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PabloSRT8

macrumors member
Original poster
Aug 25, 2016
69
48
Does anyone know the size of a 4k movie from iTunes vs the size of a Blu-ray 4k?
Thanks.
 

HobeSoundDarryl

macrumors G5
There's no set answer to this beyond "considerably smaller." Every movie vs. movie will have a different answer, be that a comparison of streaming vs. disc version or even one streaming movie vs. another streaming movie.

The BD version is going to be considerably larger because it contains the added detail that comes with less compression. The disc doesn't have to worry about squeezing through the constrained pipes of some consumer's slow(er) broadband connections. The BD author can use up to ALL of the available space on the disc for the movie.

On the other hand, the streaming file author is probably trying to target some arbitrary tradeoff of quality vs. file size to maximize playback capability for even those with relatively slow broadband connections. How do they do this? One way is to squeeze compression much more than disc (which throws out detail). Another way is trade higher quality audio for lower quality. Etc. One can do the same kind of thing by ripping the disc and then putting the squeeze on compression, throwing out various audio options, etc to turn a large file into a smaller file (albeit by sacrificing visual & audio quality).

For a blanket guess at a generic answer to this question, I'm going to guess that the target will generally be to make the streaming version about 2/3rds or more smaller than the same movie on disc. But maybe some people who have the discs can compare to the iTunes versions and start offering some specific numbers. I expect such comparisons to be all over the place because- compressed or not- different movies will have different outcomes even with the same compression variables applied. For example, if my guess is right, this means I would expect some streaming versions to weigh in at maybe 15%-20% of the disc version while others might get up toward 40%-50%, averaging out to about 1/3rd over many movies. But again- just a guess.
 
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2010mini

macrumors 601
Jun 19, 2013
4,698
4,806
There's no set answer to this beyond "considerably smaller." Every movie vs. movie will have a different answer, be that a comparison of streaming vs. disc version or even one streaming movie vs. another streaming movie.

The BD version is going to be considerably larger because it contains the added detail that comes with less compression. The disc doesn't have to worry about squeezing through the constrained pipes of some consumers slow(er) broadband connections. The BD author can use up to ALL of the available space on the disc for the movie.

On the other hand, the streaming file author is probably trying to target some arbitrary tradeoff of quality vs. file size to maximize playback capability for even those with relatively slow broadband connections. How do they do this? One way is to squeeze compression much more than disc (which throws out detail). Another way is trade higher quality audio for lower quality. Etc. One can do the same kind of thing by ripping the disc and then putting the squeeze on compression, throwing out various audio options, etc to turn a large file into a smaller file (albeit by sacrificing visual & audio quality).

For a blanket guess at a generic answer to this question, I'm going to guess that the target will generally be to make the streaming version about 2/3rds or more smaller than the same movie on disc. But maybe some people who have the discs can compare to the iTunes versions and start offering some specific numbers. I expect such comparisons to be all over the place because- compressed or not- different movies will have different outcomes even with the same compression variables applied. For example, if my guess is right, this means I would expect some streaming versions to weigh in at maybe 15%-20% of the disc version while others might get up toward 40%-50%, averaging out to about 1/3rd over many movies. But again- just a guess.

Is there a usual range for HEVC files?
 

PabloSRT8

macrumors member
Original poster
Aug 25, 2016
69
48
I think I hear HEVC is almost half somewhere.

And 2010mini, yes, I meant to say of the same movie.

Thank you!
 

HobeSoundDarryl

macrumors G5
Again, there won't be one answer to the question. Each movie processed for HEVC is likely to yield a different result through whatever compression level is chosen for the iTunes version. More simply, the generality about HEVC is that it can fit the same movie into about 1/2 to 2/3rds of the space of an h.264 version.

And the original question appears to be 4K iTunes file size vs. 4K Blu Ray file size. If I'm not mistaken 4K Blu Ray is using HEVC. So this won't be the 1/2 to 2/3rds generality of H.265 vs. H.264. Instead, I think it's generally going to be h.265 rendered with much consideration for modest streaming bandwidth potential issues (iTunes) vs. h.265 rendered for up to all of the available space on a 4K Blu Ray disk.

In short: if you get a single movie response, all that tells you is the difference of the iTunes render vs. the Blu Ray render for that one movie. Let's say some movie comes it at 50% smaller in the iTunes render. That won't automatically mean that all iTunes versions will be 50% smaller than their Blu Ray equivalents- just that one movie worked out that way.

And again, key concept here is not some great innovation in the iTunes render yields a much smaller file- just much more compression to have a better chance at working well with relatively limited bandwidth pipes. If file size trumps quality, one can always squeeze the larger Blu Ray version even further than the iTunes target file size to achieve almost any target file size. Quality just gets worse and worse as more details are jettisoned in the name of compression.
 
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iDento

macrumors 6502a
Sep 8, 2011
855
1,472
iCloud Servers
Generally, the size of an 1080p movie from iTunes is 4.5 GB with 5000 Bitrate, using h.264. What, in general, is the size of a 4K movie?
 

BODYBUILDERPAUL

Suspended
Feb 9, 2009
1,773
1,438
Barcelona
Generally, the size of an 1080p movie from iTunes is 4.5 GB with 5000 Bitrate, using h.264. What, in general, is the size of a 4K movie?

Well, here goes... I buy 4K h.264 films from VIMEO. They average 8 to 9GB per 60 minutes. So a 2 hour film could be 18GB. Vimeo's compression is SLIGHTLY smaller file than an iTunes equivalent in 1080p (around 400mb).
Now, h.265 is SMALLER than h.264 in size BUT you have to allow for a larger size due to DV/HDR. An iTunes 1080p film on my iPhone X is 4.5GB with the DV 1080p HD file coming in at 6.5GB.

So is it safe to say that a 2 hour iTunes 4K DV film should not be larger than 20GB? Bearing in mind that it temporarily downloads/caches to the ATV 4K whilst playing - works on a 32GB ATV 4K BUT and here's the but, Apple RECOMMENDED The 64GB ATV 4K model 'If you are going to be watching a lot of 4K iTunes film'.

Surely, if you stream ONE iTunes 4K film, you can check it on your broadband breakdown of usage on your daily usage page? That would be able to inform you instantly.
 
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