mp4san is an MP4 format "sanitizer".

Currently the sanitizer always performs the following functions:

• Return all presentation metadata present in the input as a self-contained contiguous byte array.
• Find and return 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.

The original metadata may or may not need to be modified in order to perform these functions. In the case that the original metadata does not need to be modified, the returned [SanitizedMetadata::metadata] will be [None] to prevent needless data copying.

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.

# use mp4san_test::{example_ftyp, example_mdat, example_moov};
#
let example_input = [example_ftyp(), example_mdat(), example_moov()].concat();

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

assert_eq!(sanitized.metadata, Some([example_ftyp(), example_moov()].concat()));
assert_eq!(sanitized.data.offset, example_ftyp().len() as u64);
assert_eq!(sanitized.data.len, example_mdat().len() as u64);
# Ok::<(), mp4san::Error>(())

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