Async mp4

An mp4 muxer demuxer for mp4, made to work in WASM and async contexts.

State

• [x] Standard for Fragmented mp4
• [ ] Easy to use api
• [ ] Performant async reader (too many async calls currently)

Why not mp4-rust ?

• Their code does not implement all the necessary features for fragmented mp4 streams
• Their reader is not async
• We set flags automatically according to data
• We use a very clean macro for box definition for easy implementation: rust full_box! { box (b"mvhd", Mvhd, MvhdBox, u32) data { creation_time: Mp4DateTime, modification_time: Mp4DateTime, timescale: u32, duration: Mp4Duration, rate: I16F16, volume: I8F8, _r1: u16, // reserved _r2: [u32; 2], // reserved matrix: MP4Matrix, _r3: [u32; 6], // reserved next_track_id: u32 } }

Usage

```rust let ftyp = FtypBox { majorbrand: *b"iso5", minorversion: 1, compatiblebrands: vec![*b"isom", *b"avc1", *b"iso2", *b"iso5"], }; let moov: MoovBox = Moov { mvhd: Some(Default::default()), mvex: Some(Mvex { trex: traks.iter().map(|trak| { Trex { trackid: trak.tkhd.asref().map(|it|it.trackid).unwrapor(0), defaultsampledescriptionindex: 1, defaultsampleduration: 0, defaultsamplesize: 0, defaultsampleflags: Default::default(), }.into() }).collect(), }.into()), traks: vec![Trak { /* trak info... */ }.into()], }.into();

let mut buf = std::io::Cursor::new(vec![]); ftyp.write(&mut buf)?; moov.write(&mut buf)?; return buf.into_inner(); ```

Todo

• Make async reader read full box chunks once the size is known and decode using a synchronous reader (so we don't allocate for every byte)
• Make the box macro generate a View structure of the box so that existing data can be read without decoding everything and preserving the original structure
• Make an easy-to-use builder to generate files from a stream of codec wrapping boxes and headers