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iTunes HD videos low bitrate, include iPod-ready versions - Page 3

post #81 of 97
I have the free episode of Battlestar Galactica. The HD file is 720p It is definitely crisper than the SD version but definitely not up to the quality of the HD DVDs of the first season. It's hard to do frame grabs, no way to step frames so screen caps match the same frame.
post #82 of 97
Quote:
Originally Posted by dfiler View Post

The interlacing you see on most TV shows is that of normal frames split perfectly into two fields. Only live broadcasts are every temporally accurate individual fields... and i'm not sure if even that is true anymore. For one, any show shot on film has no greater temporal accuracy by going the interlaced route. (most primetime scripted programming)

I'm not sure what you mean by temporal accuracy. But in general providing more frames of information within a given time does appear as a sharper image to the eye, which is an increase in temporal resolution.

Quote:
Next, while you are correct about 24fps being too slow for convincing motion pictures, it isn't played back at 48fps except in movie theaters with real projectors. These projects do flash the same frame twice in succession. However this isn't true for any other type of display. Other displays just hold the image for a 24th of a second. Except that most displays don't have a refresh rate that is a multiple of 24. Granted phosphorous glow of CRT screen elements do decay in brightness between scans. But they aren't really flashing the frame twice either.

Yes it isn't literally played back at 48fps. Even in a movie theater the film is still run at 24fps and a double leaf shutter splits the image to trick the eye into seeing 48fps.

Whatever you want to call it or whichever technique is used. A visual framerate above 24fps has to be played to fool the eye into seeing consistent motion.
post #83 of 97
Quote:
Originally Posted by GregAlexander View Post

I have to admit I haven't downloaded a TV show, just movies.
I'm also wondering if you definitely got the HD version - or did you purchase via the shopping cart which seems to be sending people the SD version (as discussed 10-15 posts above).

No, I definitely got the HD version. I just double-checked.

Quote:
Originally Posted by GregAlexander View Post

The quality of broadcast FTA changes in different areas too. As I understand it, the cable networks recompress FTA HD to a lower bitrate, while the broadcast FTA is usually clearer. In Australia we get about 12Mbps MPEG2 on FTA HD, and I think that's compressed on the fly during transmission. In comparison iTunes' HD is 4.5Mbps MPEG4, pre compressed.

Apple's HD content is without a doubt more pixelated, and softer than broadcast HD. It also suffers from severe blocking that I've never seen in a broadcast, although because this can usually only be seen in large solid areas that aren't the focus of the picture, I find it to be less of an issue than the overall softness of the image It's the overall lack of sharpness and the pixelation that leaves internet-based HD content looking like nicely-upscaled DVDs rather than high definition.
post #84 of 97
I watched the Heroes sample HD episode, I think its video quality was better than that of the BSG sample HD episode. Pretty nice. itunes can be annoying though, it asked for my authentication for each HD episode, not something I like to see if I need to have confidence that I can ever play the episode again.

Quote:
Originally Posted by dfiler View Post

Anyway, how this pertains to iTS is that I'm curious which content is at native frame rate. Are any shows encoded at 24fps. (not that I have a display that is capable of temporally accurate playback of 24fps content. (the iMac and mac portables aren't capable)

It would be nice though if apple were forward thinking enough to provide iTS video content at native frame rate, knowing that someday people might be able to take advantage of it.

Why do you want them to offer higher for sale when there isn't much out there that can even play it? I have an original Mac Pro and it had troubles at times. If I only move the the floating window it stutters for a few seconds.

The frame rate just stuck to an old standard, but it's handy to have because of the demands of higher framerates. Even going to 30 is going to increase bitrate, file size and computational demands by 25%.
post #85 of 97
Quote:
Originally Posted by JeffDM View Post

I watched the Heroes sample HD episode, I think its video quality was better than that of the BSG sample HD episode. Pretty nice.

What are the resolutions and bitrates?
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post #86 of 97
Quote:
Originally Posted by solipsism View Post

What are the resolutions and bitrates?

