Backing up anamorphic DVDs

[smackyourfupa]

might be a dumb question, but when backing up an anamorphic DVD does it stay anamorphic?

[FulciLives]

might be a dumb question, but when backing up an anamorphic DVD does it stay anamorphic?

If you are dong DVD to DVD-R then yes ... it will stay 16x9 anamorphic WS if the original is that way.

- John "FulciLives" Coleman

[Gurm]

And we had an interesting discussion going a couple weeks back on whether it was possible to "un-anamorphize" it to save space...

Note that if you're re-encoding with DVD-RB and CCE or something like that, you will LOSE the anamorphic data.

[aterlecki]

Note that if you're re-encoding with DVD-RB and CCE or something like that, you will LOSE the anamorphic data.

Can you explain this a little further for those newbies among us? I use DVD-RB with CCE basic and have backed up a number of anamorphic discs without any problems. What is the DVD-RB/CCE combo losing?

[guns1inger]

I'd have to challenge that statement as, purely on the grounds of experience. It encodes the existing video as is, so it doesn't lose the extra video data that anamorphic disks have, and it keeps the 16:9 flags.

I'd be interested in hearing your reasoning behind that statement, Gurm.

[manono]

He can't back up his statement as it's nonsense. I also have used the DVD-RB/CCE combo with several versions of DVD-RB and 2 versions of CCE and never had a problem getting 16:9 back from what was originally 16:9.

If there was an authoring error of some sort in the original DVD, then that's something else entirely. I have read of problems along those lines when coming out of DVD-RB. No video data was lost (no resizing done, no black bars added or removed), but the DVD displayed wrongly. That kind of problem can be corrected with IFOEdit or PGCEdit.

[Gurm]

I'm sorry, my bad. I misspoke. DVD-RB keeps the flags in place and handles the resizing properly.

*ahem*

It'd be a nice feature to make optional though, as you could save a PILE of space by throwing that extra data out when re-encoding.

[SLK001]

It'd be a nice feature to make optional though, as you could save a PILE of space by throwing that extra data out when re-encoding.

WTF??

What "extra" data? A normal 16:9 video has a real encoded resolution of 720x480. A normal 4:3 video also has a real encoded resolution of 720x480. Notice that there is no difference between the two, so the encoder doesn't know (or care) what the display resolution is.

With the proper aspect ratio flags set, the player will resize the video accordingly.

[Gurm]

*sigh*

Ok, look. If a 16x9 video is encoded at 720x480... then it's "anamorphic". Not all 16x9's are encoded at 720x480. Many have substantially lower vertical resolution.

It would be nice to have the encoder, as a space-saving option for backups, downsample the vertical resolution of anamorphic videos. That's what your DVD player is doing if you have a 4x3 TV!

[SLK001]

Maybe I should have been more clear. What I call "normal" 16:9 is anamorphic. That other crap is just "letterboxed" (the "lazy man's" 16:9). An anamorphic 16:9 video makes MAXIMUM use of the encoder/available space on a disk (RE: doesn't have any black bars to encode).

But then, all (99.99% of commercial) DVDs are encoded at 720x480, REGARDLESS of the displayed AR. But the movie area in that letterboxed crap DOES have significant vertical resolution.

[Gurm]

Right. I too prefer to have Anamorphic, and am glad it's now the norm. But when I'm encoding and would REALLY like to make a backup that I can watch anywhere (most people do NOT have widescreen TV's) and keep the deleted scenes and cool menus, it'd be nice to have the option to "letterbox" the movie.

[SLK001]

I personally do NOT have a WS TV. I still encode everything (where possible) to 16:9 anamorphic. I author the DVD to display automatically in letterbox mode on a 4:3 TV. The DVD player will then display 16:9 with the "black bars" (RE: true anamorphic).

[manono]

Yeah, but Gurm does have a point there (not that I agree with turning 16:9 into 4:3 widescreen letterbox-he and everyone else will have a 16:9 TV within a few years, and then he'll wish he'd kept the 16:9). Although I understand that most PAL 4:3 TVs can do the "Anamorphic Squeeze" keeping all lines of resolution, but just compressing them, only a few high end 4:3 NTSC TVs can do that. What they end up doing is tossing out whole lines of resolution (25% of them) when the source is an anamorphic 16:9 DVD. So his point is why encode at 16:9 if you're just going to lose some of it anyway when playing on a 4:3 NTSC TV set. And his other point is that when backing up a complete DVD, and you don't have enough bits to go around to give everything decent quality, why not make the main movie 4:3 widescreen letterbox, freeing up bits for the rest of the DVD.

The Anamorphic Squeeze can be accomplished on most TV sets, but not without going into the service menu and fooling around. It's some serious work. Here's some more information on it:

http://www.keohi.com/keohihdtv/learnabout/definitions/anamorphicsqueeze.html

[adam]

Ok you guys are going to have to explain this to me. My understanding is that the whole point of anamorphic encoding is just to keep from having to digitally store the letterboxing (frees up bits for movie) and to ease the transition to widescreen playback since you now don't have to crop any picture. I don't see how hard coding in letterboxing that wasn't there can do anything but waste the bits saved by the anamorphic process. Gurm says this will save bits, manono says this will save vertical resolution, but I don't understand how it will help either.

manono, I understand that little blurb on anamorphic squeezing. It is a nice feature but it seems exclusive of this issue to me. The point of that feature is that when letterboxing is displayed on the tv, it reserves the lines of resolution for the picture itself and doesn't use any on the letterboxing. If you hard code the letterboxing in, that letterboxing is still going to use up lines of resolution when displayed on a tv that doesn't support anamorphic squeeze, only now you've also had to waste bits on that letterboxing during encoding. De-anamorphisizing the DVD doesn't free up any more vertical resolution for a tv that supports anamorphic squeeze than it does for a tv that doesn't support this.

