Industry Insiders Q&A MASTER THREAD [separate thread for Xbox/Add On & PS3] - Page 86 - AVS Forum
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post #2551 of 4841 Old 03-02-2007, 03:40 PM
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Hi,

On another subject, 24p... Following Toshiba postponing 24p on XE1/XA2 to july; Can insiders told us what is the status of 24p regarding each format ?

Is it well defined in red/white/yellow books ? up to the player implementation ?

I've read subtitles (still being pictures, unfortunately) can be a problem on HD-DVD, then how BD implement it ? (it does works afaik).

--Patrice

French speaking home theater HCFR Forum
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post #2552 of 4841 Old 03-02-2007, 05:09 PM
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Quote:
Originally Posted by Talkstr8t View Post

There are two types of non-volatile memory ("local storage") defined in the Blu-ray spec - the Application Data Area (known as "Persistent Storage" in MHP) for preferences, bookmarks, and such, and the Binding Unit Data Area for storage of A/V clips. All Blu-ray players must support the Application Data Area, albeit not a huge amount. All BD-Video 1.1 and BD-Live players must also support the Binding Unit Data Area (256MB for BD-Video and 1GB for BD-Live).

So is this why SMP8634 Blu-ray player development kit has two flash modules with one being 1 GB and the other being 64 MB? Also does Blu-ray require that the flash modules for local storage and persistent storage be kept separate or was this done just for ease of design?
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post #2553 of 4841 Old 03-02-2007, 05:16 PM
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Quote:
Originally Posted by Richard Paul View Post

So is this why Blu-ray player development kit has two flash modules with one being 1 GB and the other being 64 MB?

Ease of design. The 64MB flash is used for persistent storage and also to store the encrypted player firmware. The 1GB flash module is for local storage and can be easily changed for more or less depending on the manufacturer's specific design.

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post #2554 of 4841 Old 03-02-2007, 05:22 PM
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Quote:
Originally Posted by eightninesuited View Post

Is there an inherent bandwidth issue with HD DVD. I ask this because I've yet to see a movie with True HD and a high VC-1 encode.

"Phantom of the Opera", which was a launch title?

There haven't been any True HD titles with insufficent bitrate I'm aware of.

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post #2555 of 4841 Old 03-02-2007, 05:31 PM
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Keith, just curious but have any of the manufacturer's specific designs included both Dolby TrueHD and DTS-HD MA decoding?
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post #2556 of 4841 Old 03-02-2007, 06:08 PM
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Originally Posted by eq_shadimar View Post

Question about 2.35 subtitles and menus to all insiders -

Many pages ago there was discussion on how to accommodate users with constant height systems by adding some code (HDi and BD-Java??)that would automatically allow the menus and subtitles to fit in the 2.35 frame vs the letterbox or black bar portion of the 1.78 frame.

Have any studios expressed interest in doing this or should we just give up hope on this front? If there was interest are there any US titles that are released or soon to be released that will have this feature?

Thanks for your time,
Jeff

We are looking into this... don't give up hope.

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post #2557 of 4841 Old 03-02-2007, 07:04 PM
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Quote:
Originally Posted by eightninesuited View Post

Is there an inherent bandwidth issue with HD DVD. I ask this because I've yet to see a movie with True HD and a high VC-1 encode.

Phantom of the Opera, Batman Begins, Troy, Harry Potter and the Goblet of Fire all had TrueHD and a great PQ, IMO. HPGoF and Batman Begins had that AND IME.

Or am I misunderstanding the question? Did you mean a high video bitrate or were you referring to PQ?



edit: And I want to add that Troy had IME as well.

*************************************************

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...with a bitrate meter and screencaps.
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post #2558 of 4841 Old 03-02-2007, 07:55 PM
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The question of how much it cost to replicate BD and HD DVD is still a subject of speculation on this board. And while this was understandable prior to the launch of BD, I can't see any reason why some of the insiders haven't gotten the real cost and price by now. Surely several of you know people who are telling you what people are being charged, and estimates for the actual cost to master and produce SL and DL HD DVD and BD disc.

By now, someone should know where we are at with yields on BD50. Given that Sony is about to produce 500K BD50's for Europe, one might think they have that process somewhat under control now.

So the general question I have is: To what extent has the BD solved it's replication and mastering cost issues?

More specifically, if someone can, What do we know about the price and cost of BD SL and DL compared to HD DVD SL and SL? Do we knowing anything about yields?


Thanks in advance.
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post #2559 of 4841 Old 03-03-2007, 04:25 AM
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Quote:
Originally Posted by amirm View Post

I have not yet watched it. I was sick and now in Japan and way behind watching movies . But even if I did, I wouldn't be able to say anything useful here. I already mentioned that even within one movie, Batman Begins, there are variations in apparent sharpness. So what can you expect, comparing different movies? Really, there is nothing to be learned from these kinds of comparisons.


Actually, Universal does not do any encoding themselves. They use a post house that others also utilize. But I do agree with your point on VC-1. Feed us VHS, and we can only make it look like VHS .


It really doesn't. Per above, there is zero information to be gained here. Thousands of people work on a movie. Budgets vary. Equipment varies. Experience changes. Intent evolves. I know you all looking for some way of getting relative comparisons done but "this dog don't hunt. " If you don't trust me, as Paid to see what he thinks. I am confident he would agree.


Hopefully we can put this to rest and move on to other things...

Amir, thank you for taking the time to respond to my question.

At your suggestion, I will ask if Paidgeek has any comments on my question regarding whether the difference in results in terms of PQ as between Batman Begins and The Prestige are likely to be attributable solely to differences in the source material. Paidgeek, any comments on this?

