Super Bit DVDs ? - Page 2 - AVS Forum
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post #31 of 42 Old 09-21-2001, 06:53 PM
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Quote:
Originally posted by Bjoern Roy:
Robert,

enough is enough. Please stop the profanity or take your attitude to the newsgroups.
You know, you're right. While my irreverence is (mostly) meant for entertainment purposes, perhaps I will take this chance to tone down my cynicism with this hobby and all things related.

However, I respectfully disagree with your responses to my statements entirely. I've actually worked with mastering video for DVD (and yes, this includes working with different encoding methods).

Consider that the highest "peak" of bitrates are around 5-7 megabits. Some may even go up beyond the 7mb rate. But if you understand how MPEG video works, you'd realize that what has been said here is, for the most part, utterly foolish and wrong.

So, VBR chucks out unneeded bits and peaks. It peaks at 7 megabit (the highest I've ever seen was 6.8). So, where is the loss of bits in the fixed rate? There are none. In fact, you have more bits left over. Plus, depending on who encoded it (and the alignment of the moons and how many twinkie's they've had before breakfast, etc), they can really crank up the compression... tossing out more information... more PICTURE information.

So, instead of variable bitrate, we have a fixed bitrate. That means when the normal variable bitrate MPEG stream would peak, recede, peak, recede... the fixed high bitrate allocates a linear (bit wise) amount of bits to the entire picture.

Keep in mind that this is in simple terms. I could spend pages going on about how to allocate bits depending on key frames, I frames, A/S/L frames, blah blah blah.

-- Robert


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post #32 of 42 Old 09-21-2001, 07:31 PM
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I think the general idea is to increase the bitrate for all scenes, a Good Thing. I'm no expert on bitrate, but if the peak bitrate on a standard DVD is around 7Mb/sec, then fixing the bitrate at that value on a SuperBit DVD is a good thing.

But according to the DVD FAQ , the maximum bitrate for DVD is 9.8Mb/sec. So I would assume that certain scenes with rapidly-changing content could be encoded with better quality at higher than 7Mb/sec.

Robert, you don't say how you know that the maximum bitrate is 7Mb/sec. If you're simply reading it off the bitrate display of a DVD player, I'm not sure I'd trust it. The players that I've seen only update the bitrate display about once per second or so, so you're seeing an averaged value and not a real instantaneous peak.

I'd expect that a desirable way to encode these SuperBit DVDs would be to use a minimum bitrate of 7Mb/sec, and allow up to the full 9.8Mb/sec for those (usually brief) portions that need it.

I disagree that 7Mb/sec is "wasted" on static scenes - on my computer display I can easily see the "pulsing" on many DVDs that's produced by the I-frames in the MPEG stream (I-frames are "complete repaints" of the video stream, as opposed to the "delta difference" frames used for scenes that have little change from one frame to the next). Even a static scene has small variants (such as film grain) that cause the encoder to "lose sync" with the original frames, and when the I-frame comes along you can see an appreciable difference in the entire frame at once. Once you notice this "pulsing" effect it can become very irritating. A higher bitrate would allow more I-frames or more encoding in the P- and B-frames so that the changes in the scene brought on by the next I-frame are minimized. This would be a Good Thing.
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post #33 of 42 Old 09-21-2001, 08:45 PM
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Well, recent good transfers show a bitrate which is consistently above 8 Mb/s, so I don't see how a fixed 7 Mb/s can be an improvement.

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post #34 of 42 Old 09-22-2001, 01:03 AM
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mmh, Columbia just intended these superbits for the masses then...... and it also seems WSR says no brand new telecine sources have been created for these discs, while they advertise it on the back cover.........

as for WSR, their system seems so super high ranged that these new dvds don't look "that" imroved..... while they could look better on "average to good" systems.
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post #35 of 42 Old 09-22-2001, 06:14 AM
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Robert,
let me see if I get this right. You believe that the higher bitrate should provide uniformly better picture quality. You have refused to address other issues with regard to DVD quality, like the excessive use of aperture correction or the use of a good film element.

