# gpac/mp4box.js

JavaScript version of GPAC's MP4Box tool

Repository: https://github.com/gpac/mp4box.js
Canonical: https://ross.abutalabs.com/products/mp4boxjs
Homepage: https://gpac.github.io/mp4box.js/test/filereader.html
Language: TypeScript
License: BSD-3-Clause
License Family: permissive
Last push: 2026-07-28T15:06:16+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 94, release rhythm 89, longevity 100
- inputs: {"age_days": 4515, "days_push": 36, "days_rel": 75, "gap_med": 4, "n_releases_24m": 30}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2463, forks 391 (observed 2026-08-28T04:06:53.510185+00:00)

## What it is
MP4Box.js is a JavaScript/TypeScript library for parsing, segmenting, and extracting samples from MP4 (ISOBMFF) files, inspired by GPAC's MP4Box tool. It works progressively in both browser and Node.js environments, enabling MSE-based streaming and client-side file inspection.

## Use cases
- parse mp4 files in javascript
- inspect mp4 metadata and box structure in the browser
- segment mp4 files for media source extensions playback
- extract media samples from mp4 tracks
- build adaptive streaming with fragmented mp4
- analyze isobmff box structure client-side
- extract subtitle tracks from mp4

## When to choose
- you need to parse or fragment MP4 files in JavaScript in a browser or Node.js
- you want client-side MP4 inspection without uploading files to a server
- you are building MSE-based video players or adaptive streaming
- you need progressive parsing of media data as it loads

## When to avoid
- you need full MP4 remuxing or transcoding capabilities of the native MP4Box tool
- you work with non-ISOBMFF container formats like MKV or AVI
- you need server-side heavy video encoding or processing

## Facets
- artifact type: library
- maturity: active
- function: parser, video-processing, developer-tools
- domain: media, web-development, developer-tools
- platform: browser, cross-platform
- tags: mp4, isobmff, mse, streaming, typescript, media-parsing, video, nodejs

## Member repositories
- gpac/mp4box.js (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:53.510185+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:29:16.915287+00:00, confidence not recorded.
  - readme: https://github.com/gpac/mp4box.js (fetched 2026-08-28T04:06:53.510185+00:00, sha 533dd5af6e3a)
  - homepage: https://gpac.github.io/mp4box.js/test/filereader.html (fetched 2026-08-29T10:10:50.136751+00:00, sha 5d83ada54084)
- Data as of 2026-08-30T08:39:29.467469+00:00.