diff --git a/examples/mp4dump.rs b/examples/mp4dump.rs
new file mode 100644
index 0000000..33b3ec0
--- /dev/null
+++ b/examples/mp4dump.rs
@@ -0,0 +1,116 @@
+use std::env;
+use std::fs::File;
+use std::io::prelude::*;
+use std::io::{self, BufReader};
+use std::path::Path;
+
+use mp4::{Result, Mp4Box};
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() < 2 {
+        println!("Usage: mp4dump <filename>");
+        std::process::exit(1);
+    }
+
+    if let Err(err) = dump(&args[1]) {
+        let _ = writeln!(io::stderr(), "{}", err);
+    }
+}
+
+fn dump<P: AsRef<Path>>(filename: &P) -> Result<()> {
+    let f = File::open(filename)?;
+    let boxes = get_boxes(f)?;
+
+    // print out boxes
+    for b in boxes.iter() {
+       println!("[{}] size={}", b.name, b.size); 
+    }
+
+    Ok(())
+}
+
+#[derive(Debug, Clone, PartialEq, Default)]
+pub struct Box {
+    name: String,
+    size: u64,
+    indent: u32,
+}
+
+fn get_boxes(file: File) -> Result<Vec<Box>> {
+    let size = file.metadata()?.len();
+    let reader = BufReader::new(file);
+    let mp4 = mp4::Mp4Reader::read_header(reader, size)?;
+
+    // collect known boxes
+    let mut boxes = Vec::new();
+
+    // ftyp, moov, mvhd
+    boxes.push(build_box(&mp4.ftyp));
+    boxes.push(build_box(&mp4.moov));
+    boxes.push(build_box(&mp4.moov.mvhd));
+
+    // trak.
+    for track in mp4.tracks().iter() {
+        boxes.push(build_box(&track.trak));
+        boxes.push(build_box(&track.trak.tkhd));
+        if let Some(ref edts) = track.trak.edts {
+            boxes.push(build_box(edts));
+            if let Some(ref elst) = edts.elst {
+                boxes.push(build_box(elst));
+            }
+        }
+
+        // trak.mdia
+        let mdia = &track.trak.mdia;
+        boxes.push(build_box(mdia));
+        boxes.push(build_box(&mdia.mdhd));
+        boxes.push(build_box(&mdia.hdlr));
+        boxes.push(build_box(&track.trak.mdia.minf));
+
+        // trak.mdia.minf
+        let minf = &track.trak.mdia.minf;
+        if let Some(ref vmhd) = &minf.vmhd {
+            boxes.push(build_box(vmhd));
+        }
+        if let Some(ref smhd) = &minf.smhd {
+            boxes.push(build_box(smhd));
+        }
+
+        // trak.mdia.minf.stbl
+        let stbl = &track.trak.mdia.minf.stbl;
+        boxes.push(build_box(stbl));
+        boxes.push(build_box(&stbl.stsd));
+        if let Some(ref avc1) = &stbl.stsd.avc1 {
+            boxes.push(build_box(avc1));
+        }
+        if let Some(ref mp4a) = &stbl.stsd.mp4a {
+            boxes.push(build_box(mp4a));
+        }
+        boxes.push(build_box(&stbl.stts));
+        if let Some(ref ctts) = &stbl.ctts {
+            boxes.push(build_box(ctts));
+        }
+        if let Some(ref stss) = &stbl.stss {
+            boxes.push(build_box(stss));
+        }
+        boxes.push(build_box(&stbl.stsc));
+        boxes.push(build_box(&stbl.stsz));
+        if let Some(ref stco) = &stbl.stco {
+            boxes.push(build_box(stco));
+        }
+        if let Some(ref co64) = &stbl.co64 {
+            boxes.push(build_box(co64));
+        }
+    }
+    Ok(boxes)
+}
+
+fn build_box<M: Mp4Box + std::fmt::Debug>(ref m: &M) -> Box {
+    return Box{
+        name: m.box_type().to_string(),
+        size: m.box_size(),
+        indent: 0,
+    };
+}
diff --git a/examples/simple.rs b/examples/simple.rs
new file mode 100644
index 0000000..783150a
--- /dev/null
+++ b/examples/simple.rs
@@ -0,0 +1,27 @@
+use mp4;
+use std::env;
+use std::fs::File;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() < 2 {
+        println!("Usage: mp4dump <filename>");
+        std::process::exit(1);
+    }
+
+    let filename = &args[1];
+    let f = File::open(filename).unwrap();
+    let mp4 = mp4::read_mp4(f).unwrap();
+
+    println!("Major Brand: {}", mp4.major_brand());
+
+    for track in mp4.tracks().iter() {
+        println!("Track: #{}({}) {} {}",
+            track.track_id(),
+            track.language(),
+            track.track_type().unwrap(),
+            track.box_type().unwrap(),
+        );
+    }
+}
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index fde9222..5cfa938 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,6 @@
+use std::io::{BufReader};
+use std::fs::File;
+
 mod error;
 pub use error::Error;
 
