diff --git a/libavformat/utils.c b/libavformat/utils.c
index fd0b10b917..1e0b344b5c 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -673,6 +673,21 @@ fail:
 
 /*******************************************************/
 
+static void force_codec_ids(AVFormatContext *s, AVStream *st)
+{
+    switch(st->codec->codec_type){
+    case AVMEDIA_TYPE_VIDEO:
+        if(s->video_codec_id)   st->codec->codec_id= s->video_codec_id;
+        break;
+    case AVMEDIA_TYPE_AUDIO:
+        if(s->audio_codec_id)   st->codec->codec_id= s->audio_codec_id;
+        break;
+    case AVMEDIA_TYPE_SUBTITLE:
+        if(s->subtitle_codec_id)st->codec->codec_id= s->subtitle_codec_id;
+        break;
+    }
+}
+
 int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     int ret, i;
@@ -721,17 +736,7 @@ int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
 
         st= s->streams[pkt->stream_index];
 
-        switch(st->codec->codec_type){
-        case AVMEDIA_TYPE_VIDEO:
-            if(s->video_codec_id)   st->codec->codec_id= s->video_codec_id;
-            break;
-        case AVMEDIA_TYPE_AUDIO:
-            if(s->audio_codec_id)   st->codec->codec_id= s->audio_codec_id;
-            break;
-        case AVMEDIA_TYPE_SUBTITLE:
-            if(s->subtitle_codec_id)st->codec->codec_id= s->subtitle_codec_id;
-            break;
-        }
+        force_codec_ids(s, st);
 
         if(!pktl && st->request_probe <= 0)
             return ret;