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Thread: OBS + NDI instead of NDI Scan Converter for desktop capturing

  1. #1
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    OBS + NDI instead of NDI Scan Converter for desktop capturing

    I'm currently investigating ways to get a full framerate 1080p60 video game stream from a computer into my TC1 - specifically an iMac, but this observation is platform agnostic.

    Converting a display output into physical SDI isn't feasible for me since these are iMacs, and is also generally a pain because of HDMI/HDCP and other shenanigans.

    NDI is an ideal solution since it doesn't really care about framerate or resolution, and the encoding and network overhead is impressively low.

    Unfortunately, let's be honest, for full framerate game/video desktop capturing to NDI, NDI Scan Converter stinks.

    Video game streamers often employ a single computer to play and stream games, and the quality can be seriously impressive. That includes overhead that doesn't apply here, like internet bandwidth and H264 encoding.

    Luckily that community is starting to embrace NDI for video transport, and by installing two free pieces of software, you can get fantastic results even with the weird scaled resolutions of 5k iMacs.

    https://obsproject.com

    Open Broadcaster Software (OBS Studio) is powerful (and free!) software to capture and mix desktop sources, then output it however you please. By default it's set up for internet streaming services and local recording, but by installing a small plugin, NDI output is easily enabled.

    https://github.com/Palakis/obs-ndi/releases/

    obs-ndi can be described as a "media converter" plugin of sorts - it employs the NDI redistributable runtime and OBS integration to easily add NDI outputs to OBS Studio.

    With those both installed and OBS running, resolution and framerate for NDI output are controlled by the "Output (Scaled) Resolution" and "FPS Value" settings in the Video tab within OBS settings. My requirements are 1920x1080 at 60 fps, which OBS/obs-ndi handles very easily.

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    OBS then needs a Source defined, which is generally Display Capture. You can also set things like cursor visibility and cropping within the Sources setting.

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    NDI output can then be enabled via the Tools menu. I've had better luck with the "asynchronous send" option enabled for high framerate sources.

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    The result is your computer pumping out a full resolution and full framerate NDI feed of its own display, capable of streaming any application including video games and full screen video without issues. NDI Scan Converter has never been able to do that for me, and has only been acceptable for mostly static content.
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    Hey lukerctv! I have been a huge advocate of NDI for OBS for a while now. I use it on a daily basis and it is an absolute beast. I did notice, however, that installing OBS and the plugin on every machine that I wanted to be shared was a bit troublesome. After doing some research, I found a wonderful piece of software from vMix called Desktop Capture. It can be ran from a portable installer! We keep it on a USB drive and give it to whoever wants to share their screen. It works very well, supports full 1080p60 on Windows and 1080p30 on Mac (hopefully to be updated in the future). Check out the link and see what you think! It doesn't give quite as much customization as the full OBS/NDI experience, but it is much less cumbersome on the host machine and very simple to get up and running. Link: https://www.vmix.com/software/download.aspx - it is under the Desktop Capture heading. Cheers!

  3. #3
    When the new NDI Scan Converter with NDI Tools 3.5 is released, I think you will be very impressed. Up to 60fps with little CPU overhead, most of the new NDI Scan Converter code runs right in the GPU. The performance is much better than anything else I've seen (OBS, XSplit, vMix desktop capture or the previous NDI Scan Converter). However this new version is only on Windows.
    Kane Peterson
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    Quote Originally Posted by kanep View Post
    When the new NDI Scan Converter with NDI Tools 3.5 is released, I think you will be very impressed. Up to 60fps with little CPU overhead, most of the new NDI Scan Converter code runs right in the GPU. The performance is much better than anything else I've seen (OBS, XSplit, vMix desktop capture or the previous NDI Scan Converter). However this new version is only on Windows.
    I absolutely cannot wait for this! I have been checking the forums like a mad man, subscribed to every post even remotely hinting at a drop date. Any info would be greatly appreciated!! Thanks for the heads up about the updated performance!!

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    Hi,

    I've noticed in the 3.5 version of Scan Converter you can no longer specify which application you wish to capture. There is now the ROI feature but it's quite cumbersome in comparison, I guess this is a tradeoff from moving from GDI capture to the faster capture method. Are there any plans to reintroduce the ability to create an NDI source from application names?

    Also, a nice feature with the OBS Desktop capture system is that an application window isn't required to be at the 'front' to be captured, i.e it can be behind other windows or even be offscreen (as long as it isn't minimised). Are there any plans to add this capability?

    Thanks,

  6. #6
    'the write stuff' SBowie's Avatar
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    Quote Originally Posted by Harvey3141 View Post
    Are there any plans to reintroduce the ability to create an NDI source from application names?
    as policy, we do not discuss future plans - but no.

    Sorry - few statements we make in respect to development can ever really be taken as aboslutely final, given the ever changing landscape, but at present there really are no such plans.

    Quote Originally Posted by Harvey3141 View Post
    Are there any plans to add this capability?
    I have to refer to the answer above here, too.
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  7. #7
    I'll add that you can download the NDI Tools Portable that still has the previous version of NDI Scan Converter. This version has the application window support as you describe. You can have both NDI Tools 3.5 and the NDI Scan Conveter portable on a system and use the tool you need for the task at hand.
    Kane Peterson
    Solutions Architect
    NewTek, Inc.

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    Another option is to have multiple screens connected to the computer. Scan converter works on the main screen, so you can do something else on a second screen. The potential problem would be if you mistakenly open something onto the main screen.

  9. #9
    'the write stuff' SBowie's Avatar
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    Quote Originally Posted by TheMissingLink2 View Post
    Scan converter works on the main screen, so you can do something else on a second screen.
    Scan converter serves up multiple screens, but of course you can determine which screen to connect to at the receiver.
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  10. #10
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    the new Scan Converter with ROI is not capturing a secondary screen if that screen is an AMD Eyefinity Group. This OBS screengrab may function much better in that regard, I'm going to give it a whirl. But as of now, testing on a machine that successfully sends well over 4k over 10GbE is currently giving me a black screen when trying to either send the secondary screengroup over NDI. Works just fine on the primary monitor, but not if it is an Eyefinity group. When I spoke with someone at Newtek recently, it seemed that multiple video cards were going to be considered in this release...is that no longer the case? I feel like this version of Scan Converter is less functional than the old one, even if it does perform at the new NDI rates.

  11. #11
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    Quote Originally Posted by kanep View Post
    I'll add that you can download the NDI Tools Portable that still has the previous version of NDI Scan Converter. This version has the application window support as you describe. You can have both NDI Tools 3.5 and the NDI Scan Conveter portable on a system and use the tool you need for the task at hand.
    Thanks, that's good to know, could you point me to this download please. I can't seem to find it on the website anymore.

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