cbs_vp9: Ensure that reserved zero bits are actually zero

libavcodec/cbs_vp9.c

@@ -314,6 +314,12 @@ static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
         current->name = prob; \
     } while (0)
 
+#define fixed(width, name, value) do { \
+        av_unused uint32_t fixed_value = value; \
+        CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
+                                   0, &fixed_value, value, value)); \
+    } while (0)
+
 #define infer(name, value) do { \
         current->name = value; \
     } while (0)
@@ -331,6 +337,7 @@ static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
 #undef fle
 #undef delta_q
 #undef prob
+#undef fixed
 #undef infer
 #undef byte_alignment
 
@@ -370,6 +377,11 @@ static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
             xf(8, name.prob, current->name, subs, __VA_ARGS__); \
     } while (0)
 
+#define fixed(width, name, value) do { \
+        CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
+                                    0, value, value, value)); \
+    } while (0)
+
 #define infer(name, value) do { \
         if (current->name != (value)) { \
             av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
@@ -392,6 +404,7 @@ static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
 #undef fle
 #undef delta_q
 #undef prob
+#undef fixed
 #undef infer
 #undef byte_alignment
 

libavcodec/cbs_vp9.h

@@ -84,7 +84,6 @@ typedef struct VP9RawFrameHeader {
     uint8_t frame_marker;
     uint8_t profile_low_bit;
     uint8_t profile_high_bit;
-    uint8_t profile_reserved_zero;
 
     uint8_t show_existing_frame;
     uint8_t frame_to_show_map_idx;
@@ -99,7 +98,6 @@ typedef struct VP9RawFrameHeader {
     uint8_t color_range;
     uint8_t subsampling_x;
     uint8_t subsampling_y;
-    uint8_t color_config_reserved_zero;
 
     uint8_t refresh_frame_flags;
 

libavcodec/cbs_vp9_syntax_template.c

@@ -55,7 +55,7 @@ static int FUNC(color_config)(CodedBitstreamContext *ctx, RWContext *rw,
         if (profile == 1 || profile == 3) {
             f(1, subsampling_x);
             f(1, subsampling_y);
-            f(1, color_config_reserved_zero);
+            fixed(1, reserved_zero, 0);
         } else {
             infer(subsampling_x, 1);
             infer(subsampling_y, 1);
@@ -65,7 +65,7 @@ static int FUNC(color_config)(CodedBitstreamContext *ctx, RWContext *rw,
         if (profile == 1 || profile == 3) {
             infer(subsampling_x, 0);
             infer(subsampling_y, 0);
-            f(1, color_config_reserved_zero);
+            fixed(1, reserved_zero, 0);
         }
     }
 
@@ -258,7 +258,7 @@ static int FUNC(uncompressed_header)(CodedBitstreamContext *ctx, RWContext *rw,
     f(1, profile_high_bit);
     profile = (current->profile_high_bit << 1) + current->profile_low_bit;
     if (profile == 3)
-        f(1, profile_reserved_zero);
+        fixed(1, reserved_zero, 0);
 
     f(1, show_existing_frame);
     if (current->show_existing_frame) {