# RxPlayer Main Thread

| Consideration           | Status                                                     |
| ----------------------- | ---------------------------------------------------------- |
| Preferred import style  | The `main_thread` directory shouldn't be imported directly |
| Multithread environment | It should only be relied on the main thread                |

## Overview

The "main_thread" directory regroups multiple modules constituting the central logic of
the RxPlayer that has to run in main thread (as opposed to `core`, which optionally runs
in a WebWorker).

Those modules are:

- **the `API` (./api)**

  Defines the public API of the RxPlayer and provides abstractions to help implementing
  it.

- **the `ContentInitializer` (./init)**

  Initialize playback and connects different modules between one another.

- **the `ContentDecryptor` (./decrypt)**

  Negotiate content decryption. Only used for contents with DRM (Digital Right
  Management).

- **the `TracksStore` (or `MediaElementTracksStore`) (./tracks_store)**

  Ease up text/audio/video track switching to provide a simple-to-use API.

  It has another sister block the `MediaElementTracksStore`
  (./tracks_store/media_element_tracks_store.ts), has the same role but for "directfile"
  contents - which are contents directly played by the browser (by setting the media file
  as the `src` of a media element).

- **the `TextDisplayer` (./text_displayer)**

  Allows to display subtitles on screen. Either through HTML elements, or through native
  HTMLTrackElement (`<track>`).