The Add'l info
posting on the first page of this thread has a section Aspect Ratio Information
which has all the links needed to understand the issue of Anamorphic vs 4:3 letterboxed DVDs, but the question comes up from time to time and I thought I would summarize it here.
This is not about anamorphic lenses for projectors. See the stickies in the Constant Image Height
forum for that.
Nor is it about the sometimes unexpected black bars at the top and bottom of some movies. See Why Don't the Black Bars Go Away?
for more on that.
If you have unexpected black bars on all four sides: read on.
In brief, there are two ways of putting widescreen titles on DVD. 4:3 letterboxed
is less desirable; anamorphic
is better. The undesirable 4:3 letterboxed was more commonly used in the earlier years of DVD, but you still find examples. These are the ones that display black bars on all four sides.
The two ways of authoring a title on DVD are as 4:3
. This is confusing because old-style TV displays are also called 4:3 and new widescreen displays are called 16:9, but this is something different. Even more confusing, movies also have aspect ratios and some are (or are close to) 4:3 and 16:9, but that is not the real issue here either.
The difference between a 4:3 and a 16:9 title on a DVD is just a flag on the disc indicating how the disc space is used. The maker of the DVD sets the flag and the player has to read it and process the image data properly.
Why have two methods? Because DVD allows only so much image data: 720x480 (NTSC
) and 720x576 (PAL
) pixels are the most DVD-Video can hold, never any more. We would like to use that space efficiently, packing as much image data into it as we can. Depending on the aspect ratio of the movie, we might do it one way or another.
4:3 is "perfect" for old movies and TV shows where the aspect ratio of the program is close to 1.33:1, the traditional Academy Ratio
. Every pixel on the DVD is used for good image data, nothing is wasted.
Similarly, 16:9 is "perfect" for titles close to an aspect ratio of 1.78:1, which is the HDTV standard. All pixels on the DVD are used for image data.
[The astute reader will have noticed at neither 720x480 nor 720x576 are anything like 1.33:1 or 1.78:1. The pixels stored on the DVD are not "square"; they need to be stretched one way or another when displayed. This all happens automatically, so forget about it].
Where do wasted pixels come in? What if you have a title that is not 1.33:1 or 1.78:1? 2.35:1 is very common; see, for example, Master and Commander
. The image has to include black bars above and below to make the original aspect ratio come out right. We don't like wasting valuable image space on black bars, but what else to do? The alternative would be either to stretch the image vertically, which would look weird, or to zoom it larger and chop off the sides, which no one wants.
An old article: The Ultimate Guide to Anamorphic Widescreen DVD
has some example illustrations of the above.
So what's the problem? The problem is that the studios, especially in the early years, put widescreen movies on 4:3 discs. That means:
- they waste precious image data by including large black bars on 1.78:1 titles, when they could have made a 16:9 disc and used all the space for image data. Or even larger black bars on 2.35:1 titles when a 16:9 disc would have required smaller ones.
- your DVD player + TV see this as an old-style 4:3 program, so it is displayed in the center of the screen with black bars ("pillarboxes") on either side, in addition to the ones above and below. Again, you can distort the image by stretching it or zooming, but the image will never be as good as a properly done anamorphic disc: a widescreen title encoded on a 16:9 disc.
These problem discs are called 4:3 letterboxed
. It seems like a serious technical error. Why did they do it? In 2000, Bill Hunt wrote:
So doing anamorphic on DVD is a win-win situation for everyone, right? Sure. But there was a time, early on in the history of the format, where the studios were reluctant. In many cases, they simply didn't understand the anamorphic feature of DVD. You'd be surprised how many studio executives in charge of DVD that I had to explain it to early on. And some were concerned that all that electronic "squishing and unsquishing" of the video signal would degrade the picture quality on current TVs. To be fair, some early players weren't so good at the process. But that problem has long since been resolved. Current DVD players almost universally render amazing widescreen images from anamorphic DVDs.
