf(h->avctx, "pred_8x16: (%2d %2d %2d) at %2d %2d %d list %d\n",
-                diagonal_ref, C[0], C[1], h->mb_x, h->mb_y, n, list);
+                diagonal_ref, C[0], C[1], sl->mb_x, sl->mb_y, n, list);
 
         if (diagonal_ref == ref) {
             *mx = C[0];
@@ -299,7 +299,7 @@ static av_always_inline void pred_pskip_motion(H264Context *const h,
     }
 
     tprintf(h->avctx, "pred_pskip: (%d) (%d) at %2d %2d\n",
-            top_ref, left_ref, h->mb_x, h->mb_y);
+            top_ref, left_ref, sl->mb_x, sl->mb_y);
 
     if (USES_LIST(sl->topright_type, 0)) {
         diagonal_ref = ref[4 * sl->topright_mb_xy + 2];
@@ -378,7 +378,7 @@ static void fill_decode_neighbors(H264Context *h, H264SliceContext *sl, int mb_t
     if (FRAME_MBAFF(h)) {
         const int left_mb_field_flag = IS_INTERLACED(h->cur_pic.mb_type[mb_xy - 1]);
         const int curr_mb_field_flag = IS_INTERLACED(mb_type);
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             if (left_mb_field_flag != curr_mb_field_flag) {
                 left_xy[LBOT] = left_xy[LTOP] = mb_xy - h->mb_stride - 1;
                 if (curr_mb_field_flag) {
diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index 64dae07a16..cea213e158 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -719,7 +719,8 @@ static int h264_frame_start(H264Context *h)
     return 0;
 }
 
-static av_always_inline void backup_mb_border(H264Context *h, uint8_t *src_y,
+static av_always_inline void backup_mb_border(H264Context *h, H264SliceContext *sl,
+                                              uint8_t *src_y,
                                               uint8_t *src_cb, uint8_t *src_cr,
                                               int linesize, int uvlinesize,
                                               int simple)
@@ -735,9 +736,9 @@ static av_always_inline void backup_mb_border(H264Context *h, uint8_t *src_y,
     src_cr -= uvlinesize;
 
     if (!simple && FRAME_MBAFF(h)) {
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             if (!MB_MBAFF(h)) {
-                top_border = h->top_borders[0][h->mb_x];
+                top_border = h->top_borders[0][sl->mb_x];
                 AV_COPY128(top_border, src_y + 15 * linesize);
                 if (pixel_shift)
                     AV_COPY128(top_border + 16, src_y + 15 * linesize + 16);
@@ -777,7 +778,7 @@ static av_always_inline void backup_mb_border(H264Context *h, uint8_t *src_y,
             return;
     }
 
-    top_border = h->top_borders[top_idx][h->mb_x];
+    top_border = h->top_borders[top_idx][sl->mb_x];
     /* There are two lines saved, the line above the top macroblock
      * of a pair, and the line above the bottom macroblock. */
     AV_COPY128(top_border, src_y + 16 * linesize);
@@ -1207,8 +1208,8 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl, H264Contex
     slice_type = get_ue_golomb_31(&h->gb);
     if (slice_type > 9) {
         av_log(h->avctx, AV_LOG_ERROR,
-               "slice type %d too large at %d %d\n",
-               slice_type, h->mb_x, h->mb_y);
+               "slice type %d too large at %d\n",
+               slice_type, first_mb_in_slice);
         return AVERROR_INVALIDDATA;
     }
     if (slice_type > 4) {
@@ -1556,12 +1557,12 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl, H264Contex
         av_log(h->avctx, AV_LOG_ERROR, "first_mb_in_slice overflow\n");
         return AVERROR_INVALIDDATA;
     }
-    h->resync_mb_x = h->mb_x =  first_mb_in_slice % h->mb_width;
-    h->resync_mb_y = h->mb_y = (first_mb_in_slice / h->mb_width) <<
+    h->resync_mb_x = sl->mb_x =  first_mb_in_slice % h->mb_width;
+    h->resync_mb_y = sl->mb_y = (first_mb_in_slice / h->mb_width) <<
                                FIELD_OR_MBAFF_PICTURE(h);
     if (h->picture_structure == PICT_BOTTOM_FIELD)
-        h->resync_mb_y = h->mb_y = h->mb_y + 1;
-    assert(h->mb_y < h->mb_height);
+        h->resync_mb_y = sl->mb_y = sl->mb_y + 1;
+    assert(sl->mb_y < h->mb_height);
 
     if (h->picture_structure == PICT_FRAME) {
         h->curr_pic_num = h->frame_num;
@@ -1895,7 +1896,7 @@ static av_always_inline void fill_filter_caches_inter(H264Context *h,
     }
 
