Problem with aspect ratio

[MalcolmClark]

OK, I have an odd problem – I have spent a lot of time trying to understand it, but I think I need the input of someone with more basic knowledge than me.
The subject was touched upon here some time ago:
https://forum.videohelp.com/threads/338483-Aspect-ratio-problems-please-help!
And although the original poster obtained a resolution, I don’t think that the basic problem was answered.
I have a number of DVDs of BBC TV programmes. And they are all 2000 era programmes and therefore would be expected to play at 16:9 and indeed do play at 16:9 on a normal DVD player or media player.
When I open the title in WinXDVD Platinum, it recognises that the title is 16:9, however when I rip them using the full title copy mode, they output file is 2.4:1.
Having done a bit of research, I can see that there is a different aspect ratio reported on the original DVD INF and VOB files:
Here is the INF file:
General
Complete name : D:\VIDEO_TS\VIDEO_TS.IFO
Format : DVD Video
Format profile : Menu
File size : 16.0 KiB
Overall bit rate mode : Variable
Video
ID : 224 (0xE0)
Format : MPEG Video
Format version : Version 2
Bit rate mode : Variable
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Standard : PAL
Compression mode : Lossy
And here is a VOB:
General
Complete name : D:\VIDEO_TS\VTS_02_1.VOB
Format : MPEG-PS
File size : 1 024 MiB
Duration : 19mn 7s
Overall bit rate mode : Variable
Overall bit rate : 7 485 Kbps
Video
ID : 224 (0xE0)
Format : MPEG Video
Format version : Version 2
Format profile : Main@Main
Format settings, BVOP : Yes
Format settings, Matrix : Default
Format settings, GOP : M=3, N=13
Duration : 19mn 7s
Bit rate mode : Variable
Bit rate : 6 568 Kbps
Maximum bit rate : 8 500 Kbps
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 2.40:1
Frame rate : 25.000 fps
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.633
Time code of first frame : 10:00:00:00
Time code source : Group of pictures header
Stream size : 898 MiB (88%)
Color primaries : BT.601 PAL
Transfer characteristics : BT.470 System B, BT.470 System G
Matrix coefficients : BT.601
Both are 720x576, but the aspect ratio is different.
If I force a 16:9 rip, using WinXDVD I can achieve a file which is 16:9 but its resolution is 720 x 406 pixels. I realize this must be a function of the mismatch in the aspect ratios that I am referring to, but I really do not understand what is going on.
Logically I assume that if my resultant file only has 406 lines, then I am losing quality somewhere.
Really it is a 720X576 16:9 file that I want, but perhaps that is not achievable.
I look forward to hearing from any experts.
Thank you
Malcolm

[Baldrick]

A DVD can only be in 4:3 or 16:9 display aspect ratio. The 2.40:1 must be something wrong. Is it mediainfo that says that?

720x406 is 16:9 pixel aspect ratio and with a 1:1 display aspect ratio it will look correct. And you wont lose that much by resizing if you are shrinking the video also.

Or try another free converter like vidcoder,handbrake, xvid4psp. Open/Import the dvd folder and not invidual vob files.

[DB83]

How to keep this simple.

All PAL DVDs have a Storage Aspect Ratio of 720*576 pixels. The Display Aspect Ratio determines how the final video will look. The Pixel Aspect Ratio, since the stored pixels are not square, determines whether you have a 4:3 video or a 16:9 video.

When you convert the non-square pixels to a square pixel format you change that 720*576 to as near as ratio in your example to 16:9. So 406/9*16 gives you 721.777. The near equivalent for a 4:3 dvd would be 720*544.

So there is nothing wrong with your result and that has not affected to final quality.

[manono]

If I force a 16:9 rip, using WinXDVD I can achieve a file which is 16:9 but its resolution is 720 x 406 pixels. I realize this must be a function of the mismatch in the aspect ratios that I am referring to, but I really do not understand what is going on.
Logically I assume that if my resultant file only has 406 lines, then I am losing quality somewhere.

Depending on the output format, you may be able to keep it 720x576 and set a DAR, just as a DVD does, so it plays at the right aspect ratio. Or resize it to some other 1.78:1 ratio, one such as 1024x576.

[MalcolmClark]

Thank you for the answers.

Baldrick - the 2.4:1 ratio that I posted is from MediaInfo.

I'm sorry if this sounds really dense, but if the original is 720x576, and plays 16:9, why is it that when I rip it to the same 720x576 I get a file that shows it's 2.4:1 in MediaInfo (and does play at 2.4:1). Presumably the pixels must get squashed vertically.

Baldrick also suggested a different ripper - that is something that I was thinking about, but sometimes having too much to play with leads to more uncertainty. Do you think that any of the other rippers would do differently?

So, I tried another rip, and this time forced a 1024x576 resolution - this seemed 'right' to me because it meant that I would keep the same number of vertical 'lines' - this worked ok, but I'm still puzzled.

[sanlyn]

A 720x576 encoded PAL video involves several aspect ratios. The only two display aspect ratios that can be specified in a PAL or NTSC encoded video are 16:9 and 4:3. The physical movie image within that displayed frame might have borders, pillars, etc., depending on the display device and depending on the physical aspect ratio of the original image itself.

Apparently you have a video containing a movie that was filmed as a 2.4:1 image. That is a wide screen image that will not completely fill a 16x9 display. So if you play that encoded video it will display as a 16x9 frame with a 2.4:1 image inside of it. That is, if you look at your 16x9 display you'll see that the movie image inside of that 16x9 display frame has top and bottom border pixels. The 2.4:1 image aspect ratio also indicates that the movie was shot as digital video, not as film.

The motion picture industry doesn't produce 16x9 movies. That aspect ratio is for TV shows and consumer video cameras. In fact Hollywood doesn't even produce 4:3 movies (also known as 1.33333:1). Movies were/are produced as 1:37:1, 1.6666:1, 1.87:1, 2.4:1, 2.35:1 (the latter being Wide Panavision or CinemaScope).

In some cases, media analyzer apps might display the actual image ratio (2.4:1) or the encoded display aspect ratio (16:9). If you resize the video to 16x9 and it completely fills a 16x9 screen without top and bottom borders, the image has been vertically stretched (distorted). IF the original encoding did contain top and bottom borders, which is often the case, then it should properly display on a 16x9 screen with top and bottom borders to make that 2.4:1 image fit inside a 16x9 frame.

[MalcolmClark]

Thank you Sanlyn
I think I follow what you're saying, and I also think it's difficult to explain things that we see sometimes - it's so much easier if we could look at the same thing, point etc.

Nevertheless, I'm not sure (but could be wrong) that my 'problem' is fully understood.

Firstly the DVD I have is a DVD of a BBC TV programme (and I have a number of similar DVDs of BBC programmes that manifest similar behaviour, but not all of them do.)

And so if it's a TV programme, then it would never have been intended for 2.4:1 playback. The DVD does playback at 16:9 with no black bars and no distortion.

However my rip (the original one that I refer to) which comes out at 720x576 and 2.4:1 is distorted. That is it plays as a long strip, with black bars top and bottom. But it is also distorted - everything is short and fat. And I cannot understand why the original would ever have been produced in that way (if indeed it was). It doesn't seem logical to my poor confused mind.

[aedipuss]

the "rip" was done wrong. bad software probably but you don't say what did it. try vidcoder, it's fairly easy to learn and has a preview button so you can see what the result will look like. the output should be 16/9 or 1024x576 for pal when converted to square pixel mp4. or 720x406. media info apps are NOT always accurate.

[MalcolmClark]

aedipuss
Thank you for your reply. But I did say what I used to do the rip - WinXDVD Platinum.

I've had this several years and it seems quite reliable, but I never read much about it on forum searches - perhaps it's not that good after all.

[sanlyn]

Firstly the DVD I have is a DVD of a BBC TV programme (and I have a number of similar DVDs of BBC programmes that manifest similar behaviour, but not all of them do.)

