What does anamorphic do???

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powerbook911
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What does anamorphic do???

Post by powerbook911 »

Hi,

I encode for iPhone and Apple TV.

However, I do not understand anamorphic. I understand what it does on a DVD, but what does it do with a H264 file? I don't understand. Should I select anamorphic, or not?

Thanks!!!

Also, my name is powerbook, but I don't encode with Powerbook, so don't worry, I know that would be really slow.

Also, I don't understand the difference between "main" h264, iPod h264, x264, etc. ? They all play on a computer and AppleTV can play the main and ipod one. What is actually different in them? Thanks.

I'm an idiot, but I have used handbrake for 2 years + haha.
PuzZLeR
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Re: What does anamorphic do???

Post by PuzZLeR »

However, I do not understand anamorphic. I understand what it does on a DVD, but what does it do with a H264 file? I don't understand. Should I select anamorphic, or not?
You have to do some reading on PAR (pixel aspect ratio) to truly understand this. As an intro: a PAR of 1:1 means that the pixels are square (height=width). This is actually the norm for stuff that is only for PC playback and the only PAR that Apple TV and iPod support.

Now in NTSC land, most DvDs have a resolution of 720x480, yet may have an display aspect ratio (DAR) of 4:3, or 1.33, however doing the math 720/480 is not 1.33. To make it "fit", you have to change the shape of the pixels from 1:1 to 8:9. (Do the math.) If you select anamorphic, HB will automatically do this for you. If you instead input 720x480 but don't select anamorphic, HB will assume a PAR of 1:1 and you will get a picture with "fatter" characters. If you must use a PAR of 1:1, you're better off encoding 4:3 material to instead 640x480.

Similar scenario for movies with a DAR of 16:9 (1.77). If the rez is 720x480 and you select anamorphic, HandBrake will change the shape of the pixels to PAR 32:27 to make it "fit". (Do the math again.) Otherwise, if you want to select square pixels, then encode at 640x360, or rather 640x352 to make it all divisible by 16 (compatibility).

There is a "flag" in the video stream that tells the playback device of what the PAR will be. If there is no "flag", or the device doesn't read it, it will assume a PAR of 1:1, so make sure you know in advance what your device or decoder supports.

I personally prefer anamorphic - much more natural to the DvD source. Unfortunately Apple devices don't support it (yet). It's up to you.
Also, my name is powerbook, but I don't encode with Powerbook
You can call yourself whatever you want my friend. I will not judge you... :D
Also, I don't understand the difference between "main" h264, iPod h264, x264, etc. ? They all play on a computer and AppleTV can play the main and ipod one. What is actually different in them? Thanks.
The least common denominator is iPod H.264 which will play on all of them. However this profile is actually Baseline H.264. It has weaker settings, really only fit for a tiny device like an iPod is with limited hardware capabilities. Apple TV can handle higher complexity video than iPod, but still doesn't handle the full capabilities of Main profile. Full Main Profile has a feature called CABAC, which gives better compression, but is not supported by Apple TV.

H.264 is the standard. x264 is an implementation of the standard. HandBrake only uses the x264 "version" of H.264.
I'm an idiot
Careful. Someone may quote you on this... :D
powerbook911
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Post by powerbook911 »

Well an idiot on this video stuff at least. Thanks so much!

Yeah I was wondering if the iPod format was baseline that was confusing me a bit. Thanks for clarifying that.

The main profile for Apple TV then is not "real," so to say? Does that make the videos we include for Apple TV not as compatible than if it supported full main profile?

Many thanks.
hawkman
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Re: What does anamorphic do???

Post by hawkman »

PuzZLeR wrote:Apple TV can handle higher complexity video than iPod, but still doesn't handle the full capabilities of Main profile. Full Main Profile has a feature called CABAC, which gives better compression, but is not supported by Apple TV.
Sorry, that's not true. Of course AppleTV supports cabac, it's just a QuickTime box. There are no official video specifications published for h.264 with cabac on the AppleTV, though.

