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Uncompressed and pixel resolution.
Right, I know this is probably a stupid question, but I wanted to confirm what I think:
Full HD is just the pixel resolution of 1920 by 1080.
Uncompressed is to do with subsampling? (ie, anything which is less than 444 is NOT uncompressed HD)- so in theory “Uncompressed HD comes in lots of varieties of codecs etc?
How is it normally wrapped?
What bitrate does it need to be to be classed as uncompressed?Cheers!
😀
Tom Morter-Laing
Freelance Editor
Certified Apple Product Proffessional, 2010
http://www.depictproductions.co.ukSony Z5, with Rode NTG2.
iMac 27″ intel i7 2.93GHz, 12GB RAM, ATI HD5750 [1GB GDDR5], 2TB Int. SATA with 2TB External HDD; (FW800), with Elgato Turbo H264HD. -
14 Replies
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4:2:2 is uncompressed.
apple 10-bit & 8-bit uncompressed work this way.
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Forgive me then, but I dont understand. If there is subsampling, isnt that still being compressed? What is uncompressed about something which has chroma subsampling applied and is only 8 bit? I know 8 bit uncompressed HD exists, but I dont understand why its called uncompressed. Thats like saying a Z5 to a nanoflash can record Uncompressed HD?
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Tom Morter-Laing
Freelance Editor
Certified Apple Product Proffessional, 2010
http://www.depictproductions.co.ukSony Z5, with Rode NTG2.
iMac 27″ intel i7 2.93GHz, 12GB RAM, ATI HD5750 [1GB GDDR5], 2TB Int. SATA with 2TB External HDD; (FW800), with Elgato Turbo H264HD. -
[Thomas Morter-Laing] ” I know 8 bit uncompressed HD exists, but I dont understand why its called uncompressed.”
I don’t mean this to sound rude, but uncompressed really does simply mean “not compressed.” If I capture something uncompressed, that means that I’m not adding any compression during capture and there’s no compression in the file stored on disk.
Just because one step in a workflow operates in uncompressed doesn’t mean the entire workflow is uncompressed, and I think this is what you’re questioning.
For example, HDCAM is compressed when laid down to tape and decompressed on playback. If I ingest HDCAM via analog component or HD-SDI with an “Uncompressed” codec, it’s called uncompressed video because the file on disk is not compressed.
Uncompressed capture is a bit like the video version of one of the principles of the Hippocratic Oath: first, do no harm.
It’s worth noting that there are two kinds of compression: lossless compression (which results in lower bandwidth/storage requirements, but can be decompressed to a mathematically perfect copy of the original), and lossy compression (in which data is permanently removed to reduce bandwidth/storage requirements).
[Thomas Morter-Laing] “Forgive me then, but I dont understand. If there is subsampling, isnt that still being compressed?”
I suppose you could consider chroma subsampling is a form of lossy compression, since you’re throwing away visual information to reduce the amount of bandwidth necessary for the video signal, but subsampling is engineered into most video standards. SDI and HD-SDI carry 4:2:2 signals. You have to jump to 3 Gbps or dual-link SDI to allow other color encodings, including 4:4:4 YCbCr or RGB.
As I said above, the term “uncompressed” usually applies to individual steps in a workflow, not necessarily the entire workflow from start to finish.
[Thomas Morter-Laing] “Thats like saying a Z5 to a nanoflash can record Uncompressed HD?”
No, it’s not. A NanoFlash stores XDCAM-compressed files, so it’s not uncompressed by definition.
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
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[Thomas Morter-Laing] “I know this is probably a stupid question”
There are no stupid questions…
[Thomas Morter-Laing] “Full HD is”
Means absolutely nothing, and no true professional would ever use the term. It’s completely amateurish. You’re either using SD or HD, period. You never hear anyone saying full SD do you? There are uncompressed HD codecs and compressed HD codecs, but all are nonetheless HD.
[Thomas Morter-Laing] “Uncompressed is to do with subsampling? (ie, anything which is less than 444 is NOT uncompressed HD)- so in theory “Uncompressed HD comes in lots of varieties of codecs etc?”
