Test for Anamorphic?

[Nelson37]

I have two MPG files which appear to display correctly on my widescreen TV. Loading them in Vdub and taking BMP screenshots, one appears to be elongated vertically and the other does not. Both screenshots when converted to JPG appear in correct aspect ratio.

Does this indicate the squished video is indeed Anamorphic?

Also, is there any encoding difference for such video, is it more or less bitrate efficient, or about the same? Anything which should be done differently in handling such video, aside from authoring as 16x9?

What about the other one, which looks correct but does not show the squished BMP, should this be authored as 16x9? This would look squished on a 4:3 TV, correct? But if I author as 4:3, then it would look wrong on the widescreen, while the anamorphic one should play correct on both when authored as 16x9?

This aspect ratio stuff makes my head hurt, and differential calculus didn't do that!

[SLK001]

IIRC, if it has the 16:9 AR flag, it should expand to 16:9. As for bit efficiency, all the encoder sees is a 720x480 bit space, so you really don't pick up much.

That said, there are videos that get a psuedo 16:9 AR by letterboxing the 720x480 displays. These are encodings done by clowns (RE: unprofessional) and usually look like crap. These also retain the 4:3 AR flag.

If it looks "squished" (your technical term) then it is anamorphic.

[manono]

What about the other one, which looks correct but does not show the squished BMP, should this be authored as 16x9? This would look squished on a 4:3 TV, correct? But if I author as 4:3, then it would look wrong on the widescreen, while the anamorphic one should play correct on both when authored as 16x9?

4:3 DVDs and 16:9 DVDs (if encoded and authored properly) will both play on both kinds of TV sets with the proper aspect ratio. If you have a widescreen 4:3 DVD, while it'll play with the right AR, it'll play with black on all 4 sides when viewed on a widescreen TV set. You can zoom it to fill the screen left to right with correct AR, but that's not a real good solution. From the sound of it, your elongated one is 16:9, and the other one that looks more "normal (it really isn't - it's flattened a bit, if NTSC) is 4:3. A widescreen 4:3 source can be converted and encoded as 16:9 (for NTSC), by cropping 60 pixels from both the top and bottom, and resizing to 720x480. This is best accomplished by using AviSynth.

To find out if your MPEGs are 4:3 or 16:9, open them in GSpot, DGIndex, ReStream, BitRate Viewer, or any one of a number of other apps.

[Nelson37]

Thanks for the info.

I'm looking for a visual cue as I'm the one setting the flag when the files are captured. Looking for round circles, they all seem slightly off after a while. The very obvious "squish" effect is the only time I am really certain, but of exactly what I don't know. The BMP is an accurate reflection of the file as stored, and the jpg is the way it will display, or put another way, BMP files ignore aspect ratio and JPG's don't, if I've got that right.

Current subject video is Star Trek Enterprise, capped both from Sci-fi in SD and HDNet in HD downsampled thru S-Video. Both were capped as 16:9, I guess the Sci-fi should be set to regular 4:3? I can already feel the headache coming on. I don't want to edit, crop, and re-encode, especially if I can get it right on the capture in the first place.

Does the fact that both are flagged as 16:9 on creation affect whether the observed "BMP Squish" is an accurate test?

I've got the same episodes in both formats and have been doing a lot of comparison testing. When I start trying to figure out what each station originally sent, how and where it gets letterboxed, and what the differences are on my two different TV's (16:9 LCD and 4:3 CRT) with all the different view settings, I quickly reach a point where either everything looks wrong or I can't see any difference at all.

The HD caps are definitely superior, true anamorphic is better SFAIK whether I have a handle on why that is or not, and the filesizes appear similar. Less bitrate used on the letterboxing (I think) so that's a bonus. Plus the HD caps IVTC quite well!

[manono]

If capped from a standard-def station, they'll always be 4:3.

BMP files ignore aspect ratio and JPG's don't, if I've got that right.

You don't, although you haven't said exactly how you're taking the pics. For example, if I take a JPEG of a VOB being played using Media Player Classic, it's always 720x480, no matter whether the VOB is 16:9 and playing at 854x480, or if it's 4:3 and playing at 640x480.

If you really want to have to tell by eyeballing them if they're 16:9 or 4:3, then your method is OK. The 16:9 ones make people look tall and thin, and the 4:3 ones look more normal. This is assuming you're capping at 720x480. Other capture resolutions may look differently.

Does the fact that both are flagged as 16:9 on creation affect whether the observed "BMP Squish" is an accurate test?

