add top level public function mp4::read_mp4 for using the Mp4Reader with a file path. Added simple example.

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(),
+        );
+    }
+}

src/lib.rs

@@ -1,3 +1,6 @@
+use std::io::{BufReader};
+use std::fs::File;
+
 mod error;
 pub use error::Error;
 
@@ -17,3 +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)
+}