Originally posted by BDub
Thanks, Jupiter.
I tried switching between progressive and interlaced on Mission Impossible and it didn't affect the playback (except for quality).
Any other ideas? Were the A/V salesperson and the Philips Support guy full of it?

Originally posted by X
Maybe your player has trouble deinterlacing badly flagged DVDs?

crappy cables? You want a good quality set of cables -

PS- Also on Titanic and Mission Impossible, the aspects don't display correctly. I set the DVD player to display in 16x9 but If I put the TV on normal, they have a box all around. If I set the TV to wide (which is correct for most of my titles) it stretches the image.

Originally posted by hoyalawya
Both Titanic and Mission Impossible are not 16x9 enhanced. Do yourself a favor and get a Momitsu V880 DVD player or a Bravo D2. Those two players will work wonders to your DLP display.

Anamorphic Video - With TV type set to 16:9, the V880 presents non-anamorphic DVDs in correct proportions but in a "zoomed out" letterboxed format. By this I mean that the image has black bars on top, bottom, and both sides. Hence, the image although not squished is much smaller than the actual TV screen. One can "force" the image to zoom in by setting the TV Type in the SetUp menu from 16:9 to 4:3 Letterbox. This however results in the annoying stretched look (see picture below).

What Can Go Wrong

Flag Reading vs. Cadence Reading

Before we get into specific problems, be aware that progressive DVD players can be divided into two basic types: flag-reading and cadence reading. Flag-reading players use the flags embedded in the MPEG stream to make decisions about what deinterlacing algorithm to use. Cadence-reading players ignore the flags, and analyze the content of the frames as they come out of the MPEG decoder to figure out which algorithms to use.

Flag-reading players have two major difficulties: they are often tripped up by errors in the MPEG stream, where the flags are not correct, and they drop to video mode if the encoding is non-standard, even on good film material. They generally have no way of doing 3-2 pulldown detection other than looking for the alternating "repeat_first_field" flag, so if it's missing, the film mode won't kick in, and you end up seeing the video-mode deinterlacing. This is watchable, but the main reason to get a progressive DVD player is to get film-mode deinterlacing. You can get video-mode deinterlacing from the deinterlacer in the TV. In general, we marked a test "fail" if the player went to video mode on material that was sourced from film.

Cadence-reading players are not tripped up by non-standard or missing flags, which is good, but they can be tripped up by glitches in the cadence. If the 3-2 sequence is interrupted, sometimes the cadence-reading players will stay in film mode for a handful of frames, and the result on screen is combing, which is very distracting. Similarly, once a cadence-reading player is in video mode, it typically takes a few moments to re-synchronize to the cadence and return to film mode. During that time, the player is using the inferior video-mode deinterlacing when it perhaps doesn't need to. Our tests will tell you how long it took the player to return to film mode after being forced into video mode by a bad cadence break.

Some flag readers blindly follow the flags on the disc exactly as they are encoded, which fails miserably on a wide variety of films. The most common problem with this is the hundreds of discs that have a common encoding error where the progressive_frame flag alternates off and on every other frame. This causes the simple flag readers to constantly slip in and out of film mode, and potentially in and out of progressive chroma upsampling mode, both of which are very bad. The result is a constantly strobing image, sometimes subtly and sometimes grossly. This problem in the flags was caused by a bug in an MPEG encoder, but that MPEG encoder was extremely popular, and is still in use, for example for a variety of recent Disney releases. Players ignore this problem at their peril.

The better flag readers try to look at the overall pattern of flags and make good decisions based on the sequences going by. For example, when they see the alternating progressive_frame flag, they treat it (correctly) as though the progressive_frame flag was always on. Some of them have a small set of flag patterns that they recognize as "film" and ignore any other pattern. For example, they may only go into film mode if they see a progressive frame with repeat_first_field set, followed by a progressive_frame without repeat_first_field set (which is the most common 3-2 pulldown pattern used on most big Hollywood releases). Where this fails to do the right thing is with 2-2 pulldown content. 2-2 is not terrifically common in this country (though it does exist) but is very common in Europe.

