[FFmpeg-devel] [PATCH v2 2/7] lavc/hevc_ps: Add sps parse support for HEVC SCC extension syntax

[Haihao Xiang]

From: Linjie Fu <linjie.fu at intel.com>

According to 7.3.2.2.3 in T-REC-H.265-201911.

Signed-off-by: Linjie Fu <linjie.justin.fu at gmail.com>
Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>
---
v2 update: 
- Ignore sps_multilayer_extension_flag, sps_3d_extension_flag and
  sps_scc_extension_flag for non-SCC streams
- Return AVERROR_PATCHWELCOME for sps_multilayer_extension_flag(1) and
sps_3d_extension_flag(1).
- sps_palette_predictor_initializer is an u(v) value instead of an ue(v) 

 libavcodec/hevc.h    |  3 +++
 libavcodec/hevc_ps.c | 44 +++++++++++++++++++++++++++++++++++++++++---
 libavcodec/hevc_ps.h | 15 +++++++++++++++
 3 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/libavcodec/hevc.h b/libavcodec/hevc.h
index 1804755327..6b454a75c1 100644
--- a/libavcodec/hevc.h
+++ b/libavcodec/hevc.h
@@ -154,6 +154,9 @@ enum {
     // get near that, though, so set a lower limit here with the maximum
     // possible value for 4K video (at most 135 16x16 Ctb rows).
     HEVC_MAX_ENTRY_POINT_OFFSETS = HEVC_MAX_TILE_COLUMNS * 135,
+
+    // A.3.7: Screen content coding extensions
+    HEVC_MAX_PALETTE_PREDICTOR_SIZE = 128,
 };
 
 
diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
index 584e2ba0d6..d65efc1aef 100644
--- a/libavcodec/hevc_ps.c
+++ b/libavcodec/hevc_ps.c
@@ -909,7 +909,7 @@ int ff_hevc_parse_sps(HEVCSPS *sps, GetBitContext *gb, unsigned int *sps_id,
     HEVCWindow *ow;
     int ret = 0;
     int log2_diff_max_min_transform_block_size;
-    int bit_depth_chroma, start, vui_present, sublayer_ordering_info;
+    int bit_depth_chroma, start, vui_present, sublayer_ordering_info, num_comps;
     int i;
 
     // Coded parameters
@@ -1130,8 +1130,20 @@ int ff_hevc_parse_sps(HEVCSPS *sps, GetBitContext *gb, unsigned int *sps_id,
         decode_vui(gb, avctx, apply_defdispwin, sps);
 
     if (get_bits1(gb)) { // sps_extension_flag
-        sps->sps_range_extension_flag = get_bits1(gb);
-        skip_bits(gb, 7); //sps_extension_7bits = get_bits(gb, 7);
+        sps->sps_range_extension_flag      = get_bits1(gb);
+
+        /* To keep consistency with the workaround for hevc-conformance-PS_A_VIDYO_3
+         * in PPS, here ignore sps_multilayer_extension_flag, sps_3d_extension_flag
+         * and sps_scc_extension_flag for non-SCC streams too. Note multilayer_extension
+         * or 3d_extension is not implemented in FFmpeg */
+        if (sps->ptl.general_ptl.profile_idc == FF_PROFILE_HEVC_SCC) {
+            sps->sps_multilayer_extension_flag = get_bits1(gb);
+            sps->sps_3d_extension_flag         = get_bits1(gb);
+            sps->sps_scc_extension_flag        = get_bits1(gb);
+            skip_bits(gb, 4); //sps_extension_4bits = get_bits(gb, 4);
+        } else
+            skip_bits(gb, 7);
+
         if (sps->sps_range_extension_flag) {
             sps->transform_skip_rotation_enabled_flag = get_bits1(gb);
             sps->transform_skip_context_enabled_flag  = get_bits1(gb);
@@ -1157,6 +1169,32 @@ int ff_hevc_parse_sps(HEVCSPS *sps, GetBitContext *gb, unsigned int *sps_id,
                 av_log(avctx, AV_LOG_WARNING,
                    "cabac_bypass_alignment_enabled_flag not yet implemented\n");
         }
+        if (sps->sps_multilayer_extension_flag || sps->sps_3d_extension_flag) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "multilayer_extension or 3d_extension not yet implemented\n");
+            return AVERROR_PATCHWELCOME;
+        }
+
+        if (sps->sps_scc_extension_flag) {
+            sps->sps_curr_pic_ref_enabled_flag = get_bits1(gb);
+            sps->palette_mode_enabled_flag     = get_bits1(gb);
+            if (sps->palette_mode_enabled_flag) {
+                sps->palette_max_size = get_ue_golomb_long(gb);
+                sps->delta_palette_max_predictor_size = get_ue_golomb_long(gb);
+                sps->sps_palette_predictor_initializers_present_flag = get_bits1(gb);
+
+                if (sps->sps_palette_predictor_initializers_present_flag) {
+                    sps->sps_num_palette_predictor_initializers_minus1 = get_ue_golomb_long(gb);
+                    num_comps = !sps->chroma_format_idc ? 1 : 3;
+                    for (int comp = 0; comp < num_comps; comp++)
+                        for (i = 0; i <= sps->sps_num_palette_predictor_initializers_minus1; i++)
+                            sps->sps_palette_predictor_initializer[comp][i] =
+                                    get_bits(gb, !comp ? sps->bit_depth : sps->bit_depth_chroma);
+                }
+            }
+            sps->motion_vector_resolution_control_idc   = get_bits(gb, 2);
+            sps->intra_boundary_filtering_disabled_flag = get_bits1(gb);
+        }
     }
     if (apply_defdispwin) {
         sps->output_window.left_offset   += sps->vui.def_disp_win.left_offset;
diff --git a/libavcodec/hevc_ps.h b/libavcodec/hevc_ps.h
index 2a1bbf6489..be23758008 100644
--- a/libavcodec/hevc_ps.h
+++ b/libavcodec/hevc_ps.h
@@ -223,6 +223,21 @@ typedef struct HEVCSPS {
     int persistent_rice_adaptation_enabled_flag;
     int cabac_bypass_alignment_enabled_flag;
 
+    // Not yet implemented
+    int sps_multilayer_extension_flag;
+    int sps_3d_extension_flag;
+
+    int sps_scc_extension_flag;
+    int sps_curr_pic_ref_enabled_flag;
+    int palette_mode_enabled_flag;
+    int palette_max_size;
+    int delta_palette_max_predictor_size;
+    int sps_palette_predictor_initializers_present_flag;
+    int sps_num_palette_predictor_initializers_minus1;
+    int sps_palette_predictor_initializer[3][HEVC_MAX_PALETTE_PREDICTOR_SIZE];
+    int motion_vector_resolution_control_idc;
+    int intra_boundary_filtering_disabled_flag;
+
     ///< coded frame dimension in various units
     int width;
     int height;
-- 
2.25.1