Bluescreen composite from Sony FX1 footage at DVinfo.net

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Sony HVR-Z1 / HDR-FX1
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Old April 26th, 2005, 12:28 PM   #1
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Bluescreen composite from Sony FX1 footage

Tried and FAILED to pull a decent blue screen from FX1's footage!

Problem: too much digital noise in the captured m2t file - it propagates itself as blockiness to the keying software, making it impossible to pull a good key.

Workflow: FX1 in Cineframe 30 mode (makes deinterlaced 1080i output in-cam = 30p). Captured into m2t via CapDVHS utility. Noise is NOT really visible by the naked eye, but as soon as you start processing the image, it pops out.

Processing was done in AVI after transcoding using HDLink Medium, Large, and DVD2AVI Uncompressed RGB. All 3 results are the same: unacceptable matte no matter the keyer settings. Edges of straight objects dance; and the supposedly keyed out matte also shows dancing particles on animated preview.

Keyer is Ultimatte AdvantEdge - evidently the best there is, in AE 6.0. Tried other keyers that came with AE, plus Keylight - results are worse than AdvantEdge.

To check my theory about the noisy m2t video, I captured exactly the same bluescreen footage with the same cam, but in DV. AdvantEdge then pulls a good matte out of it. Granted, I get smaller image size due to the lower resolution at the acquisition stage.

So my conclusion - unless I'm missing something? - is that HDV is simply unuseable for the bluescreen work.

I had had the same problem with JVC's HD10 cam a year ago. Side-to-side visual test showed that Sony FX1's image is cleaner and less noisy by leaps and bounds, so I had high hopes FX1 would be OK for the bluescreen.

Anyone has a successful workflow? Or is it a dead end?

(I'm afraid it's the latter, unless I use a much higher-sampled acquisition process...)
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Old April 26th, 2005, 12:56 PM   #2
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Alex,

Check out this thread:

http://www.dvinfo.net/conf/showthread.php?t=42828
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Old April 26th, 2005, 01:07 PM   #3
 
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I wouldn't be messing with blue, but I've pulled several successful keys from green using the Z1 as my cam. I've used Serious Magic's Ultra, Sony Vegas, and AE to pull keys with, no issues for me. I also don't work on m2t files, I convert them to an intermediary first, or better still, a 4:2:2 YUV file.
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Old April 26th, 2005, 01:23 PM   #4
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I used Blue and Green with Z1. No problems at all.

Of course the first thing to do is, making uncompressed media like TARGAs or something like that.
Working with that in Aftereffects and supplied keylight keyer is excellent to me and my customers :)

By the way ... Douglas. I am not quite sure how do I get a 4:2:2 YUV ?
Or is it what I am doing when converting the cineform-Codec AVI into TARGAs ?

Thanks!

Peter
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Old April 26th, 2005, 01:56 PM   #5
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Bryan, thanks. After re-reading the thread, I realized that the main difference is the amount of lighting. I had FX1 fully open at F2 in my failed experiments.

So I jacked the lights up on both bluescreen and on the model. Voila! - now with F5.2, HDV footage looks very good after keying, even better than DV!

I used Cineforms's Aspect HD at Large Size setting as avi file AE/AdvantEdge worked with.

I guess, next step is to use another codec for compositing, instead of the lossy AHD.

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Originally Posted by Douglas Spotted Eagle
I also don't work on m2t files, I convert them to an intermediary first, or better still, a 4:2:2 YUV file.
DSE, how?
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Old April 26th, 2005, 02:55 PM   #6
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Hey Alex,
You should make sure to shoot in 60i not cineframe 30. By shooting in CF30 your losing half of your vertical resolution which will seriously effect your key.

My 2 c,
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Old April 26th, 2005, 03:22 PM   #7
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Eric, this may be exactly right.

CF30 looks great in regular viewing, because the resolution loss occurs only in the moving areas and is not perceived by eyes of the viewer.

However it probably does affect the way the keyers work.

So I guess a better workflow for me will be:

1. Shoot models in 60i
2. Capture in CapDVHS as mpg (required by the next step)
3. Convert mpg to Uncompressed RGB-24bit AVI by DVD2AVI utility (is there a better/alternative way?)
4. Import that uncompressed AVI into the AE, process with the keyer with Interleaved settings (AdvantEdge allows i/p switch).
5. Deinterlace the composited video (what is the best way?) and export as Cineform's Aspect HD to be included as part of the Premiere Pro timeline.

Right?

--------------------

Question to David Newman:

I did the AE processing as above in the AE project created with AHD template, thinking that it will ensure correct Export features.

However, the final exported AHD video is stretched horizontally by 24%, although it did look fine in AE.

What should I do to prevent this problem? Thanks!
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Old April 26th, 2005, 06:08 PM   #8
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Sounds pretty good...

I'm sure there's a better utility than DVD2AVI to convert the files though, and I would expect that AdvantEdge would deinterlace after the composite (which would be fine), although you'll probably find, not being a specialised filter, there are better ways to do it.

As for deinterlacing seperately, theres a very in-depth discussion here: http://www.dvinfo.net/conf/showthread.php?t=38539

That stuff gets quite complex, so if you want a decent one-step solution you could do worse than Magic Bullet imho, which also gives you some great "film look" filters and some fairly pointless ratio masks (why did they put those in there?!).

I would personally advise shooting everything in 60i and deinterlacing later as this allows more time for advanced deinterlacing which can preserve 100% of the vertical resolution on a still image and will have the effect you mention of only losing resolution on moving images, which is harder to perceive (the method CF30 uses does not do this - it simply strips one field away halving all of the vertical resolution regardless of movement, I believe).
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Old April 27th, 2005, 01:27 PM   #9
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OK, here's the conclusions if anyone is interested in bluescreen jobs with Sony FX1 footage.

- Interlaced vs Pogressive: same results, so I'm staying with Cineframe 30 = progressive acquisition

- Capture using CapDVHS, "Outup PS" checkbox marked, for Program Stream mpg capture.

- Import that file into AE 6.0. That's right, you can import HDV mpg video WITHOUT the need for any conversion, thus preserving maximum quality.

- Use Keylight or AdvantEdge plug-ins for your matte work.

- Voila! - all done.

The only trick is to light the bluescreen background as bright as possible (evenly of course); and to drop the original mpg footage into AE so to cut all intermediate steps, conversions, and time waste.

From AE, export as Cineform AHD and use in your PPro editing timeline.

Enjoy! :)
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Old April 27th, 2005, 03:24 PM   #10
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Quote:
- Interlaced vs Pogressive: same results, so I'm staying with Cineframe 30 = progressive acquisition
Phew. While the talk about resolution loss above is true, it makes no sense to me that a lower resolution has anything to do with keying performance, other than picking out very fine edges that would likely be lost in an adaptive deinterlace anyway.

Quote:
- Capture using CapDVHS, "Outup PS" checkbox marked, for Program Stream mpg capture.
This wouldn't really change anything other than a file header... would it?

Quote:
- Import that file into AE 6.0. That's right, you can import HDV mpg video WITHOUT the need for any conversion, thus preserving maximum quality.
- Use Keylight or AdvantEdge plug-ins for your matte work.
My experience with FX work was that my AE performance was poor with the native HDV from a computational perspective, and it was faster to render to uncompressed for my FX work, so that AE didn't have to decode the GOP.

-Steve
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