EDIT: Ok after reading some on dvddemystifed FAQ I understand more where you are coming from, but the loss of vertical resolution you get from the player adding the letterboxing isn't much different than the loss you get from adding it yourself...DVD Demystifed says there is a slight difference depending on the quality of your equipment's scaling. But the anamorphic encoding process reduces the encoded picture by 25%. That certainly more than offsets the slight loss of vertical resolution unless your bitrate is of no concern, and Gurm is talking about squeezing more content on the disk. If you want to do this, the last thing you would do is hard code the letterboxing.

*sigh*

Ok, look. If a 16x9 video is encoded at 720x480... then it's "anamorphic". Not all 16x9's are encoded at 720x480. Many have substantially lower vertical resolution.

It would be nice to have the encoder, as a space-saving option for backups, downsample the vertical resolution of anamorphic videos. That's what your DVD player is doing if you have a 4x3 TV!

I guess you are talking about vertical display resolution and not vertical resolution? Because 720x480 is the minimum supported resolution for 16:9 video. So you are saying bits are wasted since you are encoding 720x480 of pure picture as opposed to say 720x360 of actual picture and an additional 120 lines of letterboxing? Basicaly like if you compared encoding a 1.33:1 in both fullscreen and in letterboxed widescreen (same horizontal resolution but less "picture" to encode.)

If this is what you mean then you are mistaken. The whole point of anamorphic encoding is that a pixel is no longer a pixel. The pixels are vertically stretched during encoding and then squeezed back again during decoding, and this is something that is supported by all dvd players on all tv's. So even though you appear to have more picture to encode, it doesn't actually require more bits. On the contrary, by not having to encode the letterboxing you are saving bits. That is the whole point of anamorphic encoding.

Adding letterboxing digitally as opposed to letting the decoder do it, decreases the bits that are used on your picture, it doesn't increase it. This is true regardless of how or where the picture is played back.

[FulciLives]

So you are saying bits are wasted since you are encoding 720x480 of pure picture as opposed to say 720x360 of actual picture and an additional 120 lines of letterboxing? Basicaly like if you compared encoding a 1.33:1 in both fullscreen and in letterboxed widescreen (same horizontal resolution but less "picture" to encode.)

If this is what you mean then you are mistaken. The whole point of anamorphic encoding is that a pixel is no longer a pixel. The pixels are vertically stretched during encoding and then squeezed back again during decoding, and this is something that is supported by all dvd players on all tv's. So even though you appear to have more picture to encode, it doesn't actually require more bits. On the contrary, by not having to encode the letterboxing you are saving bits. That is the whole point of anamorphic encoding.

Adding letterboxing digitally as opposed to letting the decoder do it, decreases the bits that are used on your picture, it doesn't increase it. This is true regardless of how or where the picture is played back.

Very interesting!

I had always thought that converting 16x9 WS to 4:3 WS means you get a better encode since more of the encoded image is "dead black space" which should take up less bitrate than the actual image of the movie.

So I was under the impression that a 2.35:1 aspect ratio film is "easier" to convert to MPEG-2 when you resize it to 720x272 with 104 black added on the top and bottom to make it 720x480 ... as opposed to leaving it at 16x9 WS.

I have done this ONLY a few times since I don't have a 16x9 WS TV.

- John "FulciLives" Coleman

[adam]

Nope FulciLives, anamorphic encoding uses 33% more of the storage area (vertical resolution) for the image making it much more efficient from an encoding standpoint. Its not that the black bars take up extra bits, because though they do its minimal, its that you've only got 720x480 to work with and without anamorphic processing about 25% (% of the picture, equal to about 33% of the total resolution) is wasted on the letterboxing.

Here is the "worlds easiest explanation of Anamorphic 16:9 WidescreenEnhancement in DVDs."

http://gregl.net/videophile/anamorphic.htm

[Gurm]

The issue is this...

In Anamorphic encoding, there's DATA taking up all 480 vertical lines.

In 4x3 letterbox encoding, the black bars consist of the following:

- INSERT BLACK PIXEL x 720

Perhaps two bytes of run-length encoded data. It doesn't move, it doesn't change, it's minute in comparison. A savings of perhaps 25% overhead.

I'm not saying it's a GREAT idea to to letterboxing, but rather that it saves so much space that, in the quest to fit stuff on a single-layer disc...

[SLK001]

A anamorphic video has a display area of 852x480 (it's really 853 and change, but there are problems with colorspaces with the "odd" or the "not-divisible-by-4" number). A 2.35:1 AR video (1128x480) is resized to fit into the 16:9 window, with letterboxing black bars hard coded into the video. Prior to encoding, the "fit" video - letterboxing bars and all - is resized to 720x480, since that is the native DVD resolution.
The 16:9 flag will resize it normally to the proper aspect ratio. If this video is played on a 4:3 screen, the DVD player will display both the hard coded black bars, plus will add some of its own, in order to display the 2.35:1 video on a 4:3 TV.

However, the TV doesn't know, and doesn't care about what AR it is being fed. In fact, the "squeezing" or "expanding" is all done in the DVD player. There is a menu in the player setup (at least in mine) where you tell the player what AR screen you will be displaying on, and also how to handle squeezed video (whether to letterbox, or pan and scan).

[Gurm]

Yup. The DVD player does it - and in reality tosses a bunch of vertical lines on an anamorphic DVD when it's set to 4x3 Letterbox. I propose using those lines for our own nefarious purposes. MUHAHAHAHAHA!