Amir, I am not sure what is the "this" that you think should be put to rest? It seems to me that the general question of whether differences in PQ are attributable to differences in the source material or instead are attributable to differences introduced in the transfer process is not a question that deserves to be put to rest so easily.
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post #2560 of 4841 Old 03-03-2007, 07:59 AM
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Quote:
Originally Posted by patrick99 View Post

Amir, thank you for taking the time to respond to my question.

At your suggestion, I will ask if Paidgeek has any comments on my question regarding whether the difference in results in terms of PQ as between Batman Begins and The Prestige are likely to be attributable solely to differences in the source material. Paidgeek, any comments on this?


Film making has changed quite a lot in the last 10 years by incorporating electronic cameras and production tools into the process. For instance, if an actor or director is not happy with the way their character looks in a particular scene, they might use electronic methods in post to say, remove a few wrinkles... This happens more than you might think as the capability to make adjustments once you are in a DI color correction suite may be too tempting to pass up.

It is really not possible for a consumer of BD or HD-DVD to determine if a picture looks soft or lacks grain as a result of compression. The compressionist can make direct comparisons with the master, but naturally consumers don't have that available to them. There are artifacts that can be attributed to compression such as blocking, but even then you have to be careful because on certain types of content, the director may elect to show a scene shot in a consumer HD format as a way of expressing the immediacy of a handheld camcorder. Normally a situation like this is too obvious to misinterpret.

As I mentioned in a previous post, comparing the same version of a movie on two different formats that used different codecs is fair game as these should be sourced from the same master and any observed differences should be attributed to the results of compression.

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post #2561 of 4841 Old 03-03-2007, 08:15 AM
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Quote:
Originally Posted by paidgeek View Post

Film making has changed quite a lot in the last 10 years by incorporating electronic cameras and production tools into the process. For instance, if an actor or director is not happy with the way their character looks in a particular scene, they might use electronic methods in post to say, remove a few wrinkles... This happens more than you might think as the capability to make adjustments once you are in a DI color correction suite may be too tempting to pass up.

It is really not possible for a consumer of BD or HD-DVD to determine if a picture looks soft or lacks grain as a result of compression. The compressionist can make direct comparisons with the master, but naturally consumers don't have that available to them. There are artifacts that can be attributed to compression such as blocking, but even then you have to be careful because on certain types of content, the director may elect to show a scene shot in a consumer HD format as a way of expressing the immediacy of a handheld camcorder. Normally a situation like this is too obvious to misinterpret.

As I mentioned in a previous post, comparing the same version of a movie on two different formats that used different codecs is fair game as these should be sourced from the same master and any observed differences should be attributed to the results of compression.

Thanks for the response, Paidgeek. So if it is correct that Warner is planning to put out The Prestige in a European version using VC-1, it would be fair to compare that to the BVHE AVC version?
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post #2562 of 4841 Old 03-03-2007, 08:19 AM
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I know my costs...and I have a good idea of what others pay. However it would not be appropriate to post specific costs in a public forum as that is confidential information.

What is your purpose for wanting this information by the way? I can safely say it costs about $1.00 more per disc than a DVD Disc to produce the HD Formats....in addition to much higher mastering and authoring costs.

Why do you wnat to know?

Rich



Quote:
Originally Posted by skogan View Post

The question of how much it cost to replicate BD and HD DVD is still a subject of speculation on this board. And while this was understandable prior to the launch of BD, I can't see any reason why some of the insiders haven't gotten the real cost and price by now. Surely several of you know people who are telling you what people are being charged, and estimates for the actual cost to master and produce SL and DL HD DVD and BD disc.

By now, someone should know where we are at with yields on BD50. Given that Sony is about to produce 500K BD50's for Europe, one might think they have that process somewhat under control now.

So the general question I have is: To what extent has the BD solved it's replication and mastering cost issues?

More specifically, if someone can, What do we know about the price and cost of BD SL and DL compared to HD DVD SL and SL? Do we knowing anything about yields?


Thanks in advance.


Richard J. Casey



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post #2563 of 4841 Old 03-03-2007, 08:25 AM
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Yes, there is a bandwidth spec and limitation for both formats.

HD-DVD has less bandwidth for Audio/Video encodes than BD. However, as encoders get more efficient over time, there may be more HD-DVD discs with DTS Master Audio Lossless and Dolby True HD, which is really just MLP Audio.

It is a fine line between audio/video and where to compromise when it comes to producing HD Titles. Most people will more readily notice the impact on Video before they will the Audio when it comes to choosing which one takes the "squeeze" of lossy compression so to speak.

Rich

Quote:
Originally Posted by eightninesuited View Post

Is there an inherent bandwidth issue with HD DVD. I ask this because I've yet to see a movie with True HD and a high VC-1 encode.


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post #2564 of 4841 Old 03-03-2007, 12:27 PM
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Quote:
Originally Posted by paidgeek View Post

Film making has changed quite a lot in the last 10 years by incorporating electronic cameras and production tools into the process. For instance, if an actor or director is not happy with the way their character looks in a particular scene, they might use electronic methods in post to say, remove a few wrinkles... This happens more than you might think as the capability to make adjustments once you are in a DI color correction suite may be too tempting to pass up.

It is really not possible for a consumer of BD or HD-DVD to determine if a picture looks soft or lacks grain as a result of compression. The compressionist can make direct comparisons with the master, but naturally consumers don't have that available to them. There are artifacts that can be attributed to compression such as blocking, but even then you have to be careful because on certain types of content, the director may elect to show a scene shot in a consumer HD format as a way of expressing the immediacy of a handheld camcorder. Normally a situation like this is too obvious to misinterpret.

