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Improved H.264 Compression Holds Down File Sizes on 1080p iTunes Store Content

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Apr 12, 2001
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Ars Technica takes a look at the new 1080p content available on the iTunes Store, showing how a "High" compression profile for H.264-encoded content on the iPhone 4S and new iPad and Apple TV are minimizing the increase in file size needed to move from 720p to 1080p.




Comparison of 720p (left) and 1080p (right) video quality in iTunes Store content
In a survey of several titles now available in 1080p on the iTunes Store, the report found that file sizes generally increased by 15-25% over their respective 720p versions, despite the number of pixels more than doubling to reach the higher standard.
The reason that the 1080p versions of the iTunes Store videos can be a good deal better without doubling the file size--or worse--can be found in the tech specs of the new AppleTV and the new iPad. The AppleTV now supports H.264 compression for 1920x1080 resolution video at 30 frames per second using High or Main Profile up to level 4.0, the iPad and the iPhone 4S the same up to level 4.1. The profile indicates what kind of decompression algorithms the H.264 decoder has on board--the "High" profile obviously has some tricks up its sleeve that the "Main" or "Baseline" profiles known to previous devices don't support. The level value indicates how many blocks or bits per second a device can handle.
The report also offers a comparison of video quality between the 720p and 1080p formats on the iTunes Store, noting that the increase in image quality for 1080p content is minor in many cases, but more significant in brighter scenes.

Article Link: Improved H.264 Compression Holds Down File Sizes on 1080p iTunes Store Content
 

tazinlwfl

macrumors regular
Jul 14, 2008
219
154
Florida
Not bad. There is some definite improvement there. I just wish they would bump it up across the board to 5.0

At least 4.1 on the ATV.
 
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SB27

macrumors member
Feb 26, 2008
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The Hidden Side of Apple Value

The press mainly focuses on the hardware, sales figures, etc. What people miss about the value that Apple is delivering to customers can be found in this story. At every turn and in every nook and cranny of the Apple ecosytem, their engineers are finding ways to deliver better bang for the buck. Video compression is just one of thousands of ways that Apple thinks completely differently about the user experience than anyone else. This is why they are a $500B company.

I was also struck while watching the keynote for the iPad by the amount of energy and focus put into iLife and iWork. That stuff is simply amazing for only $4.99 a copy (and with mostly free upgrades).

Yes, we are trapped in a closed Apple ecosytem. I like to think of myself as "happily trapped" given the sheer amount of energy, dollars, focus and excellence being delivered in every aspect of their ecosystem.

I will put the pom-poms down now, but this story prompted a visceral reaction and I felt it was worth noting.
 
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kolax

macrumors G3
Mar 20, 2007
9,181
115
Looks like the sharpness is increased - I don't see any better clarity. Colour is more saturated which I guess is a good thing.
 
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CZSZSZ

macrumors member
Jan 27, 2010
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Comparison should be between how and high compression of 1080p format, to be meaningful.
 
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luke.mac1

macrumors member
Jun 1, 2011
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United Kingdom
noting that the increase in image quality for 1080p content is minor in many cases, but more significant in brighter scenes.

So what they're saying is that the difference between 720p and 1080p in the iTunes store is almost negligible? I mean you can see the difference there on the scaled up image, but I imagine you can't really see it on a small screen. Maybe it will be better on a 27" imac or 50" HDTV.
I still think they should offer a larger, higher quality file size for people who wish to download it... maybe something to select in the preferences section of iTunes...
 
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3282868

macrumors 603
Jan 8, 2009
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I downloaded 1080P versions of my movies from iTunes and played them on my system (have a 1st gen aTV with a Crystal HD card for 1080P/DTS content on my 60" Pioneer Elite). Truthfully, I saw little difference between the 1080P and 720P iTunes versions, yet a major difference between my 1080P handbraked encodes and direct Blu-Ray movies.

Again, let me reiterate as some have misread my comment. My first gen Apple TV is hacked, using an after market Crystal HD video card in place of the WiFi card in order to play my 1080P DTS mkv's, without it the unit simply crashes. :)
 
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bacaramac

macrumors 65816
Dec 29, 2007
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Ha, I was wondering how they were doing this. Glad to see the file size didn't jump too much as I plan to re-download my good HD movies in 1080P.
 
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chrono1081

macrumors 604
Jan 26, 2008
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Isla Nublar
How can you tell if something is in 1080p on the store or not? I haven't seen anything that differentiates between 720 and 1080.
 
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swarmster

macrumors 6502a
Jun 1, 2004
625
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Looks like the sharpness is increased - I don't see any better clarity. Colour is more saturated which I guess is a good thing.

You can click through for another comparison with "brighter scenes" referenced in the article.

720p


1080p
 
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illitrate23

macrumors 6502a
Jun 11, 2004
572
130
uk
must go to the eye doctors - i can't really see any difference in clarity between the pictures. possibly the colour is better on the right one?

still, i guess at least i can feed good about sticking with my AppleTV2 for the time being then :)
 
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Deadman64

macrumors 6502a
Jun 2, 2008
613
60
I downloaded 1080P versions of my movies from iTunes and played them on my system (have a 1st gen aTV with a Crystal HD card for 1080P/DTS content on my 60" Pioneer Elite). Truthfully, I saw little difference between the 1080P and 720P iTunes versions, yet a major difference between my 1080P handbraked encodes and direct Blu-Ray movies.

I think that would be a good comparison.

1080P iTunes/Apple TV vs. a 1080P Blu-Ray.
 
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iBug2

macrumors 601
Jun 12, 2005
4,220
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It's a minor improvement as I have compared around 20 tv episodes of various shows yesterday.

But I'd still prefer 1080p in any case. As long as it doesn't get "worse" while it's going sharper, higher res is better. And I haven't found considerably more artifacts on 1080p rips so far.
 
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11thIndian

macrumors regular
Oct 5, 2007
166
0
Hamilton, Ontario
Comparison should be between how and high compression of 1080p format, to be meaningful.

It has to be both those things. Knowing the compression is interesting, but ultimately it's all about the image in motion. Even stills give a skewed sense of quality. The only way to get a great still is to have basically no compression.
 
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nuckinfutz

macrumors 603
Jul 3, 2002
5,502
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Middle Earth
must go to the eye doctors - i can't really see any difference in clarity between the pictures. possibly the colour is better on the right one?

still, i guess at least i can feed good about sticking with my AppleTV2 for the time being then :)

The text on the bottle. The color looks the same but the text and other fine detail will be better often on 1080
 
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commander.data

macrumors 65816
Nov 10, 2006
1,021
113
Not bad. There is some definite improvement there. I just wish they would bump it up across the board to 5.0

At least 4.1 on the ATV.
I wonder why they only support 4.0 on the new Apple TV given it's using the Apple A5 albeit single core? H.264 decoding on SoCs is done by a dedicated video decoder unit so less CPU or GPU cores shouldn't be the determining factor.
 
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