     {
-        int16_t(*mv_src)[2] = &h->cur_pic.motion_val[list][4 * h->mb_x + 4 * h->mb_y * b_stride];
+        int16_t(*mv_src)[2] = &h->cur_pic.motion_val[list][4 * sl->mb_x + 4 * sl->mb_y * b_stride];
         AV_COPY128(mv_dst + 8 * 0, mv_src + 0 * b_stride);
         AV_COPY128(mv_dst + 8 * 1, mv_src + 1 * b_stride);
         AV_COPY128(mv_dst + 8 * 2, mv_src + 2 * b_stride);
@@ -1924,7 +1925,7 @@ static int fill_filter_caches(H264Context *h, H264SliceContext *sl, int mb_type)
     if (FRAME_MBAFF(h)) {
         const int left_mb_field_flag = IS_INTERLACED(h->cur_pic.mb_type[mb_xy - 1]);
         const int curr_mb_field_flag = IS_INTERLACED(mb_type);
-        if (h->mb_y & 1) {
+        if (sl->mb_y & 1) {
             if (left_mb_field_flag != curr_mb_field_flag)
                 left_xy[LTOP] -= h->mb_stride;
         } else {
@@ -2056,7 +2057,7 @@ static void loop_filter(H264Context *h, H264SliceContext *sl, int start_x, int e
 {
     uint8_t *dest_y, *dest_cb, *dest_cr;
     int linesize, uvlinesize, mb_x, mb_y;
-    const int end_mb_y       = h->mb_y + FRAME_MBAFF(h);
+    const int end_mb_y       = sl->mb_y + FRAME_MBAFF(h);
     const int old_slice_type = sl->slice_type;
     const int pixel_shift    = h->pixel_shift;
     const int block_h        = 16 >> h->chroma_y_shift;
@@ -2074,8 +2075,8 @@ static void loop_filter(H264Context *h, H264SliceContext *sl, int start_x, int e
                     h->mb_mbaff               =
                     h->mb_field_decoding_flag = !!IS_INTERLACED(mb_type);
 
-                h->mb_x = mb_x;
-                h->mb_y = mb_y;
+                sl->mb_x = mb_x;
+                sl->mb_y = mb_y;
                 dest_y  = h->cur_pic.f.data[0] +
                           ((mb_x << pixel_shift) + mb_y * h->linesize) * 16;
                 dest_cb = h->cur_pic.f.data[1] +
@@ -2098,7 +2099,7 @@ static void loop_filter(H264Context *h, H264SliceContext *sl, int start_x, int e
                     linesize   = sl->mb_linesize   = h->linesize;
                     uvlinesize = sl->mb_uvlinesize = h->uvlinesize;
                 }
-                backup_mb_border(h, dest_y, dest_cb, dest_cr, linesize,
+                backup_mb_border(h, sl, dest_y, dest_cb, dest_cr, linesize,
                                  uvlinesize, 0);
                 if (fill_filter_caches(h, sl, mb_type))
                     continue;
@@ -2115,15 +2116,15 @@ static void loop_filter(H264Context *h, H264SliceContext *sl, int start_x, int e
             }
     }
     sl->slice_type  = old_slice_type;
-    h->mb_x         = end_x;
-    h->mb_y         = end_mb_y - FRAME_MBAFF(h);
+    sl->mb_x         = end_x;
+    sl->mb_y         = end_mb_y - FRAME_MBAFF(h);
     sl->chroma_qp[0] = get_chroma_qp(h, 0, sl->qscale);
     sl->chroma_qp[1] = get_chroma_qp(h, 1, sl->qscale);
 }
 
