OBS is completely, 100% free. You don't have to pay for it at all. It is a great, high quality program that excels at streaming and recording. It is completely virus and malware free.
Windows XP unfortunately lacks DirectX 10 features and the audio subsystem present in Vista and up that OBS makes use of, and as such, will never be supported. OBS is currently being rewritten as multi-platform under the name OBS Studio. It will be available for Windows, Mac and Linux when it is done.
Check out our settings estimator for general recommendations based on your setup
A scene "holds" the list and order of the sources you add to it. Sources are for example images, a webcam input, window or monitor capture, anything you would want to add to your recording. So you can set up different Scenes that will hold different sources. For example a "welcome" scene with a picture and some text. A "game" scene that shows the game you want to stream and your webcam and an "end" scene that will show a "thanks for watching" message or whatever you want. The amount of scenes is not limited in OBS and the amount of sources per scene aint limited either.
If you are familiar with tools like Photoshop, a scene is similar to the Canvas or a Page in a Photoshop file while the sources are the different layers.
You already have the 64bit version if you used the installer. It can be found in your Start Menu under Programs -> Open Broadcaster Software -> Open Broadcaster Software (64 bit). If you still can't find it, it is usually in C:\Program Files\OBS. Be aware that the 64 bit version is not compatible with certain video devices and plugins, there is rarely a reason to use it.
List of plugins https://obsproject.com/forum/resources/categories/plugins.3/
Use the estimator to get good starting values for your settings in OBS: http://obsproject.com/estimator
Yes thanks to R1ch, we have a very useful Stream analyzer available:
Live stream analyzer: http://r-1.ch/analyzer/
You either did not fit your source to the full size of your stream or your choose the wrong aspect ratio/resolution, check this tutorial: http://obsproject.com/forum/resources/how-to-select-the-correct-resolution-aspect-ratio.13/
(v0.62+) If you need to use a recording device such as a Line In or Mic as your primary OBS device, close OBS and find your profile .ini file in %appdata%\obs\profiles. Under [Audio] add InputDevicesForDesktopSound=1
Getting the most out of your webcam https://obsproject.com/forum/threads/getting-the-most-out-of-your-webcam.1036/
If you use Comodo (Anti Virus or similar) and get a DNS error with the latest version of OBS, add an exclusion for the OBS folder and disable auto-sandbox. Disabling Comodo won't help. If you need help to add an exlusion look here: http://imgur.com/a/CvLQl
How to test your CPU / memory with LinX http://obsproject.com/forum/viewtopic.php?f=18&t=5361
Try the DirectX End-User Runtimes (June 2010) http://www.microsoft.com/en-us/download/details.aspx?id=8109
Your graphics card does not have sufficient support for DirectX 10. It does not matter if you have newer versions of DirectX software installed; your hardware does not support the necessary features, and no you cannot do anything about it apart from upgrading it.
Make sure you have the latest version of DirectX and that your video card drivers are up to date.
To disable exclusive mode, right click the speaker icon in the system tray, select "Recording Devices" then choose your microphone and press "Properties". Go to the "Advanced" tab and uncheck both checkboxes.
Problems getting the Razer Kraken working? Just use 64bit OBS (gets installed automatically, look in your start menu). Or if you're on a 32bit system, disable the Kraken Launcher in msconfig and reboot to get it working with OBS.
In OBS select Help > Log Files > Upload last Log File. Copy the URL and paste it here. See picture for steps: http://i.imgur.com/1tOZwtC.png
The best way to stream LoL is to set up 2 scenes. First, keep Aero enabled. Then, in the first scene, have a Window Capture of the LoL client, and in the second scene, have a Game Capture of the actual LoL game (or Window capture if the game is in windowed or borderless mode). Then use the Simple Scene Switcher to automatically swap between them: https://obsproject.com/forum/viewtopic.php?f=11&t=1785 Avoid Monitor capture altogether.
Do NOT use Monitor Capture on Windows Vista/7. Instead, try adding a Game Capture source and selecting "[DWM] Monitor Capture" from the list of capture targets. Aero must be ENABLED and only the primary screen will be captured.
Enable your windows aero theme (taskbar and window transparency): http://en.kioskea.net/faq/30281-how-to-rapidly-enable-or-disable-aero-under-windows-7
Go to "Settings" > "Broadcast Settings" and check "Save to file", click "Browse" and navigate to the desired location, enter a file name, or enter % to have the files named automatically, and click "Save". If you do not stream, set Mode to "File Output Only" and follow this guide: https://obsproject.com/forum/resources/how-to-make-high-quality-local-recordings.16/
If the Quick Sync option in OBS is grayed out, follow this tutorial: https://obsproject.com/forum/resources/how-to-use-quicksync.82/
Note that Quick Sync will slightly reduce your video quality compared to x264.
How to convert flv to mp4 or vice versa without quality loss: https://obsproject.com/forum/resources/how-to-convert-flvs-to-mp4-fast-without-re-encoding.78/
Random downclocking? Intel users: Disable SpeedStep. AMD desktop users: Disable Cool 'n' Quiet. AMD laptop users: Disable PowerNow!
How to install the Vista Platform Update: http://windows.microsoft.com/en-US/windows-live/essentials-install-windows-platform-update-ui
If you're playing back a video created with OBS but there's no audio, and you're using Windows Media Player or QuickTime Player, you're missing codecs required to play back the audio properly. Use VLC instead: http://www.videolan.org/vlc/index.html
Firstly, make sure you have created a scene and added a source to actually be seen. After that, you'll need to turn on 'Preview Stream' or be streaming in order to see your stream
You need to be previewing your stream, or actually streaming and click 'Edit Scene' to move things around. You can also hold Ctrl while moving a source to prevent it from snapping to the screen edges, Shift while resizing to ignore the aspect ratio, and Alt while dragging the edge of a source to crop.
Are you trying to stream a fullscreen game? You'll need to hook into it using the 'Game Capture' source in OBS. As well, OpenGL games like Minecraft have issues with Window Capture and you'll need to use Monitor Capture to show them. If desktop capture is showing up as black, it indicates that you either need to update windows or update DirectX.
4k is supported fine but you need to use the "high" encoding profile in settings -> advanced, it will require up to 4 times as much processing power as encoding 1080p
Your capture device may still be unsupported -- please visit the Problems and Bugs forum and read the thread regarding red output from devices.