As I mentioned in a previous post, comparing the same version of a movie on two different formats that used different codecs is fair game as these should be sourced from the same master and any observed differences should be attributed to the results of compression.

Thank you for the informative post, it's appreciated.

I've one question: What happens if there's a film with a very soft master (let me mention HOFD as a prime example). Does the soft master always have to be a consequence of the original 35mm film recording? Or is it possible, that the DI manipulation steps are responsible for the softness? Or in other words: Is it totally impossible for such a movie to get some more details/sharpness out of the master without resorting to digital algorithms like sharpening/detail enhancement? E.g. could the DI be redone? Or could the original film be scanned again with better equipment? Or is all hope lost? I'm wondering because very old movies such as Casablanca and Robin Hood look quite fine after restauration. So I'm wondering whether such a restauration would be possible for newer movies with soft masters (like HODF) without negative side effects, too?
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post #2565 of 4841 Old 03-03-2007, 12:32 PM
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Quote:
Originally Posted by RBFilms View Post

Yes, there is a bandwidth spec and limitation for both formats.

HD-DVD has less bandwidth for Audio/Video encodes than BD. However, as encoders get more efficient over time, there may be more HD-DVD discs with DTS Master Audio Lossless and Dolby True HD, which is really just MLP Audio.

It is a fine line between audio/video and where to compromise when it comes to producing HD Titles. Most people will more readily notice the impact on Video before they will the Audio when it comes to choosing which one takes the "squeeze" of lossy compression so to speak.

Rich

But how much does HD-DVD need lossless (especially when it's only 16/48) if 24/48 1.5mbps Dolby Digital Plus is virtually transparent? This seems to be a question that a lot of people don't want to address, as
1. BD supporters don't want to bring it up because BD can't do 1.5mbps Dolby Digital Plus.
2. Certain people want to keep up the illusion that DTS Master Audio and True HD are something spectacularly better, even at 16/48.
3. Certain people want to keep up the illusion that PCM is better than everything else, even when it is only 16/48.
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post #2566 of 4841 Old 03-03-2007, 12:37 PM
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Quote:
Originally Posted by RBFilms View Post

Why do you wnat to know?

Rich

Because we analyze everything to the Nth degree around here

One of the advantage of HD DVD was lower cost of replication. Obviously, that cost is not always passed on to smaller studios, because your price may be dictated by supply and demand rather than cost to replicate - until you get high volume. But there was some evidence that a BD disc cost about 30% more to replicate than an HD DVD.

In another thread you said that the glass master cost the same for each format - about $3k. You are the first person I know that has said that. So apprearently Bd has brought down the cost of creating the glass master. There were some advances we had talked about before, and maybe those are coming onto the market now.

But I haven't heard anything about replication cost around here in a long time. That could be because they have made advancements in yields, and there is no longer a big difference. Or maybe people just got tired of talking about it. Still, i'm particularly interested in the experience of small studios in replication.

Without getting into specifics, can you give me a percentage of how much more BD cost to replicate? Is it 0%? 30%? These are the kind of things we like to talk about around here.

And thank you in advance. I really appreciate the insiders on this board giving us this kind of insight.
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post #2567 of 4841 Old 03-03-2007, 12:39 PM
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Hello,
I have two questions for paidgeek, you may or may not know the answers
Firstly at what point does a film become a catalgue title in Sony's eyes is it when it finishes it's run in the cinema or does a certain amount of time pass.

And secondly, Is there anyway, or any section of Sony Pictures that we in other regions can contact to find out if a Region A disc is region ABC or just A.
I ask because there are a few titles coming up that I would love to get but no Blu-ray release is scheduled yet, or due to international disctribution won't show up. Below are a few of the titles from Sony that I would like to get,

Stranger Than Fiction
Layer Cake
The Holiday (2006)
Rocky Balboa
Identity
Volver
Secret Window
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post #2568 of 4841 Old 03-03-2007, 12:45 PM
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Quote:
Originally Posted by patrick99 View Post

Thanks for the response, Paidgeek. So if it is correct that Warner is planning to put out The Prestige in a European version using VC-1, it would be fair to compare that to the BVHE AVC version?

Yes, that could provide some interesting insight on how the the two codecs (and compressionists) perform on these titles.

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post #2569 of 4841 Old 03-03-2007, 12:58 PM
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Quote:
Originally Posted by madshi View Post

Thank you for the informative post, it's appreciated.

I've one question: What happens if there's a film with a very soft master (let me mention HOFD as a prime example). Does the soft master always have to be a consequence of the original 35mm film recording? Or is it possible, that the DI manipulation steps are responsible for the softness? Or in other words: Is it totally impossible for such a movie to get some more details/sharpness out of the master without resorting to digital algorithms like sharpening/detail enhancement? E.g. could the DI be redone? Or could the original film be scanned again with better equipment? Or is all hope lost? I'm wondering because very old movies such as Casablanca and Robin Hood look quite fine after restauration. So I'm wondering whether such a restauration would be possible for newer movies with soft masters (like HODF) without negative side effects, too?

I don't see the DI process causing the master to be softer. It is possible to make to make the image softer by over use of grain reduction tools, but this is rarely a problem. At the risk of disappointing you, I don't think you will ever see a version of HOFD that is dramatically sharper than the one you have. These days, the film transfer is only one step in actually finishing the film. Special effects, wire removal, color correction and so on are all done in the digital domain. It is possible that the tools used to perform these functions will get better over time, but I think it will be a rare case to get an editor and other creative people to redo a title in order to try to squeeze out another 5% improvement, that is unless it is a classic...

