4:3 video does not fill 4:3 screen when in fullscreen mode

[Byron]

Windows XP / VLC media player 0.8.2

When I play the 4:3 making-of documentary included on the U.S. Anchor Bay Evil Dead II DVD in fullscreen mode, the picture is "boxed in" by large black bars on all four sides of the 4:3 screen of my computer monitor. This perplexes me, because when I watch the same featurette on a DVD player connected to a 4:3 television, the picture fills the entire width and height of the screen.

Curiously, when I play the 4:3 version of the main feature (i.e., the actual movie) in VLC's fullscreen mode, there are no black bars. The 16:9 version of the movie (also included on the DVD) has bars only on the top and bottom, as would be expected on a 4:3 monitor. I have also been able to play a lot of other 4:3 DVDs (e.g., Evil Dead I) in VLC's fullscreen mode without any black bars.

The obvious thing to do would be to set the source aspect ratio to 4:3. This causes the horizontal bars on the top and bottom to disappear, but the vertical bars on the left and right remain. The picture also appears stretched (distorted) vertically.

It is as if the documentary is actually 16:9 and the vertical bars on the left and right are part of the encoded picture, while the horizontal bars on the top and bottom are inserted (or, rather, left there) by VLC. But why, then, does the picture fill the screen of a 4:3 TV when the DVD is played on a regular, ordinary DVD player? My DVD player inserts horizontal bars on the top and bottom when playing the anamorphic widescreen version of the main feature, so why would it instead crop the left and right sides of the featurette if it is indeed 16:9 rather than 4:3?

If anyone knows what causes this phenomenon and/or how to fix it so that the 4:3 video fills the screen of my 4:3 monitor, I would appreciate the information. Thanks in advance.

[Byron]

It has occurred to me that both the menus and the making-of featurettes included on Anchor Bay's Evil Dead II and Army of Darkness DVDs appear in fullscreen when I view them on a DVD player that is configured for and connected to a 4:3 television, while they appear in letterboxed 16:9 when I view them on a 4:3 computer monitor using VLC media player. The actual movies (as opposed to the menus and featurettes) appear in letterboxed 16:9 regardless of whether I view them with the DVD player or VLC media player.

I don't know a lot about DVD authoring/encoding, nor do I know about the internal workings of VLC media player and its handling of DVD playback. Nevertheless, I think that the explanation must be that there is a flag that tells the DVD player that the 16:9 feature presentations must not under any circumstances be cropped to 4:3, but rather letterboxed so that the left and right sides of the picture are preserved. For the menus and featurettes, on the other hand, the flag informs the DVD player that it is OK--or even preferable--to crop the 16:9 picture to 4:3 if the player is in fact connected to a 4:3 television.

I knew that a DVD player configured for a 4:3 TV would automatically letterbox an anamorphic widescreen picture, but I did not until now realize that DVD players could also, under some circumstances, trim the left and right sides of a 16:9 picture so that it fills the screen of a 4:3 television. I guess I thought that there were separate widescreen and fullscreen versions of the DVD menus; in fact, it seems that there is only one, widescreen version of the menus, which can be cropped to a 4:3 aspect ratio when viewed on a 4:3 display. I have also noticed that my DVD player can be configured for 4:3-letterboxed (the default) or 4:3-"Pan & Scan" (crop), but apparently the DVD flag usually overrides this setting, rarely leaving the decision up to the owner of DVD player.

VLC media player does not seem to honor this "how to handle 16:9 on a 4:3 display" flag in the same way that a DVD player does. VLC media player never crops the picture to 4:3; an anamorphic widescreen picture is always shown in letterboxed format on a 4:3 monitor. This is fine if the left and right sides of the picture contain additional meaningful video, as is the case with the menus on the Evil Dead II and Army of Darkness DVDs. However, the authors of these two DVDs seem to have decided, for some strange reason, to encode the two 4:3 making-of featurettes as 16:9 rather than 4:3, with nothing but black bars filling the extra space along the left and right sides. I have noticed that the TV spots included on the Dawn of the Dead DVD--also from Anchor Bay--have the vertical black bars as well.

As far as I know, VLC media player does not have an easy-to-access "Crop to 4:3" option. (Nor does it have a "Crop to 16:9" option for cases in which the picture has encoded horizontal bars on the top and bottom and one wishes to watch the picture fullscreen on a 16:9 monitor.) The crop filter supposedly has an automatic cropping feature, but I couldn't get it to work.

The solution, I have discovered, is to manually configure the crop filter. (The crop filter can be enabled and configured via the preferences dialog.) For my 800x600 monitor, I had to type "540 x 480" (with spaces around the "x") in the "crop geometry (pixels)" text box in order get those two documentaries to fill the screen. (I also had to be sure to press STOP and then re-open the appropriate title of the DVD.) The reason that it needs to be "540 x 480" rather than "640 x 480" is that VLC media player (or at least my installation of VLC media player) seems to inflate the width of the crop geometry by about 18.4375%, and 18.4375% of 540 pixels happens to be about 100 pixels.

One disadvantage of this solution is that on-screen feedback no longer appears when, for example, the volume is changed or the movie is paused.

[zorg47]

I have the AoD disk (cool movie!). That 19-minute extra feature is mastered weird. The DVD track is 16:9 anamorphic, but it contains 4:3 content, so the studio simply blacked out the side bars. The clip also contains some widescreen content, but the studio shrunk it to fit into the middle 4:3 area, so it's severely windowboxed with black all the way around. It looks silly, but that's how the studio created it.

However, VLC doesn't automatically switch to 16:9 mode when playing that track, so everything looks silly *and* too skinny. It's as if that track doesn't contain any aspect ratio information, so whatever mode VLC was using during the previous track is what's used during this track too. I don't know if this is a VLC bug or a DVD mastering bug. Maybe there's a clue in the debug messages, but I don't know what to look for.

[Byron]

"Bug" might be too strong of a word, but I think that the black bars are a "problem" with both the disc and VLC. On the one hand, there is no reason that black bars should ever be encoded into the picture on a DVD. But on the other hand, VLC should be able to handle the goofy encoding better. I've tested the Army of Darkness extra feature on regular DVD players connected to 4:3 TVs, and the picture is automatically cropped so that the black bars disappear.

As I described above, you can manually configure VLC's crop filter by typing in pixel quantities, but this is cumbersome. I'm actually OK with the fact that VLC doesn't automatically crop, but I think that there should at least be "Crop to 4:3" and "Crop to 16:9" options, so that it is easier to manually configure the crop filter.

I personally didn't notice any aspect ratio errors with the Army of Darkness extra feature. What I mean is that, though I initially suspected an aspect ratio error, I later decided that the aspect ratio (16:9) was technically correct; the problem was that there were black bars flanking a 4:3 picture, and it never should have been encoded that way to begin with. Once I figured out how to use the crop filter to trim off the encoded black bars, the picture seemed fine other than being somewhat reduced in resolution, as would be expected.

I don't understand much of the debug messages either, but my guess would be that, if the aspect ratio is in fact wrong, the fault would lie with the disc rather than with VLC. There is, however, a "Force source aspect ratio" option somewhere in the preferences. (You can type things like "16:9" and "4:3" in the text box.) If the DVD is already playing when you change this setting, you will probably have to press STOP and then re-open the DVD in order for it to take effect.