There are also hybrid players that use both flag reading and cadence reading, as well as players that allow the user to select between the two strategies. Sadly, all the players that allow you to switch between the two strategies label the menu item incredibly cryptically, and some give terrible advice in the owner’s manual. One in particular suggests that "Mode 2," which is the flag-reading mode, should be used to avoid losing detail in dark areas, which makes no sense at all. We can only assume that the tech writer confused the black level setting with the deinterlacing setting, though that advice is bad even for the black level setting. In addition, the players that allow switching generally have excellent cadence-reading deinterlacers, so the flag reading mode is most of the time a big step down in quality.

The ones that use both flags and cadence usually have a small set of flag patterns that they will "trust" as being film mode. Typically this is one or two variants of the standard 3-2 pattern. If they don't see the 3-2 flag pattern, they hand off the decision-making to the cadence analysis on the deinterlacing chip, which then gets a chance to make the right choice. When the cadence analysis isn't very good, this tends to improve the deinterlacing. When the cadence analysis is good, there's no real reason to use this strategy because the likelihood of a good cadence reading chip missing a strong 3-2 pattern is very low.

A hybrid strategy that we believe would provide a small improvement over cadence analysis would be to use the flags to change the bias of the cadence analysis algorithm. If the flags say the source is film, then the cadence analysis would be weighted to be a bit more likely to choose film mode. If the flags say the source is video, the cadence analysis would be weighted the other way. If the cadence is strong, the weighting wouldn't make much difference. But in cases where the cadence is hard to read, the flag weighting would make a larger difference. This could give a player the best of both worlds, though there might be a handful of titles that would do worse than with cadence reading alone. Overall we think it would be an improvement. Unfortunately, we know of no player that does this.

Most of the problems listed below only affect one kind of player or the other. Flag problems don't trip up cadence-reading players, and cadence problems usually don't trip up flag-reading players. We prefer cadence-reading players, as they handle more material properly. No flag reading player has ever done very well in our tests. They just can't handle odd material.

So, That Said, Here is a Partial List of Things That Can Go "Wrong" on a DVD:

Alternating Progressive Flag

On some material sourced originally from film, the progressive_frame flag is on for one frame, then off for the next frame, then on for the next frame, and so on. This causes no problems for an interlaced display, but progressive decoders that use the flags religiously will switch every other frame between film-mode decoding and video-mode decoding, with results that range from almost unnoticeable, to very annoying. Titanic, Austin Powers, Bad Company, Return to Neverland, and Monsters Inc. are examples of discs with this problem, and there are many more, so it's not isolated to obscure discs. On the WHQL disc, the Film Alternate 2 sequence has this problem.

No Progressive Flag

Some discs have no progressive_frame flag set on any pictures on the disc, and don’t use repeat_first_field. They just dump the film transfer with its inherent 3-2 pulldown onto the disc without any special flags, as though it was video. When this is done, 2 out of every 5 frames on the disc contain fields from two different frames of film (see the third MPEG flags table at the top of the article for a diagram). Again, a player that uses the flags exclusively will treat this material as video, and you lose the special film mode deinterlacing that makes a progressive player look so good. In the worst case, the player will combine fields that are stored in one MPEG frame, but came from two different film frames, causing combing. Cirque Du Soleil: Quidam and the trailer on the Galaxy Quest disc are two examples of this problem, but there are literally thousands of discs that were transferred this way, mostly titles from smaller studios and video companies. In addition, you often see short spurts of this problem even on major-label discs, sometimes for hundreds of frames in a row, including titles like. Con Express, Cross Roads, Dinotopia, Felicity, Friends, Buffy the Vampire Slayer, Once and Again, and Mad About You are examples of discs with this problem, and there are many more, so it's not isolated to obscure discs. In fact, the majority of TV shows released on DVD are encoded this way. You also see this on a huge amount of supplementary material like documentaries and trailers.

Progressive Flag on Non-Progressive Material

This is a rare problem, but one that does crop up. This is when material that came originally from video, or film that has not been transferred correctly, has the progressive_frame flag set on every picture in the MPEG stream, even though some or all of the fields come from different points in time. This particular problem causes players that read the flags to comb badly (see below for pictures of combing). The Galaxy Quest main menu intro, The Big Lebowski making-of documentary, and the Apollo 13 making-of documentary all have this problem, as does the WHQL Mixed Mode Alternate 1 sequence.

