I used to read the OBS classic code base before it was replaced by OBS Studio. The original OBS was monumental when it came out. Yes, it was a Windows-only code

I used to read the OBS classic code base before it was replaced by OBS Studio. The original OBS was monumental when it came out. Yes, it was a Windows-only code base, with the GUI coded in straight Win32, and didn’t support the extensive array of sources that OBS Studio now does. But it opened instantly, and had the best D3D and OpenGL capture performance available. To my mind OBS Classic single-handedly boosted Twitch streaming to the stratosphere. This happened despite existing and new competition in live streaming apps (primarily Wirecast and XSplit). OBS Classic was just that good for its time. OBS Classic even enabled shared texture capture of Direct3D9 contexts, via a hack to d3d9.dll which had to be maintained for every new major Windows update that came out. OBS Studio carries the torch with a much cleaner cross-platform core library written in C, and better performance and stability, which itself is an achievement. Since OBS Classic is now gone, I’d recommended anyone interested in programming video, audio and cross platform native apps to read through the current OBS Studio code base on GitHub.