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CPU usage with multiple NDI desktop capture's
Rank: Newbie
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Joined: 10/18/2016(UTC)
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Location: Brisbane
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Heya team,
We're trying to to test a setup with multiple pc's and capturing Desktop Capture NDI .
Multiple PC's running 1080p60 games with NDI desktop capture -> 10gigabit fibre -> VMIX machine
The Vmix machine we're testing with has a quad core i7-6700, nvidia 750 gfx card, 16gb ram and windows 10.
When we add about 4 inputs on vmix machine it's CPU usage jumps to 100%. I'm just wondering is this normal behaviour or is there any tweaks we can do ?
- vmix ver 17.0.0.112
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Rank: Advanced Member
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Joined: 3/7/2012(UTC) Posts: 2,642  Location: Canada Thanks: 33 times
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@ jbhewitt This is what admin said about NDI earlier on when first introduced: admin wrote:Some answers to some common questions below:
Is it GPU or CPU based?
NDI encoding/decoding is CPU based using around 5% per 1080p30 camera on a modern i7 CPU.
What color spaces are supported?
Frames are sent/received from NDI at 4:2:2 8 bit, but NDI compresses at 16 bit internally.
NDI also has full support for alpha, sent as a separate channel. (so 4:2:2:4)
Will there be converter boxes?
More than likely, possibly from more than one manufacturer.
We are working on our own prototypes using off the shelf SFF (small form factor) PCs, but
the codec can theoretically be used on devices as small as a standard HDMI to SDI mini converter.
The main advantage of one of these converters is you will no longer need a capture card
opening up most laptops to multi camera productions without the need for thunderbolt!
My hope is the converters will be affordable.
What is the stream bitrate?
To my knowledge it is variable bit rate.
I've seen around 50Mbps to 100Mbps per camera in my tests so far.
Will there be iOS and Android support?
Support for these devices, specifically the ARM processor is being worked on at NewTek.
Not sure if they will release software for these devices, but then NDI is open so if you are a developer
sign up for the SDK and start building your own!
Will Desktop Capture use NDI?
Yes, we plan to completely replace vMix Desktop Capture to use NDI.
NewTek will also release an app that does much the same thing.
What vMix licenses will we need?
One vMix license per PC that is running vMix at the same time.
If you use a 3rd party NDI app on a second PC or vMix Desktop Capture, you won't need the second license.
Do I need two copies of vMix to use capture cards from multiple PCs?
No. One of the cool things NewTek is working on is a universal PC app that can convert
any capture cards in the PC it is running from into NDI.
So you could have a vMix laptop in your studio and a rackmount PC with all the capture gear
locked away!
Not sure if that fully addresses your question or issue, but hopefully puts you on the right track. Ice
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Rank: Advanced Member
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I think "around 5% per 1080p30 camera" was quite optimistic, my own experience is that NDI uses a lot more resources than a capture card input.
Martin told me at IBC the NDI version 2 will be better when it comes to resource usage.
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Rank: Newbie
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Joined: 10/18/2016(UTC)
Posts: 4
Location: Brisbane
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It seems to me it's using 20-30% cpu of an i7 6700 per NDI source on decoding - not encoding.
I'm just wondering if there is anything i can do on the vmix machine to ease up the decoding ?
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Rank: Advanced Member
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I just did a quick test.
VLC playback (not NDI) of a MP4 clip at 1920x1080@30fps uses about 5% of my laptop's i7 CPU
VLC with the NDI plug-in of same clip, uses about 8% of my laptop's i7 CPU.
NDI Monitor is using about 6% CPU to decode the NDI source.
Not saying that other applications won't be different as they might be doing much more than the above tools, but that is what I'm seeing in a simple test of encoding and decoding.
Kane Peterson
NewTek
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Rank: Newbie
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Joined: 10/18/2016(UTC)
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Location: Brisbane
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Yes this is why i think it's very strange on Vmix i'm seeing such high cpu usage when i go over say 4 channels.
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Rank: Advanced Member
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I just realized something. The numbers I listed above is with a beta NDI v2 on my system. I totally forgot that I had it installed, so that is probably improving my results.
Kane Peterson
NewTek
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Joined: 1/13/2010(UTC) Posts: 5,228 Location: Gold Coast, Australia Was thanked: 4332 time(s) in 1528 post(s)
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jbhewitt, You can give the vMix 18 beta a try to see if there is any improvement with CPU usage: http://forums.vmix.com/d....aspx?g=posts&t=7083It's worth noting that 1080p60 will use around twice the CPU of 1080p30, so setting the vMix Desktop Capture frame rate to 30 will halve the CPU usage, but I understand that you may want the full 60 for gaming. Also, if some NDI sources only need to be previewed you can right click and select Low Bandwidth mode which will bring in the source in a resolution suitable for previewing, but at much reduced CPU. You can then switch this back off before using the source live. Regards, Martin vMix
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Rank: Newbie
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Joined: 10/18/2016(UTC)
Posts: 4
Location: Brisbane
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awesome thanks for the info - will give v18 a try and report back!
also will test 30fps and report back
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Rank: Advanced Member
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In the discovery phase it is using multicast.
When you set up a connection, it uses unicast between the source and receiver.
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Rank: Advanced Member
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Joined: 8/2/2013(UTC) Posts: 1,073  Location: Fairhope, Alabama USA Thanks: 555 times
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Mathijs wrote:In the discovery phase it is using multicast.
When you set up a connection, it uses unicast between the source and receiver. Good to know. Thank you. - Tom
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