avformat/mux: Fix some codecpar non uses

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mux.c

@@ -557,7 +557,7 @@ static int compute_muxer_pkt_fields(AVFormatContext *s, AVStream *st, AVPacket *
         av_log(s, AV_LOG_TRACE, "compute_muxer_pkt_fields: pts:%s dts:%s cur_dts:%s b:%d size:%d st:%d\n",
             av_ts2str(pkt->pts), av_ts2str(pkt->dts), av_ts2str(st->cur_dts), delay, pkt->size, pkt->stream_index);
 
-    if (pkt->duration < 0 && st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {
+    if (pkt->duration < 0 && st->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
         av_log(s, AV_LOG_WARNING, "Packet with invalid duration %"PRId64" in stream %d\n",
                pkt->duration, pkt->stream_index);
         pkt->duration = 0;
@@ -623,7 +623,7 @@ static int compute_muxer_pkt_fields(AVFormatContext *s, AVStream *st, AVPacket *
     st->priv_pts->val = pkt->dts;
 
     /* update pts */
-    switch (st->codec->codec_type) {
+    switch (st->codecpar->codec_type) {
     case AVMEDIA_TYPE_AUDIO:
         frame_size = (pkt->flags & AV_PKT_FLAG_UNCODED_FRAME) ?
                      ((AVFrame *)pkt->data)->nb_samples :