@@ -7,6 +10,7 @@ mod types;
 pub use types::*;
 
 mod mp4box;
+pub use mp4box::{Mp4Box};
 
 mod track;
 pub use track::{Mp4Track, TrackConfig};
@@ -16,3 +20,10 @@ pub use reader::Mp4Reader;
 
 mod writer;
 pub use writer::{Mp4Config, Mp4Writer};
+
+pub fn read_mp4(f: File) -> Result<Mp4Reader<BufReader<File>>> {
+    let size = f.metadata()?.len();
+    let reader = BufReader::new(f);
+    let mp4 = reader::Mp4Reader::read_header(reader, size)?;
+    Ok(mp4)
+}
\ No newline at end of file
diff --git a/src/mp4box/avc1.rs b/src/mp4box/avc1.rs
index 27f428e..f051c6c 100644
--- a/src/mp4box/avc1.rs
+++ b/src/mp4box/avc1.rs
@@ -43,18 +43,26 @@ impl Avc1Box {
             avcc: AvcCBox::new(&config.seq_param_set, &config.pic_param_set),
         }
     }
-}
 
-impl Mp4Box for Avc1Box {
-    fn box_type() -> BoxType {
+    pub fn get_type(&self) -> BoxType {
         BoxType::Avc1Box
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + 8 + 70 + self.avcc.box_size()
     }
 }
 
+impl Mp4Box for Avc1Box {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for Avc1Box {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -102,7 +110,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Avc1Box {
 impl<W: Write> WriteBox<&mut W> for Avc1Box {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         writer.write_u32::<BigEndian>(0)?; // reserved
         writer.write_u16::<BigEndian>(0)?; // reserved
@@ -154,7 +162,7 @@ impl AvcCBox {
 }
 
 impl Mp4Box for AvcCBox {
-    fn box_type() -> BoxType {
+    fn box_type(&self) -> BoxType {
         BoxType::AvcCBox
     }
 
@@ -209,7 +217,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for AvcCBox {
 impl<W: Write> WriteBox<&mut W> for AvcCBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         writer.write_u8(self.configuration_version)?;
         writer.write_u8(self.avc_profile_indication)?;
diff --git a/src/mp4box/co64.rs b/src/mp4box/co64.rs
index 511db77..829acf8 100644
--- a/src/mp4box/co64.rs
+++ b/src/mp4box/co64.rs
@@ -10,16 +10,26 @@ pub struct Co64Box {
     pub entries: Vec<u64>,
 }
 
-impl Mp4Box for Co64Box {
-    fn box_type() -> BoxType {
+impl Co64Box {
+    pub fn get_type(&self) -> BoxType {
         BoxType::Co64Box
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
     }
 }
 
+impl Mp4Box for Co64Box {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for Co64Box {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -46,7 +56,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Co64Box {
 impl<W: Write> WriteBox<&mut W> for Co64Box {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/ctts.rs b/src/mp4box/ctts.rs
index 49d666a..db0ccd3 100644
--- a/src/mp4box/ctts.rs
+++ b/src/mp4box/ctts.rs
@@ -10,6 +10,16 @@ pub struct CttsBox {
     pub entries: Vec<CttsEntry>,
 }
 
