OBS Studio 21.0.1

What's new in this version:

Scripting:
- Added Luajit/Python3 scripting support. Scripting can be accessed via the "Tools" menu -> "Scripts"
- Lua is supported via Luajit, which comes with the program. Lua is recommended for high performance scripts, automation, and sources
- Python is available if access to its convenient libraries is desired. On windows, to use Python, Python version 3.6 must be installed separately ("x86-64" version if 64bit OBS Studio, "x86" version if 32bit OBS Studio), and the Python 3.6 install path must be configured in the Python settings tab
- Scripting documentation can be found in the developer documentation
- Added an example Lua script: An "Analog Clock" source which draws an analog clock (added like any other source when the script is active)
- Added an example Lua script: A "Countdown Timer" script which sets the text of a text source to a countdown timer which counts down when that text source is displayed on stream
- Added an example Lua script: An "Instant Replay" script which automatically save a replay if there's an active replay buffer, and then plays back that replay in a specified media source after that replay has saved
- Added an example Python script: A "URL Text" script which sets the text of a specified text source to the text downloaded from a specified URL every specified interval

New Audio Features:
- Added sidechain/ducking support to the compressor filter. This allows the ability to lower the audio level of an audio source based upon how loud another source is. For example, to apply microphone ducking to a desktop audio source, add a compressor filter to the desktop audio source, then select the microphone audio source in the "Sidechain/Ducking Source" property
- Added surround sound audio output support, which allows outputting 2.1, 4.0, 4.1, 5.1, and 7.1 audio to stream/recording. (When using this feature, please also make sure to increase your audio bitrate to support all the channels in output settings. Although some services like Twitch support it, note that certain services such as YouTube may not fully support surround sound streaming, and may not downmix them correctly for stereo viewers)
- Added new audio meters to allow the ability to see the audio levels of each audio channel of that source. This allows the ability to know if there are any issues with a specific audio channel (e.g. if just the left or right audio channel is somehow low or muted)
- Changed audio meters to behave like peak programme meters. This will make it easier to see if your audio is clipping and set your audio levels correctly
- Added an "Audio Meter Decay Rate" option in audio settings to allow selecting a specific delay rate (fast, medium, slow) for the audio meters if desired
- Added the ability to rename audio sources via right-clicking them in the audio mixer, including desktop and microphone audio capture sources added via audio settings

New Production and Studio Mode Features:
- Added a "Multiview" projector (accessible via the View menu), which allows the ability to view the preview/program and up to 8 scenes at the same time. Scenes in the Multiview can be clicked to change the scene (or the preview scene in studio mode). You can blacklist certain scenes from displaying in the multi-view by right-clicking the scene in the scenes list and unchecking "Show in Multiview". You can also change the Multiview's layout style in general settings
- Added an option in general settings that allows you to transition to a scene in studio mode simply by double-clicking on it. This also applies to the multiview projector
- Added separate projectors for both preview and program views in studio mode
- Added a portrait/vertical layout option for studio mode in general settings which makes the preview/program views vertical relative to each other instead of horizontal
- Added per-scene transition overriding, which allows you to select a specific transition to use for a specific scene. To use this feature, right-click on the scene in the scene list, and select the transition/duration via the right-click context menu. (This override does not apply to studio mode quick transitions)

Developer Documentation:
- Spent about a week or so and finally wrote full developer API documentation/reference (useful for both native and script developers)

Other General Changes and Fixes:
- Added a new program theme: Acri
- Changed the default program theme to dark mode for new users
- Changed the text of "Multi-adapter Compatibility" in game capture to "SLI/Crossfire Capture Mode (Slow)". This was changed because the wording "Multi-adapter Compatibility" was a bit vague, and users are not typically aware of the potential performance impact when using the option
- Optimized the preview pane and reduced GPU usage by 2-8% depending on how many sources were in the preview
- The streaming/recording buttons in the main window now highlight while streaming/recording
- Fixed a bug on Windows where desktop audio capture could go slightly out of sync with display/game/window capture on certain audio devices
- Fixed an issue where certain Elgato devices would not output audio by default, and would require users to select the audio device manually
- Fixed a bug with studio mode where scenes that are set to fully duplicate would not retain their filters
- Fixed a stuttering bug on Linux with audio monitoring
- Fixed MP3 audio support in the browser source on macOS
- Fixed a few Dark/Rachni theme issues
- Fixed a lot of minor bugs and a few minor memory leaks
- Fixed a known crash that could happen on startup for certain AMD cards/drivers