You raise a good point about some of the older titles. Films were shot, edited and transferred using more basic techniques in the past. I think the saying that sometimes less is more holds true here because I have seen masters for films 10 - 40 years old that can stand up to or even exceed the quality of new films being released for the first time.

Sony Pictures BD Insider
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post #2570 of 4841 Old 03-03-2007, 01:01 PM
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Quote:
Originally Posted by Neftoon View Post

Hello,
I have two questions for paidgeek, you may or may not know the answers
Firstly at what point does a film become a catalgue title in Sony's eyes is it when it finishes it's run in the cinema or does a certain amount of time pass.

And secondly, Is there anyway, or any section of Sony Pictures that we in other regions can contact to find out if a Region A disc is region ABC or just A.
I ask because there are a few titles coming up that I would love to get but no Blu-ray release is scheduled yet, or due to international disctribution won't show up. Below are a few of the titles from Sony that I would like to get,

Stranger Than Fiction
Layer Cake
The Holiday (2006)
Rocky Balboa
Identity
Volver
Secret Window

As a rule, if a title is still in theatrical release anywhere in the world, it is not considered catalog. This can take up to a year.

The labelling of the discs to correctly identify them as region ABC should be sorted out by now, so you should be able to get this information straight off the packaging.

Sony Pictures BD Insider
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post #2571 of 4841 Old 03-03-2007, 01:13 PM
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Quote:
Originally Posted by RBFilms View Post

I know my costs...and I have a good idea of what others pay. However it would not be appropriate to post specific costs in a public forum as that is confidential information.

What is your purpose for wanting this information by the way? I can safely say it costs about $1.00 more per disc than a DVD Disc to produce the HD Formats....in addition to much higher mastering and authoring costs.

Would you say there was a difference in cost for you to produce Chronos on Blu-ray versus HD DVD? Common perception on these forums says it's more expensive for BD but that Sony is subsidizing...

Do you have any thoughts to ofter on that? Being a smaller studio, I'd find your perspective on the whole thing to be very illuminating for any studio in a similar position.

-- "No matter where you go, there you are."

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post #2572 of 4841 Old 03-03-2007, 01:22 PM
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Quote:
Originally Posted by paidgeek View Post

Yes, that could provide some interesting insight on how the the two codecs (and compressionists) perform on these titles.

I think you are saying this but to be clear, even that doesn't do the job (compare "two codecs"). We are not talking about codecs that auto-encode the movies and as such, the only difference would be the technology. This is a manual process and with different operators, equipment, budget for encoding, and skill of the operator, you get different results. Worse yet, one scene may look better in one, and another in the alternative version.

And of course, the HD DVD version will use a different video data rate and may accommodate other a/v tracks, making the comparison more difficult yet, if you want to figure out if the BD version could have benefited from use of VC-1 (which is I think the topic people have angst over). So at objective level, this is not a codec shoot out (although subjectively, may not matter much).

Anyway, I may be mixing up my titles but from what I recall hearing, The Prestige looks very good in VC-1/HD DVD. If so, this whole discussion will be academic for the world at large...

Amir
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post #2573 of 4841 Old 03-03-2007, 01:34 PM
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Quote:


As an aside, he should also rename the title of his thread. The MPEG-2 encode is probably running at 2X the data rate of VC-1. Remember, the HD DVD version actually has two video streams with a Picture-in-Picture on top of the move itself - BD version in MPEG-2 lacks that. So if that scene is the pinnacle of what is wrong with the VC-1 encode running at half the data rate of MPEG-2, while at the same time providing a secondary video stream, I still stand proud even if this were an issue with VC-1

does this suggest that the bandwidth limitations of HD DVD force inherent compromises when 1080p video, PIP secondary streaming, and high-quality audio reproduction are all desired by a disc producer?

1080p and lossless audio. EVERY BD should have them both.
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post #2574 of 4841 Old 03-03-2007, 02:21 PM
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So at long last, here are some of the key reasons that VC-1 differentiates itself from AVC in preserving more of the natural texture/resolution and grain of the original HD content. Everything I state here is factual and can be confirmed by looking at the specs and history of these technologies. And apologies in advance for any typos, grammar errors. I am still pretty jetlagged in Japan.

As the discussion of codec technology at mathematical level quickly runs into Star Trek language (my term for fancy stuff that make no sense to someone not schooled in them), I am going to provide some high level context and historical perspective for these design choices first. Hopefully that makes it easier to digest the meat of the post, which follows.

MPEG-4 AVC's origins come from work done by ITU (international standards setting organization) to create an alternative to then leading compression technologies on the internet: namely, Real network's video codec and Microsoft's. At the time, MPEG-4 ASP (or Part 2 as it is called) had failed to gain any traction due to not being competitive from performance point of view with these other codec. And MPEG-2 lacked the efficiency to be useful at internet rates.

The ITU initiative, called H.264 (coming after an earlier standard called H.263) was led by Dr. Gary Sullivan who happens to work on my team. Gary is world renowned in the compression/standards circuits and was honored for his work on H.264/AVC with IEEE fellowship award. He has the temperament and skills to drive these things like few have.

Unlike previous standardization efforts, the ITU put computational complexity at very low priority, instead focusing on best compression efficiency as a top goal almost regardless of implementation cost. This allowed them to take on algorithms which were very compute intensive, but generated compression efficiency gains nevertheless (the so called CABAC is an excellent example where it might take 20% of a chip just to perform this one function).

H.264 gained the interest and contributions from some of the top compression experts worldwide. As such, the codec started to show significant gains over then best open standard, MPEG-4 Part 2. Not to be upstaged by ITU, MPEG group proposed that H.264 become a joint project between the two standards group and hence the moniker JVT that you sometime see (J standards Joint). Later the standard was renamed, confusingly so, to MEPG-4 AVC (or Part 10) giving more power to the standard (see below).