+impl CttsBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::CttsBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Default)]
 pub struct CttsEntry {
     pub sample_count: u32,
@@ -17,12 +27,12 @@ pub struct CttsEntry {
 }
 
 impl Mp4Box for CttsBox {
-    fn box_type() -> BoxType {
-        BoxType::CttsBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
+        return self.get_size();
     }
 }
 
@@ -55,7 +65,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for CttsBox {
 impl<W: Write> WriteBox<&mut W> for CttsBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/edts.rs b/src/mp4box/edts.rs
index c36b59c..2cd0d09 100644
--- a/src/mp4box/edts.rs
+++ b/src/mp4box/edts.rs
@@ -12,14 +12,12 @@ impl EdtsBox {
     pub(crate) fn new() -> EdtsBox {
         Default::default()
     }
-}
 
-impl Mp4Box for EdtsBox {
-    fn box_type() -> BoxType {
+    pub fn get_type(&self) -> BoxType {
         BoxType::EdtsBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE;
         if let Some(ref elst) = self.elst {
             size += elst.box_size();
@@ -28,6 +26,16 @@ impl Mp4Box for EdtsBox {
     }
 }
 
+impl Mp4Box for EdtsBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for EdtsBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -54,7 +62,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for EdtsBox {
 impl<W: Write> WriteBox<&mut W> for EdtsBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         if let Some(ref elst) = self.elst {
             elst.write_box(writer)?;
diff --git a/src/mp4box/elst.rs b/src/mp4box/elst.rs
index ecd1d32..ebbbaf0 100644
--- a/src/mp4box/elst.rs
+++ b/src/mp4box/elst.rs
@@ -18,12 +18,12 @@ pub struct ElstEntry {
     pub media_rate_fraction: u16,
 }
 
-impl Mp4Box for ElstBox {
-    fn box_type() -> BoxType {
+impl ElstBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::ElstBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE + HEADER_EXT_SIZE + 4;
         if self.version == 1 {
             size += self.entries.len() as u64 * 20;
@@ -35,6 +35,16 @@ impl Mp4Box for ElstBox {
     }
 }
 
+impl Mp4Box for ElstBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for ElstBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -78,7 +88,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for ElstBox {
 impl<W: Write> WriteBox<&mut W> for ElstBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/ftyp.rs b/src/mp4box/ftyp.rs
index 418f3a0..dfdf524 100644
--- a/src/mp4box/ftyp.rs
+++ b/src/mp4box/ftyp.rs
@@ -10,16 +10,26 @@ pub struct FtypBox {
     pub compatible_brands: Vec<FourCC>,
 }
 
-impl Mp4Box for FtypBox {
-    fn box_type() -> BoxType {
+impl FtypBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::FtypBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + 8 + (4 * self.compatible_brands.len() as u64)
     }
 }
 
+impl Mp4Box for FtypBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for FtypBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -50,7 +60,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for FtypBox {
 impl<W: Write> WriteBox<&mut W> for FtypBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         writer.write_u32::<BigEndian>((&self.major_brand).into())?;
         writer.write_u32::<BigEndian>(self.minor_version)?;
diff --git a/src/mp4box/hdlr.rs b/src/mp4box/hdlr.rs
index a7bf34b..62d7a32 100644
--- a/src/mp4box/hdlr.rs
+++ b/src/mp4box/hdlr.rs
@@ -11,16 +11,26 @@ pub struct HdlrBox {
     pub name: String,
 }
 
-impl Mp4Box for HdlrBox {
-    fn box_type() -> BoxType {
+impl HdlrBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::HdlrBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 20 + self.name.len() as u64 + 1
     }
 }
 
+impl Mp4Box for HdlrBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for HdlrBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -58,7 +68,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for HdlrBox {
 impl<W: Write> WriteBox<&mut W> for HdlrBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/mdhd.rs b/src/mp4box/mdhd.rs
index 5e53982..7696088 100644
--- a/src/mp4box/mdhd.rs
+++ b/src/mp4box/mdhd.rs
@@ -15,6 +15,25 @@ pub struct MdhdBox {
     pub language: String,
 }
 
