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Understanding How vMix Processes Renders and Outputs Sources
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geigs  
#1 Posted : Monday, March 10, 2014 5:57:40 PM(UTC)
geigs

Rank: Newbie

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Joined: 7/26/2013(UTC)
Posts: 8
Location: Canada
I am trying to understand how vMix Processes Renders and Outputs Video.

I have vMix basic working with SD video, when I input a local video, then output the video through the graphics card to a second monitor, it plays fine. But when I try to output to an external rendered, in this case a Decklink card, the render time increases from 1~2ms to over 20ms and playback is choppy.
When I use a faster GPU (Geforce GTS 450) it can handle output to the external renderer ok, But when I Input a live video feed from a viewcast capture card into vMix and output to external renderer, render time goes over 20ms and playback is choppy. Again when only outputting to second monitor through graphics card, playback seems to be fine.
Why is this ?

In regards to DirectShow Filters, the default Microsoft DVD Decoder filter for MPEG video is also causing playback to be choppy, disabling it seems to have worked and playback is now smooth, but when I look under Decoders I can not choose another DirectShow custom MPEG 2 codec in the drop down menu to use, and I do have more installed on my system.

I am trying to understand why playback output through the GPU is ok, but choppy with a sudden increase in render time when outputting to an external renderer ?

Other hardware or configuration to recommend ?
Should I try different Decoders or can I even tell vMix what decoders to use ?

Thanks


Windows 7 x64
Intel Xeon Quad Core
4GB DDR2 RAM
Nvidia Geforce GTS 450
Decklink SP PCIe
Viewcast Osprey 210
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admin  
#2 Posted : Monday, March 10, 2014 10:55:37 PM(UTC)
admin

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vMix uses the graphics card for all processing. Some graphics cards and devices
are quite slow in downloading video back from the card which is what vMix needs to do before sending the video to the Decklink.

Some of the specs you mention are quite old, so they may have performance issues that are causing problems or delays.

I would check:

1. That the latest graphics, osprey and decklink drivers are installed.
2. Make sure the Output Size and Frame Rate in vMix Settings and External Output setting exactly match that of the decklink output.
3. Check under Performance and make sure Output Format is set to the default of UYVY

If everything is working ok, the specs you presented should definitely be able to process SD, so my guess is there is a driver issue
causing a problem somewhere.

Regards,

Martin
vMix
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geigs  
#3 Posted : Tuesday, March 11, 2014 11:00:13 AM(UTC)
geigs

Rank: Newbie

Groups: Registered
Joined: 7/26/2013(UTC)
Posts: 8
Location: Canada
Ok thanks for the info Martin,

I do have latest drivers installed for all devices, I also have a Intensity Pro card I can try, but not sure if it will make a difference.

I may have to resort to outputting through the graphics card as the main output.

Is there any new Nvidia cards that support SD TV Out ?

thanks
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