avconv: pass the actually selected decoder to filter_codec_opts().

avconv_opt.c

@@ -448,12 +448,12 @@ static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
         ist->file_index = nb_input_files;
         ist->discard = 1;
         st->discard  = AVDISCARD_ALL;
-        ist->opts = filter_codec_opts(o->g->codec_opts, ist->st->codec->codec_id, ic, st, NULL);
 
         ist->ts_scale = 1.0;
         MATCH_PER_STREAM_OPT(ts_scale, dbl, ist->ts_scale, ic, st);
 
         ist->dec = choose_decoder(o, ic, st);
+        ist->opts = filter_codec_opts(o->g->codec_opts, ist->st->codec->codec_id, ic, st, ist->dec);
 
         switch (dec->codec_type) {
         case AVMEDIA_TYPE_VIDEO: