174 lines
8.6 KiB
Text
174 lines
8.6 KiB
Text
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What is OBS?
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This project is a rewrite of what was formerly known as "Open Broadcaster
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Software", software originally designed for recording and streaming live
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video content, efficiently.
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Bug Tracker: https://obsproject.com/mantis/
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We are no longer using GitHub issues! Please use Mantis, and only report
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bugs and major issues. Do NOT use mantis to ask questions or request
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features, please keep that to the forums.
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Forum accounts are now linked to Mantis Bug Tracker. To use the bug
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tracker, simply log in to the forums and then go to the bug tracker link
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above.
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What's the goal of rewriting OBS?
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- Make it multiplatform. Use multiplatform libraries/functions/classes where
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possible to allow this. Multi-platform support was one of the primary
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reasons for the rewrite. This also means using a UI toolkit will be
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necessary for user interface. It also means allowing the use of OpenGL as
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well as Direct3D.
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- Separate the application from the core, allowing custom application of
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the core if desired, and easier extending of the user interface.
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- Simplify complex systems to not only make it easier to use, but easier to
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maintain.
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- Write a better core API, and design the entire system to be modular.
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- Now that we have much more experience, improve the overall design of all
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the subsystems/API, and minimize/eliminate design flaws. Make it so we can
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do all the things we've had trouble with before, such as custom outputs,
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multiple outputs at once, better handling of inputs, custom services.
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- Make a better/cleaner code base, use better coding standards, use standard
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libraries where possible (not just STL and C standard library, but also
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things like ffmpeg as well), and improve maintainability of the project as a
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whole.
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- Implement a new API-independent shader/effect system allowing better and
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easier shaders usage and customization without having to duplicate shader
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code.
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- Better device support. Again, I didn't know what I was getting into when
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I originally started writing code for devices. It evolved into a totally
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convoluted mess. I would have improved the existing device plugin code, but
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it was just all so fundamentally bad and flawed that it would have been
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detrimental to progression to continue working on it rather than rewrite it.
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What was wrong with the original OBS?
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The original OBS was rewritten not because it was bad, at least in terms of
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optimization. Optimization and graphics are things I love. However, there
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were some serious problems with the code and design that were deep and
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fundamental, which prevented myself and other developers from being able to
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improve/extend the application or add new features very easily.
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First, the design flaws:
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- The original OBS was completely and hopelessly hard-coded for windows,
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and only windows. It was just totally impossible to use it on other
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systems.
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- All the sub-systems were written before I really knew what I was getting
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into. When I started the project, I didn't really fully comprehend the
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scope of what I would need or how to properly design the project. My
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design and plans for the application were just to write something that
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would "stream games and a webcam, with things like overlays and such."
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This turned out fine for most casual gamers and streamers (and very
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successful), but left anyone wanting to do anything more advanced left
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massively wanting.
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- Subsystems and core functionalities intermingled in such a way that it
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was a nightmare to get proper custom functionality out of it. Things
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like QSV had to be meshed in with the main encoding loop, and it just
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made things a nightmare to deal with. Custom outputs were nigh
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impossible.
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- The API was poorly designed because most of it came after I originally
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wrote the application, it was more of an afterthought, and plugin API
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would routinely break for plugin developers due to changing C++
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interfaces (one of the reasons the core is now C).
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- API was intermeshed with the main executable. The OBSApi DLL was
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nothing more than basically this mutant growth upon OBS.exe that allowed
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plugin developers to barely write plugins, but all the important API
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code was actually stored in the executable. Navigation was a total mess.
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- The graphics subsystem, while not bad, was incomplete, and though far
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easier to use than bare D3D, wasn't ideal, and was hard-coded for D3D
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specifically.
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- The devices and audio code was poor, I had no idea what I was getting into
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when I started writing them in. I did not realize beforehand all the
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device-specific quirks that each device/system could have. Some devices
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had bad timing and quirks that I never aniticipated while writing them.
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I struggled with devices, and my original design for the audio subsystem
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for example morphed over and over into an abomination that, though works,
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is basically this giant duct-taped zombie monster.
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- Shaders were difficult to customize because they had to be duplicated if
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you wanted slightly different functionality that required more than just
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changing shader constants.
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- Orientation of sources was fixed, and required special code for each
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source to do any custom modification of rotation/position/scale/etc.
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This is one of those fundamental flaws that I look back on and regret, as
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it was a stupid idea from the beginning. I originally thought I could
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get more accurate source position/sizes, but it just turned out to be
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totally bad. Should have been matrices from the beginning just like with
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a regular 3D engine.
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Second, the coding flaws:
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- The coding style was inconsistent.
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- C++98, C-Style C++, there was no exception usage, no STL. C++ used
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poorly.
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- Not Invented Here Syndrome everywhere. Custom string functions/classes,
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custom templates, custom everything everywhere. To be fair, it was all
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hand-me-down code from the early 2000s that I had become used to, but
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that was no excuse -- C-standard libraries and the STL should have been
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used from the beginning over anything else. That doesn't mean to say
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that using custom stuff is always bad, but doing it to the extent I did
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definitely was. Made it horrible to maintain as well, required extra
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knowledge for plugin developers and anyone messing with the code.
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- Giant monolithic classes everywhere, the main OBS class was paricularly
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bad in this regard. This meant navigation was a nightmare, and no one
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really knew where to go or where to add/change things.
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- Giant monolithic functions everywhere. This was particularly bad
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because it meant that functions became harder to debug and harder to
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keep track of what was going on in any particular function at any given
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time. These large functions, though not inefficient, were delicate and
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easily breakable. (See OBS::MainCaptureLoop for a nightmarish example,
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or the listbox subclass window procedure in WindowStuff.cpp)
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- Very large file sizes with everything clumped up into single files (for
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another particularly nightmarish example, see WindowStuff.cpp)
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- Bad formatting. Code could go beyond 200 columns in some cases, making
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it very unpleasant to read with many editors. Spaces instead of tabs,
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K&R mixed with allman (which was admittedly my fault).
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New (actual) coding guidelines
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- For the C code (especially in the core), guidelines are pretty strict K&R,
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kernel style. See the linux kernel "CodingStyle" document for more
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information. That particular coding style guideline is for more than just
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style, it actually helps produce a better overall code base.
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- For C++ code, I still use CamelCase instead of all_lowercase just because
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I prefer it that way, it feels right with C++ for some reason. It also
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helps make it distinguishable from C code.
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- I've started using 8-column tabs for almost everything -- I really
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personally like it over 4-column tabs. I feel that 8-column tabs are very
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helpful in preventing large amounts of indentation. A self-imposed
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limitation, if you will. I also use actual tabs now, instead of spaces.
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Also, I feel that the K&R style looks much better/cleaner when viewed with
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8-column tabs.
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- Preferred maximum columns: 80. I've also been doing this because in
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combination with 8-column tabs, it further prevents large/bad functions
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with high indentation. Another self-imposed limitation. Also, it makes
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for much cleaner viewing in certain editors that wrap (like vim).
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