.

src/track.rs

@@ -4,6 +4,7 @@ use std::convert::TryFrom;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::time::Duration;
 
+use crate::elst::ElstEntry;
 use crate::mp4box::traf::TrafBox;
 use crate::mp4box::trak::TrakBox;
 use crate::mp4box::trun::TrunBox;
@@ -929,9 +930,24 @@ impl Mp4TrackWriter {
     }
 
     pub(crate) fn write_end<W: Write + Seek>(&mut self, writer: &mut W) -> Result<TrakBox> {
+        return self.write_end_with_offset(writer, 0);
+    }
+
+
+    pub(crate) fn write_end_with_offset<W: Write + Seek>(&mut self, writer: &mut W, offset: u64) -> Result<TrakBox> {
         self.write_chunk(writer)?;
 
         let max_sample_size = self.max_sample_size();
+        self.trak.edts = Some(EdtsBox { elst:  Some(ElstBox {
+            version: 1,
+            flags: 0,
+            entries: vec![ElstEntry {
+                segment_duration: self.trak.mdia.mdhd.duration,
+                media_time: offset,
+                media_rate: 1,
+                media_rate_fraction: 0,
+            }],
+        })});
         if let Some(ref mut mp4a) = self.trak.mdia.minf.stbl.stsd.mp4a {
             if let Some(ref mut esds) = mp4a.esds {
                 esds.es_desc.dec_config.buffer_size_db = max_sample_size;

src/writer.rs

@@ -146,4 +146,21 @@ impl<W: Write + Seek> Mp4Writer<W> {
         moov.write_box(&mut self.writer)?;
         Ok(())
     }
+
+    pub fn write_end_with_offset(&mut self, offset: u64) -> Result<()> {
+        let mut moov = MoovBox::default();
+
+        for track in self.tracks.iter_mut() {
+            moov.traks.push(track.write_end_with_offset(&mut self.writer,offset)?);
+        }
+        self.update_mdat_size()?;
+
+        moov.mvhd.timescale = self.timescale;
+        moov.mvhd.duration = self.duration;
+        if moov.mvhd.duration > (u32::MAX as u64) {
+            moov.mvhd.version = 1
+        }
+        moov.write_box(&mut self.writer)?;
+        Ok(())
+    }
 }