The joint initiative got a lot of interest around the world. The aging patent portfolio around MPEG-2 motivated some of the largest companies to contribute to AVC, in the hopes of replenishing their revenue stream one day with patents in that format, when MPEG-2 royalty stream starts to run dry. Alas, that proved difficult as a form of gold rush occurred here, with some 150+ organizations contributing to the final standard (almost 10 times more than did with MPEG-2!). I remember Gary telling me how shocked he was as to the number of attendees in some meetings.

We did our share too and evidenced by Microsoft being one of the members of the MPEG-4 AVC patent pool (we were not part of MPEG-2 but do hold a similar position in MPEG-4 Part 2). And like the other patent holders, we stand to make a few pennies out of AVC one day. Given our involvement both in driving the standard and contributions to the algorithm and business terms/licensing, I hope people realize that my discussions around AVC is not the typical bashing of your competitor as we take some ownership and pride in development of AVC (although obviously not nearly as much as VC-1).

Given that 99% of video on the internet at the time of AVC development was CIF resolution (quarter screen/SD) and lower, strong emphasis was put to do well there. Test clips where used to evaluate effective performance various proposals with almost all at CIF resolution. This masked any issues that might have existed in higher resolution material with these algorithms.

JVT work finished around 2003, generating a truly advanced codec, rivaling anything we or Real Networks had. At SD resolution and lower, AVC is a formidable competitor to VC-1 and whether one wins or not in any comparison, is a very subjective thing. More so in its favor, AVC has the power of MPEG brand (with government mandate in some countries), and lack of direct association with Microsoft, which in many situations puts it ahead of VC-1 before the game even starts. This combination has resulted in many strong design wins for AVC in a number of applications from broadcast to satellite, IPTV, and of course, HD DVD/BD.

Computationally, AVC was about 3X slower than MPEG-2 to decode (and many times slower in encode). So making this a lower priority goal, did indeed take its toll on difficulty of implementation.

Of course, we were not sitting still during the development of AVC. We were hard at work, designing our next generation video codec, while being fully aware of work being done in ITU/MPEG.

Like AVC, we wanted to create a standard. And by that, I mean that we wanted to license it to others in the industry to implement in their hardware which meant that once we did that, we could not change it again without breaking compatibility. This meant that the algorithm had to last and stay competitive for a long time (5+ years). The final implementation, known as Windows Media Video 9 (or WMV-9) pushed way beyond our previous revisions of our video work, producing significant compression efficiency. Using MPEG's own test clips, we were able to show 3X gain in objective PSNR measurements as compared to MPEG-2 and 2X compared to MPEG-4 Part 2 (at internet data rates).

The WMV-9 codec later became known as VC-1, when we opened its specifications, and submitted it to SMPTE organization for standardization. This was a requirement of it being adopted by DVD Forum.

Unlike AVC, we did not want to put computational efficiency at the bottom of the goal list. We wanted to run in millions of portable devices and there, battery power becomes directly proportional to how many MIPS you use. So even if we didn't care how much the hardware cost, we still wanted to be more efficient.

During the development of VC-1, a sequence of events led to changes to our design which literally put us on the map when it comes to HD encoding. While our mainstream business was internet video with SD resolution and lower, we started to do some prototype encodings at HD resolution to see how well the codec performed there.

As we expected, the coding gain (compression efficiency) was quite significant at HD resolutions just the same. Many of the techniques that improve the quality per bit are resolution independent, letting us produce similar quality to MPEG-2 but doing so at much lower data rate. Excited, we showed a sample of our HD VC-1 encode to one of the (technical) studio executives. That led to us participating in DVD Forum HD DVD codec shootout which per my earlier note, resulted in us defeating the other technologies and becoming a mandatory standard in HD DVD and later, BD.

The reason we did so well was the result of another unintended development earlier. Since there were no real applications at the time for HD on the internet, we used our new capabilities simply to showcase what the codec could do. You know, kind of how Honda does Formula 1 racing and uses that as bragging rights to sell you an Accord . But someone thought we really wanted to sell them a race car, and next thing we know there was a company who was packaging a PC, a dark chip DLP projector, and chasing art houses and smaller cinemas to switch to digital using this low cost system! The package worked quite well, solving the major cost issue of higher end systems being developed in Hollywood and art houses started to deploy it rapidly (they could run digital advertisements on it to make money).

So we started to encode a bunch of independent movies and going through the evaluations with the creative community. Unfortunately, we quickly realized that some of the lessons we had learned on the internet were backfiring on us. In subjective test after test for internet applications, we had seen that people would sacrifice resolution to get a softer but artifact-free video (well, as artifact free as one can make internet video ). When it came to digital cinema though, one couldn't soften the picture when the thing is being blown up on such a big screen. And people didn't want to be told to pick between softness or artifacts. They wanted to have their cake and eat it too with transparent resolution to the source and no artifacts.

Our early tests showed up that indeed, we were sacrificing some grain/textures with our algorithm as designed. Worried that if we optimized the codec differently for HD, we would lose the battle on the internet, we made the algorithm adaptive with respect to resolution/data rate. Namely, if you feed VC-1 content above SD resolution, it will behave differently, even though its core algorithm is the same across the board.

The above changes proved very effective and nicely improved our HD performance. We shortly became one of the standard submission formats for Sundance film festival (the only electronic format allowed). I also got to meet Robert Redford and learned that this job has some nice perks . But I had to pay for it dearly, sitting at midnight (the only time we could time on the Sundance theaters during the festival) trying to prove to them that we had not lost the film look. After all, these guys don't call themselves film makers for nothing!