All said, it took a couple of years for some studios to finally make the move to anamorphic widescreen on DVD. Buena Vista and Fox have only recently started doing anamorphic transfers for their discs (Tarzan is anamorphic, for example, as will be Fox's upcoming Fight Club disc). But some studios have been doing right by DVD straight out of the gate, like Columbia TriStar, Warner Bros., New Line and DreamWorks (once they finally hopped on the DVD bandwagon). Others, like Paramount, MGM and Universal, soon adopted the feature on at least some of their releases. The bottom line, is that for many of the studios, anamorphic widescreen has become the rule for DVD, instead of the exception. And every major studio has now released at least a few anamorphic discs.
How to tell if a DVD is anamorphic? See the packaging hints in Anamorphic widescreen
or page 2 of Bill Hunt's article, which I quoted above and linked previously: The Ultimate Guide to Anamorphic Widescreen DVD
You can research DVD editions at the IMDB
, or at DVD Compare
Remember it only matters for widescreen titles. There is no need for an anamorphic Casablanca
What to do with your 4:3 letterboxed titles?
- Live with them.
- Zoom in so they are full width.
- Replace them with anamorphic versions, if they are available.
For example, I have purchased anamorphic replacements for these titles, originally 4:3 letterboxed:
- High Plains Drifter
- Last of the Mohicans
- Robin Hood: Prince of Thieves
- A Room with a View
Sadly, I have a long list of titles where anamorphic versions are not available as of this writing, at least not in Region 1. They include:
- Cutthroat Island
- The Doors
- Emma (Paltrow)
- The Ghost and the Darkness
- Hell in the Pacific
- Hope and Glory
- The Horseman on the Roof
- House season 1
- A Life Less Ordinary
- A Midsummers Nights Dream (Kline)
- Picnic at Hanging Rock
- Queen Margot
- The Rocketeer
- Sliding Doors
- Streets of Fire (available on HD-DVD)
- While You Were Sleeping
- Withnail and I
There are many more. Some of these may be available from other regions as anamorphic PAL discs. A good reason to have a multisystem player.
Else, we wait for anamorphic new editions, or better yet, Blu-Ray.
Finally, the distinction between letterboxed and anamorphic goes away for Blu-Ray and HD-DVD: they are always 16:9 and use "square" pixels; none are anamorphic. If titles require aspect ratios other than 1.78:1 the black bars are included as part of the image.A speculative aside
. Skip over this part if you're not interested in what might have been.
A good question: why only two ways of authoring DVDs? Instead of a two-choice flag, why not a setting allowing a range of values covering all reasonable movie aspect ratios, not only the 2.35:1 of Master and Commander
, but the even wider 2.76:1 of Ben Hur
? Then there would never be a need to include black bars on the disc and the DVD would be filled with valuable image data. The player would scale the data as necessary to restore the original aspect ratio.
In fact, why have fixed x/y dimensions at all? Given disc space and bandwidth limitations, we'll accept that 720x576 = 414720 pixels per frame is the limit. Why not allow the DVD author to choose how this space is allocated in the horizontal and vertical dimensions? From a programmer's perspective it is just a pool of bits.
Answer: I don't know. Maybe when DVD-Video was designed there was not enough processing power in the players to allow this type of scaling. Maybe there was simply no interest in more complicated title encoding by the content providers. But Blu-Ray and HD-DVD were designed more recently, and they allow only one aspect ratio on disc: 16:9, square pixels, 1920x1080 max. All titles not 1.78:1 must have black bars as part of the image.
Now, to be fair, this is less of an issue with High Def media, which has plenty of resolution for most consumers. And as long as we live in a world where 1920x1080 is the maximum display size there is no place to put the extra pixels of resolution anyway. The Constant Image Height users with anamorphic lenses on their projectors could make use of anamorphically encoded HD discs now, so they complain sometimes. And if displays with resolutions greater than 1920x1080 or wider than 16:9 are ever common we may wish the standard had included selectable aspect ratios.