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Video Levels for Canon EOS 7D

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Rui Coutinho
Video Levels for Canon EOS 7D
on Dec 8, 2010 at 7:10:51 pm

Hi !!
I have to edit some footage generated by Canon EOS 7D on Avid Media Composer 5.

What video levels should I choose,
REC 709 ?? or RGB levels ??

Thanks!!


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Noah Kadner
Re: Video Levels for Canon EOS 7D
on Dec 8, 2010 at 7:44:36 pm

Depends on the destination- if it's for web use RGB, if it's intended for broadcast use REC709. Also ask this on the AVID forum.

Noah

Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Canon 5D Mark II and 7D.


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Rui Coutinho
Re: Video Levels for Canon EOS 7D
on Dec 8, 2010 at 9:27:38 pm

Thanks!!

But I still want to know what video levels Canon EOS D7 generates ?

Rui


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Noah Kadner
Re: Video Levels for Canon EOS 7D
on Dec 8, 2010 at 9:59:49 pm

Don't know the precise answer to that- doubt it's exactly either but this might help:

http://www.cinema5d.com/viewtopic.php?f=64&t=13198

Noah

Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Canon 5D Mark II and 7D.


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Chris Wright
Re: Video Levels for Canon EOS 7D
on Dec 9, 2010 at 12:36:24 am

if its going to web, sRGB-EC 61966-2-1:1999 should be used/converted to so that the browser displays correctly. and wow, yea, DO NOT shoot in sRGB mode unless you're positive you're going to web.

sRGB is like 1/4x gamut of Adobe RGB. sRGB is default because beginners just plop it in i-movie or windows movie maker so that the sRGB somewhat matches your monitor. it's sad when people actually have FCP or CS5 and mess that up.

http://technicolorsoftware.hostzi.com/


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Peter Burger
Re: Video Levels for Canon EOS 7D
on Dec 9, 2010 at 12:48:17 pm

Chris,

Can you really shoot footage in Adobe RGB with a Canon VDSLR? Or are you referring to working with sRGB/Adobe RGB in an NLE or compositing program?


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Chris Wright
Re: Video Levels for Canon EOS 7D
on Dec 9, 2010 at 8:49:47 pm

first off, RAW images get post assigned(they can't have a profile, only jpeg's do). That's why the RED camera is so great. You can post-assign a color profile. .709. or red's proprietary etc.

the recommended profile is adobe 1998, but for video, the Y'Cb'Cr thing people get confused about is not a color management. It's a math relationship to derive the greens. For instance, you can have Y'Cb'Cr from a miniDV tape but its color profile is BTU.601(SDTV)

whenever you shoot video, always shoot flat. This means the widest gamut, lowest contrast, 0 sharpness, etc. Plus the fact that sRGB is the smallest gamut(it was made for web)

The color space is indeed changed in video mode as well although this option is not available when you access the menu in movie mode.

and if you are indeed editing in sRGB, well, let's just hope you are going only to vimeo, youtube, or cellphones.

http://technicolorsoftware.hostzi.com/


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Peter Burger
Re: Video Levels for Canon EOS 7D
on Dec 10, 2010 at 10:14:48 am

Thanks Chris for that explanation!
Much appreciated!


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Keith Pratt
Re: Video Levels for Canon EOS 7D
on Dec 11, 2010 at 6:14:29 pm

Chris Wright: "if its going to web, sRGB-EC 61966-2-1:1999 should be used/converted to so that the browser displays correctly. and wow, yea, DO NOT shoot in sRGB mode unless you're positive you're going to web."

Noah Kadner: "Depends on the destination- if it's for web use RGB, if it's intended for broadcast use REC709."

Gary Adcock and the makers of 5DtoRGB are saying the Canon video is full range Rec.601.

I'm also sceptical it's best to use full range or a photo colour profile for web-destined video. Aren't most video players expecting YCbCr?


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Chris Wright
Re: Video Levels for Canon EOS 7D
on Dec 12, 2010 at 8:25:57 am

first off Rec.601 is standard def. not only would an encode 16-235 delete data, which a prores encoding unfortunately does(which a lot of people do and completely destroy their video because canon uses a special full 0-255 h.264), but the actual color management comes from the camera's menu before you go into movie mode. You can do a simple test yourself by switching from sRGB to adobe in photo mode, then go into movie mode to compare 2 video clips of the same object.

all web browsers use sRGB for video/images and again,Y′CbCr is not an absolute color space, it is a way of encoding RGB information. The actual color displayed depends on the actual RGB colorants used to display the signal. Therefore a value expressed as Y′CbCr is only predictable if standard RGB colorants or an ICC profile are used.

http://technicolorsoftware.hostzi.com/


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Thomas Worth
Re: Video Levels for Canon EOS 7D
on Dec 12, 2010 at 12:15:59 pm

Rec.601 is indeed SD, that is if you are following the rules. Canon aren't. This doesn't really matter since in order to do anything useful with the video you need to transcode it. You'll get what's expected (Rec.709, 16-235) after transcoding because the transcoder reads the 601 flag in the MOV and (hopefully) does a cross-conversion from one matrix to another.