Almost the same for both shows. Both are 1280x720. BSG: He That Believeth in Me is 4489 kbps, Heroes: Four Months Later... is 4439 kbps. I think the differences in cinematography might be the biggest factor here, BSG is dark, grainy and heavy on the jerky-cam. Heroes has a lot more bright scenes, not so heavy on grain and I think they actually use a tripod.
post #87 of 97
Quote:
Originally Posted by JeffDM View Post

...
Why do you want them to offer higher for sale when there isn't much out there that can even play it? I have an original Mac Pro and it had troubles at times. If I only move the the floating window it stutters for a few seconds.

The frame rate just stuck to an old standard, but it's handy to have because of the demands of higher framerates. Even going to 30 is going to increase bitrate, file size and computational demands by 25%.

We weren't talking about _higher_ frame rates, but rather _native_ frame rates.

Shows shot on film are at 24fps. Almost all current displays and all current broadcasts via OTA, cable, satellite, etc... are all at 30fps or 60fps. This makes it impossible to watch these shows or movies at their native framerate. Motion appears more jerky and less convincing. This compounds the problem of 24fps being so close to threshold of perceivable individual images.

When people say that they see jerky motion (judder) while watching 24fps movies, part of what they are experiencing is also non-native frame rate. Half of the frames are displayed longer than intended while the other half of frames are displayed shorter than intended. When movies are converted to PAL, there are different trade-offs. If playback is sped up by 4%, then all frames can be displayed for the same amount of time. Make the 24fps into 25fps and it fits nicely into 50hz. The same isn't possible when going from 24fps to the 60hz like is needed in America (and other NTSC based countries).

HD resolution is likely be high enough, for most people, for the foreseeable future. Further increases will have diminishing returns in terms of perceived improvement in quality. Perhaps the public will latch onto more complex metrics kind of like how "the megahertz myth" is finally being understood by more and more of the masses. For video, this will mean that people will start caring less about resolution and more about things like bit-rate and native frame rate. In my opinion, the HD specs should have at least included a classification system for bit-rate. All 720p or 1080i weren't created equal. ;-)

Can anyone report if apple is using 24fps encoding for any TV shows?
post #88 of 97
Quote:
Originally Posted by dfiler View Post

Can anyone report if apple is using 24fps encoding for any TV shows?

I can't speak for the encoding, but the playback is stated as being 24fps for the AppleTV. I assume this would be for the desktop, too. This is well outside of my scope. Hope that helps.
http://www.apple.com/appletv/specs.html
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post #89 of 97
Quote:
Originally Posted by solipsism View Post

I can't speak for the encoding, but the playback is stated as being 24fps for the AppleTV. I assume this would be for the desktop, too. This is well outside of my scope. Hope that helps.
http://www.apple.com/appletv/specs.html

Are you saying the appleTV is reporting it as a 24fps clip? Or simply that the specs of the appleTV support 24fps?

(If the former, it is doubtful that "playback" was actually at 24fps. That is, unless you spent many thousands on your display and bought it within the last couple years.)
post #90 of 97
Quote:
Originally Posted by dfiler View Post

Are you saying the appleTV is reporting it as a 24fps clip? Or simply that the specs of the appleTV support 24fps?

(If the former, it is doubtful that "playback" was actually at 24fps. That is, unless you spent many thousands on your display and bought it within the last couple years.)

