Basic example of parsing mp4 atom boxes in rust.

.gitignore

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+/target
+**/*.rs.bk
+*.exe
+*.pdb
+*.mp4

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "mp4"
+version = "0.1.0"
+

Cargo.toml

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+[package]
+name = "mp4"
+version = "0.1.0"
+authors = ["Alf <alf.g.jr@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

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+use std::io::prelude::*;
+use std::io::{BufReader, Read, SeekFrom};
+use std::fs::File;
+use std::convert::TryInto;
+
+// struct Box {
+//     name: String,
+//     size: u32,
+//     offset: u32,
+// }
+
+fn main() -> std::io::Result<()> {
+
+    // Using BufReader.
+    let mut f = File::open("tears-of-steel-2s.mp4")?;
+    let filesize = f.metadata().unwrap().len();
+    println!("{:?}", filesize);
+    let mut reader = BufReader::new(f);
+
+    let mut offset = 0u64;
+
+    while offset < filesize {
+
+        // reader.seek(SeekFrom::Current(40 + 2872360));
+        reader.seek(SeekFrom::Current(offset as i64));
+
+        let mut buf = [0u8;8];
+        let n = reader.read(&mut buf);
+
+        let s = buf[0..4].try_into().unwrap();
+        let size = u32::from_be_bytes(s);
+        
+        let t = buf[4..8].try_into().unwrap();
+        let typ = match std::str::from_utf8(t) {
+            Ok(v) => v,
+            Err(e) => panic!("Invalid UTF-8 sequence: {}", e),
+        };
+
+        // Exit loop if size is 0.
+        if size == 0 { break; }
+
+        // println!("{}", buf.len());
+        // println!("{:?}", buf);
+        println!("{:?}", size);
+        println!("{:?}", typ);
+
+        // This will find all boxes, including nested boxes.
+        // let mut offset = match size {
+        //     1 => 4 + 4 + 8,
+        //     _ => 4 + 4,
+        // };
+        // assert!(offset <= size);
+
+        offset = (size - 8) as u64;
+        println!("skip {:?}\n", offset);
+    }
+
+    println!("done");
+    Ok(())
+}