Will Blu-ray's space advantage be an advantage for long movies? - High-Def Digest Forums
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Old 08-07-2007, 06:43 PM
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Default Will Blu-ray's space advantage be an advantage for long movies?

This is a question that came up in another thread, the thread whether or not 30 GB is enough. I think it is an interesting question that deserves some exploration in its own thread.

The question is:
Will Blu-ray's space advantage be an advantage for long movies?

Many here think so. This is not a personal attack, but zzap64 has been the most vocal on this point, so I will use a quote he wrote:

Quote:
Originally Posted by zzap64 View Post
30GB is okay if your movie is under 2.5 hours. Anything over that and you are compromising the picture quality by using a low bitrate. Blu-ray can hold a 4 hour movie on a 50GB disc without compromising the bitrate.

The problem with HD DVD is the maximum bitrate ceiling is 30mbps, which is not very high. Blu-ray has a much healthier maximum bitrate of 48mbps. When watching the Pirates movies the bitrate regularly goes over 40mbps during action scenes. If the Pirates movies were encoded on HD DVD there would be a lot of information discarded through both the 30GB and 30mbps ceiling.

Blu-ray is able to present a movie closer to the HD master than HD DVD. With that fact alone I prefer Blu-ray.
Now if we consider the limit of a "properly done" movie on HD-DVD to 2.5 hours, that would work out to about 12 GB per hour of video AND audio. We know from the Matrix that you can fit a movie almost 2.5 hours long with lossless audio, so this is not a contestable point. At that rate, 12 GB per hour, that would mean Blu-ray could hold approximately (50/12=4.1667 hours) 4 hours and 10 minutes of the exact same quality video.

Here comes the problem. That 4 hours and 10 minutes is only possible if using the exact same bit rate and TrueHD lossless audio that would be on the HD-DVD. Increasing the bit rate or using PCM will bring that 4 hour limit down very quickly.

For example, the Lord of the Rings Trilogy: (theatrical/extended)
LOTR-FOTR = 178/208 (extended) 2 hours 58 minutes/3 hours 28 minutes.
LOTR-TTT = 179/223 (extended) 2 hours 59 minutes/3 hours 43 minutes.
LOTR-ROTK = 201/251 (extended) 3 hours 21 minutes/4 hours 11 minutes.

Many BD fans have screamed that LOTR could not possibly be given adequate treatment on HD-DVD, and they are right...on 1 HD-DVD. It could easily be treated properly on 2. Especially the last movie would take a severe hit in PQ if it were attempted to be put on 1 disc. Some BD fans then rage about the idea of a movie spread over 2 discs, and will then brag a Blu-ray could easily handle it...but could it really?

PCM is a space hog, which would cut BD's maximum high quality video to well under 4 hours, and any improvement in the steady bit rate would hamper it's ability as well. This means that even a BD-50 CANNOT handle the extended cuts of these movies if given the higher bitrate and PCM treatment BD fans brag about. They could most likely handle the theatrical versions, but only if the bit rate were kept around where HD-DVD would be able to keep it over 2 discs!!!

In short, BD cannot have both advantages when it comes to long movies. Either you have more capacity and can fit a longer movie, or you can maximize the bit rate and use PCM. If you try to do both, you may find LOTR split over 2 Blu-rays, just like the HD-DVD version would have to be.

So make your choice...either you want 1 BD disc with the exact same quality HD-DVD gets, or you get the PCM audio and incredible bitrate advantages that Blu-ray can offer...on 2 discs just like HD-DVD. One advantage or the other, but not both.

DISCLAIMERS (PLEASE READ BEFORE POINTLESS ARGUMENTATIVE POSTS):
-This is not an argument that HD-DVD is equal to Blu-ray, or an argument that 30 GB is enough. Blu-ray does have a space advantage, and they also have a bitrate advantage. I have simply been noticing that BD fans brag about these 2 advantages being able to happen at the same time even on long movies, whereas this does not appear to be the case.
-Obviously, on a movie of normal length, the bitrate advantage and ability to use PCM would be clear. This post is not about normal length movies.

This is intended to be a discussion point, not an argument point. This is something I would like to discuss, so let's keep sarcasm out of it if possible. And if you have a problem with the math, please explain why, and I will adjust this original post if necessary. But remember, the basis of this math was taken from a staunch Blu-ray supporter.
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Old 08-07-2007, 06:51 PM
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Is that a fact though? That the longest movie a BD can hold at its highest quality is 4 hours and for HD DVD its 2.5? I wasn't aware if thats the case, it seems like they'd both be able to hold more to me.
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Old 08-07-2007, 06:55 PM
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Quote:
Originally Posted by Mr.Speed29 View Post
Is that a fact though? That the longest movie a BD can hold at its highest quality is 4 hours and for HD DVD its 2.5? I wasn't aware if thats the case, it seems like they'd both be able to hold more to me.
Well, that's my question! Many BD fans say that long movies will not fit on HD-DVD, and give about 2.5 hours as the max...or else the PQ will start suffering. But if that is the case, then my above post happens...which will they prefer? If BD can handle anything on 1 disc, then that increases the length of what HD-DVD can handle and makes 3 hours and more possible and disproves their argument.
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Old 08-07-2007, 06:55 PM
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Quote:
Originally Posted by pkremer View Post
So make your choice...either you want 1 BD disc with the exact same quality HD-DVD gets, or you get the PCM audio and incredible bitrate advantages that Blu-ray can offer...on 2 discs just like HD-DVD. One advantage or the other, but not both.
Yes, that's fine. 1 BD disc for a four hour movie with the same quality that HD DVD offers a 2.5 hour movie seems fine and is certainly something HD DVD can't deliver.

