Cannot get correct aspect ratio with one DVD

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Cannot get correct aspect ratio with one DVD

Postby Steerpike » 01 Apr 2007 20:14

Initially I tried to transcode a chapter from a DVD (49-Up, FWIW), but could not get the correct output aspect ratio. To simplify the problem, I found that I could replicate the problem just by playing the Chapter using VLC's 'Quick Open File...' menu item. The chapter starts playing at 64:27 (2.37:1). I can 'fix' the display by choosing 'video/aspect-ratio/16:9' from the menu, but I can't get this aspect ratio change to apply when transcoding.

If I extract a chapter from another 16:9 DVD (March of the Penguins, FWIW), it plays correctly at 16:9 using default settings.

The 49-UP chapter has this info in the log:
[00000355] main video output debug: picture in 720x480 (0,0,720x480), chroma I420, ar 64:27, sar 128:81
[00000355] main video output debug: picture user 720x480 (0,0,720x480), chroma I420, ar 64:27, sar 128:81
[00000355] main video output debug: picture out 720x480 (0,0,720x480), chroma I420, ar 64:27, sar 128:81

While the 'March' chapter has this info in the log:
[00000354] main video output debug: picture in 720x480 (0,0,720x480), chroma I420, ar 16:9, sar 32:27
[00000354] main video output debug: picture user 720x480 (0,0,720x480), chroma I420, ar 16:9, sar 32:27
[00000354] main video output debug: picture out 720x480 (0,0,720x480), chroma I420, ar 16:9, sar 32:27

As you can see, the 49-UP chapter shows 'ar' as 64:27, which is 2.37 - but the material is 16:9.

Both sources are 720x480 NTSC DVD.

So I can fix the problem when simply playing the chapter (by using video/aspect-ratio/16:9), but I cannot figure out how to fix the video during transcoding. I've tried all manner of 'aspect ratio' commands in the transcode command, to no avail. I've googled and experimented till I'm blind ... any tips?

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Postby DJ » 01 Apr 2007 22:03

The 2.37:1 aspect ratio is Enhanced 16x9 and will not fill a 16x10 monitor and maintain the aspect ratio. You are asking to distort the picture. This issue is the same in hardware.

Some hardware is offering a zoom function that eliminates a portion of the picture to maintain the aspect ratio, but I have not seen this option in software (while it may exist somewhere) it does not exist in VLC.

There are filters available for both the play and transcode functions in VLC. You may want to look at Preferences, Stream output, Sout stream, Transcode to see the available options.

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Postby CloudStalker » 01 Apr 2007 23:34

I believe PowerDVD has the option to Pan & Scan for fullscreen. If you’re watching a DVD with a source aspect ratio of 2:35:1 then you can set the Pan & Scan to 2:35:1 and it will zoom in enough to fill a fullscreen without changing the aspect ratio.

DJ is right, I do see anything in VLC that can do this; why not make it into a feature request?

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Postby Steerpike » 01 Apr 2007 23:36

Thanks. I've been banging my head against this one for about 8 hours non-stop now! I have read the forums, wiki, and faqs, including a very extensive thread between yourself and another poster on the topic of 'enhanced 16:9'.

Now, while this problem first manifested itself while trying to transcode, I reproduced it by doing nothing other than launching VLC, and choosing 'File/Quick Open File..' and pointing to the chapter in question. (and having done a 'reset' in preferences to ensure no non-default settings are in play). The video starts playing in VLC in an obviously distorted manner - it's very 'wide' - short fat people. Is this the expected behavior for an 'enhanced 16x9' source? As soon as I switch the video from 'default' to '16:9' on the video/aspect ratio menu, the visual appearance is clearly correct.

I've looked at all the options in the preferences, but cannot find one that causes the video to play correctly using 'quick file open' (without having to modify aspect ratio from the menu once started) (trying to eliminate transcoding from the mix as it's an extra layer). What preferences section applies to the simple playing of a video (without any transcoding)? Maybe I'm not looking in the right place. In other words, what 'preferences' or command line option would implement the same action as 'video/aspect ratio/16:9'?