If it's flagged as 16:9 and it was really encoded as 4:3, then when played, people will look short and fat. There's no way to tell just from looking at the 720x480 pic. Unless it's widescreen, like I suppose the Enterprise caps are. The 4:3 ones will have black above and below, and the 16:9 ones from an HD channel will be all active video. You can open the MPEG in VDubMod, right-click the picture, and switch back and forth between 4:3 and 16:9 and see which looks the more "normal" when you scroll around. I guess that's how I'd do it if in doubt as to the real DAR.

[AlanHK]

Current subject video is Star Trek Enterprise, capped both from Sci-fi in SD and HDNet in HD downsampled thru S-Video. Both were capped as 16:9, I guess the Sci-fi should be set to regular 4:3?

Every Sci-fi network series, including Enterprise, that I've seen was widescreen.

In Enterprise there are plenty of control panels with round displays you can check out.

[Nelson37]

Checking the two in vdub was exactly what I did, the screencaps were taken from that program. If there is a difference, I can't be sure. The screenshot bmp was the most definite indicator I had.

[Nelson37]

[Nelson37]

OK, posting the pics did not fly, but while there is letterboxing on both there is much less on the HD clip, in the captured file. On TV both are the same or nearly so.

The sci-fi clip would be an example of correct treatment of a widescreen film, in that it is broadcast letterboxed rather than pan and scan?

This should be captured as 4:3, as that is what it is. Display on the 16:9 TV is accurate? This is where I start to get lost, as it seems like it should be wrong on one or the other, or should be trimmed or something.

What seems to happen is that the TV adds zero letterboxing to the Sci-fi show, and adds some to the HD show, resulting in both looking roughly the same. Which I guess is what is supposed to happen.

BTW, what IS the trick for posting a pic? Did the image tag, pics are 720x480, 45K, browsed to file, copy name after tag, close image tag, close all tags, nada. maybe too wide.

[jagabo]

https://forum.videohelp.com/images/guides/p1753880/hd2.jpg

https://forum.videohelp.com/images/guides/p1753880/sd2.jpg

One of them seems to have made it. Did you upload both? You can only upload one at a time. To add the second you EDIT the message and attach the other file.

When you post an image put just the name of the file between the img tags, not the full path:

[jmg]filenname.jpg[/jmg]

Note I deliberately misspelled the img tag as jmg so it wouldn't be interpreted as an image tag in this message.

[manono]

Hi-

This should be captured as 4:3, as that is what it is. Display on the 16:9 TV is accurate?

My cable standard definition Enterprise shows on the Sci-Fi channel are broadcast as widescreen 4:3. So, yes, you want to cap as 4:3 if possible. Widescreen video is not by definition 16:9. 4:3 and 16:9 are DARs (Display Aspect ratios) which tell the player how to resize the video. Widescreen video can be and is often encoded as 4:3. And unless I use the Zoom (which I don't), my Sci-Fi channel Enterprise is displayed on my widescreen TV set with black on all 4 sides of the video, but with accurate aspect ratio. It has letterboxing above and below, and pillarbars added by the TV to the left and right

[Nelson37]

Odd, I can only see the quoted image, not in the original post.



That's the good one.

So the sci-fi one should display pillarboxed? Crap. Mine doesn't, so that would mean somewhere in the cable box or TV something ain't right. Cable box is set for 16:9 display, don't tell me I have to change this for HD and SD stations every time.

Oh well. This is where I try various settings and can't decide which looks right, but pillarboxes on the Sci-fi Enterprise I can easily identify. Many shows I can see that there is extra video at the sides when compared to the 4:3 display, as in not stretched on the widescreen but like the 4:3 is cropped. I thought Enterprise was like this, though have not specifically checked on other display. You are sure that it should be Pillarboxed for proper AR?

And then I start thinking I should set my Widescreen TV to receive a 4:3 signal from the cablebox when the show is broadcast as 4:3 but the program is actually widescreen itself with hard-coded letterboxing for 4:3 tv, which I have in the other room but without an HD receiver but I'll get one and then how do I set the 4:3 tv to get a "fake" widescreen or a real one ..........

Then I just go take a break and forget about it. It doesn't make logical sense to me, nothing looks perfectly round anymore. That's why I was looking for an obvious visual reference, the "squish" and the pillarboxing are clear and unmistakeable.

Although speaking of Enterprise, there are a couple of very nearly perfectly rounded objects in there.

As for the actual "squish" display of the BMP, it's not the file type, just the image viewer, correct? Some may display the BMP in correct AR, just luck of the draw as opposed to AR flag not being used in BMP?[/img]

[jagabo]

Odd, I can only see the quoted image, not in the original post.

You need to edit your post and fix the link. I fixed the links in my quoted section but you probably only uploaded one of the two files.

Most image viewers (and VirtualDub's default setting) display everything with square pixels. Neither 4:3 nor 16:9 video appears with the correct aspect ratio because 704:480 is neither 4:3 nor 16:9.

