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Grading 8 bit video question


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#1 Davyd Melnyk

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Posted 20 April 2013 - 09:20 AM

Hi, I'm new here, first post! I plan to shoot an indie film using a Sony FS100 which is limited to 8 bit color depth, 4:2:0, and about 24 Mbps by the AVCHD codec. This is apparently not very robust for grading, and I do plan to convert the film to b/w in post. I am considering getting an external recorder which would give me 4:2:2 and the potential for much higher bit-rates. My understanding is that the 4:2:2 sampling would help with keying, but staying stuck on 8 bit color depth might cause problems with banding. My question is: in what respects will the higher bit-rate help my latitude in grading, and where might the law of diminishing returns kick in?

Grateful for any insight.

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#2 Robert Houllahan

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Posted 20 April 2013 - 11:09 AM

Using the SDI out to a recorder and recording to ProRes will avoid some of the issues with low bit rate h264 recording but won't help with banding issues that may arise from the 8 bit recording. You could record 10 bit ProRes and then add some grain in post to dither the image which can help conceal banding a bit.

 

-Rob-


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#3 Davyd Melnyk

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Posted 24 April 2013 - 12:24 PM

Thanks!
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#4 Phil Rhodes

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Posted 24 April 2013 - 01:42 PM

I just shot a small project on an FS700 with an Atomos Samurai SDI recorder. The FS100 does not have an SDI output, so you would need to use a recorder capable of recording the HDMI output. I found that the ProRes results look very, very much better than the rather overcompressed recordings made by the camera itself, to the extent that shots which could be saved in the grade from ProRes were unusable otherwise. On the FS700, you can't really use an external recorder to do high-speed stuff, as it comes out interlaced (an unfathomable design decision), so I had several shots where we had both ProRes and AVCHD of the same shot. The difference, especially if you're grading up for exposure, is pronounced.

 

So yes, do that.

 

P


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#5 Robert Houllahan

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Posted 24 April 2013 - 03:18 PM

Did you see the Odyssey 7Q and that it will record 4K 'raw' including highspeed from the FS700? Interesting package at around $10k

 

http://www.convergen...s/Odyssey7.aspx

 

 

-Rob-


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#6 Phil Rhodes

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Posted 24 April 2013 - 03:37 PM

The new FS700 stuff is an interesting option - if you can stand the rolling shutter, it's got a very good little sensor in it, in my view. The thing is that I suspect it'll only really be of interest to existing FS700 owners, on the basis that a complete FS700 + recorder package probably won't be that price competitive with an F5.


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#7 Robert Houllahan

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Posted 24 April 2013 - 05:42 PM

Maybe with the Sony 4K recorder but I think the FS700 plus the 7Q recorder should be around $10-12K which isn't too bad for a highspeed capable camera up to 240fps at '4K' I believe. I hate the rolling shutter personally but I would imagine it's minimized at higher framerates. The FS700 rents for $250-300 / day here in Boston and I would think that the cam and recorder would be around $400/day not too bad.

 

I like the F55 better though...... but not as much as emulsion...


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#8 Paul Bartok

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Posted 25 April 2013 - 06:21 AM

The grain is a good technique to hide banding. As well adds a nice look to B&W in my opinion


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#9 Phil Rhodes

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Posted 25 April 2013 - 07:37 AM

I shot the FS700 at +9dB because the diffusion dithering is quite nice.


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#10 Will Montgomery

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Posted 25 April 2013 - 02:17 PM

The grain is a good technique to hide banding. As well adds a nice look to B&W in my opinion

An old technique to avoid banding in CMYK print work involves adding a little bit of noise to each color channel individually; the result when printed on most digital printers is pleasing and avoids the banding effect. 


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