I have no idea what it means on the whole, I can only tell you want it says. I put the link in my post.
Video formats supported
  • H.264 and protected H.264 (from iTunes Store): Up to 5 Mbps, Progressive Main Profile (CAVLC) with AAC-LC audio up to 160 Kbps (maximum resolution: 1280 by 720 pixels at 24 fps, 960 by 540 pixels at 30 fps) in .m4v, .mp4, and .mov file formats
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post #91 of 97
Quote:
Originally Posted by solipsism View Post

I have no idea what it means on the whole, I can only tell you want it says. I put the link in my post.[INDENT]Video formats supported

It took me a bit to understand WTF was being requested, but I think it's the display framerate, and I don't see it:

Compatible with enhanced-definition or high-definition widescreen TVs capable of 1080p/1080i 60/50Hz, 720p 60/50Hz, 576p 50Hz (PAL format), or 480p 60Hz,

I think Apple does stick to 60Hz on their displays, I'm not sure if the LCD controller of most computer displays can handle 72Hz actual refresh.
post #92 of 97
Quote:
Originally Posted by solipsism View Post

I have no idea what it means on the whole, I can only tell you want it says. I put the link in my post.

Thanks. From my reading, that's just what can be played, not what is actually available from the iTS.
post #93 of 97
Quote:
Originally Posted by dfiler View Post

Are you saying the appleTV is reporting it as a 24fps clip? Or simply that the specs of the appleTV support 24fps?

(If the former, it is doubtful that "playback" was actually at 24fps. That is, unless you spent many thousands on your display and bought it within the last couple years.)

Quicktime reports framerate of 23.98fps, playback at 24fps (of course, my monitor isn't doing 24hz)

This was for an episode of New Amsterdam purchased last year and an episode of Jericho. Both were Standard Definition. I also downloaded the free HD episodes of Battlestar & Psych - both also report the same framerate for HD and SD versions.

I'm surprised that the standard def shows are 24, not 30.

Apple said that the maximum framerate of AppleTV for 1280x720 files is 24fps. It turns out that 1280x720 works at 25fps too, for PAL countries (I suppose they've updated the website since then).

ps. Many high end TVs advertise being able to extract the 24fps from a 60hz signal. I helped set up my father and brother's TVs (and my own) and one of them displayed at 72hz - so an even 3 frames per cycle after a 3:2 pulldown.
post #94 of 97
Quote:
Originally Posted by GregAlexander View Post

Quicktime reports framerate of 23.98fps, playback at 24fps (of course, my monitor isn't doing 24hz)

I didn't think to check Qucktime. I see the same numbers for the videos I have as well.

As far as I know, my projector won't do any fancy inverse telecine, but it is spec'd to take in a 24fps video signal. I think it operates at 72Hz refresh.
post #95 of 97
Thanks everyone, that is excellent news. I wouldn't have been suprised if movies were native fps. But hearing that TV shows are as well? (even when never shown on TV at the native fps) Excellent.

An interesting comparison would be iTS content actually displayed at 24 fps vs. a full bandwidth equivalent. The full bandwidth version would be more detailed but also at non-native frame rate.

Most people have no clue whether they're more perceptive of low bit rates or of the 3:2 pulldown. Hell, most people have never even seen TV shows at a native frame rate. It'll be a while before we know for sure since most 120hz displays don't do proper 24fps even when they claim that they do.

I probably sound like a lunatic... but mark my words, in a few years, everyone will be all about the native frame rate.
post #96 of 97
Quote:
Originally Posted by dfiler View Post

Most people have no clue...

When it comes to this topic I have no clue.
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post #97 of 97
I know video was traditionally 60 interlaced low res frames, film has been 24 progressive frames. Movies have largely stayed that way - tests of 60 progressive frames have subjects reporting that 24 looks more realistic to them.

Also, 24 progressive frames are simply de-interlaced from a 1080i signal so they display as perfect 1080p pictures (while material filmed interlaced can't be de-interlaced so easily).

For TV it's not so easy and they've been playing with lots of combinations. It seems they're mainly filming at 1080 but is it progressive or interlaced? 30 frames? 24 frames? 60frames (I know 1080p60 is a goal.. then they can convert it to any signal they want).

Wonder what rates Psych/Battlestar/NewAmsterdam are filmed at?

It looks like Apple converts whatever they've got to be
1) progressive
2) 24 fps
3) 1280x720 for HD, or
640x480 or 640x360 for SD (both resolutions support widescreen now).

I wonder if they do 25fps for England/Australia/etc
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