So they demanded to have a shootout against film projection before giving us the green light to use the VC-1 encodes. And of course, they were always finishing their movies a couple of days before the show, given us little time to encode them and hence the midnight viewings.

Fortunately, in every case, the producer/director agreed that our VC-1 encode outperformed the equiv. film projection, while sitting in the front row of the theater and watching a 30 foot screen. And we went on to watch some really great, and some really not-so-great independent films on our technology.

During one of the Sundance festivals, we also met with Lionsgate folks who were thinking of releasing T2. Impressed with what we had done with VC-1 at Sundance, they agreed to do a dual disc release creating what later became WMV-HD format (VC-1 content but using our audio and file format on red laser DVDs). That started a trend and soon, we had some 50+ titles using the same technology, pushing us nicely to keep improving our codec for HD movie encoding. You really get good as this stuff, when you try to do 1080p in 10 mbit/sec maximum rate for both audio/video and video files the same size as regular SD DVDs in MPEG-2! WMV-HD also got my start at AVS Forum, answering questions about WMV-HD. So if you are unhappy about my postings here, you have Lionsgate to blame .

During this journey, Joe Kane, frustrated with the poor quality of D-VHS MPEG-2 on his HD DVE test patterns, got interested in releasing a WMV-HD disc. So we worked with him and learned a few things to fine tune there. His final VC-1 encode was below 12 mbit/sec (constant bit rate no less), yet outperformed his D-VHS equivalent showing that even on pathological test sequences (i.e. stuff that is hard but never occurs in real life), we had a significant efficiency and quality gain over MPEG-2. So Joe became a believer and continues to advocate VC-1 in his demonstrations to this date (going as far as using HD DVD/VC-1 in the Samsung booth at IFA last year instead of BD/MEPG-2!).

Computationally, we also met our goals in that we achieved great compression efficiency, yet our decoder would only take 2X more MIPS than MPEG-2 (compared to 3X on AVC). Encoding was a lot slower than MPEG-2 at higher quality settings, but way better than AVC. We also use less memory for both encode and decode than AVC.

OK, enough with history. Let's get into the details.

Both AVC and VC-1, like MPEG-2 before it and many other video codecs, are transform based. The screen is divided into blocks which are then independently compressed (think JPEG) and their motion is tracked on screen (so that we don't have to retransmit the whole block when some part of the image moves but other parts don't). We call this motion estimation.

There is a lot more sophistication however in both AVC and VC-1 as compared to MPEG-2's much simpler algorithm (which was heavily constrained by what hardware could do a decade back). We have such features as adaptive (as opposed to fixed) block size, quarter pixel motion estimation (as opposed to half pixel), and more efficient entropy coding (lossless component of all video codecs to squeeze the final set of bits as tightly as possible). And much more.

While both AVC and VC-1 are advanced codecs, they differ significantly in how they gain their efficiency over MPEG-2:

1. Transform block size differences. MPEG-2 uses fixed 8x8 blocks. AVC changed this to 4x4 blocks (with the transform designed by Microsoft btw ). VC-1 on the other hand, supports 8x8, 4x4, 4x8 and 8x4. This gives VC-1 much more flexibility to pick the optimal block size based on picture content. For example, the outline of a person may be better coded using vertical blocks that suck in less of the background grain (letting the block be optimized for the subject or background gain and not both at the same time). And larger blocks can preserve texture better.

After losing the picture quality test to VC-1 in DVD Forum (and in some cases, finishing even behind MPEG-2), reality set in with AVC folks just as it had for us sometime back. Surprisingly, they chose to modify the standard and add adaptive block size of VC-1 to AVC, post standardization. I say surprisingly because this addition broke compatibility with the just finished standard which is a rare situation.

The paper proposal from Sand Video started it all and is an interesting read in this respect: http://ftp3.itu.ch/av-arch/jvt-site/...VT-H029r1.doc:

The faithful reproduction of fine detail, including film grain, is required in high definition (HD) broadcasts, HD-DVD, and Digital Cinema. To meet this requirement, more high frequency information must survive quantization than is typical in lower bit rate applications. This contribution demonstrates that the frequency selectivity and reduction in boundary effects realized by using adaptive block transforms (ABT) helps meet the high standards of the HD community. We present average RD performance improvements of 9.75% on HD film sequences and significant perceptual gains in areas of fine detail and film grain. (emphasis mine)

And then this:

Test Sequences: Five HD-scans of major release Hollywood movies (designated Movies 1-5) (footnote 1).
(Footnote 1) Due to licensing arrangements with the Hollywood Studios, Sand Video cannot disclose the names of the movies nor show the results of the processing to non-DVD Forum members. (emphasis mine)

Yes, you guessed it right. They are talking about the DVD Forum tests that I mentioned. They used the same test clips to show the improve quality using adaptive/larger block size which VC-1 used.

And who is Sand Videoyou ask? They were a start-up that was developing AVC encoders and decoders. The company was subsequently sold to Broadcom and their work became the foundation of the single chip AVC/MPEG-2/VC-1 decoders powering Blu-ray and HD DVD players. But at the time, they were a proponent of AVC and one of the companies participating in the tests, with an AVC encoder.

Since the AVC standard was already cast in concrete prior to this submission, a High Profile extension was created with the addition of 8x8 block size. The standard AVC spec was then called Baseline or Main profile. Despite being a late comer, HP extension was added to both HD DVD and BD specifications.

Note that per my previous note, the HP profile is incompatible with the Baseline Profile which many AVC systems use (i.e. crashes the decoder). So unless you see HP after MPEG-4 AVC, you don't get adaptive block size. And even if you do see it, you have half the choices that VC-1 has. Per earlier mention, non-square blocks are quite handy in coding the picture, letting us to better avoid clustering non-similar pixels.