Alternatively, a long movie split over 2 discs with maxed-out specs is also delivering advantages unique to blu-ray.

I've never contende that 50 Gb is enough space, you can always use more. What is certain is that 50Gb gives studios more options and less compromises when encoding super long movies.
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Old 08-07-2007, 06:57 PM
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Quote:
Originally Posted by pkremer View Post
Well, that's my question! Many BD fans say that long movies will not fit on HD-DVD,
Or more accurately, that very long movies will not ft on HD DVD without obvious compromises.
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Old 08-07-2007, 06:59 PM
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If most movies were over 3 hours long, then the extra capacity would obviously be a major factor. But they are'nt, so having to put up with 2 discs on a very infrequent basis would not really be a deal breaker for me personally.
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Old 08-07-2007, 07:22 PM
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To talk intelligently about this topic, we need to establish a few things.

First, runtime for The Matrix is 136 minutes (2 hrs, 16 min) that's about 11% shorter than the runtime used in your initial calculation.

Second, "properly done" isn't a precise measure. Hot Fuzz is only 15 minutes shorter than The Matrix, got top marks in PQ and AQ AND packed 18 hours of special crap onto its disc (including hours of SD video). To me, that means that a high quality transfer is possible at less than 12 GB per hour.

Bit rate is a far better measure, especially since HD DVD's throughput is less than BD. Since your conversation doesn't use bitrate as a measure and relies on a faulty initial calculation for storage capacity, I'm not sure how it holds up.

Using YOUR methodology however, I would say that given a much-touted five star visual presentation of a two-hour movie with 18 hours of additional soundtracks, video, stills and everything else, the real data used FOR THE MOVIE is closer to 17-18 GB on HD. Even if it's 20 GB for the movie-only content, BD has MORE than enough space for the 4 hr 11 ROTK:Extended runtime... with some room to spare for a Possible uptweak in PQ.

HD-DVD would have no choice however in using a second disc... no matter what. What are your thoughts?
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Old 08-07-2007, 07:25 PM
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Originally Posted by Office Ed View Post
If most movies were over 3 hours long, then the extra capacity would obviously be a major factor. But they are'nt, so having to put up with 2 discs on a very infrequent basis would not really be a deal breaker for me personally.
I just think about movies like:

Kill Bill (the whole bloody affair)
Grindhouse
Lord of the Rings
Troy Extended Edition
Alexander extended edition (I don't actually want this, but it fits)
The Sound of Music
Fiddler on the Roof
Titanic (don't really want this one either, but I'm sure plenty do)
Ben Hur

There are plenty situations where multiple discs are needed for the whole movie, and that's not even looking at TV series'.
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Old 08-07-2007, 07:28 PM
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Quote:
Originally Posted by Office Ed View Post
If most movies were over 3 hours long, then the extra capacity would obviously be a major factor. But they are'nt, so having to put up with 2 discs on a very infrequent basis would not really be a deal breaker for me personally.
I have a feeling that more and more studios will be adding HD extras in the very near future

With that said, a 2-2.5 hour movie with another 2+ hours of HD extras, a lossy track, a lossless track, and room for AACS/BD+ and other extras and subtitles and 30GB get full pretty quickly.
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Old 08-07-2007, 07:38 PM
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Quote:
Originally Posted by AltonDarwin View Post
First, runtime for The Matrix is 136 minutes (2 hrs, 16 min) that's about 11% shorter than the runtime used in your initial calculation.
Well, actually the only reason I used the Matrix is to establish that not only can there be 5-star video, there can also be a 5-star lossless audio track. About the run time, though...there were hours and hours of special features on the Matrix discs (Complete version), so I believe it could have handled 2.5 hours without a problem.

Quote:
Originally Posted by AltonDarwin View Post
Bit rate is a far better measure, especially since HD DVD's throughput is less than BD. Since your conversation doesn't use bitrate as a measure and relies on a faulty initial calculation for storage capacity, I'm not sure how it holds up.

Using YOUR methodology however, I would say that given a much-touted five star visual presentation of a two-hour movie with 18 hours of additional soundtracks, video, stills and everything else, the real data used FOR THE MOVIE is closer to 17-18 GB on HD. Even if it's 20 GB for the movie-only content, BD has MORE than enough space for the 4 hr 11 ROTK:Extended runtime... with some room to spare for a Possible uptweak in PQ.
But don't forget...my initial calculation (which you consider faulty) was created by a BD fan who specifically and authoritatively said that if a movie surpassed 2.5 hours, it would result in a serious loss of bit rate (and thereby PQ).

Second, don't forget that PCM is a space hog. For every minute of movie there is, there is another minute of uncompressed PCM that needs to fit on the same disc. Let's assume what you said, a potential 20 GB for 2 hours. A 4 hour 11 minute movie with NO bit rate tweak would then take 41 GB just for video! On top of which you would then need to add lossless PCM and a 5.1 track for people unable to take advantage of it. Would 4 hours of PCM and 4 hours of 5.1 audio fit inside the 9 GB that are left? And even if they could fit, don't forget that you haven't tweaked the bit rate at all yet! Meaning you will end up with an equal transfer to HD-DVD to keep it on 1 disc, hence negating the bit rate advantage!

If on the other hand, we go lower, and figure 8 GB for video on HD-DVD, then that would make it about 34 GB for video for LOTR extended cut, plenty of room for the PCM and a tweaked bitrate. But if you make that concession, that also means that HD-DVD could fit over 3 hours of 5-star PQ and lossless audio, which takes care of the vast majority of movies, hence making 30 GB enough for just about every movie out there, destroying a HUGE argument for BD fans...do you want to do that?

You are right, though...HD-DVD would have no choice but to use 2 discs.
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