diff --git a/examples/mp4copy.rs b/examples/mp4copy.rs
index aa55fb3..c5a6c4d 100644
--- a/examples/mp4copy.rs
+++ b/examples/mp4copy.rs
@@ -70,8 +70,8 @@ fn copy<P: AsRef<Path>>(src_filename: &P, dst_filename: &P) -> Result<()> {
 
         let track_id = track_idx as u32 + 1;
         let sample_count = mp4_reader.sample_count(track_id)?;
-        for six in 0..sample_count {
-            let sample_id = six + 1;
+        for sample_idx in 0..sample_count {
+            let sample_id = sample_idx + 1;
             let sample = mp4_reader.read_sample(track_id, sample_id)?.unwrap();
             mp4_writer.write_sample(track_id, &sample)?;
             // println!("copy {}:({})", sample_id, sample);
diff --git a/examples/mp4info.rs b/examples/mp4info.rs
index 62ca2d0..f3ef4bd 100644
--- a/examples/mp4info.rs
+++ b/examples/mp4info.rs
@@ -35,11 +35,7 @@ fn info<P: AsRef<Path>>(filename: &P) -> Result<()> {
         compatible_brands.push_str(",");
     }
     println!("  compatible_brands: {}", compatible_brands);
-    println!(
-        "Duration: {}, timescale: {}",
-        mp4.duration(),
-        mp4.timescale()
-    );
+    println!("Duration: {:?}", mp4.duration());
 
     for track in mp4.tracks().iter() {
         let media_info = match track.track_type()? {
diff --git a/src/reader.rs b/src/reader.rs
index fbb9191..bf1f7aa 100644
--- a/src/reader.rs
+++ b/src/reader.rs
@@ -1,4 +1,5 @@
 use std::io::{Read, Seek, SeekFrom};
+use std::time::Duration;
 
 use crate::mp4box::*;
 use crate::*;
@@ -95,8 +96,8 @@ impl<R: Read + Seek> Mp4Reader<R> {
         &self.ftyp.compatible_brands
     }
 
-    pub fn duration(&self) -> u64 {
-        self.moov.mvhd.duration
+    pub fn duration(&self) -> Duration {
+        Duration::from_millis(self.moov.mvhd.duration * 1000 / self.moov.mvhd.timescale as u64)
     }
 
     pub fn timescale(&self) -> u32 {
diff --git a/tests/lib.rs b/tests/lib.rs
index 9c34180..1cc8a48 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,6 +1,7 @@
 use mp4::{AudioObjectType, AvcProfile, ChannelConfig, MediaType, SampleFreqIndex, TrackType};
 use std::fs::File;
 use std::io::BufReader;
+use std::time::Duration;
 
 #[test]
 fn test_read_mp4() {
@@ -29,7 +30,7 @@ fn test_read_mp4() {
         assert_eq!(t, true);
     }
 
-    assert_eq!(mp4.duration(), 62);
+    assert_eq!(mp4.duration(), Duration::from_millis(62));
     assert_eq!(mp4.timescale(), 1000);
     assert_eq!(mp4.tracks().len(), 2);