examples/decoding_encoding: remove misplaced and confusing comment

doc/examples/decoding_encoding.c

@@ -531,8 +531,6 @@ static void video_decode_example(const char *outfilename, const char *filename)
         exit(1);
     }
 
-    /* the codec gives us the frame size, in samples */
-
     f = fopen(filename, "rb");
     if (!f) {
         fprintf(stderr, "Could not open %s\n", filename);