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What to use ProRes or ProRes HQ
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[Keith Pratt] “I wasn’t aware something could be both RGB and Rec.601 at once but assumed this was some sort of bastardisation of that standard (perhaps just Rec.601 gamut or something).”
yeah,
welcome to the DSLR, one is the camera setting the other is the file playback setting.the canon cameras record the image using a REC 601 color space & gamut
the files are handled and compressed as 15 frame LongGOP at 4:2:0
then recorded in a Full Range (0-254) SMPTE RGB file as H.264
gary adcock
Studio37Post and Production Workflow Consultant
Production and Post Stereographer
Chicago, ILhttps://blogs.creativecow.net/24640
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I’m not specifying any particular uncompressed codec, just that it is turned into “video” in the conversion, just as it would be if it were played out. Perhaps non-compressed is the appropriate word — when you transcode you are starting with a fresh batch of non-compressed video each time.
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This is getting silly. Jeremy Garchow mentioned “4:2:0 RGB source material” and I replied with the question “Is the RGB really subsampled 4:2:0?” Jeremy responded: “How else would it be?” Gary Adcock responded to my same question: “There is no such thing as subsampled RGB”. I hope Jeremy and Gary will reach an agreement.
To say there is no such thing as subsampled RGB is an overstatement. Such a thing, in principle, could be as I described it although it wouldn’t be smart visually. Also every Bayer filtered RGGB sensor involves a kind of RGB subsampling. There are two questions in my original question: What does 4:2:0 RGB mean?; What image formats, if any, use it?
[Dennis Couzin] “Red is a significant contributor to luminance and therefore to visual sharpness.”
Gary disagrees with both parts of that statement.
[Gary Adkins] “Red contributes to the contrast but not the luma in video. Much like the human eye, the contrasty nature of a red light and its rather short wavelength have the effect allowing you to “see” more, but in reality you are seeing is the edge contrast rather and actually luminance.”
This is plain false, both for video and for vision. Just look at the definition of video luma:
Y’ = 0.299 R’ + 0.587 G’ + 0.114 B’
R’, which is gamma corrected red, has a significant weight in the calculation. Likewise red contributes significantly to visual luminance. If red images on your RGB monitor look dark to you I’m sorry you’re prejudiced. Consider why yellow looks look so light on your RGB monitor. This yellow consists of the monitor’s red plus its green. This yellow’s luminance equals the sum of the red’s luminance and the green’s luminance. So if the yellow looks significantly lighter than the green, the red must have significant luminance.
Does the false belief that red doesn’t contribute to video luma come from use of the poor notation Y’CbCr?
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[Dennis Couzin] “This is getting silly.”
Sure is-
Then explain to me how you can subsample RGB.While a video signal in the Y”Cb’Cr’ color space allows for color sampling since the Chroma information is separate from the Luma.
In the RGB color space all channels hold both Chroma and Luma – therefor reducing one of the colors for subsampling also reduces the associated luma for that channel.
Preprocessing of the signal off the imager uses the GRGB “bayer” pattern to increase the dynamic range of sensor. but the image is not being subsampled- actually the Luma is being oversampled to expand the DR of the imager.
[Dennis Couzin] “This is plain false, both for video and for vision. Just look at the definition of video luma:
Y’ = 0.299 R’ + 0.587 G’ + 0.114 B’ “You are talking about the Digital Component (its video in the Y”Cb’Cr’ space not RGB) so that the Luma vs Chroma is allowed to be subsampled since it is.
gary adcock
Studio37Post and Production Workflow Consultant
Production and Post Stereographer
Chicago, ILhttps://blogs.creativecow.net/24640
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[gary adcock] “Sure is- Then explain to me how you can subsample RGB”
Gary, what’s getting silly is that two men pictured side-by-side over the Creative Cow FCP forum gave opposite answers to the simple question: “Is the RGB really subsampled 4:2:0?” and no one notices.
It’s also silly that you can write “Red contributes to the contrast but not the luma in video” on one day and the next day write “In the RGB color space all channels hold both Chroma and Luma.”
You also have a whacky idea of subsampling which only allows chroma to be subsampled. Subsampling as commonly done amounts to the pixels being larger for some channels than for other channels (and the large pixels being comprised of the small pixels). The channels with the larger pixels are said to be subsampled. We agree that it is visually smart to subsample the chroma channels, keeping the luminance channel pixels small. But this doesn’t make other subsampling impossible. If a camera made the red pixels double the size of the green pixels and the blue pixels double the size of the red pixels this wouldn’t be terribly stupid from a visual standpoint, and it would reduce bandwidth (or filesize) by 42%. We don’t have a notation for such R’G’B’ subsampling. Such notations as 4:2:0 were developed for Y’CbCr specifically chroma subsampling. Hence my original questions to Garchow. But more is allowed in this world than you wish to imagine.
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[Dennis Couzin] “Gary, what’s getting silly is that two men pictured side-by-side over the Creative Cow FCP forum gave opposite answers to the simple question: “Is the RGB really subsampled 4:2:0?” and no one notices.”