 static void predict_field_decoding_flag(H264Context *h, H264SliceContext *sl)
 {
-    const int mb_xy = h->mb_x + h->mb_y * h->mb_stride;
+    const int mb_xy = sl->mb_x + sl->mb_y * h->mb_stride;
     int mb_type     = (h->slice_table[mb_xy - 1] == sl->slice_num) ?
                       h->cur_pic.mb_type[mb_xy - 1] :
                       (h->slice_table[mb_xy - h->mb_stride] == sl->slice_num) ?
@@ -2136,7 +2137,7 @@ static void predict_field_decoding_flag(H264Context *h, H264SliceContext *sl)
  */
 static void decode_finish_row(H264Context *h, H264SliceContext *sl)
 {
-    int top            = 16 * (h->mb_y      >> FIELD_PICTURE(h));
+    int top            = 16 * (sl->mb_y      >> FIELD_PICTURE(h));
     int pic_height     = 16 *  h->mb_height >> FIELD_PICTURE(h);
     int height         =  16      << FRAME_MBAFF(h);
     int deblock_border = (16 + 4) << FRAME_MBAFF(h);
@@ -2181,7 +2182,7 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 {
     H264SliceContext *sl = arg;
     H264Context       *h = sl->h264;
-    int lf_x_start = h->mb_x;
+    int lf_x_start = sl->mb_x;
 
     sl->mb_skip_run = -1;
 
@@ -2211,53 +2212,53 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
             // FIXME optimal? or let mb_decode decode 16x32 ?
             if (ret >= 0 && FRAME_MBAFF(h)) {
-                h->mb_y++;
+                sl->mb_y++;
 
                 ret = ff_h264_decode_mb_cabac(h, sl);
 
                 if (ret >= 0)
                     ff_h264_hl_decode_mb(h, sl);
-                h->mb_y--;
+                sl->mb_y--;
             }
             eos = get_cabac_terminate(&sl->cabac);
 
             if ((h->workaround_bugs & FF_BUG_TRUNCATED) &&
                 sl->cabac.bytestream > sl->cabac.bytestream_end + 2) {
-                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, h->mb_x - 1,
-                             h->mb_y, ER_MB_END);
-                if (h->mb_x >= lf_x_start)
-                    loop_filter(h, sl, lf_x_start, h->mb_x + 1);
+                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, sl->mb_x - 1,
+                             sl->mb_y, ER_MB_END);
+                if (sl->mb_x >= lf_x_start)
+                    loop_filter(h, sl, lf_x_start, sl->mb_x + 1);
                 return 0;
             }
             if (ret < 0 || sl->cabac.bytestream > sl->cabac.bytestream_end + 2) {
                 av_log(h->avctx, AV_LOG_ERROR,
                        "error while decoding MB %d %d, bytestream %td\n",
-                       h->mb_x, h->mb_y,
+                       sl->mb_x, sl->mb_y,
                        sl->cabac.bytestream_end - sl->cabac.bytestream);
-                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, h->mb_x,
-                             h->mb_y, ER_MB_ERROR);
+                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, sl->mb_x,
+                             sl->mb_y, ER_MB_ERROR);
                 return AVERROR_INVALIDDATA;
             }
 
-            if (++h->mb_x >= h->mb_width) {
-                loop_filter(h, sl, lf_x_start, h->mb_x);
-                h->mb_x = lf_x_start = 0;
+            if (++sl->mb_x >= h->mb_width) {
+                loop_filter(h, sl, lf_x_start, sl->mb_x);
+                sl->mb_x = lf_x_start = 0;
                 decode_finish_row(h, sl);
-                ++h->mb_y;
+                ++sl->mb_y;
                 if (FIELD_OR_MBAFF_PICTURE(h)) {
-                    ++h->mb_y;
-                    if (FRAME_MBAFF(h) && h->mb_y < h->mb_height)
+                    ++sl->mb_y;
+                    if (FRAME_MBAFF(h) && sl->mb_y < h->mb_height)
                         predict_field_decoding_flag(h, sl);
                 }
             }
 
