diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 25c699e5d5..92b7d6c773 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -72,7 +72,6 @@ typedef struct OutputStream {
     int bit_rate;
     char bandwidth_str[64];
 
-    int codec_str_extradata_size;
     char codec_str[100];
 } OutputStream;
 
@@ -503,12 +502,6 @@ static int write_manifest(AVFormatContext *s, int final)
             if (st->codec->codec_type != AVMEDIA_TYPE_VIDEO)
                 continue;
 
-            if (os->codec_str_extradata_size != st->codec->extradata_size) {
-                memset(os->codec_str, 0, sizeof(os->codec_str));
-                set_codec_str(s, st->codec, os->codec_str, sizeof(os->codec_str));
-                os->codec_str_extradata_size = st->codec->extradata_size;
-            }
-
             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->width, st->codec->height);
             output_segment_list(&c->streams[i], out, c);
             avio_printf(out, "\t\t\t</Representation>\n");
@@ -524,12 +517,6 @@ static int write_manifest(AVFormatContext *s, int final)
             if (st->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                 continue;
 
-            if (os->codec_str_extradata_size != st->codec->extradata_size) {
-                memset(os->codec_str, 0, sizeof(os->codec_str));
-                set_codec_str(s, st->codec, os->codec_str, sizeof(os->codec_str));
-                os->codec_str_extradata_size = st->codec->extradata_size;
-            }
-
             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->sample_rate);
             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
             output_segment_list(&c->streams[i], out, c);
@@ -664,8 +651,7 @@ static int dash_write_header(AVFormatContext *s)
         else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
             c->has_audio = 1;
 
-        set_codec_str(s, s->streams[i]->codec, os->codec_str, sizeof(os->codec_str));
-        os->codec_str_extradata_size = s->streams[i]->codec->extradata_size;
+        set_codec_str(s, st->codec, os->codec_str, sizeof(os->codec_str));
         os->first_pts = AV_NOPTS_VALUE;
         os->max_pts = AV_NOPTS_VALUE;
         os->segment_index = 1;
@@ -750,6 +736,29 @@ static void find_index_range(AVFormatContext *s, const char *full_path,
     *index_length = AV_RB32(&buf[0]);
 }
 
+static int update_stream_extradata(AVFormatContext *s, OutputStream *os,
+                                   AVCodecContext *codec)
+{
+    uint8_t *extradata;
+
+    if (os->ctx->streams[0]->codec->extradata_size || !codec->extradata_size)
+        return 0;
+
+    extradata = av_malloc(codec->extradata_size);
+
+    if (!extradata)
+        return AVERROR(ENOMEM);
+
+    memcpy(extradata, codec->extradata, codec->extradata_size);
+
+    os->ctx->streams[0]->codec->extradata = extradata;
+    os->ctx->streams[0]->codec->extradata_size = codec->extradata_size;
+
+    set_codec_str(s, codec, os->codec_str, sizeof(os->codec_str));
+
+    return 0;
+}
+
 static int dash_flush(AVFormatContext *s, int final, int stream)
 {
     DASHContext *c = s->priv_data;
@@ -853,6 +862,10 @@ static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
     int64_t seg_end_duration = (os->segment_index) * (int64_t) c->min_seg_duration;
     int ret;
 
+    ret = update_stream_extradata(s, os, st->codec);
+    if (ret < 0)
+        return ret;
+
     // If forcing the stream to start at 0, the mp4 muxer will set the start
     // timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.
     if (os->first_pts == AV_NOPTS_VALUE &&