You may want to check out the pictures in the paper, showing the effectiveness of 8x8 blocks and its performance for preservation of grain.


2. Loop filter differences. Loop here refers to a feedback loop which is part of all modern video encoders. To figure out what to send next, the codec subtracts the decoded frame from the source (finding the error signal), and then compresses that difference and ships it to the decoder to keep refining the picture to bring it closer to the source (assuming the scene has not changed). Since we feed the output of the encoder back to the input, it creates a feedback loop in the classic engineering terminology.

AVC and VC-1 deviate from MPEG-2 in that they can insert a filter in the feedback loop. By taking into account the distortion created in the stream as a result of compression, and filtering it, one can gain significant compression efficiency. This is the key reason neither AVC nor VC-1 degrade as badly as MPEG-2 into a sea of blocks when starved for bits. Think of it as soft clipping for you all audiophiles .

The existence of loop filter also means that increasing the bit rate may not necessarily improve perceived quality because the codec is able to some extent mask compression artifacts. The corollary of this is that the quality curve of these advanced codecs is more non-linear with a longer asymptote at higher rates, as compared to say, MPEG-2. They reach higher quality sooner, and increases in bitrate beyond some point do not gain you as much visually as it might in MPEG-2 (this is a good thing, not bad ).

The strength of the loop filter in both codecs is dynamic and based on heuristics (educated guesses) by the encoder. They may also be tunable by the operator.

While both codecs sport loop filters, their filter characteristic varies substantially. The difference here is a direct result of our digital-cinema work where we found the loop filter to be very disruptive to film grain and texture. So we optimized the VC-1 filter by reducing its length to one pixel on each side of the block being encoded. Think of this as an eraser with a very sharp point, gently touching up those three pixels so that you can't tell there is a line through them at the block boundary. Again, note that even this light touch is applied adaptively, i.e. only when needed and by the right amount.

Instead of just one, the AVC filter softens up to 3 pixels on either side of the block edge. Now think of a 4x4 block. If you go into the block two pixels from each side, you will be filtering the pixels twice (once from left, and then one more time from the right)! In contrast, the VC-1 filter only touches those pixels once since we only go one pixels to left or right. In the case of an 8x8 block, VC-1 never touches the center pixels whereas AVC filters them once.

So think of AVC loop filter as a giant eraser, three times bigger than that of VC-1, attempting to smooth the block boundaries.

If the scene gets too difficult to code and block boundaries become visible according to internal heuristics, AVC essentially filters every pixel on screen (and sometimes twice in case of 4x4 blocks), whereas VC-1 judiciously filters block boundaries only. Assuming same filter strength used in both codecs, VC-1 picture is bound to look sharper, with less resolution pumping (picture getting soft when it gets hard to encode and then sharper when not) than AVC.

The same video in MPEG-2 by the way, would show blocking artifacts as you see in live HD sports on TV. And since the efficiency of MPEG-2's algorithm is lower in general as compared to AVC/VC-1 (e.g. in the entropy coding section of the codec), and its blocks always the larger 8x8, its blocking artifacts are more severe and easier to see. Some people may prefer this to the softer look of AVC though in some cases.

As you can imagine, if the content is easy to encode, the filtering does not kick in at full strength and the picture can look fine in AVC. But as the scene complexity increases, AVC becomes heavy handed, smearing detail. Give it easier (e.g. clean) material, or exceedingly high data rate, and it will do much better as its loop filter gets reduces in strength (hence my earlier comment that BD's data rate erases some of the AVC sins).

Don't even think of turning off the filter though, as some claim to get around this design limitation. Doing so, will take away the distortion mitigation system and you kind of wind up with MPEG-2 style artifacts (we know, we have tested it that way). Put another way, the AVC filter is more like a big on/off switch, without effective graduations, despite its adaptive nature. You are damned if you do, damned if you don't with this loop filter for HD content.

Now you know why telling us this movie or that movie looks good in AVC, doesn't impress us as much . We know that some content will suffer less but in many general cases, you are going to run into this loop filter deficiency which works wonderfully for internet video, but not as well at the quality levels we are talking about. And that softening occurs in some scenes and requires knowing what segment is difficult and looking for its effect there.


3. Interpolation filter size. As I mentioned in the introduction, both AVC and VC-1 use quarter pixel resolution to track motion of blocks. This by definition means that you have to interpolate the intermediate values between pixels as you decide to move the same block in the decoder frame buffer within subpixel boundaries.

VC-1, roughly speaking, uses bicubic filtering with 4 taps. AVC on the other hand, uses a 6-tap filter. One would think that more of anything is better here but such is not the case when you are compressing HD video. By using more taps, you are using more of the pixels in the frame to find the interpolated one. This has the unintended effect of smearing adjacent pixels into each other with resulting loss of resolution (think of an object being averaged with black background with grain in it). And more taps in digital filters means more ringing, (some frequencies emphasizes more than others) causing edges to not be crisp. The shorter taps in the VC-1 filter is also one of the reasons we are much faster than AVC as we don't need to touch as many pixels.

Are you still with me? If so, you are doing good and could do my job one day! I warned you this stuff gets complicated fast.

Hopefully the above gives you some insight into the differences between these two (very good) codecs and why there are some fundamental differences between them when it comes to HD encoding. While both algorithms can run circles around older technologies such as MPEG-2 (and contrary to popular myth, can be defeatured to behave just like MPEG-2), at the end of the day, one is a better fit for the application in mind.