-            if (eos || h->mb_y >= h->mb_height) {
+            if (eos || sl->mb_y >= h->mb_height) {
                 tprintf(h->avctx, "slice end %d %d\n",
                         get_bits_count(&h->gb), h->gb.size_in_bits);
-                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, h->mb_x - 1,
-                             h->mb_y, ER_MB_END);
-                if (h->mb_x > lf_x_start)
-                    loop_filter(h, sl, lf_x_start, h->mb_x);
+                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, sl->mb_x - 1,
+                             sl->mb_y, ER_MB_END);
+                if (sl->mb_x > lf_x_start)
+                    loop_filter(h, sl, lf_x_start, sl->mb_x);
                 return 0;
             }
         }
@@ -2270,44 +2271,44 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
             // FIXME optimal? or let mb_decode decode 16x32 ?
             if (ret >= 0 && FRAME_MBAFF(h)) {
-                h->mb_y++;
+                sl->mb_y++;
                 ret = ff_h264_decode_mb_cavlc(h, sl);
 
                 if (ret >= 0)
                     ff_h264_hl_decode_mb(h, sl);
-                h->mb_y--;
+                sl->mb_y--;
             }
 
             if (ret < 0) {
                 av_log(h->avctx, AV_LOG_ERROR,
-                       "error while decoding MB %d %d\n", h->mb_x, h->mb_y);
-                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, h->mb_x,
-                             h->mb_y, ER_MB_ERROR);
+                       "error while decoding MB %d %d\n", sl->mb_x, sl->mb_y);
+                er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, sl->mb_x,
+                             sl->mb_y, ER_MB_ERROR);
                 return ret;
             }
 
-            if (++h->mb_x >= h->mb_width) {
-                loop_filter(h, sl, lf_x_start, h->mb_x);
-                h->mb_x = lf_x_start = 0;
+            if (++sl->mb_x >= h->mb_width) {
+                loop_filter(h, sl, lf_x_start, sl->mb_x);
+                sl->mb_x = lf_x_start = 0;
                 decode_finish_row(h, sl);
-                ++h->mb_y;
+                ++sl->mb_y;
                 if (FIELD_OR_MBAFF_PICTURE(h)) {
-                    ++h->mb_y;
-                    if (FRAME_MBAFF(h) && h->mb_y < h->mb_height)
+                    ++sl->mb_y;
+                    if (FRAME_MBAFF(h) && sl->mb_y < h->mb_height)
                         predict_field_decoding_flag(h, sl);
                 }
-                if (h->mb_y >= h->mb_height) {
+                if (sl->mb_y >= h->mb_height) {
                     tprintf(h->avctx, "slice end %d %d\n",
                             get_bits_count(&h->gb), h->gb.size_in_bits);
 
                     if (get_bits_left(&h->gb) == 0) {
                         er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y,
-                                     h->mb_x - 1, h->mb_y, ER_MB_END);
+                                     sl->mb_x - 1, sl->mb_y, ER_MB_END);
 
                         return 0;
                     } else {
                         er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y,
-                                     h->mb_x - 1, h->mb_y, ER_MB_END);
+                                     sl->mb_x - 1, sl->mb_y, ER_MB_END);
 
                         return AVERROR_INVALIDDATA;
                     }
@@ -2320,14 +2321,14 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
 
                 if (get_bits_left(&h->gb) == 0) {
                     er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y,
-                                 h->mb_x - 1, h->mb_y, ER_MB_END);
-                    if (h->mb_x > lf_x_start)
-                        loop_filter(h, sl, lf_x_start, h->mb_x);
+                                 sl->mb_x - 1, sl->mb_y, ER_MB_END);
+                    if (sl->mb_x > lf_x_start)
+                        loop_filter(h, sl, lf_x_start, sl->mb_x);
 
                     return 0;
                 } else {
-                    er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, h->mb_x,
-                                 h->mb_y, ER_MB_ERROR);
+                    er_add_slice(h, sl, h->resync_mb_x, h->resync_mb_y, sl->mb_x,
+                                 sl->mb_y, ER_MB_ERROR);
 
                     return AVERROR_INVALIDDATA;
                 }
@@ -2346,12 +2347,15 @@ int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count)
 {
     AVCodecContext *const avctx = h->avctx;
     H264Context *hx;
+    H264SliceContext *sl;
     int i;
 
     if (h->avctx->hwaccel)
         return 0;
     if (context_count == 1) {
-        return decode_slice(avctx, &h->slice_ctx[0]);
+        int ret = decode_slice(avctx, &h->slice_ctx[0]);
+        h->mb_y = h->slice_ctx[0].mb_y;
+        return ret;
     } else {
         for (i = 1; i < context_count; i++) {
             hx                 = h->thread_context[i];
@@ -2363,8 +2367,8 @@ int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count)
 