And so if it's a TV programme, then it would never have been intended for 2.4:1 playback. The DVD does playback at 16:9 with no black bars and no distortion.

If what the BBC was broadcasting was a wide screen 2.4:1 movie, it would have to play with those borders on a 16x9 screen, so it would be broadcast over the air as 16:9 with a 2.4:1 image inside it. However, the DVD could have resized and encoded in a number of ways. I assume this is a commercially produced issue, not something you recorded yourself. As ripping isn't something I do with commercial issues, it's out of my line. Played in a DVD player, if that movie is really a 2.4:1 original, it would be letterboxed on a TV, and it would be letterboxed if played on youyr PC monitor -- that is, if your media player is playing it correctly. Other members might have something to say about what was used for ripping. I suspect the rip app might have removed any borders that were in the original. Difficult to say.

I think I follow what you're saying, and I also think it's difficult to explain things that we see sometimes - it's so much easier if we could look at the same thing, point etc.

Well, class, it's time for a little game. In the pic below are two images. The top image is a 16x9 panel, the same aspect ratio as your 16x9 TV. The bottom image is a 2.4:1 panel that is the same height as your TV screen -- but of course the bottom image is much wider than the TV. The trick is to make the bottom 2.4:1 image fit into the width of the 16x9 frame without distorting the shapes in the 2.4:1 image.

[Attachment 19941 - Click to enlarge]

We can paste the 2.4:1 image onto a 16x9 frame. But we've cropped off the edges of the image. That won't do.

[Attachment 19942 - Click to enlarge]

We can squish the wider image so that it's width is 16x9 and its height remains the same. But we've distorted the shapes. That won't do, either.

[Attachment 19943 - Click to enlarge]

Voila! The wider image is resized proportionately so that it fits the width. Unfortunately, the laws of physics say that we can't fit to the height and to the width at the same time without distorting the image. So we fit to the width (that's what those wide-screen TV's are all about, correct? Width!).

[Attachment 19944 - Click to enlarge]

And here, incredible as it may seem, is the way that 16x9 resized image will look when encoded to 720x576 PAL. That's right, its encoded width is squished and its vertical height looks stretched. This PAL image is of course about 1/3 the size of a real PAL frame.

[Attachment 19945 - Click to enlarge]

The encoded 720x576 frame has an aspect ratio of 1.25:1 (alternately stated as 4:5). Why? Because pixels in a 720x576 PAL encoded DVD are rectangular, not square. They are higher than they are wide. Why is PAL (or NTSC) encoded with these odd pixels? It's a long story, and the more one reads that story the more it reads like something by Lewis Carroll.

[DB83]

@MalcolmClark

I think we can both agree that the BBC does not transmit tv broadcasts in a 2.40:1 ratio. In fact it is only quite recently that they have shown films in the correct AR. before this they tended to do some scanning on panavision or similar formats. That should not come out in the report which should just show 16:9.

Why mediainfo is showing this who knows. It is not perfect software but that result sure is oddball.

[DB83]

Well, I have one theory.

What if the 16:9 transmision was broadcast as for a 4:3 tv ie letterboxed and then re-recorded for 16:9 ?

Do the people look a little short/fat in these vids ?

[MalcolmClark]

Sanlyn - thank you for explaining the hidden mysteries of DVDs - I'm beginning to think that I am never going to understand the answer to my problem.

DB83 - I am sure that my DVDs were produced for 16:9 transmission - everything looks about right if you watch the original. If you want a bit more information, the DVDs that I refer to are for the series Life on Mars, which was broadcast is 2006 and 2007. The follow up to Life on Mars was Ashes to Ashes, where there were 3 series produced in 2008, 2009 and 2010.

Interestingly both series of Life on Mars and the first series of Ashes to Ashes manifest the 'problem' that I am describing, but not the final 2 Ashes to Ashes series - these show as 16:9 on the INF file, the VOB files, they play as 16:9 and rip to 16:9.

But please don't think it is only these videos - I have a number of other series (and I'm only talking about series of BBC TV programmes) - some are ok, and others show the same 'problem' - I suppose it could be a timing issue, but I would need to do a lot more research on that.