VC-1 was optimized (and redesigned) before becoming final with real world HD applications and content. AVC was modified quickly, post standardization to perform better but not to the same level as VC-1. Smart people worked on both, but were given different design criteria so they came up with different solutions.

Is there a down side to the differences mentioned? Yes, a bit. VC-1 can become blocky sometimes because it attempts to both preserve detail while at the same time not resorting to excessive filtering of the source as AVC does. This impacts us the most at internet rates as compared to AVC (even there, we opt for sharper pictures). But we think for the formats in question, that can be dialed out by hand optimization and better automated analysis (the main focus of our R&D for the last year). And once there, you have a sharper picture for it. Not everyone agrees of course, especially at below SD resolution. But enough people do thankfully to have gotten us 200+ VC-1 titles in HD DVD/BD and great praise for many of the encodings

Amir
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post #2575 of 4841 Old 03-03-2007, 02:24 PM
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Originally Posted by DaViD Boulet View Post

does this suggest that the bandwidth limitations of HD DVD force inherent compromises when 1080p video, PIP secondary streaming, and high-quality audio reproduction are all desired by a disc producer?

In my opinion no. But to the extent the same people think BD should use VC-1 at higher rate, they can't turn around and claim that lower rate VC-1 should match or outperform MPEG-2/AVC at higher BD rate. Either accept that lower rate is just fine, or don't claim that we should beat the other guy at lower rate. The two stances together make no sense.

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post #2576 of 4841 Old 03-03-2007, 03:17 PM
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Amir,

Thank you for the very informative VC-1/AVC comparison. Can you recommend any books/articles on video compression technology that are not overly mathematical? I would like to learn more about this area.

Also, any dates yet on when the Mobile Experience will be in Atlanta?
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Quote:
Originally Posted by amirm View Post

The paper proposal from Sand Video started it all and is an interesting read in this respect: http://ftp3.itu.ch/av-arch/jvt-site/...VT-H029r1.doc:

The faithful reproduction of fine detail, including film grain, is required in high definition (HD) broadcasts, HD-DVD, and Digital Cinema. To meet this requirement, more high frequency information must survive quantization than is typical in lower bit rate applications. This contribution demonstrates that the frequency selectivity and reduction in boundary effects realized by using adaptive block transforms (ABT) helps meet the high standards of the HD community. We present average RD performance improvements of 9.75% on HD film sequences and significant perceptual gains in areas of fine detail and film grain. (emphasis mine)

...

And who is Sand Videoyou ask? They were a start-up that was developing AVC encoders and decoders. The company was subsequently sold to Broadcom and their work became the foundation of the single chip AVC/MPEG-2/VC-1 decoders powering Blu-ray and HD DVD players. But at the time, they were a proponent of AVC and one of the companies participating in the tests, with an AVC encoder.

Since the AVC standard was already cast in concrete prior to this submission, a High Profile extension was created with the addition of 8x8 block size. The standard AVC spec was then called Baseline or Main profile. Despite being a late comer, HP extension was added to both HD DVD and BD specifications.

Note that per my previous note, the HP profile is incompatible with the Baseline Profile which many AVC systems use (i.e. crashes the decoder). So unless you see HP after MPEG-4 AVC, you don't get adaptive block size. And even if you do see it, you have half the choices that VC-1 has. Per earlier mention, non-square blocks are quite handy in coding the picture, letting us to better avoid clustering non-similar pixels.

Amir, did Tom McMahon not clairfy the ABT vs. 8x8 issue before?

http://archive2.avsforum.com/avs-vb/...&&#post6594314

"Finally, we didn't even make up an 8 bit 4:2:0 High Profile (which is the High Profile under discussion here) using the 8x8 transform until July of 2004. What we ended up over a year later was ***NOT*** ABT. It was only the addition of an 8x8 transform to the Standard (incidentally, variations on the 8x8 transform had been proposed by FastVDO and others well before ABT itself, in January of 2002 I believe)." - Tom

PS: I wish Tom well in his recovery.
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post #2578 of 4841 Old 03-03-2007, 03:38 PM
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Thanks for the explaination Amir.
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Amir,

Thank you very, very much for the highly informative read. Like f300v10, I also would like some recommendations on books/publications to read more about the subject.

Thanks again .
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Quote:
Originally Posted by restart View Post

Amir, did Tom McMahon not clairfy the ABT vs. 8x8 issue before?

http://archive2.avsforum.com/avs-vb/...&&#post6594314

"Finally, we didn't even make up an 8 bit 4:2:0 High Profile (which is the High Profile under discussion here) using the 8x8 transform until July of 2004. What we ended up over a year later was ***NOT*** ABT. It was only the addition of an 8x8 transform to the Standard (incidentally, variations on the 8x8 transform had been proposed by FastVDO and others well before ABT itself, in January of 2002 I believe)." - Tom

The key part of what Tom is saying is the same as what I mentioned. That is, 8x8 blocks were added in HP profile. He says this is not ABT but adaptive block size is just that, it lets the codec decide (adapt) which block size is better: 4x4 or 8x8. But if one assumes that Tom is saying the codec can only use one or the other, or not adapt, then that makes AVC weaker, not better . Alas, my understanding is that AVC encoders in use do indeed sport an adaptive algorithm to pick the appropriate block sizes like VC-1.

The only thing I can think of is that Tom is saying the baseline profile, does not use ABT. That would be correct since the baseline only allows one block size: 4x4.

Tom does point out something I forgot to mention. That is, other block sizes were proposed for standardization in the baseline profile. But the AVC team thought they would not be advantageous to have. So they were dismissed -- only to be added later in HP, when evidence to the contrary became available.

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PS: I wish Tom well in his recovery.

Me too .

Amir
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