I've also looked at the Preferences, Stream output, Sout stream, Transcode section. I see an option for 'video canvas aspect ratio', and I've tried setting it to 16:9, but it has no impact on the visual appearance of the transcoded output. I also see filters 'video scaling filter' and 'video transformation filter'. I'll play with those - but my gut feeling is, if I can't get the simple 'play' to appear correctly, I've no hope with transcoding!

Thanks!

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Postby CloudStalker » 01 Apr 2007 23:47

I've looked at all the options in the preferences, but cannot find one that causes the video to play correctly using 'quick file open' (without having to modify aspect ratio from the menu once started)
If you’re trying to force the aspect ratio 16:9 so that you don’t have to keep switching it every time you start a video, then try this, go to: Preferences > Video and scroll down to “Source aspect ratio”, set it to 16:9, save and restart your video. As for all the other stuff, I have no idea. :P

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Postby Steerpike » 02 Apr 2007 00:03

GOT IT! thanks. Yes, going to preferences/video/source aspect ratio and setting it to 16:9 DOES cause the 'quick file open' method to play the video correctly without user intervention. Wonderful! I happen to notice, now, two identical 16:9 entries in the video/aspect ratio menu, for what it's worth.

Now - how do I apply that same 'logic' to a transcode? I've tried setting source aspect ratio to 16:9 in the 'transcode' section, but it does not have the same beneficial effect. I'm getting there ... any ideas?

Thanks again ... I was up till 4am playing with this, dreamed about it, and woke up and started all over ... :)

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Postby CloudStalker » 02 Apr 2007 00:18

Transcoding is out of my field for the moment, at least until I take the time out to learn more about it. Sorry.

For what it’s worth, I happen to know who will come into this thread and probably solve your transcoding issue. [Cough "DJ" Cough] :lol:

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Postby DJ » 02 Apr 2007 00:44

If the aspect ratio is truly 2.37:1 selecting 16x9 or 16x10 to fill a wide screen monitor is incorrect, but considering you are saying that the people are short and fat suggests an incorrect flag in the header info... for this DVD.

I have already stated where you can find the transcode options for the change. Command line options are also available.

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Postby Steerpike » 02 Apr 2007 01:45

If the aspect ratio is truly 2.37:1 selecting 16x9 or 16x10 to fill a wide screen monitor is incorrect, but considering you are saying that the people are short and fat suggests an incorrect flag in the header info... for this DVD.
yes, once I set 'preferences'/'video'/(general video settings)/source aspect ratio to 16:9, the simple played output is perfect. And just fyi, I'm not trying to do this to fill any particular monitor; I'm just doing it to make the bodies appear normal. Playing the same input material in (eg) winDVD displays perfectly, by the way.
I have already stated where you can find the transcode options for the change. Command line options are also available.
I found the transcode options, and I've tried several of them, but as yet I don't get the result I need. I've also tried command line options till I'm blue in the face! I understand I'm probably being a dimwit, but if you could actually tell me which setting to use I would be incredibly grateful. To recap, I've tried: 'preferences'/'stream output'/'sout stream'/'transcode', video canvas aspect ratio (16:9) - this does not affect the transcoded video aspect ratio (remains 2.37:1) If I set it to 'dumb' things (obviously wrong, just to verify the setting is being read) like 1:1, the output properties show 0.914:1; setting 4:3 gives output properties of 0.0517:1 (totally distorted!). When I say 'output properties', I'm looking at the 'properties' after opening the transcoded output in WMP (win media player).

I also see under the above properties area, entries for canvas width and height, but they don't seem to be having any useful effect - I've tried a variety of them. I also see 'video transformation filter' but have not tried that yet. If you can just give me a clue as to which of the many settings I should play with, I'll happily waste the rest of my weekend on this!

Thanks again!

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Postby DJ » 02 Apr 2007 06:43

I've never had a video where I wanted to change the aspect ratio. Don't get me wrong, I see lots of errors when downsizing original movies, but nothing so gross as to make tall thin people or fat squatly people.