         /* pull back stuff from slices to master context */
         hx                   = h->thread_context[context_count - 1];
-        h->mb_x              = hx->mb_x;
-        h->mb_y              = hx->mb_y;
+        sl                   = &h->slice_ctx[context_count - 1];
+        h->mb_y              = sl->mb_y;
         h->droppable         = hx->droppable;
         h->picture_structure = hx->picture_structure;
         for (i = 1; i < context_count; i++)
diff --git a/libavcodec/svq3.c b/libavcodec/svq3.c
index bd35942539..56b5fb40b9 100644
--- a/libavcodec/svq3.c
+++ b/libavcodec/svq3.c
@@ -378,11 +378,11 @@ static inline int svq3_mc_dir(SVQ3Context *s, int size, int mode,
 
     for (i = 0; i < 16; i += part_height)
         for (j = 0; j < 16; j += part_width) {
-            const int b_xy = (4 * h->mb_x + (j >> 2)) +
-                             (4 * h->mb_y + (i >> 2)) * h->b_stride;
+            const int b_xy = (4 * sl->mb_x + (j >> 2)) +
+                             (4 * sl->mb_y + (i >> 2)) * h->b_stride;
             int dxy;
-            x = 16 * h->mb_x + j;
-            y = 16 * h->mb_y + i;
+            x = 16 * sl->mb_x + j;
+            y = 16 * sl->mb_y + i;
             k = (j >> 2 & 1) + (i >> 1 & 2) +
                 (j >> 1 & 4) + (i      & 8);
 
@@ -488,20 +488,20 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
     uint32_t vlc;
     int8_t *top, *left;
     const int mb_xy         = sl->mb_xy;
-    const int b_xy          = 4 * h->mb_x + 4 * h->mb_y * h->b_stride;
+    const int b_xy          = 4 * sl->mb_x + 4 * sl->mb_y * h->b_stride;
 
-    sl->top_samples_available      = (h->mb_y == 0) ? 0x33FF : 0xFFFF;
-    sl->left_samples_available     = (h->mb_x == 0) ? 0x5F5F : 0xFFFF;
+    sl->top_samples_available      = (sl->mb_y == 0) ? 0x33FF : 0xFFFF;
+    sl->left_samples_available     = (sl->mb_x == 0) ? 0x5F5F : 0xFFFF;
     sl->topright_samples_available = 0xFFFF;
 
     if (mb_type == 0) {           /* SKIP */
         if (h->pict_type == AV_PICTURE_TYPE_P ||
             s->next_pic->mb_type[mb_xy] == -1) {
-            svq3_mc_dir_part(s, 16 * h->mb_x, 16 * h->mb_y, 16, 16,
+            svq3_mc_dir_part(s, 16 * sl->mb_x, 16 * sl->mb_y, 16, 16,
                              0, 0, 0, 0, 0, 0);
 
             if (h->pict_type == AV_PICTURE_TYPE_B)
-                svq3_mc_dir_part(s, 16 * h->mb_x, 16 * h->mb_y, 16, 16,
+                svq3_mc_dir_part(s, 16 * sl->mb_x, 16 * sl->mb_y, 16, 16,
                                  0, 0, 0, 0, 1, 1);
 
             mb_type = MB_TYPE_SKIP;
@@ -533,7 +533,7 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
          */
 
         for (m = 0; m < 2; m++) {
-            if (h->mb_x > 0 && sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - 1] + 6] != -1) {
+            if (sl->mb_x > 0 && sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - 1] + 6] != -1) {
                 for (i = 0; i < 4; i++)
                     AV_COPY32(sl->mv_cache[m][scan8[0] - 1 + i * 8],
                               h->cur_pic.motion_val[m][b_xy - 1 + i * h->b_stride]);
@@ -541,14 +541,14 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
                 for (i = 0; i < 4; i++)
                     AV_ZERO32(sl->mv_cache[m][scan8[0] - 1 + i * 8]);
             }
-            if (h->mb_y > 0) {
+            if (sl->mb_y > 0) {
                 memcpy(sl->mv_cache[m][scan8[0] - 1 * 8],
                        h->cur_pic.motion_val[m][b_xy - h->b_stride],
                        4 * 2 * sizeof(int16_t));
                 memset(&sl->ref_cache[m][scan8[0] - 1 * 8],
                        (sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride]] == -1) ? PART_NOT_AVAILABLE : 1, 4);
 