+impl MdhdBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::MdhdBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
+
+        if self.version == 1 {
+            size += 28;
+        } else {
+            assert_eq!(self.version, 0);
+            size += 16;
+        }
+        size += 4;
+        size
+    }
+}
+
 impl Default for MdhdBox {
     fn default() -> Self {
         MdhdBox {
@@ -30,21 +49,12 @@ impl Default for MdhdBox {
 }
 
 impl Mp4Box for MdhdBox {
-    fn box_type() -> BoxType {
-        BoxType::MdhdBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
-
-        if self.version == 1 {
-            size += 28;
-        } else {
-            assert_eq!(self.version, 0);
-            size += 16;
-        }
-        size += 4;
-        size
+        return self.get_size();
     }
 }
 
@@ -90,7 +100,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MdhdBox {
 impl<W: Write> WriteBox<&mut W> for MdhdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/mdia.rs b/src/mp4box/mdia.rs
index cf7ff07..e8ea27a 100644
--- a/src/mp4box/mdia.rs
+++ b/src/mp4box/mdia.rs
@@ -10,16 +10,26 @@ pub struct MdiaBox {
     pub minf: MinfBox,
 }
 
-impl Mp4Box for MdiaBox {
-    fn box_type() -> BoxType {
+impl MdiaBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::MdiaBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + self.mdhd.box_size() + self.hdlr.box_size() + self.minf.box_size()
     }
 }
 
+impl Mp4Box for MdiaBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for MdiaBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -77,7 +87,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MdiaBox {
 impl<W: Write> WriteBox<&mut W> for MdiaBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         self.mdhd.write_box(writer)?;
         self.hdlr.write_box(writer)?;
diff --git a/src/mp4box/minf.rs b/src/mp4box/minf.rs
index 0da39a9..1dad192 100644
--- a/src/mp4box/minf.rs
+++ b/src/mp4box/minf.rs
@@ -10,12 +10,12 @@ pub struct MinfBox {
     pub stbl: StblBox,
 }
 
-impl Mp4Box for MinfBox {
-    fn box_type() -> BoxType {
+impl MinfBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::MinfBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE;
         if let Some(ref vmhd) = self.vmhd {
             size += vmhd.box_size();
@@ -28,6 +28,16 @@ impl Mp4Box for MinfBox {
     }
 }
 
+impl Mp4Box for MinfBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for MinfBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -83,7 +93,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MinfBox {
 impl<W: Write> WriteBox<&mut W> for MinfBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         if let Some(ref vmhd) = self.vmhd {
             vmhd.write_box(writer)?;
diff --git a/src/mp4box/mod.rs b/src/mp4box/mod.rs
index 0721e2c..180a96c 100644
--- a/src/mp4box/mod.rs
+++ b/src/mp4box/mod.rs
@@ -99,7 +99,7 @@ boxtype! {
 }
 
 pub trait Mp4Box: Sized {
-    fn box_type() -> BoxType;
+    fn box_type(&self) -> BoxType;
     fn box_size(&self) -> u64;
 }
 
diff --git a/src/mp4box/moov.rs b/src/mp4box/moov.rs
index 045440e..3a9cae5 100644
--- a/src/mp4box/moov.rs
+++ b/src/mp4box/moov.rs
@@ -9,12 +9,12 @@ pub struct MoovBox {
     pub traks: Vec<TrakBox>,
 }
 
-impl Mp4Box for MoovBox {
-    fn box_type() -> BoxType {
+impl MoovBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::MoovBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE + self.mvhd.box_size();
         for trak in self.traks.iter() {
             size += trak.box_size();
@@ -23,6 +23,16 @@ impl Mp4Box for MoovBox {
     }
 }
 
+impl Mp4Box for MoovBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for MoovBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -74,7 +84,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MoovBox {
 impl<W: Write> WriteBox<&mut W> for MoovBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         self.mvhd.write_box(writer)?;
         for trak in self.traks.iter() {
diff --git a/src/mp4box/mp4a.rs b/src/mp4box/mp4a.rs
index 77d0b3f..8a44cff 100644
--- a/src/mp4box/mp4a.rs
+++ b/src/mp4box/mp4a.rs
@@ -34,14 +34,12 @@ impl Mp4aBox {
             esds: Some(EsdsBox::new(config)),
         }
     }
-}
 
