vvcdec: add CTU parser

Co-authored-by: Xu Mu <toxumu@outlook.com>
Co-authored-by: Frank Plowman <post@frankplowman.com>
Co-authored-by: Shaun Loo <shaunloo10@gmail.com>
Co-authored-by: Wu Jianhua <toqsxw@outlook.com>

libavcodec/vvc/vvc_ctu.h

@@ -459,6 +459,17 @@ typedef struct ALFParams {
     uint8_t applied[3];
 } ALFParams;
 
+/**
+ * parse a CTU
+ * @param lc local context for CTU
+ * @param ctb_idx CTB(CTU) address in the current slice
+ * @param rs raster order for the CTU.
+ * @param rx raster order x for the CTU.
+ * @param ry raster order y for the CTU.
+ * @return AVERROR
+ */
+int ff_vvc_coding_tree_unit(VVCLocalContext *lc, int ctu_idx, int rs, int rx, int ry);
+
 //utils
 void ff_vvc_set_neighbour_available(VVCLocalContext *lc, int x0, int y0, int w, int h);
 void ff_vvc_decode_neighbour(VVCLocalContext *lc, int x_ctb, int y_ctb, int rx, int ry, int rs);