-                if (h->mb_x < h->mb_width - 1) {
+                if (sl->mb_x < h->mb_width - 1) {
                     AV_COPY32(sl->mv_cache[m][scan8[0] + 4 - 1 * 8],
                               h->cur_pic.motion_val[m][b_xy - h->b_stride + 4]);
                     sl->ref_cache[m][scan8[0] + 4 - 1 * 8] =
@@ -556,7 +556,7 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
                          sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride]] == -1) ? PART_NOT_AVAILABLE : 1;
                 } else
                     sl->ref_cache[m][scan8[0] + 4 - 1 * 8] = PART_NOT_AVAILABLE;
-                if (h->mb_x > 0) {
+                if (sl->mb_x > 0) {
                     AV_COPY32(sl->mv_cache[m][scan8[0] - 1 - 1 * 8],
                               h->cur_pic.motion_val[m][b_xy - h->b_stride - 1]);
                     sl->ref_cache[m][scan8[0] - 1 - 1 * 8] =
@@ -599,13 +599,13 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
         memset(sl->intra4x4_pred_mode_cache, -1, 8 * 5 * sizeof(int8_t));
 
         if (mb_type == 8) {
-            if (h->mb_x > 0) {
+            if (sl->mb_x > 0) {
                 for (i = 0; i < 4; i++)
                     sl->intra4x4_pred_mode_cache[scan8[0] - 1 + i * 8] = sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - 1] + 6 - i];
                 if (sl->intra4x4_pred_mode_cache[scan8[0] - 1] == -1)
                     sl->left_samples_available = 0x5F5F;
             }
-            if (h->mb_y > 0) {
+            if (sl->mb_y > 0) {
                 sl->intra4x4_pred_mode_cache[4 + 8 * 0] = sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride] + 0];
                 sl->intra4x4_pred_mode_cache[5 + 8 * 0] = sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride] + 1];
                 sl->intra4x4_pred_mode_cache[6 + 8 * 0] = sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride] + 2];
@@ -646,8 +646,8 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
         if (mb_type == 8) {
             ff_h264_check_intra4x4_pred_mode(h, sl);
 
-            sl->top_samples_available  = (h->mb_y == 0) ? 0x33FF : 0xFFFF;
-            sl->left_samples_available = (h->mb_x == 0) ? 0x5F5F : 0xFFFF;
+            sl->top_samples_available  = (sl->mb_y == 0) ? 0x33FF : 0xFFFF;
+            sl->left_samples_available = (sl->mb_x == 0) ? 0x5F5F : 0xFFFF;
         } else {
             for (i = 0; i < 4; i++)
                 memset(&sl->intra4x4_pred_mode_cache[scan8[0] + 8 * i], DC_128_PRED, 4);
@@ -822,7 +822,7 @@ static int svq3_decode_slice_header(AVCodecContext *avctx)
     if ((header & 0x9F) == 2) {
         i              = (h->mb_num < 64) ? 6 : (1 + av_log2(h->mb_num - 1));
         sl->mb_skip_run = get_bits(&h->gb, i) -
-                         (h->mb_y * h->mb_width + h->mb_x);
+                         (sl->mb_y * h->mb_width + sl->mb_x);
     } else {
         skip_bits1(&h->gb);
         sl->mb_skip_run = 0;
@@ -845,17 +845,17 @@ static int svq3_decode_slice_header(AVCodecContext *avctx)
         skip_bits(&h->gb, 8);
 
     /* reset intra predictors and invalidate motion vector references */
-    if (h->mb_x > 0) {
+    if (sl->mb_x > 0) {
         memset(sl->intra4x4_pred_mode + h->mb2br_xy[mb_xy - 1] + 3,
                -1, 4 * sizeof(int8_t));
-        memset(sl->intra4x4_pred_mode + h->mb2br_xy[mb_xy - h->mb_x],
-               -1, 8 * sizeof(int8_t) * h->mb_x);
+        memset(sl->intra4x4_pred_mode + h->mb2br_xy[mb_xy - sl->mb_x],
+               -1, 8 * sizeof(int8_t) * sl->mb_x);
     }
-    if (h->mb_y > 0) {
+    if (sl->mb_y > 0) {
         memset(sl->intra4x4_pred_mode + h->mb2br_xy[mb_xy - h->mb_stride],
-               -1, 8 * sizeof(int8_t) * (h->mb_width - h->mb_x));
+               -1, 8 * sizeof(int8_t) * (h->mb_width - sl->mb_x));
 