-impl Mp4Box for Mp4aBox {
-    fn box_type() -> BoxType {
+    pub fn get_type(&self) -> BoxType {
         BoxType::Mp4aBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE + 8 + 20;
         if let Some(ref esds) = self.esds {
             size += esds.box_size();
@@ -50,6 +48,16 @@ impl Mp4Box for Mp4aBox {
     }
 }
 
+impl Mp4Box for Mp4aBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for Mp4aBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -86,7 +94,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Mp4aBox {
 impl<W: Write> WriteBox<&mut W> for Mp4aBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         writer.write_u32::<BigEndian>(0)?; // reserved
         writer.write_u16::<BigEndian>(0)?; // reserved
@@ -124,7 +132,7 @@ impl EsdsBox {
 }
 
 impl Mp4Box for EsdsBox {
-    fn box_type() -> BoxType {
+    fn box_type(&self) -> BoxType {
         BoxType::EsdsBox
     }
 
@@ -171,7 +179,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for EsdsBox {
 impl<W: Write> WriteBox<&mut W> for EsdsBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/mvhd.rs b/src/mp4box/mvhd.rs
index bd38fbf..377bab8 100644
--- a/src/mp4box/mvhd.rs
+++ b/src/mp4box/mvhd.rs
@@ -14,6 +14,24 @@ pub struct MvhdBox {
     pub rate: FixedPointU16,
 }
 
+impl MvhdBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::MvhdBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
+        if self.version == 1 {
+            size += 28;
+        } else {
+            assert_eq!(self.version, 0);
+            size += 16;
+        }
+        size += 80;
+        size
+    }
+}
+
 impl Default for MvhdBox {
     fn default() -> Self {
         MvhdBox {
@@ -29,20 +47,12 @@ impl Default for MvhdBox {
 }
 
 impl Mp4Box for MvhdBox {
-    fn box_type() -> BoxType {
-        BoxType::MvhdBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
-        if self.version == 1 {
-            size += 28;
-        } else {
-            assert_eq!(self.version, 0);
-            size += 16;
-        }
-        size += 80;
-        size
+        return self.get_size();
     }
 }
 
@@ -87,7 +97,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MvhdBox {
 impl<W: Write> WriteBox<&mut W> for MvhdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/smhd.rs b/src/mp4box/smhd.rs
index 3879a18..454bea9 100644
--- a/src/mp4box/smhd.rs
+++ b/src/mp4box/smhd.rs
@@ -10,6 +10,16 @@ pub struct SmhdBox {
     pub balance: FixedPointI8,
 }
 
+impl SmhdBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::SmhdBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        HEADER_SIZE + HEADER_EXT_SIZE + 4
+    }
+}
+
 impl Default for SmhdBox {
     fn default() -> Self {
         SmhdBox {
@@ -21,12 +31,12 @@ impl Default for SmhdBox {
 }
 
 impl Mp4Box for SmhdBox {
-    fn box_type() -> BoxType {
-        BoxType::SmhdBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        HEADER_SIZE + HEADER_EXT_SIZE + 4
+        return self.get_size();
     }
 }
 
@@ -51,7 +61,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for SmhdBox {
 impl<W: Write> WriteBox<&mut W> for SmhdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stbl.rs b/src/mp4box/stbl.rs
index 8f7db65..0d37416 100644
--- a/src/mp4box/stbl.rs
+++ b/src/mp4box/stbl.rs
@@ -18,12 +18,12 @@ pub struct StblBox {
     pub co64: Option<Co64Box>,
 }
 
-impl Mp4Box for StblBox {
-    fn box_type() -> BoxType {
+impl StblBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::StblBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE;
         size += self.stsd.box_size();
         size += self.stts.box_size();
@@ -45,6 +45,16 @@ impl Mp4Box for StblBox {
     }
 }
 
+impl Mp4Box for StblBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for StblBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -132,7 +142,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StblBox {
 impl<W: Write> WriteBox<&mut W> for StblBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         self.stsd.write_box(writer)?;
         self.stts.write_box(writer)?;
diff --git a/src/mp4box/stco.rs b/src/mp4box/stco.rs
index 301cb50..c63295a 100644
--- a/src/mp4box/stco.rs
+++ b/src/mp4box/stco.rs
@@ -10,16 +10,26 @@ pub struct StcoBox {
     pub entries: Vec<u32>,
 }
 