Not many DVDs in this country are presented without a 4x3 frame. So a crop would need to be applied before resizing or the output, either it won't work or it will be very strange.

The Video height and Video width settings should be what your looking for. If you set these so that the width is the same as the original (720) and divide by 1.78 and then round to the nearest increment of 16 should give you satisfactory results. The final number should be divisible by 16. So 400 would be 1.80:1 and 416 would be 1.73:1

If you know the actual NTSC or PAL number you can also plug this in if you want, but this is a correction that isn't necessary for the film transfer nor is it necessary to display it on a computer or any of the newer LCD or Plasma TV monitors. But it will look closer to the DVD and be further away from the film.

I think the Maximum and Minimum settings here were intended to round the numbers to the nearest increment of 16, but this would be a question for the developer.

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Postby Steerpike » 02 Apr 2007 19:08

Thanks for your help. This is interesting ... I did as you suggested, setting 'width' to 720, height to round(720/1.78) = 416. The result reflects these properties (720x416) but still has the aspect ratio property of 2.37:1. Here is a 6 second snapshot, heavily compressed (vb=256, ab=64), just to show that I'm not smoking crack:
http://www.sequoiahills.com/Linked/Vide ... 20x416.wmv

In Windows Media Player, the properties show a size of 720x416, and an aspect ratio of 2.37:1, and the boy's face is a little 'fat'. If I play it in VLC, it appears visually the same as in WMP, and if you click on 'video/aspect-ratio', and select 16:9, the video aspect is visually correct.

It seems that the aspect ratio flag is getting set somewhere and nothing I do seems to change it. Now, isn't changing the height and width values simply changing the way the video is stored in the outut file, and is independent of the playback aspect ratio? I'm drawing an analogy to the way DVD media is stored - it's stored at 720x480 (NTSC), regardless of whether it's played back at 4:3, 16:9, etc.

Just for grins, I cleared out the height and width values, and instead set canvas height and canvas width; here's the result of that :
http://www.sequoiahills.com/Linked/Vide ... 20x416.wmv
Aspect ratio still 2.37:1.

and here's a version without any height/width values at all:
http://www.sequoiahills.com/Linked/Vide ... 20x480.wmv
Aspect ratio still 2.37:1.

FYI, this is a UK documentary originally made for TV, but now released on DVD and purchased in the US in NTSC format. It's made up of footage gathered over 50 years. It's a commercial DVD, and the segment in question was extracted using DVD Decrypter. And as previously stated, the original extracted material plays at the correct aspect ratio in WinDVD. I'd be happy to post the entire 17 minute source file if anyone would care to look at it - 720 Meg. I have the space!

Thanks!

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Postby DJ » 02 Apr 2007 21:33

You are dealing with (according to the default sample) an anamorphic video in what appears to be 480p or 1138x480 (2.37:1). This uses the packed pixel or DAR to display the corrected aspect ratio through DirectX.

The second sample is changing in that the aspect ratio is doing what I would expect for this kind of input. The result is 986x416 or 2.37:1 in DAR.

I'm not sure I want to comment on the last sample as it is really out to lunch even though it does display. The aspect ratio is reported as 720x4788 :?:

Anamorphic video is the most difficult to deal with as no program wants to change the aspect ratio and to add this insult to injury, 480p does not correspond to the math for having the width divisible by 16. So changing the DAR (packed pixel) is necessary).

Example: In a standard 480p (1.78:1) the aspect ratio is 854x480 but as close as you can get is 848x480 in a transcode. This is where Apple is at presently with 480p and they are doing a translation for enhanced 16x9 video (2.37:1) as 848x352, but the real numbers here are 1138x480. The best that could be done in a transcode would be 1136x480.

Now, I have dealt with this as a theoretical because in further examining your default video there appears to be errors in the way it is being displayed as though the original source was not 1138x480. This leaves some black round the edges of the video and is not proportionally correct and also to me the kid does seem to fat.