DVD has only two display aspect ratios: 4:3 and 16:9. Any video that is not one of those aspect ratios will have black borders added to the top/bottom or left/right to make it match one of those DARs.

SD broadcast (and most things you get over a composite or s-video cable) is 4:3 DAR. A widescreen source will have black bars top and bottom.

If you look at a 720x480 4:3 DAR frame with a square pixel viewer like VirtualDub the objects within the picture will look a little short/fat. In a 16:9 DAR frame everything will look noticably tall/skinny.

VirtualDub also has 4:3 and 16:9 display options. Right click on the window and select the desired DAR (4:3, 16:9) or PAR (1:1).

[manono]

You are sure that it should be Pillarboxed for proper AR?

Hehe, I'm too cheap to spring for the extra bucks for Hi-Def channels. Everything I ever watch over the cable is pillarbarred. But like I said, if you zoom it with the remote control, you can lose the pillarbars and keep the AR (unless you use one of those silly stretch modes). I don't zoom mine, because standard def TV already looks bad enough on the widescreen TV. Zooming it makes it look much worse. As you know, Monday is Enterprise day on the Sci-Fi channel, and I watch a lot of that show.

[Nelson37]

Now that I have both pics together, check the circular second stage. I used a later pic in the sequence without the obvious interlacing.

On the TV, there is additional letterboxing added to the HD pic so that the final display appearance of the two clips is very similar. The HD screenshot seems to be just slightly vertically elongated, which the added letterboxing corrects. Or is it correct as displayed, and the Sci-fi screenshot is just very slightly vertically compressed? Argh.

The effect is much more pronounced in the BMP, which gets back to my original question. Is the HD clip truly anamorphic?

That is what I am trying to achieve, capturing without the letterboxing, correct 16:9, anamorphic, 24 fps, max bitrate, edited and with captions converted to subtitles. 5.1 audio is the next goal.

I have capped the same episode from both sources, authored to disk and tested on playback. Other than the higher quality, AR appears to be identical, with both sources capped as 16:9. If I have this right, then the true anamorphic cap should be more bitrate-efficient (no black bars) and have more correct playback on a 4:3 set? Or is the loss of the black bars the only real advantage?

[jagabo]

Is the HD clip truly anamorphic?

Stretch it to 854x480 (~16:9 with square pixels) and you'll see. I don't know exactly what the image is supposed to look like but it looks to me to have the correct AR when stretched to 854x480.

the true anamorphic cap should be more bitrate-efficient (no black bars) and have more correct playback on a 4:3 set? Or is the loss of the black bars the only real advantage?

The anamorphic encoding will require more bitrate because each frame has more real picture to encode. Black bars take up very little bitrate (unless you have a noisy signal). It will look about the same as the letterboxed SD encoding on an SD TV (because your DVD player will shrink and letterbox the image) but will look better on an HDTV because it has more picture information vertically (a full 480 lines rather than ~360).

[Nelson37]

Whoopee! Testing on several sets indicates it is indeed anamorphic 16:9., and the Sci-fi capture is letterboxed 4:3.

Now I am wondering where and how this happens, as both captures were at the same AR, the broadcast itself must be flagged as 16:9. I understand the Sci-fi contains the black bars and the HD broadcast does not, but the HD indicates it is broadcast in the "squished" format and the Sci-fi is not. Interesting.

So I should cap the Sci-fi in 4:3, unless I can crop the bars during capture, but a resize would be necessary. Think I'll stick with the HD.

BTW, what do you guys think of the shots for real-time MPG capture?

[manono]

both captures were at the same AR

Meaning what, 1.78:1? Since the Sci-Fi channel often (but not always) broadcasts their stuff at the original aspect ratio, there's no surprise there.

the broadcast itself must be flagged as 16:9.

The one from the standard def cable channel is 4:3. You said so yourself in your first sentence.

but the HD indicates it is broadcast in the "squished" format and the Sci-fi is not. Interesting.

As I stated earlier, if it's 720x480 and standard-def, it gets resized for playback at 640x480. The 2 resolutions are close enough that it's sometimes hard to tell when viewing the 720x480 image that people are a bit short and fat (flattened). If you opened the MPG in VDubMod or DGIndex (to view it unresized), and found a sun, moon, ball , or something else round, it would be oval shaped.

[Nelson37]

I meant both were captured at 16:9, but only the HD one shows the squish effect, which is as it should be.

The HD one, and NOT the Sci-fi one, must be different in such a way as to cause this effect, again as it should be. I guess my point was that the setting of the flag at capture does not do the entire job, interesting that the 16:9 flag is passed thru to the S-Video connection.