3-3 and 2-2 Sequences

This usually happens when two MPEG pictures in a row have the repeat_first_field flag set the same, either true or false. If they are both true, you get a 3-3 sequence. If they are both false, you get a 2-2 sequence. Players that look exclusively at the cadence can be tripped up by both of these problems, if they continue to stay in film mode for a few frames even after they detect a cadence problem. This problem is sometimes caused by something like seamless branching, where the end of one segment ends with a 3 frame, and the next segment begins with a 3 frame. Most encoders won’t catch a problem like that. Also, some DVD encoders will do odd things to the flags right around a chapter stop, like switching to a 2-2 cadence, or dropping the progressive-frame flag, or both. A wide variety of mainstream movies have this problem scattered all over the disc, including Star Wars: Attack of the Clones, ET, Lord of the Rings: Extended Edition, Ice Age, Lilo and Stitch, and Independence Day, just to name a few.

This error is very common in supplements, but is also found distressingly often in major Hollywood releases, especially right around chapter stops. DVD encoding software often create cadence glitches right at chapter stops or at points where special features kick in and out (things like multiple angles and seamless branching). And there are films that just have cadence glitches at random intervals throughout the film for no apparent reason.

Film-to-Video Transitions

On certain kinds of material, mainly documentaries about film and making-of or behind-the-scenes videos, sections of video are interspersed with sections of film. Players that use cadence matching may see the film cadence and settle into the pattern, only to have a problem when the pattern abruptly ends. And from a flag standpoint, many MPEG encoders make mistakes in flagging right when the source switches from video to film. Some keep the progressive flag set to true for a frame or two after the film section has already ended, which causes combing, and some drop the progressive flag well before the film section has ended, which causes some players to drop into video mode before they really need to. Almost all making-of documentaries demonstrate this problem, and in fact many cadence-reading players comb on all such supplements. The Big Lebowski making-of video demonstrates this kind of problem, but in general all making-of documentaries will have the same set of issues.

Shot on Film, Edited as Video

A fairly large amount of material these days is shot on film to get a film “look,” then transferred to video for editing and other post-production, as editing and post are much cheaper for video. Almost all episodic TV, music videos, and made-for-TV movies are done this way. This is a torture test for cadence-reading deinterlacers, as each scene will have the 3-2 cadence internally, but edits will more often than not break it, since the makers didn’t care about keeping the film cadence intact. In our test suite, we used More Tales of the City, which is a textbook example of this kind of material. However, you will find that most music videos and made-for-TV material will have the same problem. In addition, shows with lots of special effects have this problem all the time, because often the live action is shot on film and has a 3-2 pulldown pattern, but the effects are produced in a computer and have a 2-2 pulldown pattern. Overlaid titles like subtitles, show credits, dates and places (things that are shown at the bottom of the screen at the beginning of a scene like "New York City, 1856") also tend to work this way - the title generators used for TV are 2-2 coherent, and cause strange cadence glitches. We've seen problems like this on the X-Files, Buffy the Vampire Slayer, and many other TV shows on DVD. Even films are not immune: the new footage on the special edition of Star Trek the Motion Picture has 2-2 special effects that screw up the cadence (and the flags).

Film Montages

This is really a special case of the above problem, where a documentary will pull together segments of film and edit them together on video. This often happens in trailers and ads designed for showing on TV, and in making-of documentaries, where segments from different parts of the film are edited together for effect. Again, the 3-2 cadence will generally break on more the half the cuts.

FAILED
Layer Change
Chroma, 4:2:0 ICP
Blacker-than-Black
3-2 Cadence, Film Flags
3-2 Cadence, Alt. Flags
3-2 Cadence, Video Flags
3-2 Cadence, Mixed Flags
2-2 Cadence, Film Flags
Film Mode High Detail
Bad Edit
Video to Film Transition
Recovery Time
Incorrect Progressive Flags
Motion Adaptive