This could have been a creative decision and an argument (or at very least a very long discussion) :) in post production as to what was right and what was wanted. The only series I can think of that the kids in the series were all to fat was Spanky and Our Gang (at least I think that was the title). Doing this translation in 480p would be a brain teaser in that almost anything you do is not 100% correct and doing a translation creatively would make the situation 100 times worse in that there would always be a unwanted black border for 16x10 monitors. Still the producers may have agreed to this trade off as it would not be apparent in a 2.37:1 aspect ratio in full screen mode. So normal hardware playing this on a wide screen would be OK by comparison to other enhanced 16x9 videos only that it would have better resolution. 8)

From my point of view, I could not figure this out or tell you exactly what to do with out having the DVD and first translating it back to a M2V and then examining the M2V in my editor. You may try to continue playing with the numbers in the various fields within VLC with the info... I have provided and come up with something that will work for you, but this is a shot in the dark with out knowing more about the source.

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Postby Steerpike » 03 Apr 2007 00:58

Thanks. I've tried several times to upload the demuxed m2v for the chapter in question (700 Meg), but it keeps timing out. I could process it through DVD Shrink to make it smaller, or do many things in IFO Edit, PGCEdit, etc - but I'm scared of touching the headers too much. If you can suggest a tool that would preserve the relevant info, and let me extract just a 20 second clip, I will gladly do that. I really don't care about this particular piece of material, but I'm determined to understand what is going on!

Here's what dvd decrypter says about the material, fwiw:
0xE0 - Video - MPEG-2 / 720x480 (NTSC) / 16:9 / Letterboxed / LBA: 2474718 / PTS: 00:49:19.003 / Delay: 0ms

and just to confirm, if I play it in Intervideo WinDVD, it plays 'just as I would expect' (visually), and that visually corresponds to what I see in VLC when I play it with the video/aspect-ratio/16:9 .

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Postby DJ » 03 Apr 2007 04:11

You might try VLC 0.8.6-bug-fix dated 3/8/07 and see if this resolves some of this issue.

http://nightlies.videolan.org/build/win ... 0308-1635/

DVD Decrypter is to old to report Anamorphic video correctly.

A late version of DGIndex may do this properly. But DGIndex will require some method of circumventing copy protection.

In VLC use Open Disc and choose dvdsimple then Title 1 and Chapter 1 and then go to the settings menu. If you choose no audio or video options within VLC and choose MPEG PS for the container, then give the file a name like anything.m2v. Now legitimately this is an .mpeg file because it has audio in the container, but if you shut audio off in Preferences, Audio and press Save and then close the player it will be an M2V that any editor will recognize as such and all the original info... in the header will be preserved.

ftp://streams.videolan.org/incoming
there you can upload problematic files, another place is
http://rapidshare.de/

I'm using WinDVD 7 and there are times when it is distinctly more accurate than VLC, But VLC is free and normally does a good job. Beside WinDVD doesn't transcode. :roll:

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Postby Steerpike » 03 Apr 2007 10:33

Before you posted your instructions, I already created and uploaded a VOB, here:
http://www.sequoiahills.com/Linked/Vide ... S_01_1.VOB
which you should be able to right-click and 'save as' or similar. This was created using a feature of DVDShrink that I'd forgotten - the ability to select a sub-set of the DVD. This vob represents just 20 seconds or so of the appropriate chapter.

I tried following your instructions but ended up with a 1 kb file. Here's what I did: Launch VLC, choose settings, preferences, reset all (to clear out any lurking settings), then on the audio screen, deslected 'Enable Audio', and then 'save'. Then I selected 'File/Open Disc', chose 'DVD' (dvd simple), then selected Title 6, Chapter 13 (Title 6 is the main movie), checked 'Stream/Save', clicked settings; Chose 'file', and named the file VLCOutput.m2v; set Encapsulation to MPEG PS, did NOT check any video or audio codecs, then clicked OK, and OK again ... and I end up with a 1 kb file that appears to have very little of use in it! Is that really what you want? Should I not be checking video codec of mp2v, or something?

Anyway, in the meantime, the VOB above shows the exact same problem in VLC as the original, so I think it's a good representation of the original material.

