diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index df87339e8bb8d8add9507895dbdddb12cde3a434..8fec18deee2a652b162d28837677e689203f6674 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -472,6 +472,7 @@ int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
 int av_add_index_entry(AVStream *st,
                        int64_t pos, int64_t timestamp, int size, int distance, int flags);
 int av_seek_frame_binary(AVFormatContext *s, int stream_index, int64_t target_ts, int flags);
+void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp);
 
 /* media file output */
 int av_set_parameters(AVFormatContext *s, AVFormatParameters *ap);
diff --git a/libavformat/ogg2.c b/libavformat/ogg2.c
index 2af5a4f9aada03d47b768b485e6f01b9947ee7e3..254415b7a37fe20b932e2f730e4f314c722bdcca 100644
--- a/libavformat/ogg2.c
+++ b/libavformat/ogg2.c
@@ -201,7 +201,6 @@ ogg_new_stream (AVFormatContext * s, uint32_t serial)
         return AVERROR_NOMEM;
 
     av_set_pts_info(st, 64, 1, 1000000);
-    st->start_time = 0;
 
     return idx;
 }
@@ -495,6 +494,16 @@ ogg_get_length (AVFormatContext * s)
 
     ogg->size = size;
     ogg_restore (s, 0);
+    ogg_save (s);
+    while (ogg_read_page (s, &i)) {
+        if (i == idx && ogg->streams[i].granule != -1 && ogg->streams[i].granule != 0)
+            break;
+    }
+    if (i == idx) {
+        s->streams[idx]->start_time = ogg_gptopts (s, idx, ogg->streams[idx].granule);
+        s->streams[idx]->duration -= s->streams[idx]->start_time;
+    }
+    ogg_restore (s, 0);
 
     return 0;
 }
@@ -572,12 +581,14 @@ ogg_read_seek (AVFormatContext * s, int stream_index, int64_t target_ts,
     ogg_t *ogg = s->priv_data;
     ByteIOContext *bc = &s->pb;
     uint64_t min = 0, max = ogg->size;
-    uint64_t tmin = 0, tmax = st->duration;
+    uint64_t tmin = st->start_time, tmax = st->start_time + st->duration;
     int64_t pts = AV_NOPTS_VALUE;
 
     ogg_save (s);
 
-    while (min <= max){
+    if ((uint64_t)target_ts < tmin || target_ts < 0)
+        target_ts = tmin;
+    while (min <= max && tmin < tmax){
         uint64_t p = min + (max - min) * (target_ts - tmin) / (tmax - tmin);
         int i = -1;
 
@@ -599,9 +610,25 @@ ogg_read_seek (AVFormatContext * s, int stream_index, int64_t target_ts,
             break;
 
         if (pts > target_ts){
+            if (max == p && tmax == pts) {
+                // probably our tmin is wrong, causing us to always end up too late in the file
+                tmin = (target_ts + tmin + 1) / 2;
+                if (tmin == target_ts) {
+                    url_fseek(bc, min, SEEK_SET);
+                    break;
+                }
+            }
             max = p;
             tmax = pts;
         }else{
+            if (min == p && tmin == pts) {
+                // probably our tmax is wrong, causing us to always end up too early in the file
+                tmax = (target_ts + tmax) / 2;
+                if (tmax == target_ts) {
+                    url_fseek(bc, max, SEEK_SET);
+                    break;
+                }
+            }
             min = p;
             tmin = pts;
         }
@@ -615,7 +642,8 @@ ogg_read_seek (AVFormatContext * s, int stream_index, int64_t target_ts,
         pts = AV_NOPTS_VALUE;
     }
 
-    return pts;
+    av_update_cur_dts(s, st, pts);
+    return 0;
 
 #if 0
     //later...
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 2c882faf4401bae85ee2d45390120204d880ffba..cefce88abca32ac69c6ecba5aae559f64b7496e2 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1097,7 +1097,7 @@ static void av_read_frame_flush(AVFormatContext *s)
  * @param timestamp new dts expressed in time_base of param ref_st
  * @param ref_st reference stream giving time_base of param timestamp
  */
-static void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp){
+void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp){
     int i;
 
     for(i = 0; i < s->nb_streams; i++) {