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Green Screening in Final Cut Pro X

COW Forums : Apple Final Cut Pro X Debates

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Bill Ballis
Green Screening in Final Cut Pro X
on Jul 28, 2011 at 3:37:47 am

I'm trying to get into HDV and green screening, doing mostly talking head, funny characters.
I've been shooting DV on a blue blanket background without green screening, but I've noticed that if the lighting isn't exactly the same on each shot, and I shoot different clips at different times of day or night, the blue background can change color, so I figured it'd be better to shoot green screen and insert a standard background so the lighting wouldn't have to match so much.
I have the Canon HV20 and after seeing some really good-looking HD footage on YouTube, I'm trying to use the HDV 60i setting on my camera and do green screening as well. I'm finding that whether green screening in DV or HDV, it takes a lot of time to render and export, but especially long in HDV. I've got an older Mac and PC, so I went up to the Apple Store at Baybrook and imported some HDV green screen footage on an iMac i5QuadCore with 4GB RAM, using the new FCProX and although I could always see what I was working on in real time, after I tried to export it, it took quite a while to render and longer to export. I've thought about getting a new Mac Mini and use FCProX, but if the iMac Quad is taking a while, the Mini would probably take longer. I'm waiting for the new Mac Pro's to come out and if they're not too expensive, maybe get one of those, but if green screen is so intensive, I'm wondering if it is easier to just keep using the blue blanket without green screening, and get some black drapes to block out all the sunlight during the day and make sure the lighting always matches exactly, whether day or night. I've got a 4 year old HP Laptop that has PremierePro and After Effects, but it takes forever to render and export. I priced an i7 2600K QuadCore pieced-out computer at Fry's to use PremierePro CS5.5 on with After Effects, but after talking with a guy a B & H Photo about it, he said if you don't have a high-end computer (they sell PremierePro-Ready computers for $3,000 to $5,000), it'll still take time to render and I'd have to stop working while it rendered. The one I was pricing at Fry's was about $1,400. I'm wondering if you might have an idea of the best way to do green screen on HDV without having to take forever on the rendering and exporting. Is that what capture cards do?

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Patrice Freymond
Re: Green Screening in Final Cut Pro X
on Jul 28, 2011 at 6:43:23 am

Without going into the details of chroma keying (your need to read more about it is obvious - not trying to be demeaning here), here's part of your solution:

If your disks are fast enough (i.e. no FW 400, FW 800 is borderline), import your HDV as ProRes (don't bother with HQ, no need)and your render times will be shorter, as you will go from a long gop codec to an intra frame one.

But don't expect fantastic CK results if you start with DV or HDV, there just isn't enough chroma information in those codecs for that.

Oh and if you plan to go the FCPx route, the ideal machine will be expensive if you want it to be really fast as FCPx can use all the RAM you will throw at it.

hope this helps


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Craig Seeman
Re: Green Screening in Final Cut Pro X
on Jul 28, 2011 at 11:20:33 am

I don't want to go into a lot details because some of your questions are better answered in some of the other COW forums but here's some basics.

When doing blue/green screen work lighting is critical as you're finding out. The background should be evenly lit. One trick to tell if the light is even is to turn on the camera's zebra pattern and see if the entire background has zebra stripes on it. I don't think the Canon Vixia HV20 has zebra pattern though. Check in the manual.

Many would say green is a little bit better choice for a background when using compressed digital codecs. There tends to be more luminance information in green and the luminance doesn't get as heavily compressed.

Interlaced tends to be a bit harder to key than progressive especially in compressed codecs.

HDV, because it's a GOP based codec and it's HD, should take longer to render than DV which is I frame and Standard Def.

In FCPX there's an important preference setting when using GOP based codecs. Preferences - Import - Transcoding - Create Optimized Media. What that will do is allow you to start working on the difficult to use HDV codec but will render to Apple ProRes in the background. As that happens your HDV will become ProRes and be easier to work with. Chroma key rendering is impacted by both the CPU and GPU.

The base model MacMini is a Dual i5 with a very weak Intel GPU. The top MacMini can optionally have a Dual i7 with a bit better graphics card. The MacMinis would be OK for basic editing but even the best wouldn't be super fast given the background transcode to ProRes plus the rendering of the chroma key.

The iMacs would be much better if you can afford it and the top of the line iMac is really fast It can be Quad i7 with a Radeon 6970 GPU. The MacPros would be another jump up and in price and would add the ability to have internal hard drives and PCIe cards. You may not need all that. The iMac would give you Firewire in for HDV and a Thunderbolt port so you can add extremely fast external hard drives. Of course the newer cameras with HDMI record to cards so you'd really only need a card reader in most cases for input.

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