The first reviews available claim no appreciable difference in picture quality. Your off the cuff response is that they must have used a bad review system. WSR does not have a bad review system. Do you feel your argument circling the drain?

Keep in mind that I am not a WSR apologist. I have disagreed with their reviews (eg Twister) in the past, but it has little to do with the equipment, and everything to do with the reviewer. In this case (with the review of the 5th element), 3 reviewers felt that the viewer would be hard-pressed to indentify an improvement.

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[This message has been edited by Don O'Brien (edited 09-22-2001).]

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post #36 of 42 Old 09-22-2001, 05:05 PM
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Robert:

Read the reviews carefully and you will see that the same person (Suzanne Hodges) reviewed the video for both AF1 and 5th Element. These are the only two reviews that I could find on the WSR web site that even mention the video quality.

I too don't trust WSR at this point. Still looking for confirmation.

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post #37 of 42 Old 09-26-2001, 10:36 AM - Thread Starter
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Besides WSR's review comments, who has actually purchased a Superbit DVD and made a comparison with the standard DVD?

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post #38 of 42 Old 09-26-2001, 06:12 PM
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My understanding is that Oct 9 is the first date we mortals will be able to get our hands on one.

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post #39 of 42 Old 10-04-2001, 10:38 AM - Thread Starter
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Another poor review for Superbit DVDs:

As a film, Air Force One offers a reasonably exciting and entertaining experience. It lacks the depth or spark to make it a great piece of work, but it delivers some good action and thrills. As a DVD, this new “Superbit†release provided virtually the same fine picture and sound found on the original disc. The image seemed a little brighter, but not helpfully so, while the DTS audio appeared slightly more powerful, but not to a significant degree. It totally lacked any extras and it did not seem to improve upon the old edition.

In my opinion, the prior DVD of Air Force One looked and sounded identical to this one for the most part, plus it tossed in a decent audio commentary that the Superbit disc dropped. With a list price that’s eight dollars lower, anyone who doesn’t own AFO but wants it should go for the original disc. Those who already have the old one should keep it and spend the money elsewhere; the new “Superbit†version of Air Force One doesn’t merit a purchase.

See: http://www.dvdmg.com/airforceonesuperbit.shtml


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post #40 of 42 Old 10-04-2001, 12:48 PM
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note: according to the dvdmg website, this reviewer's equipment is a sony 36fs12 and a non-progressive scan dvd player. the difference just might not discernable.
does the 36fs12 even do anamorphic squeeze??

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post #41 of 42 Old 10-05-2001, 12:48 PM
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Actually, I just checked and that model does have the enhanced widescreen (anamorphic squeeze) mode (I didn't think it did).

I am going to get a couple of the superbits just to check them out. I've got a smaller Wega that does do the anamorphic squeeze as well, so I'll be able to judge if there are any improvements on a low-end system. Of course, I don't have a progressive-scan player (my tv only accepts 480i anyways) so I'll have to see if there are any improvements (other than sound...).

[This message has been edited by deepfry (edited 10-05-2001).]
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post #42 of 42 Old 10-05-2001, 01:23 PM
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Why don't we reserve judgement until we actually SEE the superbit DVDs for ourselves?
I plan to get AFO & 5th element, and I'll be glad to post my results. I have an RP-91 & Panasonic HDTV so I trust I'll be able to make a fair judgement. If they really have ZERO improvement in PQ I'll say so.
I really don't understand the flak Sony seems to be getting here. It's not like they're the only studio who has re-issued DVDs. In fact, I believe these are the first re-issues by Sony. How many versions of Platoon, The Exorcist, Silence of the Lambs, Twister, Lethal Weapon, The Mummy etc are out there? When FOX did DTS reissues of X-Files, LOTM, etc people jumped up & down for joy. People have been screaming for more DTS from Sony. Now that they do it, with a "optimum PQ" twist, some people are getting their panties all in a twist. How many people really buy DVDs for the extras (and watch them) anyway? I would much rather have the best picture & sound quality available.

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[This message has been edited by Karnis (edited 10-05-2001).]
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