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Old April 24th, 2005, 01:59 PM   #1
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DVCPro HD good for Aquisistion, But not Post?

The DVCPRO HD codec compresses data using a variant of DCT , also known by many as ( discrete cosine transform) algorithm. While fine for the acquisition stage, it's not in the more complex post production environment.

What choices do we have to get the footage away from DVCproHD once it's acquired? This will be questions many will ask. This is going to be an important element when building your HD workflow for your studio and those of us that are doing more visually complex post production work.

For those that want to go to large screen projection. DCT artifacts start to look bad quite quickly. Worse looking on digital projection systems. Since the industry is going to bank roll the HD projector technology for up to 3,000 projectors in the USA, this is something to consider for those artists that are also concerned about the highest standard of quality possible from their hard work on a large screen system....


PS: Here is a short article I wrote on the JVC GY-HD100u and AG-HVX-200

http://www.pbase.com/aghvx200/pappasarts_entertainment_


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Old April 24th, 2005, 03:26 PM   #2
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Your point?

I'm not sure I understand the point of your post Michael. Are you saying that we will not be able to create high quality HD video in post when using the HVX200 in DVCProHD mode?
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Old April 24th, 2005, 04:32 PM   #3
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Quote:
Originally Posted by Pete Wilie
I'm not sure I understand the point of your post Michael. Are you saying that we will not be able to create high quality HD video in post when using the HVX200 in DVCProHD mode?
I'm not sure I understand either. MPEG is also a DCT-based compression algorithm. Every HD recording system employs some form of DCT, that I know of.

I mean, if you want to go fully uncompressed, you can. Just plug in an analog-to-HD-SDI converter board, a powerful desktop computer with something like a BlackMagic card in it, and a multi-disk RAID array that can handle 166 megabytes per second, and you can capture uncompressed HD from any of these cameras (Z1, HD100, or HVX200). Then you'll have no compression artifacts at all, depending on how your HD card stores the video. Of course, editing challenges will be extremely higher on uncompressed HD footage at 20 to 70x the storage space, but if you want to avoid compression artifacts, you can.

But that's completely impractical for almost all shooting circumstances and editing circumstances. DVCPRO-HD is an excellent editing codec as well as acquisition. In most circumstances you'll be encountering at most one generation of recompression.
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Old April 24th, 2005, 05:40 PM   #4
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I was talking about those that are doing high level HD Post work like blue screen work, model photography, roto etc etc. Where your working on material that is blown up on your computer screen 700% in post. I should have stated that. I'm sorry guy's

One area though is big screen work, that should be in an uncompressed environment. If your doing edits and simple one time pass dissolves, not a problem with most DVCproHD work, but with DCT, the more you re-compress the worse it gets very fast. I've worked with and it gets ugly quick, if not handled right with multi pass work. But then you don't do multi pass work in DVCPRO HD. People around me use Kona/Black magic solutions for their work. I know some people that use CineForm too!

Here is a Cineform test I find very interesting in regards to DVCproHD.I should say I don't use Cineform since I use FCP, but their tests were cool.

Be sure to click on the original size blowups of the frame.

Link to test:
http://www.cineform.com/technology/H...lysis10bit.htm


Quote:
Originally Posted by Pete Wilie
I'm not sure I understand the point of your post Michael. Are you saying that we will not be able to create high quality HD video in post when using the HVX200 in DVCProHD mode?
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Old April 24th, 2005, 07:08 PM   #5
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But -- Michael, what's the alternative? Every codec out there uses DCT. MPEG, DV, DVCPRO-HD, JPEG, Digital Betacam, they're all DCT-based, unless you want to get into wavelet.

You could always capture uncompressed if you want. You could transcode from DVCPRO-HD into uncompressed in your editor if you want. But how in the world does this become a DVCPRO-HD issue? It's even more applicable to something like MPEG, so why isn't this message over in the HDV forums, saying "HDV not good for aquisition, but even worse for post" or something like that? At least DVCPRO-HD has a relatively mild compression ratio and will hold up far better to recompression than HDV will.
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Old April 24th, 2005, 08:53 PM   #6
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"At least DVCPRO-HD has a relatively mild compression ratio and will hold up far better to recompression than HDV will."

