Contributing to MP4Box.js

First off, thanks for considering contributing to MP4Box.js! We appreciate your help in making this project better.

Changesets

Changesets are used to manage versioning and changelogs. When you make a user-facing change, it is advised to create a changeset. This helps keep track of changes and ensures proper versioning.

npm run changeset

Remember, not every pull request requires a changeset—only those that introduce user-facing changes affecting the API or functionality. For internal refactoring, tests, or documentation updates, a changeset is not needed.

Commit Messages

While we don't strictly enforce it, we strongly encourage you to use Conventional Commits for your commit messages. This helps us automate the release process using Semantic Release and makes it easier to understand the changes in the project history.

A typical commit message might look like:

feat: Add new 'prft' box from 14496-12

Or for a fix:

fix: Correct parsing of 'prft' box under specific conditions

Adding New Boxes

We welcome contributions for new MP4 box types! Here's how to add one:

1. Create the Box File: Each new box should be implemented in its own file under the src/boxes/ directory. For example, a new box named prft would be in src/boxes/prft.ts.

2. Re-export the Box: After creating your box file, you must re-export it from entries/all-boxes.ts. This makes the new box available to the library.

   Open entries/all-boxes.ts and add an export line for your new box:

   // ... other box exports
   export * from '#/boxes/prft'; // Add this line for your new box
   

Example Box Contribution

Here's an example of how a box class might be structured. This is the prft (ProducerReferenceTimeBox) box:

import { FullBox } from '#/box';
import type { MultiBufferStream } from '#/buffer';

export class prftBox extends FullBox {
  static override readonly fourcc = 'prft' as const;
  box_name = 'ProducerReferenceTimeBox' as const;

  ref_track_id: number;
  ntp_timestamp: number;
  media_time: number;

  parse(stream: MultiBufferStream) {
    this.parseFullHeader(stream);
    this.ref_track_id = stream.readUint32();
    this.ntp_timestamp = stream.readUint64();
    if (this.version === 0) {
      this.media_time = stream.readUint32();
    } else {
      this.media_time = stream.readUint64();
    }
  }
}

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Thank you for contributing!