[manono]

I've seen that 2.40:1 stuff in MediaInfo before too. It's only shown for the VOBs so it's nothing to worry about because almost all DVD players get the DAR from the IFOs.

I'm beginning to think that I am never going to understand the answer to my problem.

I don't see where the problem is.

I'm sorry if this sounds really dense, but if the original is 720x576, and plays 16:9, why is it that when I rip it to the same 720x576 I get a file that shows it's 2.4:1 in MediaInfo (and does play at 2.4:1).

Because you're playing the VOB and not the DVD?

[hello_hello]

The whole aspect ratio thing can take a little time before you get your head around it. It did for me. Once the penny drops though it's really very easy. What makes it confusing initally, is some video (mainly DVD) using non-sqaure pixels. Video containing square pixels is easy because the resolution and display aspect ratio are one and the same. When they pixels aren't square, they're not. Therefore when you resize video with non-square pixels to video using square pixels the resolution must change in order not to distort the picture. As you probably discovered when manually resizing 720x576 to 720x576. More on that further down....

If I force a 16:9 rip, using WinXDVD I can achieve a file which is 16:9 but its resolution is 720 x 406 pixels. I realize this must be a function of the mismatch in the aspect ratios that I am referring to, but I really do not understand what is going on.
Logically I assume that if my resultant file only has 406 lines, then I am losing quality somewhere.
Really it is a 720X576 16:9 file that I want, but perhaps that is not achievable.

Everything you said there is correct. 720x406 itself is 16:9 (or close enough to it). The software resized the height of the video "down" while keeping the original width, outputting the correct aspect ratio using square pixels. The reduction in height can (at least in theory) rob you of a little quality.

So, I tried another rip, and this time forced a 1024x576 resolution - this seemed 'right' to me because it meant that I would keep the same number of vertical 'lines' - this worked ok, but I'm still puzzled.

1024x576 is also 16:9. Once again you've taken a video with non-square pixels and resized it to square pixel dimensions. This time, the height remained the same, but the width was increased to give you the correct aspect ratio using square pixels.

It seems you want to take a 720x576 video with a 16:9 display aspect ratio and re-encode it "pixel for pixel", giving you a 720x576 encode with a 16:9 aspect ratio. Nothing wrong with that. Technically it's probably the best method, but when you tell WinXDVD Platinum to force a certain output aspect ratio, I wouldn't know how to do it as I've never use it.

I suspect when you use the "full copy" option you referred to, what goes in should be what comes out.... 720x576, 16:9 in, 720x576, 16:9 out etc (it may just copy the existing video and audio and not convert anything). Telling WinXDVD Platinum you want a particular resolution might automatically get it to re-encode and resize to square pixels and there's nothing you can do about the latter. Likewise there may not be a way to use "full copy" while correcting the Output aspect ratio, so if the Input aspect ratio is wrong, the Output aspect ratio will be too. I'm guessing as I've never used WinXDVD Platinum.

There's way's to change the aspect ratio of some video without re-encoding it. Someone else might be able to help you do that with the original video. Then when you open it with WinXDVD Platinum, it'll see it as 16:9 and everything will work as it normally does. I don't work with mpeg2 video much aside from re-encoding it, and if the aspect ratio of the original video is wrong I'd correct it when encoding, so I have no idea if it can be changed for mpeg2 and/or how easy it is.

I live in PAL-land and I used anamorphic encoding myself (720x576, 16:9 aspect ratio), then a couple of TVs with built in media players arrived which don't support aspect ratios in MKV/MP4 files, which means they display it as 720x576 worth of square pixels instead, so it looks squished. So from there I moved to resizing "up" and encoding everything at 1024x576, but found I was outputting 720p type file sizes (1024x576 isn't too far off 1280x720, and close to 1280x544 etc) so eventually I settled on resizing 16:9 PAL to 960x540 worth of square pixels. I can't see any loss of fine detail but it reduces the file size required for a particular quality a little (I use x264's quality based encoding so the output file size changes every encode, according to how hard the video is to compress).