While I completely agree that it will hold up INFINITELY better than HDV throughout the post process, it's a bit generous to call it 'relatively mild' compression. DVCProHD is more highly compressed than DV, which already has too many compression artifacts for my taste. Don't get me wrong, I shoot DV all the time, and the Varicam is my choice on every HD project I've done.... but it is pretty high compression (nothing on the scale of HDV or course, which is ridiculous for aquisition).

While it is fine for a regular post workflow, I can see Michael's point if you are involved with a lot of compositing or green screen work, etc. In those cases, for those select shots, you would be better off capturing upcompressed from the component outputs.

Of course, all of this is a rather moot point, I think. If someone is working at the high-end scale that you seem to be suggesting Michael, I doubt they'll be shooting with a $6000 fixed lens camera.
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Old April 24th, 2005, 09:53 PM   #7
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Quote:
Originally Posted by Michael Pappas
I was talking about those that are doing high level HD Post work like blue screen work, model photography, roto etc etc. Where your working on material that is blown up on your computer screen 700% in post. I should have stated that. I'm sorry guy's
FWIW, I will be compositing or integrating nearly the video I shoot with 3D animation -- as I do now with my DVX100. Working with DV does give me some issues with defining edges and keying stuff like translucent objects or hair and finely detailed things. One of the biggest headaches are the pixelated red edges. With DVCProHD and its superior color space and increased resolution, a lot of these issues should vanish or at least decrease by a very large amount.

As for which codec I will work in, I don't see where DVCProHD is any worse off than any other (and probably better than many) as others have pointed out. For most editing of the video I will probably work within the DVCProHD. For compositing or more serious post work that integrates into my animation workflow, I will do what I do now and that is move into an uncompressed format for the times I need it. With video from the HVX200, I will already be a couple steps ahead of where I start with DVX100 video as there's less uprezing to do and better color fidelity. Uncompressed isn't that big of deal other than hogging up disk space. It does take some more CPU and hard drive horsepower and makes it difficult to cope with multiple streams (which gets into a whole different discussion), but it's really the only option if you want to guarantee that nothing more is lost in the post process until you do a final encoding to your intended delivery format.
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Old April 25th, 2005, 01:11 PM   #8
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I've been talking to freelance shooters for networks and they are in a tizzy as well as us, so don't feel bad *L* They know the old betacam is out and they are wondering whether to go dvcpro50 (and use the sdx900 for people that want the film look) or buy into Sony's xdcam route...


I like dvcpro50 because fcp can handle it with just a normal machine setup...

I'd like to buy that 2/3 16.x9 dvcpro50 Ikegami but it's 20 grand....the new hvx will bring dvcpro50 down the six k level, but with 1/3 chips and a not-so-hot lens...

I don't think I can go hdv. Perhaps the JVC will change my mind.
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Old May 2nd, 2005, 12:56 AM   #9
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Cross-Posting

Michael Pappas,

I've noticed that you are cross-posting many of your threads on many of the other forums on the 'net. You use exactly the same text.

What is the purpose of this?
Are you engaged in some sort of media campaign?
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Old May 2nd, 2005, 05:21 PM   #10
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Quote:
Originally Posted by Pete Wilie
Michael Pappas,

I've noticed that you are cross-posting many of your threads on many of the other forums on the 'net. You use exactly the same text.

What is the purpose of this?
Are you engaged in some sort of media campaign?
PLEASE!! Do not start that crap again! This was a big nasty discussion on one of those other forums you mentioned. Some arrogant jack-A figured he owned the world of video and made a big stink of this and was quickly shot down by his peers. I think it is completely acceptable to post whatever you want, wherever you want on as many different boards as you want (as long as it's not cross-posting in the same boards). I do not read any other boards anymore. I like these (DVInfo.net) forums because they are professional, respectable and have some kind and generous visitors. I feel lucky that people like Michael would take the time to come here and post information that could be useful to others so I don't have to look elsewhere. It's not lazy, I just don't like the visitors at some of the other forums (like the aforementioned jack-a).

my $.02

added: Sorry Pete, the comment wasn't specifically directed negatively towards you, this exact topic came up HERE in the last weeks or so and I was really hoping this attitude wasn't spreading over here. (it's the reason this is the only forum left that I visit, I can't stand the "immaturity" running around out there.)

Last edited by Chris Hurd; February 4th, 2008 at 07:25 AM. Reason: added comment.
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Old May 2nd, 2005, 05:49 PM   #11
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Rhett,

Please, chill out dude. :-) No need to get so upset.