>which a lot of people do and completely destroy their video because canon uses a special full 0-255 h.264

Not if you use 5DtoRGB!


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Chris Wright
Re: Video Levels for Canon EOS 7D
on Dec 12, 2010 at 6:05:44 pm

.601 clips tons of data. If you shoot with beautiful colors and then capture with 5DtoRGB, you are clipping with standard def colors. I prefer adobe 1998(from canon's menu) so my skies don't get deleted, but that's just me.

Where did you get your info that canon uses .601?

http://technicolorsoftware.hostzi.com/


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Thomas Worth
Re: Video Levels for Canon EOS 7D
on Dec 13, 2010 at 1:12:38 am

5DtoRGB doesn't clip anything. It decodes every single value, and at full range per the Canon space. ProRes and DNxHD compression does not clip, but most likely "scales" full range values to broadcast range. DPX output doesn't do any of this, of course.

Canon is using the 601 space, and the way this was determined is as follows:

1. QuickTime clips recorded by the camera are flagged with a "colr" atom of type nclc. This atom tells a program how to deal with the video's color space. The atom in Canon files specifies a 601 color matrix, so even if this was wrong the opening application would decode 601 anyway. The three values in colr are:

Type: nclc
Primaries: 1 (these are actually 709)
Transfer Function: 1 (again, 709)
Matrix: 6 (601 matrix)

Why the primaries and transfer function are 709, but the matrix is 601, is up to Canon to answer. Fortunately this is all accounted for in the QuickTime file, so apps decode it properly.

2. I have tested (and you can too) decoding Canon video with Rec.709, and the colors are most certainly off. Reds tend to look more like orange. If you decode with the 601 matrix, the colors look correct.


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Keith Pratt
Re: Video Levels for Canon EOS 7D
on Dec 13, 2010 at 12:58:43 am

Chris Wright: "all web browsers use sRGB for video/images"

Safari, the latest Firefox, Chrome and IE9 all have varying levels of built-in colour management; others none at all. But that's for images, not video. With video it's the player plug-in or module that manages colour, isn't it? And in that case its expectation would be Rec.601 or Rec.709, surely? Meaning you'd be least likely to run into issues with one of the two.

Chris Wright: "and again,Y′CbCr is not an absolute color space, it is a way of encoding RGB information."

Who claimed it was?


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Chris Wright
Re: Video Levels for Canon EOS 7D
on Dec 13, 2010 at 8:21:41 pm

Thanks guys, I was stubborn so I checked it out myself. The crazy canon engineers actually compress the high def signal into SD color(601 matrix) I am going to request a feature change for the next camera model.

http://technicolorsoftware.hostzi.com/


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Thomas Worth
Re: Video Levels for Canon EOS 7D
on Dec 13, 2010 at 11:41:33 pm

I'm just speculating here, but perhaps the reason this was done due to image processor limitations. As you probably know, JPEG is 4:2:2 with a 601 color matrix per the JPEG/JFIF spec. We already know the camera writes JPEG files, so it may just apply the same matrix function to video. If so, this would explain the use of the 601 matrix when it's obviously wrong.


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Guillaue Chadaillac
Re: Video Levels for Canon EOS 7D
on Mar 29, 2011 at 11:10:51 am

Hi guys!
Obviously this thread is a bit old but i m glad i found it!
Finally some people seem to share the same problem that I have! :-)

I am shooting with a 7d. Encoding in prores LT for editing and color correcting in final cut. I am using a matrox box to do my color correction on a Sony Bravia 47'.

So far so good.

Everything will go on the web, On my personal website which uses jw player in flash and html5.

But I encounter 2 problems:

1) Encoding from prores to h264 using, squeeze, mpegstreamclip, quicktime, yields average results. Colors are not accurate and look washed out. This is not new. The web is plagued with h264 encoding problems but maybe this has to do with a color space problem as well? What do you think? Is there an easy/cunning fix?

2)When videos are online. They obviously look VERY different on all the popular browsers. Firefox and Safari are ok... but chrome ... oh my! Mostly supers washed out and merely... off. I made a lot of research with regards to color managed browsers and ICC files... but this seem to only apply to photos ... not videos...
Is that right? What can we do during the h264 encoding process that will ensure consistency across browsers?

Thanks a lot guys!!!!


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