-impl Mp4Box for StcoBox {
-    fn box_type() -> BoxType {
+impl StcoBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::StcoBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 4 + (4 * self.entries.len() as u64)
     }
 }
 
+impl Mp4Box for StcoBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for StcoBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -46,7 +56,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StcoBox {
 impl<W: Write> WriteBox<&mut W> for StcoBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stsc.rs b/src/mp4box/stsc.rs
index fe83cc7..78b7686 100644
--- a/src/mp4box/stsc.rs
+++ b/src/mp4box/stsc.rs
@@ -10,6 +10,16 @@ pub struct StscBox {
     pub entries: Vec<StscEntry>,
 }
 
+impl StscBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::StscBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (12 * self.entries.len() as u64)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Default)]
 pub struct StscEntry {
     pub first_chunk: u32,
@@ -19,12 +29,12 @@ pub struct StscEntry {
 }
 
 impl Mp4Box for StscBox {
-    fn box_type() -> BoxType {
-        BoxType::StscBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (12 * self.entries.len() as u64)
+        return self.get_size();
     }
 }
 
@@ -72,7 +82,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StscBox {
 impl<W: Write> WriteBox<&mut W> for StscBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stsd.rs b/src/mp4box/stsd.rs
index 5731c7f..d09da49 100644
--- a/src/mp4box/stsd.rs
+++ b/src/mp4box/stsd.rs
@@ -12,12 +12,12 @@ pub struct StsdBox {
     pub mp4a: Option<Mp4aBox>,
 }
 
-impl Mp4Box for StsdBox {
-    fn box_type() -> BoxType {
+impl StsdBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::StsdBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE + HEADER_EXT_SIZE + 4;
         if let Some(ref avc1) = self.avc1 {
             size += avc1.box_size();
@@ -28,6 +28,16 @@ impl Mp4Box for StsdBox {
     }
 }
 
+impl Mp4Box for StsdBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -67,7 +77,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
 impl<W: Write> WriteBox<&mut W> for StsdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stss.rs b/src/mp4box/stss.rs
index 412174b..6d60bd9 100644
--- a/src/mp4box/stss.rs
+++ b/src/mp4box/stss.rs
@@ -10,16 +10,26 @@ pub struct StssBox {
     pub entries: Vec<u32>,
 }
 
-impl Mp4Box for StssBox {
-    fn box_type() -> BoxType {
+impl StssBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::StssBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 4 + (4 * self.entries.len() as u64)
     }
 }
 
+impl Mp4Box for StssBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for StssBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -46,7 +56,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StssBox {
 impl<W: Write> WriteBox<&mut W> for StssBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stsz.rs b/src/mp4box/stsz.rs
index 99a4de6..78fc0e6 100644
--- a/src/mp4box/stsz.rs
+++ b/src/mp4box/stsz.rs
@@ -12,16 +12,26 @@ pub struct StszBox {
     pub sample_sizes: Vec<u32>,
 }
 
-impl Mp4Box for StszBox {
-    fn box_type() -> BoxType {
+impl StszBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::StszBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 8 + (4 * self.sample_sizes.len() as u64)
     }
 }
 
+impl Mp4Box for StszBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for StszBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -53,7 +63,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StszBox {
 impl<W: Write> WriteBox<&mut W> for StszBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/stts.rs b/src/mp4box/stts.rs
index 8ca673f..bb46d5b 100644
--- a/src/mp4box/stts.rs
+++ b/src/mp4box/stts.rs
@@ -10,6 +10,16 @@ pub struct SttsBox {
     pub entries: Vec<SttsEntry>,
 }
 
+impl SttsBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::SttsBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Default)]
 pub struct SttsEntry {
     pub sample_count: u32,
@@ -17,12 +27,12 @@ pub struct SttsEntry {
 }
 
 impl Mp4Box for SttsBox {
-    fn box_type() -> BoxType {
-        BoxType::SttsBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        HEADER_SIZE + HEADER_EXT_SIZE + 4 + (8 * self.entries.len() as u64)
+        return self.get_size();
     }
 }
 