If you turn cabac off, h.264 uses something called cavlc instead. It's perfectly allowable and within-spec, just less efficient.
PuzZLeR
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Post by PuzZLeR »

powerbook911 wrote:Well an idiot on this video stuff at least. Thanks so much!
You're welcome. The "idiot" thing was just humor on my part... I'm known to fool around on forums. You see, I have this reputation...:-D
Yeah I was wondering if the iPod format was baseline that was confusing me a bit. Thanks for clarifying that.
Yes it is. Only the lowest profile of H.264 can be decoded by the iPod's tiny little hardware. I'm hoping this will improve in the next model. As well, although the iPod profile is Baseline, it's only a subset of Baseline. There's a difference between a Baseline Profile and an iPod Profile. Baseline is general. iPod Profile is Baseline with specific specs within the Baseline profile (such as rez, bitrate, etc.). Not all Baseline will work on the iPod, so you need to use the specific profile for it.
The main profile for Apple TV then is not "real," so to say?
Yes, exactly. Absolutely not "real" in my opinion - an example of Apple's twisted quirkiness. The Main Profile of H.264 typically uses CABAC, and although Apple TV allows Main Profile, it does not support CABAC. Main Profile without CABAC is, in my opinion, not too different from Baseline. That's like buying a high-end automobile with economy car features only. What's the point?
Does that make the videos we include for Apple TV not as compatible than if it supported full main profile?
Not sure what you mean but here goes. If a playback device supports H.264 "full" Main Profile with CABAC, it will also support H.264 Main Profile without CABAC (which would be CAVLC) but NOT the other way around. So, although "watered down", the video content created for Apple TV will be supported on current/future hardware that will support "full" Main Profile with CABAC. CABAC is not a different format of H.264 or a "different H.264". CABAC is a higher complexity of the H.264 format - better compression - which may need faster chipsets to decode. I assume within a few years all hardware will support CABAC automatically, and that will also include CAVLC ("non-CABAC") as well.

As well, just to briefly revisit anamorphic.

HandBrake will automatically detect for you whether it's a 4:3 (1.33) or a 16:9 (1.77) source. If you select anamorphic - fear not - HandBrake will adjust the PAR automatically for you.

However, if you choose to input your own resolution instead for output, keep in mind that without anamorphic selected, HandBrake will assume square pixels (PAR of 1:1). If your resolution is "off" you could end up with fat or thin characters. This is where a calculator comes in handy, however what I would do instead is use:

640x480 for 4:3 (1.33) content.
640x352 for 16:9 (1.77) content.

Whether to use anamorphic or not is entirely up to debate. The "safe" way is square pixels - wider compatibility and ALL devices/decoders and playback apps assume PAR of 1:1 automatically.

However anamorphic is more natural to the source and better viewing. What sucks is that some devices, including Apple decoders, don't recognize any PAR value other than 1:1 and will distort your image.

Sucks, I know.

Devices will adapt over time though...
rhester
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Re: What does anamorphic do???

Post by rhester »

PuzZLeR wrote:I personally prefer anamorphic - much more natural to the DvD source. Unfortunately Apple devices don't support it (yet). It's up to you.
Just one quick point here - I am currently unaware of any Apple playback device or software that doesn't grok anamorphic, though there may be limits (*cough*iPod*cough*) to the maximum physical horizontal resolution.

Rodney
hawkman
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Post by hawkman »

PuzZLeR wrote:The Main Profile of H.264 typically uses CABAC, and although Apple TV allows Main Profile, it does not support CABAC.
You just completely ignored my post, didn't you? Let me state it a little more clearly.

The AppleTV supports CABAC.
The APPLETV will correctly play back HandBrake's anamorphic output undistorted.

Jeez. There are some caveats regarding cabac, but it is completely untrue to say that it is not supported.
PuzZLeR
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Post by PuzZLeR »

Hey Hawkman.
hawkman wrote:You just completely ignored my post, didn't you?
No I didn't. Look at the times. You submitted your post while I was about to submit mine. Yes, there was a delay as I was working at the office in the meantime ... (shhhhhhhh)... Unfortunately, after I pressed "Submit" on mine, I didn't check to see if there was another one in between... My apologies my friend.

Now to finally address your point(s):
The AppleTV supports CABAC.
Not on mine. Maybe it's because I use Windows instead and QT there sucks, so it doesn't work well with mine, and as well according to the specs at apple.com right here, CABAC is NOT supported. Apple did not include CABAC in that page because they knew it wouldn't be supported throughout. I'm not one of the lucky ones with a Mac, which would indeed make a difference.

