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OT: How does one get DV50(4:2:2) footage?
Hello all,
I’ve been trying to understand a capture issue brought
on by the topic of GreenScreen Keying. First, if you have
4:2:2 video chroma keying is much easier and the results
are better. Since every DV camcorder uses 4:1:1(NTSC) for
video compression how does one get 4:2:2? I’ve looked at
cameras that say they record 4:2:2 data but they range from
20-100K dollars. Are there no sub 5K camcorders that
record 4:2:2 video?Thanks
Mark
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7 Replies
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Nope there is no sub 5K camera 4:2:2.
The Panasonic P2 camera, which runs the gamut from DV to HD, coming out later in the year will run in the 6-7K range without the P2 cards.
And lastly DV is not 4:1:1, that is the Panasonic DVCPRO25 codec.
DV is 4:2:0.
Hope that helps.
Martin
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Martin,
Thanks for the email. I read an article about the new
panasonic camera, but it looks like the memory cards
are more expensive than the camera. 6K for a camera and
8K for a single memory stick(if I remember it correctly).
As for DV, I believe that NTSC DV uses 4:1:1 and PAL
DV uses 4:2:0.https://www.adamwilt.com/DV-FAQ-tech.html#colorSampling
Unfortunately niether PAL nor NTSC DV is great for
chroma keying… Guess I’ve got to start saving for the
big camera. 🙁Thanks again for the help.
Mark
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Have you thought about shooting in HDV? The chroma is subsampled due to it being recorded to tape at 4:2:0, but since 1080i HD video has about 6 times as many pixels as SD video, you will get a much better key. Here’s a great creative cow thread about keying with HDV. Your video editing workflow will be a bit slower, due to having to convert to SD after keying.
Another way to get an even cleaner key is to skip the chroma subsampling and mpeg2 compression that occurs when recording to tape. You can do this by using the live HD analog outputs of the Sony HDR-FX1/HVR-Z1 cameras.
You would connect the analog HD video outputs to an analog HD to HD-SDI converter. From there, you would go in to your computer with an HD-SDI capture card.
Kako Ito and others did some tests of this process.
Andy
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Andy,
I did ask on the AE forum about HDV keying and all I got
was that since it is still compressed HDV has the same problems.
It’s good to hear that the extra resolution helps.
THANKS so much for the other links. I had no idea that the
FX1 had analog outputs that allow capturing uncompressed HD
via a analog capture card. This is an excellent idea. It seems
that if one had a portable PC with an HD capture card, then
a person could capture HD video anywhere with the FX1.
Am I understanding the links you sent?Thanks again!!!
Mark
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Yep, by using the analog outputs of the FX1, you can capture uncompressed 4:2:2 HD video. 4:2:2 because the analog outputs are YUV.
The footage will have been converted to analog and back to digital, so it won’t look as good as a really high end camera. The video quality will also depend on how good the digital to analog converters are in the FX1. That’s why that test by Kaku Ito is important to scrutinize. I would do your own tests, too, if you are going to rely on this setup.
The “portable” PC will have to be powerful dual processor machine, and have a serious RAID array, too. Uncompressed HD is a lot of data. Our Blackmagic decklink edit workstation has 8 SATA drives in a RAID 5 array controlled by a Broadcom Raidcore BC4852 card. Be sure to check Blackmagic’s page for system compatibility, too.
If you have a lot of footage to capture, I suggest looking at Cineform’s Prospect HD codec for HD. It is very high quality, much better than HDV. At 65 GB/hour, the captured files are much easier to work with than the 556 GB/hour of uncompressed 10 bit HD. This eliminates the need for an expensive RAID array. Since you will have no tape copy of your footage, you’ll need to archive the captured files when you are done editing, so this will also save you a lot on external firewire drives.
If you want to do some tests for your chroma keying setup, they have a 15 day trial version of Prospect HD. I’m not sure how to get it, you might have to email them to ask for it.
Cineform has some pretty specific requirements for ingest and editing of HD-SDI material, so make sure to follow their specs. We ordered the system they recommended from QSOL to make sure to have everything working.
We haven’t been working with Prospect HD for very long. We have encountered a few bugs, but their tech team has responded quickly to any problem.
Andy
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Andy,
WOW!!! Thanks for the info. This is just what I wanted to
know about 4:2:2 capture. I’m excited that the FX1 can do it.
I’m wondering if the Prospect HD will allow for a fast portable
to capture the HD video. If not, that brings up another idea,
will the FX1 output 4:2:2 SD video out the analog port?Thanks again for all the great info. I’m reading the blackmagic
pages now. 🙂Mark
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Andy,
I would do the test again when I get a healthier Multibridge (bug fixed version) but since we have not received it for ourselves, I am not able to do the test again. One thing that I am sure to test for the next time is that I would more actively pan the camera. HDV camcorders seems to do great not compressing much when it is static. So, I regret that I provided pretty much static clip (turtles move slow you know!).
JVC’s HDV cam does uncompressed 720p analog output. Has anyone tried it?
Kaku Ito
http://www.creativesuite.com
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