@@ -55,7 +65,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for SttsBox {
 impl<W: Write> WriteBox<&mut W> for SttsBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/tkhd.rs b/src/mp4box/tkhd.rs
index effe5c2..9023269 100644
--- a/src/mp4box/tkhd.rs
+++ b/src/mp4box/tkhd.rs
@@ -52,6 +52,22 @@ pub struct Matrix {
 }
 
 impl TkhdBox {
+    pub fn get_type(&self) -> BoxType {
+        BoxType::TkhdBox
+    }
+
+    pub fn get_size(&self) -> u64 {
+        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
+        if self.version == 1 {
+            size += 32;
+        } else {
+            assert_eq!(self.version, 0);
+            size += 20;
+        }
+        size += 60;
+        size
+    }
+
     pub fn set_width(&mut self, width: u16) {
         self.width = FixedPointU16::new(width);
     }
@@ -62,20 +78,12 @@ impl TkhdBox {
 }
 
 impl Mp4Box for TkhdBox {
-    fn box_type() -> BoxType {
-        BoxType::TkhdBox
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
     }
 
     fn box_size(&self) -> u64 {
-        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
-        if self.version == 1 {
-            size += 32;
-        } else {
-            assert_eq!(self.version, 0);
-            size += 20;
-        }
-        size += 60;
-        size
+        return self.get_size();
     }
 }
 
@@ -146,7 +154,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for TkhdBox {
 impl<W: Write> WriteBox<&mut W> for TkhdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;
 
diff --git a/src/mp4box/trak.rs b/src/mp4box/trak.rs
index 30e0353..2c9724f 100644
--- a/src/mp4box/trak.rs
+++ b/src/mp4box/trak.rs
@@ -10,12 +10,12 @@ pub struct TrakBox {
     pub mdia: MdiaBox,
 }
 
-impl Mp4Box for TrakBox {
-    fn box_type() -> BoxType {
+impl TrakBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::TrakBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         let mut size = HEADER_SIZE;
         size += self.tkhd.box_size();
         if let Some(ref edts) = self.edts {
@@ -26,6 +26,16 @@ impl Mp4Box for TrakBox {
     }
 }
 
+impl Mp4Box for TrakBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for TrakBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -80,7 +90,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for TrakBox {
 impl<W: Write> WriteBox<&mut W> for TrakBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         self.tkhd.write_box(writer)?;
         if let Some(ref edts) = self.edts {
diff --git a/src/mp4box/vmhd.rs b/src/mp4box/vmhd.rs
index 623c2ff..685a3eb 100644
--- a/src/mp4box/vmhd.rs
+++ b/src/mp4box/vmhd.rs
@@ -18,16 +18,26 @@ pub struct RgbColor {
     pub blue: u16,
 }
 
-impl Mp4Box for VmhdBox {
-    fn box_type() -> BoxType {
+impl VmhdBox {
+    pub fn get_type(&self) -> BoxType {
         BoxType::VmhdBox
     }
 
-    fn box_size(&self) -> u64 {
+    pub fn get_size(&self) -> u64 {
         HEADER_SIZE + HEADER_EXT_SIZE + 8
     }
 }
 
+impl Mp4Box for VmhdBox {
+    fn box_type(&self) -> BoxType {
+        return self.get_type();
+    }
+
+    fn box_size(&self) -> u64 {
+        return self.get_size();
+    }
+}
+
 impl<R: Read + Seek> ReadBox<&mut R> for VmhdBox {
     fn read_box(reader: &mut R, size: u64) -> Result<Self> {
         let start = box_start(reader)?;
@@ -55,7 +65,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for VmhdBox {
 impl<W: Write> WriteBox<&mut W> for VmhdBox {
     fn write_box(&self, writer: &mut W) -> Result<u64> {
         let size = self.box_size();
-        BoxHeader::new(Self::box_type(), size).write(writer)?;
+        BoxHeader::new(self.box_type(), size).write(writer)?;
 
         write_box_header_ext(writer, self.version, self.flags)?;