Actually I lied. Yes. It actually does support CABAC on mine - stutter, stutter, stutter, choke, freeze, ...., stutter, stutter, ..., freeze, ..., choke, ... , yes it does indeed "play" the content...
Jeez. There are some caveats regarding cabac, but it is completely untrue to say that it is not supported.
You're right. It's "completely untrue" to say it doesn't support CABAC. But "completely true" to say it supports CABAC half-assed.
The APPLETV will correctly play back HandBrake's anamorphic output undistorted.
Absolutely correct. However, I was talking theoretically - it doesn't "naturally" support anamorphic, only that which is "hacked" by the HB team with a special atom (quite brilliantly I might add). Obviously this does not include all anamorphic video, which will come out distorted without this - and that includes everything else I've encoded in anamorphic before HandBrake was finally available for Windows.

In mathematics, to prove a statement is FALSE, you only need one example to contradict it. So therefore, by definition, the statement "Apple TV supports anamorphic H.264 content" is FALSE, even by design. So, in PURE THEORY - NO - "Apple TV does NOT support anamorphic H.264 content".

...at least not "naturally".

QED

Nevertheless, since this is the HandBrake forum, and although it's not "officially" supported, and although I have much content from other encoders previously not supported, I still should have pointed out this option. My bad... :D
rhester
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Post by rhester »

PuzZLeR wrote:
The APPLETV will correctly play back HandBrake's anamorphic output undistorted.
Absolutely correct. However, I was talking theoretically - it doesn't "naturally" support anamorphic, only that which is "hacked" by the HB team with a special atom (quite brilliantly I might add). Obviously this does not include all anamorphic video, which will come out distorted without this - and that includes everything else I've encoded in anamorphic before HandBrake was finally available for Windows.
ATV supports Apple's matrix transformation atom - it's that simple. It's not a hack and it's nothing undocumented - it's part of the QuickTime standard, and easily read about online in the Apple Developer Guide for QuickTime. There's really not much "special" about reserved3, it's just not used by movies on iTunes.

Non-Apple players, however, do not use this atom, and instead depend on a special value set as part of the H.264 stream itself (which is ignored by Apple).

The two approaches are equivalent, but incompatible, and optimum compatibility with the maximum range of devices means supporting both. This is not at all unlike the problem with chapters, subtitles, etc. in MPEG-4 containers, where Apple chose to diverge from the international standards body to do things their own way - and, granted, in many cases provided superior functionality to the standard (particularly in bidirectional matrix transforms, unsupported by H.264 standard).

Ironically, when Microsoft referred to this practice as "embrace and extend" and did so with the Microsoft JVM, people yelled bloody murder. Apple does it and it's called "innovation". Curious, that.

Rodney
hawkman
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Post by hawkman »

rhester wrote:This is not at all unlike the problem with chapters, subtitles, etc. in MPEG-4 containers, where Apple chose to diverge from the international standards body to do things their own way ...
I may be wrong but I don't believe there are many mainstream applications of "standard" chapters, are there? Of the few pieces of software that can add chapter markers, most, like Nero, go their own way. That's not so much a defence as a pondering. I've heard it mentioned that there isn't really a "standard mp4 chapter", but I've never looked into the veracity of that claim.
rhester wrote:Ironically, when Microsoft referred to this practice as "embrace and extend" and did so with the Microsoft JVM, people yelled bloody murder. Apple does it and it's called "innovation". Curious, that.
Hypocrisy is easy, I agree. I'm personally not bothered with additional functionality, so long as it doesn't break existing functionality.
rhester
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Post by rhester »

hawkman wrote:I may be wrong but I don't believe there are many mainstream applications of "standard" chapters, are there? Of the few pieces of software that can add chapter markers, most, like Nero, go their own way. That's not so much a defence as a pondering. I've heard it mentioned that there isn't really a "standard mp4 chapter", but I've never looked into the veracity of that claim.
I believe the MP4Box implementation follows the defined MPEG-4 standard, such that it is. The trouble is, virtually no playback application actually uses it - presumably because it is grotesquely implemented, but I will confess I have little detail on that.

Rodney
PuzZLeR
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Post by PuzZLeR »

hawkman wrote:Hypocrisy is easy, I agree. I'm personally not bothered with additional functionality, so long as it doesn't break existing functionality.
That's the beef with Microsoft in the first place. They are "innovative" at the expense of breaking existing functionality.

They have a history of being a second mover - taking an idea and running with it. On top of that, they use their leverage being a major OS as well to package their ideas only, setting the tone for what's supposed to be "standard".