I'll try the new version above.

Thanks again!

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Postby DJ » 04 Apr 2007 07:45

Movie-Aspect is 1.78:1

VO: [directx] 720x480 => 854x480

The Pull down (5 interlaced frames to 2 to 3 progressive frames) and the frame rate (29.9) do not appear to be correct as the audio does not sync.

I needed to use the autocrop 5 lines off the left and 3 lines off the right to make corrections. To bring this to 848x480 it should have been 6 lines and not 8 lines and personally I would have taken 2 more lines as it still didn't look right. At 6 lines off the left and 4 lines off the right it did frame correctly 10 lines total or 844x480. Then I applied the corrected resize to bring it to 848x480 (1.78:1) standard 16x9. Please note that 480i or p is off the math slightly (1.766:1).

BTW VLC will not play this DVDShrink file.

The only reason I can possibly think of the my procedure didn't work for you is that 99 times out of 100 DVDs the main title will be 1 and not 3 or 3 let alone 6. If you question this look before you set the transcode.

FYI What you sent is very strange but the aspect ratio is probably correct. But the rest sucks. Including the movement for a 480p that isn't progressive. Man who ever made this should be shot just to put them out of their misery.

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Postby Steerpike » 04 Apr 2007 09:37

Thanks; I'll try your settings tonight and see what I can come up with.
BTW VLC will not play this DVDShrink file.
I just clicked the link (repeated here for convenience: http://www.sequoiahills.com/Linked/Vide ... S_01_1.VOB )and it actually played directly in VLC - I set VLC to be my default player for VOBs.
Image
As soon as I click 'open', it starts to play (after about 20 seconds of download) - which I didn't expect when I posted the link, but seems pretty cool! Could the file have been corrupted in your download? All 20 seconds or so play for me.
The only reason I can possibly think of the my procedure didn't work for you is that 99 times out of 100 DVDs the main title will be 1 and not 3 or 3 let alone 6. If you question this look before you set the transcode.
Here's confirmation of the structure from DVD-Shrink. I haven't really used DVD shrink much but it does prove to be a nice quick way to 'review' a DVD structure:
Image

I wrote down every step I took, being very 'pedantic' in case I missed something. I literally de-selected both audio and video codecs on the 'settings' screen, 'transcoding options' section, based on my interpretatation of your instruction to "choose no audio or video options within VLC" - but without any codecs, is 'anything' getting written to the output?
FYI What you sent is very strange but the aspect ratio is probably correct. But the rest sucks. Including the movement for a 480p that isn't progressive. Man who ever made this should be shot just to put them out of their misery.
The sample is from a very unique documentary that I've been following for over 30 years - it's a documentary that interviewed 14 kids at the age of 7, then again at 14, 21, 28, 35, 42, and now 49. This is one of Roger Ebert's 10 best movies of all time -
http://en.wikipedia.org/wiki/Seven_Up!
It does contain a lot of very old footage, so that may account for some of it's odd technical nature, and I think they did some ugly cropping of the original material to make it 'widescreen'.

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Postby DJ » 04 Apr 2007 10:42

I didn't try VLC because it is a known issue that DVD Shrink doesn't work correctly and the Developers have said they won't support it.

The way I had you do the M2V was as a copy to MPEG PS without audio which should be the same as the M2V. There is no transcode here. I have re-done several movies this way and never had an issue.

So all I know is what I have already said using other programs to gain the info.... The file was not corrupted. The pull down was not correct for progressive video and the frame rate was not syncing properly with the audio. But without the original to work from I really don't know if this is DVD Shrink or the DVD. Somehow I assume it's the DVD. Specially considering the other oddities encountered with VLC and the structure of the DVD.

I just realized that your reporting says that the main title is over 2:15 but only 3.5 GB in size. I would have expected a much larger size for this resolution which means a very high compression ratio.