-        if (h->mb_x > 0)
+        if (sl->mb_x > 0)
             sl->intra4x4_pred_mode[h->mb2br_xy[mb_xy - h->mb_stride - 1] + 3] = -1;
     }
 
@@ -1132,7 +1132,7 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
 
     init_get_bits(&h->gb, buf, 8 * buf_size);
 
-    h->mb_x = h->mb_y = sl->mb_xy = 0;
+    sl->mb_x = sl->mb_y = sl->mb_xy = 0;
 
     if (svq3_decode_slice_header(avctx))
         return -1;
@@ -1245,10 +1245,10 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
         }
     }
 
-    for (h->mb_y = 0; h->mb_y < h->mb_height; h->mb_y++) {
-        for (h->mb_x = 0; h->mb_x < h->mb_width; h->mb_x++) {
+    for (sl->mb_y = 0; sl->mb_y < h->mb_height; sl->mb_y++) {
+        for (sl->mb_x = 0; sl->mb_x < h->mb_width; sl->mb_x++) {
             unsigned mb_type;
-            sl->mb_xy = h->mb_x + h->mb_y * h->mb_stride;
+            sl->mb_xy = sl->mb_x + sl->mb_y * h->mb_stride;
 
             if ((get_bits_count(&h->gb) + 7) >= h->gb.size_in_bits &&
                 ((get_bits_count(&h->gb) & 7) == 0 ||
@@ -1270,7 +1270,7 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
                 mb_type += 4;
             if (mb_type > 33 || svq3_decode_mb(s, mb_type)) {
                 av_log(h->avctx, AV_LOG_ERROR,
-                       "error while decoding MB %d %d\n", h->mb_x, h->mb_y);
+                       "error while decoding MB %d %d\n", sl->mb_x, sl->mb_y);
                 return -1;
             }
 
@@ -1278,13 +1278,13 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
                 ff_h264_hl_decode_mb(h, &h->slice_ctx[0]);
 
             if (h->pict_type != AV_PICTURE_TYPE_B && !h->low_delay)
-                h->cur_pic.mb_type[h->mb_x + h->mb_y * h->mb_stride] =
+                h->cur_pic.mb_type[sl->mb_x + sl->mb_y * h->mb_stride] =
                     (h->pict_type == AV_PICTURE_TYPE_P && mb_type < 8) ? (mb_type - 1) : -1;
         }
 
         ff_draw_horiz_band(avctx, &s->cur_pic->f,
                            s->last_pic->f.data[0] ? &s->last_pic->f : NULL,
-                           16 * h->mb_y, 16, h->picture_structure, 0,
+                           16 * sl->mb_y, 16, h->picture_structure, 0,
                            h->low_delay);
     }
 
diff --git a/libavcodec/vaapi_h264.c b/libavcodec/vaapi_h264.c
index ce7643eb9a..481d7d17f5 100644
--- a/libavcodec/vaapi_h264.c
+++ b/libavcodec/vaapi_h264.c
@@ -329,7 +329,7 @@ static int vaapi_h264_decode_slice(AVCodecContext *avctx,
     if (!slice_param)
         return -1;
     slice_param->slice_data_bit_offset          = get_bits_count(&h->gb) + 8; /* bit buffer started beyond nal_unit_type */
-    slice_param->first_mb_in_slice              = (h->mb_y >> FIELD_OR_MBAFF_PICTURE(h)) * h->mb_width + h->mb_x;
+    slice_param->first_mb_in_slice              = (sl->mb_y >> FIELD_OR_MBAFF_PICTURE(h)) * h->mb_width + sl->mb_x;
     slice_param->slice_type                     = ff_h264_get_slice_type(sl);
     slice_param->direct_spatial_mv_pred_flag    = sl->slice_type == AV_PICTURE_TYPE_B ? sl->direct_spatial_mv_pred : 0;
     slice_param->num_ref_idx_l0_active_minus1   = sl->list_count > 0 ? sl->ref_count[0] - 1 : 0;