Print parent log context too, if available.

Originally committed as revision 23200 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/log.c

@@ -68,11 +68,17 @@ void av_log_default_callback(void* ptr, int level, const char* fmt, va_list vl)
     AVClass* avc= ptr ? *(AVClass**)ptr : NULL;
     if(level>av_log_level)
         return;
+    line[0]=0;
 #undef fprintf
     if(print_prefix && avc) {
-        snprintf(line, sizeof(line), "[%s @ %p]", avc->item_name(ptr), ptr);
-    }else
-        line[0]=0;
+        if(avc->version >= (50<<16 | 15<<8 | 3) && avc->parent_log_context_offset){
+            AVClass** parent= *(AVClass***)(((uint8_t*)ptr) + avc->parent_log_context_offset);
+            if(parent && *parent){
+                snprintf(line, sizeof(line), "[%s @ %p]", (*parent)->item_name(parent), parent);
+            }
+        }
+        snprintf(line + strlen(line), sizeof(line) - strlen(line), "[%s @ %p]", avc->item_name(ptr), ptr);
+    }
 
     vsnprintf(line + strlen(line), sizeof(line) - strlen(line), fmt, vl);