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thedoble  
#1 Posted : Saturday, December 24, 2011 12:58:55 AM(UTC)
thedoble

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Location: Brisbane, Australia

Hi

I am trying to use desktop capture on the local machine to capture video of a PC game.

The problem is that the capture rate is very low. Even when setting the framerate to 30, it appears I am only recieving the default 5 fps.

My CPU is not overloaded so I am not sure what the issue is.

How can I improve the FPS of the desktop capture?

Kind regards,
Doble
thedoble  
#2 Posted : Saturday, December 24, 2011 1:11:38 AM(UTC)
thedoble

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I have just done some more testing and I've found that if I set the resolution to be smaller - for example 300x300px, then the framerate improves.

It seems that the way that the desktop capture applet works is not good for high resolution high framerate screen capture.

Is there another way to capture the screen using vmix?
admin  
#3 Posted : Saturday, December 24, 2011 1:27:28 AM(UTC)
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Hi,

The Desktop Capture program is limited by the performance of the graphics card.
So when you are using a game that uses 100% of the graphics card, the capture program won't have much performance left to work with.

There are programs out there that capture gameplay use a variety of techniques to try and improve this but they have issues as well.

Flawless game capture involves using the HDMI output of the computer set to a HD resolution such as 1080i 60hz and then capturing that
using an Intensity Pro card in the vMix computer.

Regards,

Martin
vMix
thedoble  
#4 Posted : Saturday, December 24, 2011 2:24:01 AM(UTC)
thedoble

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Hi, thanks for getting back to me.

The issue persists even if I am just capturing screen elements such as a web browser or word document - very low framerate. I have tested just by moving a Microsoft Word window around the screen, and the capture input is very jerky and low FPS.

Could there be something else?
thedoble  
#5 Posted : Saturday, December 24, 2011 2:53:41 AM(UTC)
thedoble

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While continuing to work on this, I ended up finding the VH Screen Capture Driver - it creates a virtual webcam and captures video from the screen to it. This way I can add it to vMix as a 'capture' source. Info here - http://www.splitmedialab...eo-sdk/vh-screen-capture

Unfortunately, I am having another problem with this -

When I add the capture source, the preview either shows a black screen, or shows 1 frame of the video, inverted and upside-down, no further frames are shown.

I have tested the capture source in other programs like Skype and it works perfectly.

I have also found that when I go to the 'advanced' tab of the input for the camera, and select the driver and choose 'properties' the driver configuration window appears, but vmix crashes.

If we can get desktop capture working as intended then I won't have to go down this route, but really the VH Screen Capture driver should work as well!
admin  
#6 Posted : Saturday, December 24, 2011 4:49:43 AM(UTC)
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The VH Screen Capture driver does not appear to fully support DirectShow as it fails to work when the DirectShow clock is disabled.
(vMix uses its own internal clock for timing)

I will look into improving the Desktop Capture performance.

Regards,

Martin
vMix
admin  
#7 Posted : Saturday, December 24, 2011 5:15:49 AM(UTC)
admin

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I have a quick test version of the Desktop Capture program available that should be a lot faster.
It uses JPEG compression instead of PNG as well as a couple of other optimisations.

Email me at info@vmix.com.au and I will email you a copy to try out.

Regards,

Martin
vMix
admin  
#8 Posted : Saturday, December 24, 2011 11:16:38 PM(UTC)
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Hi,

I've decided to attach the test version to this thread so other users can give it a go as well.
To install, extract the zip file to a folder on your computer and run the program.

Regards,

Martin
vMix
File Attachment(s):
vMixCaptureServer.zip (12kb) downloaded 20 time(s).

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thedoble  
#9 Posted : Sunday, December 25, 2011 3:49:02 AM(UTC)
thedoble

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Hi Martin

Thanks for that - the test version is definitely better, I'm getting around 12-15FPS now, but I still need a higher framerate, at least 25FPS.

Is there anything else that can be done to the capture server? or alternatively, is it possible to use the VH Screen Capture driver instead?

Thanks for your help with this!
admin  
#10 Posted : Sunday, December 25, 2011 4:53:12 AM(UTC)
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Hi,

Any other capture device software should work fine.
See here:

http://betterlogic.com/r...-screen-capture-filters/

It is only the VH Screen Capture driver that has a bug that prevents it from working in vMix.

The Desktop Capture Server is designed for high performance over the network which is why it is not as fast.
(It has to compress the image in realtime to send over the network).

Regards,

Martin
vMix
admin  
#11 Posted : Tuesday, December 27, 2011 11:56:50 PM(UTC)
admin

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Hi,

Further optimisations have been made that should make the capture even faster but they require vMix changes so they won't be available until
the next version of vMix due in a couple of weeks time.

Regards,

Martin
vMix
admin  
#12 Posted : Sunday, January 8, 2012 3:01:28 AM(UTC)
admin

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vMix 2012 v2 has now been released for testing:

http://forums.vmix.com.au/default.aspx?g=posts&t=285

It includes three new compression modes for the Desktop Capture: HighJPEG, MediumJPEG and LowJPEG.
These have varying levels of quality but the LowJPEG in particular should run fast on most machines at a lower quality.


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