Hey Dennis, I’m not perfect and I don’t work for Canon so I’m not 100% positive. I am wrong about things all of the time. I am human and not a robot, I am constantly learning in this constantly new, constantly changing business. I am an editor and not a compression engineer. Since this implementation of h264 was designed to go straight to the web, I don’t see why or how it would be a YUV (or whatever) file. Computer monitors usually work in RGB, am I wrong? This is a still camera that shoots RGB pictures, HDMI can send an RGB signal (as well as YUV), the 1080p files from Canon cameras are tiny, add all of those up, and I don’t see how these .movs can be anything else but a subsampled and highly compressed RGB Long GOP h264 file. The camera may capture and subsample in YUV, but converts to RGB upon compression. As far as the file being 601, that is something that I have no idea about and that Gary must have learned on his travels. Again, it’s a bit baffling and maybe an error on Canon’s part, but what the hell do I know? Only what I know.
Gary and I know each other. We chat offline and run in to each other, we live in the same city, and actually the same neighborhood. But this does not mean we both know the same things. Gary has been around longer than I and has studied video at a level that I never have. As far as no one noticing, I guess they don’t care as much, and I don’t mean that in a bad way. They are probably editing, and not thinking about this stuff. Good on them. It is not my intention to mislead, as a matter of fact it is the opposite. All of my time here is donated. Free. Gratis. For someone who makes money from being on the clock, this is something I take seriously. If I make a mistake, I admit it, learn, and move on. Sorry if I have somehow mislead you and sorry for making any mistakes. It’s not intentional.
The Canon HDSLRs, in my opinion, are going to change the way professional camera manufactures make and design cameras if they haven’t already, but there is one thing that’s certain, they aren’t video cameras. They just aren’t, and Canon will tell you that. The images coming off of these cameras have great dynamic range, and the depth of field can be an amazing dramatic look which is attractive to the eye, but the truth of the matter is, anyone who has color corrected video before will see exactly where these images are thin and noisy. Then there’s the rolling shutter, no tc, double system audio, frightful ergonomics and no real time monitoring while recording. No matter what the compression scheme, those are real life problems that are faced on a shoot. In my opinion, ProRes is totally fine for the footage as you aren’t going to cover all that up with a new shiny codec with a higher data rate.
Jeremy
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Like all these techno nerd debates over numbers, the forgotten element is what does it look like. I recently bought a 5Dmk2 (and it wasn’t just to annoy Dave LaRonde). It was because I had a need for a camera that gave me pictures at a price point that is staggering. I bought it because I got sick of waiting for the RED Scarlet and I had a project to get on with. With help from companies like Zacuto, I am able to make the 5D act and behave a bit like a video camera. I am shooting mostly tripod, exterior in a cool climate so hand held ergonomics, overheating, maximum 12 minute shots and clunky exposure adjustment don’t matter.
I convert the h264 to ProRes422, not HQ because on my monitor and in my experience it doesn’t improve the picture to go HQ. I grade docos all the time with Color so I am used to seeing HDV, XDCam, DVCProHD, HDCam and a bit of RED go through the important post stages. Everything ends up being rendered as ProRes422 in Color because my typical experience is to deliver to broadcasters.
Where does the Canon sit for me? Above HDV and XDCam, comparable to HDCam and below RED. But most importantly is the actual photography, the lenses and the end result graded on screen. With a lot of mpeg based long gop codecs being commonly used, I will continue to use ProRes422 and not care about the sub sampling characteristics, because it is more important to frame, light and shoot with good lenses.
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Dennis,
what is your issue here on the Cow?
you have now charged into multiple forums and start attacking the moderators directly, all the while offering convoluted technical jargon that is often incorrectly identified and on multiple times grievously incorrect.You seem to know only what you have read on the internet and it seems that you would rather argue about data rates and encoding issues rather than as it was eloquently stated [Michael Gissing] “Like all these techno nerd debates over numbers, the forgotten element is what does it look like. “
Do you actually work with any of the technologies you are pontificating about? Your own admissions here state that you have “seen a Red camera’ but not actually worked with one. You challenged me to the point of calling me a liar about my testing of a consumer camera that claims to do 60p, but that argument stopped when you had to admit that you had no reference of knowledge of how 60p really works to judge against.
The Cow is meant to be a place of shared knowledge and giving, not a battle ground, where someone like you with what appears to be limited amount of technical knowledge, but seemingly no practical experience with the actual tools we are discussing can gain from the experience of others.
gary adcock
Studio37Post and Production Workflow Consultant
Production and Post Stereographer
Chicago, ILhttps://blogs.creativecow.net/24640
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Dennis Couzin: your account is about ready to be closed if you don’t lighten up — and that includes writing me privately. (If you do, I’ll likely just nuke your account and be done with it.)
I have now thrown your account back onto moderation.
Ron Lindeboom
CEO, Creative COW LLC
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