diff --git a/libavformat/mov.c b/libavformat/mov.c
index 46962d7..022e3aa 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -802,31 +802,6 @@ static int mov_read_mvhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
-static int mov_read_smi(MOVContext *c, AVIOContext *pb, MOVAtom atom)
-{
-    AVStream *st;
-
-    if (c->fc->nb_streams < 1)
-        return 0;
-    st = c->fc->streams[c->fc->nb_streams-1];
-
-    if ((uint64_t)atom.size > (1<<30))
-        return AVERROR_INVALIDDATA;
-
-    // currently SVQ3 decoder expect full STSD header - so let's fake it
-    // this should be fixed and just SMI header should be passed
-    av_free(st->codec->extradata);
-    st->codec->extradata_size = 0;
-    st->codec->extradata = av_mallocz(atom.size + 0x5a + FF_INPUT_BUFFER_PADDING_SIZE);
-    if (!st->codec->extradata)
-        return AVERROR(ENOMEM);
-    st->codec->extradata_size = 0x5a + atom.size;
-    memcpy(st->codec->extradata, "SVQ3", 4); // fake
-    avio_read(pb, st->codec->extradata + 0x5a, atom.size);
-    av_dlog(c->fc, "Reading SMI %"PRId64"  %s\n", atom.size, st->codec->extradata + 0x5a);
-    return 0;
-}
-
 static int mov_read_enda(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     AVStream *st;
@@ -944,6 +919,11 @@ static int mov_read_avid(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return mov_read_extradata(c, pb, atom, CODEC_ID_AVUI);
 }
 
+static int mov_read_svq3(MOVContext *c, AVIOContext *pb, MOVAtom atom)
+{
+    return mov_read_extradata(c, pb, atom, CODEC_ID_SVQ3);
+}
+
 static int mov_read_wave(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 {
     AVStream *st;
@@ -2577,7 +2557,8 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
 { MKTAG('m','o','o','v'), mov_read_moov },
 { MKTAG('m','v','e','x'), mov_read_default },
 { MKTAG('m','v','h','d'), mov_read_mvhd },
-{ MKTAG('S','M','I',' '), mov_read_smi }, /* Sorenson extension ??? */
+{ MKTAG('S','M','I',' '), mov_read_svq3 },
+{ MKTAG('S','E','Q','H'), mov_read_svq3 },
 { MKTAG('a','l','a','c'), mov_read_alac }, /* alac specific atom */
 { MKTAG('a','v','c','C'), mov_read_glbl },
 { MKTAG('p','a','s','p'), mov_read_pasp },
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index e086b3a..f4173aa 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -712,19 +712,6 @@ static int mov_write_d263_tag(AVIOContext *pb)
     return 0xf;
 }
 
-/* TODO: No idea about these values */
-static int mov_write_svq3_tag(AVIOContext *pb)
-{
-    avio_wb32(pb, 0x15);
-    ffio_wfourcc(pb, "SMI ");
-    ffio_wfourcc(pb, "SEQH");
-    avio_wb32(pb, 0x5);
-    avio_wb32(pb, 0xe2c0211d);
-    avio_wb32(pb, 0xc0000000);
-    avio_w8(pb, 0);
-    return 0x15;
-}
-
 static int mov_write_avcc_tag(AVIOContext *pb, MOVTrack *track)
 {
     int64_t pos = avio_tell(pb);
@@ -1071,9 +1058,7 @@ static int mov_write_video_tag(AVIOContext *pb, MOVTrack *track)
         mov_write_esds_tag(pb, track);
     else if(track->enc->codec_id == CODEC_ID_H263)
         mov_write_d263_tag(pb);
-    else if(track->enc->codec_id == CODEC_ID_SVQ3)
-        mov_write_svq3_tag(pb);
-    else if(track->enc->codec_id == CODEC_ID_AVUI) {
+    else if(track->enc->codec_id == CODEC_ID_AVUI || track->enc->codec_id == CODEC_ID_SVQ3) {
         mov_write_extradata_tag(pb, track);
         avio_wb32(pb, 0);
     } else if(track->enc->codec_id == CODEC_ID_DNXHD)