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Postby Steerpike » 05 Apr 2007 18:02

Good news ... I finally figured out what was going wrong when using VLC to generate the m2v sample. When I buy a DVD these days, the first thing I do is dvd-decrypt it and then use PGC-Edit to modify the DVD such that it cuts straight to the main menu on insert, bypassing the intros, trailers, warnings, etc. Well, something in that process is tripping up VLC - sometimes. I tried 4 other DVDs that I had similarly processed, and two of them worked (File/open Disc/etc) - so there's probably something very subtle in what I changed in PGC-Edit that caused this. It's interesting because all 4 disks play in my set-top, and, all 4 even play in VLC, using it as a regular player. I was using the 'processed' version of the disk because I assumed VLC would not decrypt the disk - wrong again, cause I see now that VLC can process the original disk! Very cool. So I ran the original disk through the process you describe, and produced an m2v file, which is posted here, in case there is any value in looking at it. http://www.sequoiahills.com/Linked/VideoLan/Ch13.m2v

Regarding the general issue of the disk's aspect ratio, I note that VLC plays the disk in the corect 16:9 aspect ratio, when using VLC as a simple 'DVD Player' (on insert of disk, VLC is offered as one of the associated players for the disk), but when I use VLC to play the m2v file just generated, it plays with the incorrect 2.37:1 ratio. When I first started all this, I didn't realize VLC could even play DVDs - very cool program! If I open the m2v in 'womble MPEG VCR' - an old program I use to do simple mpeg cut editing, it plays in the correct 16:9 AR. Windows Media Player also plays it at 16:9. So 'all programs' (eg, WinDVD AND VLC) play the original DVD correctly, but VLC does not play the m2v correctly while WMP and others do. Strange! I did one more test - I Used 'File/Open File', and pointed it to the actual video_ts\VTS_02_1.VOB file on the disk itself, and it played - but at the 2.37:1 ratio. It's as if there is some info in the DVD about it's AR that is picked up if you play the entire disk, and that info is 'lost' to VLC when you play the extracted material, even though other programs do see this AR info?

Regarding using VLC to transcode the material ... I see your comments about autocropping and re-sizing "I needed to use the autocrop 5 lines off the left and 3 lines off the right to make corrections. To bring this to 848x480 it should have been 6 lines and not 8 lines and personally I would have taken 2 more lines as it still didn't look right. At 6 lines off the left and 4 lines off the right it did frame correctly 10 lines total or 844x480. Then I applied the corrected resize to bring it to 848x480 (1.78:1) standard 16x9." - I've looked at and played with the autocrop command (command line only option, and not a transcode option?) as well as regular crop (in the transcode properties section) and tried resizing, but still get an incorrectly sized output (though the AR, as reported in properties, is changing a little). I'm probably getting the syntax wrong. If you are doing this with a command line, could you dump that command line here for me so I can see it?

I obviously picked the wrong DVD to start learning about transcoding using VLC!!!

Thanks again!

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Postby DJ » 06 Apr 2007 07:38

I'm not doing the evaluation in VLC it was done in my editor. I used MPlayer to gain the correct AR and original size. An M2V does not do a unpack so it would be 720x480 which would be very wrong. I used a calculator to do the interpretation as I have done this many times before. The audocrop is also in my editor and not in VLC. The autocrop in VLC doesn't work and or work for transcoding.

The new M2V versus DVD Shrink does not give any more or different info...

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Postby Steerpike » 06 Apr 2007 18:31

This has been an interesting exercise for me as it has exposed me to many aspects of the program. I remain unable, however, to correct the AR of the material during a transcode - no matter what settings I use, the output remains 'too wide' and the bodies are 'fat'.

So far, my interpretation of the transcode settings for video width and height are that they set the 'storage' size, but have no relation to the playback AR. I can set transcode Video height / width to 720x480, 848x480, or even 480x480, and they are certainly reflected in the output (as seen in properties of the video), but the AR property remains unchanged, and the visual presentation remains unchanged. This does not surprise me. I've played with various settings of Canvas Height/Width, and Canvas Aspect, and they DO have an effect on the playback AR, but as yet I have not been able to figure out the logic behind these figures. I plug values in, and 'stuff changes', but it's not changing in any logical way that I can determine. I've done a site-wide search of 'canvas', and found nothing that actually explains the 'design purpose' of the various 'canvas...' options - just the syntax. Ironically, since VLC has such a good playback engine, I can adjust the AR during playback to the correct value, but my original goal was to correct it during transcode, so that the properties of the result would have the correct AR - and thus, playback correctly in 'any' player (eg, WMP).

