avcodec/error_resilience: Only keep what is needed from MECmpContext

ERContext currently has an embedded MECmpContext, despite only
needing exactly one function from it. This is wasteful because
MECmpContext is pretty large (135 pointers, 1080 B for eight byte
pointers). So keep only what is needed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/error_resilience.c

@@ -766,12 +766,12 @@ static int is_intra_more_likely(ERContext *s)
                 } else {
                     ff_thread_await_progress(s->last_pic.tf, mb_y, 0);
                 }
-                is_intra_likely += s->mecc.sad[0](NULL, last_mb_ptr, mb_ptr,
-                                                  linesize[0], 16);
+                is_intra_likely += s->sad(NULL, last_mb_ptr, mb_ptr,
+                                          linesize[0], 16);
                 // FIXME need await_progress() here
-                is_intra_likely -= s->mecc.sad[0](NULL, last_mb_ptr,
-                                                  last_mb_ptr + linesize[0] * 16,
-                                                  linesize[0], 16);
+                is_intra_likely -= s->sad(NULL, last_mb_ptr,
+                                          last_mb_ptr + linesize[0] * 16,
+                                          linesize[0], 16);
             } else {
                 if (IS_INTRA(s->cur_pic.mb_type[mb_xy]))
                    is_intra_likely++;
@@ -790,7 +790,9 @@ void ff_er_frame_start(ERContext *s)
         return;
 
     if (!s->mecc_inited) {
-        ff_me_cmp_init(&s->mecc, s->avctx);
+        MECmpContext mecc;
+        ff_me_cmp_init(&mecc, s->avctx);
+        s->sad = mecc.sad[0];
         s->mecc_inited = 1;
     }
 

libavcodec/error_resilience.h

@@ -52,7 +52,8 @@ typedef struct ERPicture {
 
 typedef struct ERContext {
     AVCodecContext *avctx;
-    MECmpContext mecc;
+
+    me_cmp_func sad;
     int mecc_inited;
 
     int *mb_index2xy;