lavc/rt: small wording fix in a comment.

libavcodec/realtextdec.c

@@ -65,7 +65,7 @@ static int realtext_decode_frame(AVCodecContext *avctx,
 
     av_bprint_init(&buf, 0, 4096);
     // note: no need to rescale pts & duration since they are in the same
-    // timebase than ASS (1/100)
+    // timebase as ASS (1/100)
     if (ptr && avpkt->size > 0 && !rt_event_to_ass(&buf, ptr))
         ff_ass_add_rect(sub, buf.str, avpkt->pts, avpkt->duration, 0);
     *got_sub_ptr = sub->num_rects > 0;