mp4san

A Rust MP4 format "sanitizer".

Currently the sanitizer is capable of:

• Returning all presentation metadata present in the input as a self-contained contiguous byte array.
• Finding and returning a pointer to the span in the input containing the (contiguous) media data.

"Presentation" metadata means any metadata which is required by an MP4 player to play the file. "Self-contained and contiguous" means that the returned metadata can be concatenated with the media data to form a valid MP4 file.

Unsupported MP4 features

The sanitizer does not currently support:

• "Fragmented" MP4 files, which are mostly used for adaptive-bitrate streaming.
• Discontiguous media data, i.e. media data (mdat) boxes interspersed with presentation metadata (moov).
• Media data references (dref) pointing to separate files.
• Any similar format, e.g. Quicktime File Format (mov) or the legacy MP4 version 1, which does not contain the isom compatible brand in its file type header (ftyp).

Usage

The main entry points to the sanitizer are [sanitize]/[sanitize_async], which take a [Read] + [Skip] input. The [Skip] trait represents a subset of the [Seek] trait; an input stream which can be skipped forward, but not necessarily seeked to arbitrary positions.

```rust use mp4santest::{exampleftyp, examplemdat, examplemoov};

let exampleinput = [exampleftyp(), examplemdat(), examplemoov()].concat();

let sanitized = mp4san::sanitize(std::io::Cursor::new(example_input)).unwrap();

asserteq!(sanitized.metadata, Some([exampleftyp(), examplemoov()].concat())); asserteq!(sanitized.data.offset, exampleftyp().len() as u64); asserteq!(sanitized.data.len, example_mdat().len() as u64); ```

The [parse] module also contains a less stable and undocumented API which can be used to parse individual MP4 box types.

API Documentation
Private Documentation

Crate Features

This crate has the following optional features:

• error-stack-std enables the std feature of error-stack. This can only be disabled on a nightly Rust toolchain, which is useful to disable some optional features of error-stack, but should always remain enabled otherwise.

Contributing Bug Reports

GitHub is the project's bug tracker. Please search for similar existing issues before submitting a new one.

Testing

FFMpeg and GPAC-based verification of mp4san output can be enabled using the features mp4san-test/ffmpeg and mp4san-test/gpac.

The mp4san-test/ffmpeg feature requires the following FFMpeg libraries and their headers to be installed:

• libavcodec
• libavformat
• libavutil
• libswresample
• libswscale

The mp4san-test/gpac feature requires libgpac >= 2.2 and its headers to be installed.

Integration tests on sample data files can be processed through mp4san-test-gen before being added to the mp4san-test-data repo. This removes any actual media data from the sample file, since it's not read by mp4san anyway, leaving only metadata for testing purposes. This allows even very large media files to be gzipped to very small sizes.

shell $ cargo run --bin mp4san-test-gen -- test-sample.mp4 mp4san/tests/test-data/test-sample.mp4.gz

License

Licensed under MIT.