Since this is the only DVD that has this problem and I don't really need/care to transcode it, I can simply move on.

It does seem to me that VLC has a problem, although it's a problem that may not surface with most material. here's why I'm thinking this:
1) If I insert the DVD in my drive, and choose VLC as the player, the DVD plays perfectly - with the correct AR (16:9).
2) If I insert the DVD in my drive and choose WMP as the player, ditto
3) If I use VLC to play a VOB from the DVD (or to play an M2V extracted from the DVD), it plays with the incorrect AR (2.37:1) - easily corrected during playback by selecting an AR of 16:9 from the video menu.
4) If I use WinDVD to play a VOB from the DVD, it plays with the correct AR (16:9).

The fact that VLC gets it right when playing the DVD 'from the top' (which I guess means, starting with video_ts.ifo, etc), but gets it wrong when playing a subset, while WinDVD gets it right in both cases, suggests VLC is not picking up some information that is available to it within the source material. I'm not saying this to criticize VLC, but to let others more familiar with it than me know of a potential issue that could be resolved.

DJ
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Postby DJ » 06 Apr 2007 20:31

It seems that (according to your second sample) setting the Canvas width is the key here as the width changed, so the value would be 848 which is 6 lines off the ideal of 854 but is not divisible by 16. Don't enter a value for the height as DAR is only effecting the width in this case. The height should maintain at 480, if it doesn't for some reason, put 480 in Video height and try again.

I tend to believe that FFmpeg treats a VOB like an M2V which will portray the packed pixel as is (without corrections).

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Postby Steerpike » 07 Apr 2007 19:01

I just tried this - Canvas width = 848; Canvas height = 0; video width =0; video height=0 (I'm using the settings/preferences gui, and zero is the default entry)

Result:
Core image visually unchanged - fat, short bodies.
Black borders added to left and right
Video Size (properties): 848x480
Aspect ratio (properties): 2.79:1

My hunch is, core image is still 2.37:1, and the black borders are what is pushing it to 2.79:1.

This is pretty much consistent with all my experiments - 'nothing' I seem to do will modify the actual AR of the basic image - except - if I set 'Canvas Aspect Ratio' to 3:2, or 5:4 I get an output AR of 0.914:1 (very distorted); CAR of 3:1 gives AR 19:8, etc - wild results.

Regarding "I tend to believe that FFmpeg treats a VOB like an M2V which will portray the packed pixel as is (without corrections)." - wouldn't playing the 'packed pixels as is' result in a 720 x 480 display, which is 1.5:1, which would result in 'slightly tall, thin' figures?

Thanks

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Postby DJ » 08 Apr 2007 06:59

All I can say is that is how it comes up in my editor, so I must make the corrections manually. Personally I would have tried 848 for the canvas and 480 for the video height and then looked to see what a couple of other players were doing with it.

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Postby Steerpike » 08 Apr 2007 20:09

I've now started using VLC on a number of movies, with different aspect ratios, and it's working perfectly with all of them (anamorphic 2.35:1, 16:9, 4:3, etc) and it's doing GREAT!

So my hunch is, there is some value in the header of that perticular movie (49-up) that is wrong, and is 'throwing' VLC off somehow. I started poking around the DVD with both IFO-Edit and PGC-Edit, inspecting the various header fields, but I don't know enough about the standards to spot what might be wrong. Everything I see suggests a straight-forward 16:9 movie, no reference to 2.35:1.

I popped in Apollo 13, a classic 2:25:1 anamorphic movie, and VLC very easily (that is, with default settings and no special commands) produces output that is 'overall' 16:9 with black borders top and bottom, as you would expect.


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