The term Uncompressed (i.e. “not compressed”) is actually a bit of a misnomer, because it implies that nothing is lost or discarded, when in fact the uncompressed model accounts for numerous color models and bit depths, which except for 4:4:4 toss out varying degrees of information.
[Thomas Morter-Laing] “What bitrate does it need to be to be classed as uncompressed?”
The following variables are used to mathematically calculate the answer:
1) pixel dimension
2) framerate
3) color model
4) color depthSee the bitrate calculator below to get an idea of how the variables above affect the uncompressed bitrate.
[Thomas Morter-Laing] “How is it normally wrapped?”
It can be wrapped any way you want or need it. There are uncompressed AVIs, QTs, etc.
David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
https://www.drwfilms.comPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.
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Everyone refers to 4:2:2 as uncompressed, but is it really?
If you only sample chroma at half the luminance resolution, which is what 4:2:2 is, then that is a form of compression. Just one that discards information that is not perceptible to the human eye, and takes place in a different place than traditional compression. But in a technical sense, half of the available chroma information is simply not recorded
So if you scan a frame using 4:4:4 color space, and then rescan it at 4:2:2, is there not a reduction of the files size? How do you account for that if there isn’t compression?
4:2:2 is called chroma sub-sampling, does that not imply some form of compression?
It seems to me that 4:4:4 color space is the only true uncompressed sample rate.Scott Sheriff
Director
https://www.sstdigitalmedia.comI have a system, it has stuff in it, and stuff hooked to it. I have a camera, it can record stuff. I read the manuals, and know how to use this stuff and lots of other stuff too.
You should be suitably impressed… -
[Scott Sheriff] “It seems to me that 4:4:4 color space is the only true uncompressed sample rate.”
Precisely why I said that uncompressed video is kind of a misnomer.
4:4:4 RGB is in fact the only truly uncompressed video.
David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
https://www.drwfilms.comPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.
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David,
“Precisely why I said that uncompressed video is kind of a misnomer.4:4:4 RGB is in fact the only truly uncompressed video.”
Absolutely. 4:2:2 is really, really, really, good compression that for the most part might as well be uncompressed. But it still is discarding data in the process and would eventually show degradation if you transcoded it enough.
This is a lot like the ‘is Pluto a planet’ argument but…
Let me throw some gasoline (petrol) on the fire by saying that 4:4:4 RGB is compressed if you shoot it at 23.98 instead of 29.97.
24fps in the analog (film) or digital world is a form of compression (compared to 30fps) that seems to not only be ignored, but often touted as being better quality.Scott Sheriff
Director
https://www.sstdigitalmedia.comI have a system, it has stuff in it, and stuff hooked to it. I have a camera, it can record stuff. I read the manuals, and know how to use this stuff and lots of other stuff too.
You should be suitably impressed… -
[Dave LaRonde] “So then — in the NTSC video world at least — the only true uncompressed video would then be 59.94 fps, 1920×1080, 4-4-4 RGB… at the current maximum, ten bits per channel.”
And, few (if any) cameras can record it anyway.
David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
https://www.drwfilms.comPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.
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FULL SD was actually called full CCIR if I remember right. And Avid drove it home when they were comparing their AVR77 720×486 systems to Media100s 640×480 systems. And in the end, Media100 looked immensely better because they had a better codec. Too bad their tools were so primitive.
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Hmmm so actually my question may not have been so dumb because it has opened a can of worms in a virtual community which are normally very concise and definitive: have we ascertained anything specific and certain then?
😀
Tom Morter-Laing
Freelance Editor
Certified Apple Product Proffessional, 2010
http://www.depictproductions.co.ukSony Z5, with Rode NTG2.
iMac 27″ intel i7 2.93GHz, 12GB RAM, ATI HD5750 [1GB GDDR5], 2TB Int. SATA with 2TB External HDD; (FW800), with Elgato Turbo H264HD.
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