RxPlayer Architecture documentation
Overview
The files in this directory and subdirectories establish a documentation about the RxPlayer’s architecture.
They are here to help you understand the way the player works, by describing the different bricks and algorithms that come into play.
Note: As some terms used here might be too foreign or slightly different than the one you’re used to, we also wrote a list of terms and definitions used by the RxPlayer here.
Organization of the documentation
The RxPlayer is heavily modularized.
This helps us maintaining the code and providing evolutions more quickly, as the various modules use few well-defined interfaces with the rest of the code.
Like the code, the documentation is also divided in multiple parts, which link one by one to a module in the code.
Such modules are (with link to their respective documentation, if one):
-
the API
Defines the public API of the RxPlayer and provides abstractions to help implementing it.
-
the Init
Initialize playback and connects the different modules between one another.
-
the EMEManager
Negotiate content decryption.
Only used for contents with DRM (Digital Right Management).
-
the ABRManager
Helps to choose the best quality in the current content by analyzing the current network, user settings and viewing conditions.
-
the Stream
Choose which media segments to download and push them to media buffers (here called the
SegmentBuffers) to then be able to decode them.Various files documenting the Stream architecture should be available in the
doc/architecture/streamdirectory. -
the SegmentBuffers
Implement media buffers on which loaded segments will be pushed. The corresponding media data contained in them will then be decoded at the right time.
Those buffers can depend on browser implementations (for example for audio and video contents, we rely on
SourceBufferJS objects) or may be completely defined in the code (for example, text track buffers in the"html"textTrackModeare entirely defined in the RxPlayer).Those
SegmentBuffershave added niceties over just being simple data buffers. For example, they include an inventory which allows to retrieve the metadata about every segments that is still contained within it. -
the transports
Perform manifest/segment requests, and parse them.
transportsin essence abstracts the transport protocol used (example: Smooth Streaming/DASH) to provide an unified definition of a segment or manifest to the other modules. In theory, it should be the only directory to update when adding / modifying / deleting a transport protocol -
the fetchers
Link the
transportsmodule with the rest of the code, to download segments, download/refresh the manifest and collect data (such as the user’s bandwidth) for the other modules.
The RxPlayer also has a multitude of isolated helpers (for manifest management, segment parsing, browser compatibility, feature switching, error handling etc.) which are used by these different modules.
A documentation about the file organization of the project is available here.
Global architecture
To better understand the player’s architecture, you can find below a (simplified!) schema of it:
+---------------------------------------------+ ,,,,,,,
| | ( CDN )
| Application/UI | ```````
| | ^
+---------------------------------------------+ |
| ^ |
| ~ |
-----RxPlayer------------------------------------------------------------------|----------
| ~ +-------------------+ |
V ~ Front-facing API | ---> Call | |
+-------------------------------------------+ | ~~~> Send events | |
| API | +-------------------+ |
+-------------------------------------------+ |
+--------------------+ | | ^ |
| TrackChoiceManager | <--+ | ~ |
+--------------------+ | ~ |
Facilitate track | ~ |
switching for V ~ |
the API +---------------+ |
| | +----------+ ------> +------------+
+------------+ <-------- | | --------> | Manifest | <~~~~~~ | transports |
| EMEManager | ~~~~~~~~> | Init | <~~~~~~~~ | fetcher | +------------+
+------------+ | | +----------+ Abstract ^ ~
Negotiate content | | Download the the | ~
decryption +---------------+ manifest streaming | ~
| ^ Initialize protocol | ~
| ~ playback and | ~
| ~ create/connect | ~
| ~ modules | ~
Stream | ~ | ~
+--------------------------------|-~-----------------------------+ | ~
| V ~ | | ~
| Create the right +-------------------------------+ | | ~
| PeriodStreams depending | StreamOrchestrator | | | ~
| on the current position, +-------------------------------+ | | ~
| and settings | ^ | ^ | ^ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| (audio) v ~ (video) V ~ (text) v ~ | | ~
| Create the right +----------+ +----------+ +----------+ | +--------------+ | ~
| AdaptationStream | | | | | |----> |SegmentBuffers| | ~
| depending on the | Period |-+ | Period |-+ | Period |-+ | | Store (1) | | ~
| wanted track | Stream | | | Stream | | | Stream | | | +--------------+ | ~
| (One per Period | | | | | | | | | | Create one | ~
| and one per type +----------+ | +----------+ | +----------+ | | media buffer per | ~
| of media) | | | | | | | type of media | ~
| +-----------+ +-----------+ +-----------+ | | ~
| | ^ | ^ | ^ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| (audio) v ~ (video) V ~ (text) v ~ | | ~
| +----------+ +----------+ +----------+ ---> +--------------+ | ~
| Create the right | | | | | | <~~~ |ABRManager (1)| | ~
| Representation- |Adaptation|-+ |Adaptation|-+ |Adaptation|-+ | +--------------+ | ~
| Stream depending | Stream | | | Stream | | | Stream | | | Find the best | ~
| on the current | | | | | | | | | | bitrate | ~
| network, +----------+ | +----------+ | +----------+ | | | ~
| settings... | | | | | | | | ~
| +-----------+ +-----------+ +-----------+ | | ~
| | ^ | ^ | ^ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| | ~ | ~ | ~ | | ~
| (audio) v ~ (video) V ~ (text) v ~ | | ~
| +----------+ +----------+ +----------+ ----> +------------+ | ~
| (Representation- | | | | | | <~~~~ | Segment | --+ ~
| Stream). |Represe...|-+ |Represe...|-+ |Represe...|-+ | | fetcher (1)| <~~~+
| Download and push| Stream | | | Stream | | | Stream | | | +------------+
| segments based on| | | | | | | | | | Download media
| the current +----------+ | +----------+ | +----------+ | | segments
| position and | | | | | | |
| buffer state +-----------+ +-----------+ +-----------+ |
| |
+----------------------------------------------------------------+
(1) The SegmentBuffersStore, Segment fetcher and ABRManager are actually created by the
Init and then used by the Stream.