For our purposes here, they did the exact same thing again with video standards.

When H.264 was adopted as a standard, Apple did create a "standard within a standard" of their own - called "QuickTime compatibility", yes, however, nevertheless, they DID embrace the existing standard.

What does Microsoft do? Instead of embracing H.264, a standard, even maybe creating an implementation of their own such as WMV-AVC (which would be "embrace and extend"), they create something called VC-1 (breaking existing functionality), a competitive, totally incompatible, non-beneficial-to-the-industry, and inferior standard. But since its parade is headed by Microsoft, Hollywood just "had" to accept it for the BD/HD-DvD standards as well.

Now they are packaging it with Windows, purposely excluding H.264, claiming that they can't include "all" codecs due to security and an overabundance of them... Yeah, H.264 is unsafe and "trivial"... Whatever...

There are actually a couple of threads about this going on at Doom9 at the moment. Real flames are bursting as the public is demonstrating their frustration at MS for this.

Including me. :-)
Last edited by PuzZLeR on Thu Aug 02, 2007 8:09 pm, edited 3 times in total.
PuzZLeR
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Post by PuzZLeR »

Hello Rhester,

Didn't mean to offend by calling it a "hack". It is, after all, the way it's been referred to by several and I only continued as such. However, it is "official" that QT only plays back with an assumed PAR of 1:1, so one can't help but conclude that this may be a "hack", or something "unnatural" when anamorphic "suddenly" starts working beautifully on QT, when it's not supposed to. However, nice to know it's within standards. Thanks for clarifying that.

I would like to get you to comment a bit more here though:
rhester wrote: The two approaches are equivalent, but incompatible, and optimum compatibility with the maximum range of devices means supporting both.
Do you mean that the anamorphic content produced by HB within QT compatibility is an entirely different "animal" to other anamorphic content produced by other, non-QT compatible apps? I'm a bit hazy as to what you meant here.

Thanks.
jbrjake
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Post by jbrjake »

It's quite simple.

Maurj hacked QuickTime's transformation matrix into the libmp4v2 library.

It has nothing to do with PAR and it is not unnatural nor is it not supposed to work.
PuzZLeR
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Post by PuzZLeR »

Nice to know it's more "standard" than "hack".... :D

Then again, the debate can go on and on and on as to what is a "hack" and what isn't a "hack".... :P
Konstantin Prinz
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Post by Konstantin Prinz »

PuzZLeR wrote:They have a history of being a second mover - taking an idea and running with it. On top of that, they use their leverage being a major OS as well to package their ideas only, setting the tone for what's supposed to be "standard".
Uhm, like Apple is a first mover... Where did those Widgets come from? Yes they where there before Vista's gadgets but even Apple got the idea from Konfabulator (now owned by Yahoo).

Only thing is, Apple focusses on usablility and UI design and succeeds (iPod), MS just makes things worse...
PuzZLeR
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Post by PuzZLeR »

Hey KP,

Sure Apple's "second-moved" on a couple of technologies, like other companies. But they are also innovators more than anything: GUI O/S?, digital graphics and art niche?, the mouse?...
Konstantin Prinz wrote:Only thing is, Apple focusses on usablility and UI design and succeeds (iPod), MS just makes things worse...
True, whether Apple is a first or second mover - they have a tendency to add something to the industry. They add value.

VC-1 is very typical of MS - releasing a different, and more inferior, "standard" to compete against an existing standard. VC-1 adds nothing new to the industry, only compatibility headaches. It was only released to benefit MS and no one else...

Is there any other reason for its existance?

Yeah, I know there are a dozen other companies too behind it, and yeah it's an "open standard" now, but it's still an MS entry, and meant to get the MS control out there nevertheless. Why doesn't MS prove us wrong then and create an implementation for H.264 as well? Maybe even package that too with Windows? Then I'd be convinced that MS is really promoting standards instead of their own crap. But nah, it won't happen. Then no one would use VC-1 and that would make the Big M unhappy...

Geez...
jbrjake
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Post by jbrjake »

Ok guys. We're not getting into an "Apple vs. Microsoft: Who's Evilest?" debate on the HandBrake forum.

Locking this thread.

And before someone shoots off about "but why do you have to be so quick on locking threads?!" this entire thread was ostensibly about "What does anamorphic do?" and that question is answered at length in the documentation.
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