diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 534fa75..d0a2ab5 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -62,11 +62,10 @@ typedef struct Segment {
 typedef struct OutputStream {
     AVFormatContext *ctx;
     int ctx_inited;
-    uint8_t iobuf[32768];
     AVIOContext *out;
     int packets_written;
     char initfile[1024];
-    int64_t init_start_pos;
+    int64_t init_start_pos, pos;
     int init_range_length;
     int nb_segments, segments_size, segment_index;
     Segment **segments;
@@ -100,14 +99,6 @@ typedef struct DASHContext {
     int ambiguous_frame_rate;
 } DASHContext;
 
-static int dash_write(void *opaque, uint8_t *buf, int buf_size)
-{
-    OutputStream *os = opaque;
-    if (os->out)
-        avio_write(os->out, buf, buf_size);
-    return buf_size;
-}
-
 // RFC 6381
 static void set_codec_str(AVFormatContext *s, AVCodecParameters *par,
                           char *str, int size)
@@ -174,6 +165,29 @@ static void set_codec_str(AVFormatContext *s, AVCodecParameters *par,
     }
 }
 
+static int flush_dynbuf(OutputStream *os, int *range_length)
+{
+    uint8_t *buffer;
+    int ret;
+
+    if(!os->ctx->pb) {
+        return AVERROR(EINVAL);
+    }
+
+    // flush everything
+    av_write_frame(os->ctx, NULL);
+    avio_flush(os->ctx->pb);
+
+    // write to output
+    *range_length = avio_close_dyn_buf(os->ctx->pb, &buffer);
+    avio_write(os->out, buffer, *range_length);
+    av_free(buffer);
+
+    // re-open buffer
+    ret = avio_open_dyn_buf(&os->ctx->pb);
+    return ret;
+}
+
 static void dash_free(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
@@ -185,7 +199,7 @@ static void dash_free(AVFormatContext *s)
         if (os->ctx && os->ctx_inited)
             av_write_trailer(os->ctx);
         if (os->ctx && os->ctx->pb)
-            av_free(os->ctx->pb);
+            ffio_free_dyn_buf(&os->ctx->pb);
         ff_format_io_close(s, &os->out);
         if (os->ctx)
             avformat_free_context(os->ctx);
@@ -624,9 +638,10 @@ static int dash_init(AVFormatContext *s)
         ctx->avoid_negative_ts = s->avoid_negative_ts;
         ctx->flags = s->flags;
 
-        ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, dash_write, NULL);
-        if (!ctx->pb)
-            return AVERROR(ENOMEM);
+        ret = avio_open_dyn_buf(&ctx->pb);
+        if (ret < 0)
+            return ret;
+        ctx->pb->seekable = 0;
 
         if (c->single_file) {
             if (c->single_file_name)
@@ -646,7 +661,6 @@ static int dash_init(AVFormatContext *s)
         if ((ret = avformat_init_output(ctx, &opts)) < 0)
             return ret;
         os->ctx_inited = 1;
-        avio_flush(ctx->pb);
         av_dict_free(&opts);
 
         av_log(s, AV_LOG_VERBOSE, "Representation %d init segment will be written to: %s\n", i, filename);
@@ -688,13 +702,24 @@ static int dash_init(AVFormatContext *s)
 static int dash_write_header(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
-    int i, ret;
+    int i, ret, range_length;
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
         if ((ret = avformat_write_header(os->ctx, NULL)) < 0) {
             dash_free(s);
             return ret;
         }
+
+        if ((ret = flush_dynbuf(os, &range_length)) < 0) {
+            dash_free(s);
+            return ret;
+        }
+
+        if (!c->single_file) {
+            ff_format_io_close(s, &os->out);
+        }
+
+        os->pos = os->init_range_length = range_length;
     }
     ret = write_manifest(s, 0);
     if (!ret)
@@ -803,7 +828,6 @@ static int dash_flush(AVFormatContext *s, int final, int stream)
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
         char filename[1024] = "", full_path[1024], temp_path[1024];
-        int64_t start_pos;
         int range_length, index_length = 0;
 
         if (!os->packets_written)
@@ -821,15 +845,6 @@ static int dash_flush(AVFormatContext *s, int final, int stream)
                 continue;
         }
 
-        if (!os->init_range_length) {
-            av_write_frame(os->ctx, NULL);
-            os->init_range_length = avio_tell(os->ctx->pb);
-            if (!c->single_file)
-                ff_format_io_close(s, &os->out);
-        }
-
-        start_pos = avio_tell(os->ctx->pb);
-
         if (!c->single_file) {
             dash_fill_tmpl_params(filename, sizeof(filename), c->media_seg_name, i, os->segment_index, os->bit_rate, os->start_pts);
             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);
@@ -837,26 +852,31 @@ static int dash_flush(AVFormatContext *s, int final, int stream)
             ret = s->io_open(s, &os->out, temp_path, AVIO_FLAG_WRITE, NULL);
             if (ret < 0)
                 break;
-            write_styp(os->ctx->pb);
         } else {
             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, os->initfile);
         }
 
-        av_write_frame(os->ctx, NULL);
-        avio_flush(os->ctx->pb);
-        os->packets_written = 0;
+        ret = flush_dynbuf(os, &range_length);
+        if (ret < 0)
+            break;
 
-        range_length = avio_tell(os->ctx->pb) - start_pos;
         if (c->single_file) {
-            find_index_range(s, full_path, start_pos, &index_length);
+            find_index_range(s, full_path, os->pos, &index_length);
         } else {
             ff_format_io_close(s, &os->out);
             ret = avpriv_io_move(temp_path, full_path);
             if (ret < 0)
                 break;
         }
-        add_segment(os, filename, os->start_pts, os->max_pts - os->start_pts, start_pos, range_length, index_length);
+        add_segment(os, filename, os->start_pts, os->max_pts - os->start_pts, os->pos, range_length, index_length);
         av_log(s, AV_LOG_VERBOSE, "Representation %d media segment %d written to: %s\n", i, os->segment_index, full_path);
+
+        // set new position
+        os->packets_written = 0;
+        os->pos += range_length;
+
+        // write chunk header
+        write_styp(os->ctx->pb);
     }
 
     if (c->window_size || (final && c->remove_at_exit)) {
