# mp4box
[](https://crates.io/crates/mp4box)
[](https://docs.rs/mp4box)
A minimal, dependency-light MP4/ISOBMFF parser for Rust.
Parses the MP4 box tree, supports large-size and UUID boxes, and exposes a full known-box table with human-readable names.
Includes an optional pluggable decoder registry for structured box interpretation.
Suitable for CLIs, Tauri backends, media inspectors, and developer tooling.
---
## Features
- **Zero-dependency parser** (`Read + Seek`)
- **Full MP4/ISOBMFF box tree**
- Leaf, FullBox (version/flags), Container, UUID
- **Large-size (64-bit) support**
- **UUID box support**
- **Known-Box registry**
- `ftyp → File Type Box`
- `moov → Movie Box`
- Hundreds of ISO/HEIF/MPEG boxes with full names
- **Custom decoders**
- Attach your own parser for any 4CC or UUID
- **Frontend-friendly JSON**
- Works perfectly in Tauri or WebView apps
---
## Example: Parse the box tree
```rust
use mp4box::parser::{read_box_header, parse_children};
use mp4box::boxes::{BoxRef, NodeKind};
use std::fs::File;
use std::io::{Seek, SeekFrom};
fn main() -> anyhow::Result<()> {
let mut f = File::open("input.mp4")?;
let file_len = f.metadata()?.len();
while f.stream_position()? < file_len {
let h = read_box_header(&mut f)?;
println!("Found box {} @ {:#x}, size={}", h.typ, h.start, h.size);
let end = if h.size == 0 { file_len } else { h.start + h.size };
f.seek(SeekFrom::Start(end))?;
}
Ok(())
}
```
---
## Example: Build a JSON tree (for GUIs / Tauri)
```rust
let boxes = mp4box::analyze_file("video.mp4", /*decode=*/ false)?;
println!("{} top-level boxes", boxes.len());
```
This returns:
```json
[
{
"offset": 0,
"size": 32,
"typ": "ftyp",
"full_name": "File Type Box",
"kind": "leaf",
"decoded": "major=isom minor=512 compatible=[...]",
"children": null
}
]
```
---
## Example: Command-line tool (`mp4dump`)
`mp4dump` is included as an optional binary that uses this crate to inspect MP4 files.
### Show structure
```bash
$ mp4dump input.mp4
0x0 32 ftyp
0x20 8 free
0x28 3374542 mdat
0x337df6 170458 moov (container)
0x337dfe 108 mvhd (ver=0)
...
```
### Decode known boxes
```bash
$ mp4dump input.mp4 --decode
0x0 32 ftyp
-> major=isom minor=512 compatible=["isom","iso2","avc1","mp41"]
```
```bash
$ mp4dump input.mp4 --decode --json
[
{
"offset": 0,
"size": 32,
"typ": "ftyp",
"uuid": null,
"version": null,
"flags": null,
"kind": "leaf",
"full_name": "File Type Box",
"decoded": "major=isom minor=512 compatible=[\"isom\", \"iso2\", \"avc1\", \"mp41\"]",
"children": null
},
...
```
### Dump raw bytes (like `xxd`)
```bash
$ mp4dump input.mp4 --raw stsd --bytes 256
== Dump stsd payload: offset=0x337fe6, len=156 ==
00000000: 00 00 00 00 00 00 00 01 61 76 63 31 ...
`````
---
## Adding Custom Box Decoders
```rust
use mp4box::registry::{Registry, BoxDecoder, BoxValue};
use mp4box::boxes::{BoxHeader, BoxKey};
use std::io::Read;
struct MyDecoder;
impl BoxDecoder for MyDecoder {
fn decode(&self, r: &mut dyn Read, _hdr: &BoxHeader) -> anyhow::Result<BoxValue> {
let mut buf = Vec::new();
r.read_to_end(&mut buf)?;
Ok(BoxValue::Bytes(buf))
}
}
let reg = Registry::new()
.with_decoder(BoxKey::FourCC(*b"ftyp"), "ftyp", Box::new(MyDecoder));
```
---
## License
MIT