I don't know what you are referring to when you say "Do not start that crap again!" I haven't started any "crap" here or anywhere else. I simply noticed a lot of duplication and was curious as to the intent. I did notice a number of DVInfo.net members posting in the these threads on the other sites.

It's not that big of a deal to me -- consider the subject dropped as far as I'm concerned.

Best Regards,
Pete
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Old May 2nd, 2005, 05:56 PM   #12
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No worries there Pete,

For *everybody* though, please allow me to echo Rhett's request; this site does not exist for the purpose of discussing what happens on other message boards. As far as one person posting the same message across multiple sites, that's their own business. From a moderator or administrator's point of view, it can be an annoyance, especially when the original poster forgets who said what in which forum. However, it's certainly within any individual's right to say the same thing across multiple sites in order to get responses and differing points of view from as many sources as possible (and Michael is not the only guilty party, by the way... there are at least one or two other folks who do this regularly, but it's no big deal).

All I ask of our members (actually it's a rule now) is to please do not cross-post multiple forums within *this* community. That is a serious problem, especially for those people who come in later searching for that particular topic and find themselves unable to follow a copmplicated series of cross-posted discussions. Instead of cross-posting within DV Info Net, just make one post where you think it best fits, and if that's not the right location then we'll be happy to move it for you, leaving a re-directing link behind in its place.

Again, please knock off the gossip about other sites and let's concentrate instead on what we're already best at -- accurate technical and creative discussions about digital media tools. Thanks in advance,
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Old May 2nd, 2005, 08:41 PM   #13
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I completely agree that it will hold up INFINITELY better than HDV
:: Looks up infinity ::

Okay, I didn't have to - but sheesh. At any rate I was doing some of the math on DVCPRO-HD, and I was trying to figure out how compressed it is and have a question:

Does the DVCPRO-HD codec have a more efficient algorithm than our favourite DV codec? Here's the math I was coming up with:

DVCPRO-50 is SD resolution 720x480, 4:2:2 at 50 Mbps.
DVCPRO-HD @ 720p 30 is, 4:2:2 at 50 Mbps, and exactly 2x the resolution of DVCPRO-50...

By my calculation that makes the data per 4:2:2 pixel of DVCPRO-HD at 720 30p EXACTLY the same per pixel as that of 4:1:1 DV. Is that true, and if so, does that not lead to equivalent artifacts in spades? (the same argument will hold for 720 24p of course).

What is interesting is that the resolution of 1080p DVCPRO-HD is exactly twice that of 720p DVCPRO-HD, and so at 30p, each pixel of 1080p is also has the exact same amount of data as a 4:1:1 DV pixel.

This suggests to me that upon re-compression DVCPRO-HD will hold up only as well as 4:1:1 DV. (Recompression is a big no no in my book - IMHO one should ONLY compress on the final render from the project to disk, i.e., all masters should be uncompressed). Which is troublesome, because per pixel, DVCPRO-HD pretends to hold FOUR TIMES the information as a 4:1:1 DV pixel with the same amount of data. Unless a more efficient spatial codec is used, I would therefore expect DVCPRO-HD to perform worse in a multi-generational workflow than DV.

Is this argument wrong, and if so why?

It's obvious that the bulk amount of data per frame is higher for 1080p, but it doesn't seem to me that either DVCPRO-HD format offers any actual improvement over miniDV per pixel. It ought to make for great downsamples of course - but it's HD we're after.

::Thinks a bit::

I wonder how good 100 Mbps 4:2:2 long-GOP MPEG-2 would look in comparison?

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Old May 3rd, 2005, 05:34 AM   #14
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one thing many people failed to mention was the flexible use of offline editing..

running an avid or FCP system, this isnt hard to do.. hell even Vegas 6 can do this now (albeit a lil shifty ;) ).. it takes a lil more work, however the fact that its there is fine..

with an offline edit, one can refine with perfection without the need to reprocess and rebuild a whole project and overprocess which may degrade the image..

thres always a solution and this is jsut one of them..
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Old May 3rd, 2005, 07:12 AM   #15
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"DVCPRO-50 is SD resolution 720x480, 4:2:2 at 50 Mbps.
DVCPRO-HD @ 720p 30 is, 4:2:2 at 50 Mbps, and exactly 2x the resolution of DVCPRO-50..."

4x, by my math. Note that an image twice as tall and twice as wide (in pixel count) occupies four times the area, not twice the area.

GB
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