diff --git a/src/muxer/hls/handler.rs b/src/muxer/hls/handler.rs
index f645d71..ab2d4da 100644
--- a/src/muxer/hls/handler.rs
+++ b/src/muxer/hls/handler.rs
@@ -3,6 +3,7 @@ use std::sync::{mpsc, Arc};
 use std::time;
 use std::thread;
 use std::fs;
+use std::cmp::max;
 
 use crate::util;
 use crate::muxer::hls::mp4;
@@ -36,7 +37,7 @@ impl HLSHandler {
     fn new_segment(&mut self, segment: segments::Segment) -> std::vec::Drain<String> {
         segment.dump();
         self.curr_segments.push(segment.filename);
-        self.curr_segments.drain(..self.curr_segments.len() - self.args.max_segments)
+        self.curr_segments.drain(..max(self.curr_segments.len() - self.args.max_segments, 0))
     }
 
 
diff --git a/src/muxer/hls/mp4/atoms.rs b/src/muxer/hls/mp4/atoms.rs
index 6fa86b7..735b742 100644
--- a/src/muxer/hls/mp4/atoms.rs
+++ b/src/muxer/hls/mp4/atoms.rs
@@ -1145,9 +1145,9 @@ impl MP4Atom for SampleData {
     }
 }
 
-struct MDAT {
-    v_samples: Vec<u8>,
-    a_samples: Vec<u8>,
+pub struct MDAT {
+    pub v_samples: Vec<u8>,
+    pub a_samples: Vec<u8>,
 }
 
 impl MP4Atom for MDAT {
diff --git a/src/muxer/hls/mp4/mod.rs b/src/muxer/hls/mp4/mod.rs
index 1a26208..d7ab478 100644
--- a/src/muxer/hls/mp4/mod.rs
+++ b/src/muxer/hls/mp4/mod.rs
@@ -1,5 +1,5 @@
 mod mp4muxer;
-mod atoms;
+pub mod atoms;
 pub mod samples;
 
 use std::sync::{mpsc, Arc, Mutex};
diff --git a/src/muxer/hls/mp4/mp4muxer.rs b/src/muxer/hls/mp4/mp4muxer.rs
index fb4216b..a4d6cc2 100644
--- a/src/muxer/hls/mp4/mp4muxer.rs
+++ b/src/muxer/hls/mp4/mp4muxer.rs
@@ -73,6 +73,7 @@ impl mp4::MP4Muxer {
         if self.v_samples.segment_ready(time) && self.a_samples.segment_ready(time) {
             return Some(segments::Segment {
                 filename: idx.to_string() + ".m4s",
+                idx: idx,
                 segment_video: self.v_samples.get_segment_samples(time),
                 sample_duration_v: self.v_samples.default_duration,
                 segment_audio: self.a_samples.get_segment_samples(time),
diff --git a/src/muxer/hls/segments.rs b/src/muxer/hls/segments.rs
index 18f8683..402ef16 100644
--- a/src/muxer/hls/segments.rs
+++ b/src/muxer/hls/segments.rs
@@ -1,8 +1,14 @@
 use std::time;
+use std::fs::File;
+use std::io::Write;
+
 use crate::muxer::hls::mp4::samples;
+use crate::muxer::hls::mp4::atoms;
+use crate::muxer::hls::mp4::atoms::MP4Atom;
 
 pub struct Segment {
     pub filename: String,
+    pub idx: usize,
     pub segment_video: Vec<samples::Sample>,
     pub sample_duration_v: u32,
     pub segment_audio: Vec<samples::Sample>,
@@ -11,6 +17,26 @@ pub struct Segment {
 
 impl Segment {
     pub fn dump(&self) {
-        todo!();
+        let mdat = self.new_mdat();
+        let moof = atoms::new_moof(&self.segment_video, self.sample_duration_v, &self.segment_audio, self.sample_duration_a, 0, mdat.v_samples.len(), self.idx);
+        let mut segment_bytes = moof.marshall();
+        segment_bytes.append(&mut mdat.marshall());
+
+        let mut f = File::create(&self.filename).unwrap();
+        f.write_all(&segment_bytes);
+    }
+
+    fn new_mdat(&self) -> atoms::MDAT {
+        let (mut v_samples, mut a_samples) = (Vec::new(), Vec::new());
+        for sample in &self.segment_video {
+            v_samples.extend_from_slice(sample.data.as_slice());
+        }
+        for sample in &self.segment_audio {
+            a_samples.extend_from_slice(sample.data.as_slice());
+        }
+        atoms::MDAT {
+            v_samples: v_samples,
+            a_samples: a_samples,
+        }
     }
 }