The real-time IVTC on these is nearly flawless. I do get some audio dropouts or errors, but these are in the original broadcast. 1 or two in 8 episodes.

Somewhere, somehow in this I have found a way to turn off the Closed Captions, apparently for HD stations only. I am not entirely sure how but this is the second confirmed time I disabled them and it seems to be connected to display AR settings on the TV and sat box. They still work in SD stations, and the TV displays them on all stations, but my ATI card does not see them on the HD channels. I just went through this and re-enabled them, but not sure when they came back, this time very few changes were made and I realized the they were gone right away.

How wonderfully odd.

[jagabo]

I meant both were captured at 16:9, but only the HD one shows the squish effect

No, the SD one was capture as 4:3. It doesn't matter that there's only a 16:9 image in the middle of the frame, the full frame you captured is 4:3.

which is as it should be.

Yes, the HD cap with a 16:9 image squeezed into a 720x480 frame will give you a better picture on an HDTV.

[manono]

No, the SD one was capture as 4:3.

And he can confirm it for himself by opening an MPG in DGIndex and running the Preview (File->Preview). At the top of the new information screen that opens, it'll give the DAR. Or he can open it in Bitrate Viewer, ReStream, GSpot, or any one of a number of other apps and get the same information.

[Nelson37]

Well, you're both wrong.

The sci-fi caps were made with MMC set to 16:9, and Gspot and others confirm that the file reads as 16:9. They are capped letterbox and all, with a smaller display area.

This is why I was looking for a more definite visual test, as I said I'm the one setting the flag. It's the input that varies, what I was wanting to confirm is whether these files are being handled correctly. I cannot rely on the flag for accurate information.

The Sci-fi, or any SD broadcast, should be capped as 4:3. Got that. It is possible to crop the letterboxing during capture but a resize would be necessary. Too much hassle for the poor quality source, IMO.

The HD broadcasts, even when down-sampled thru S-Video, are being handled correctly for true 16:9 video. This may not always be the case depending on individual broadcast, but for nearly all movies, and Enterprise, everything is hunky-dory. They are being capped with little or no letterboxing, a larger display area, and indicate that they are 16:9 Anamorphic, confirmed with a visual test and NOT simply by the AR flag.

Am I correct that in more extreme wide formats, since the only Broadcast format is 16:9, some letterboxing will be included and this is correct and needed to maintain 16:9 for playback and/or DVD, and there is no point in cropping beyond the specs of 16:9 video? Unless I go for Xvid or H264, something including other resolutions?

[manono]

The sci-fi caps were made with MMC set to 16:9

As we said, they're broadcast at 4:3. Is it our fault that you're capping them with the wrong DAR? But you're right in a sense. The broadcast is one thing and the capture is something entirely different. I (we) should have made the distinction, I guess. I was just assuming you were capping them in the same DAR in which they were broadcast.

Yes, whether you cap the Sci-Fi channel at 4:3 or 16:9, the 720x480 video will look the same, and not have the same elongation as the HD ones broadcast at 16:9. But when you play them, it should become immediately obvious to you that you capped them at the wrong DAR, as when stretched out to 854x480, everyone becomes very fat and short. If capped at 4:3, when resized properly to 640x480, people look normal. So for a "definitive visual test", why not just play the things? Depending on how they look, you'll know whether or not you capped them right, and what the DAR really should be.

It's the input that varies,

I don't understand. The input from a Standard-Def channel is always 4:3. So, unless you're talking about something else, it doesn't vary at all.

Am I correct that in more extreme wide formats, since the only Broadcast format is 16:9, some letterboxing will be included and this is correct and needed to maintain 16:9 for playback and/or DVD, and there is no point in cropping beyond the specs of 16:9 video? Unless I go for Xvid or H264, something including other resolutions.

Yeah, if, for example, it's 2.35:1, as many movies are, then you'll need the letterboxing for DVD. If for AVI or something like that, then you might crop away the black.

[jagabo]

I wish my cable box would ouput 16:9 HD sources anamorphically over s-video. I can only get it to output letterboxed 4:3.

[Nelson37]

The Sci-fi SD caps were made at 16:9 as a test value against the HD caps, I was hoping they would not behave the same as a true anamorphic sample and they don't. I'm kinda going at this issue from the opposite direction, but I think you guys understand.

Along these same lines, is there any similar way to determine actual resolution? Both screencaps are technically 720x480, but clearly one is less detailed than the other. Just as both are technically 16:9, but one really isn't.

Solved the Closed Caption issue, and this is a bit strange. If the source is set on the sat box at 480 or 720P, the CC works. If set to 1080i, no Closed Captions. They are present in the stream as I can either view them on the TV thru HDMI, or embed them in the video and they come thru the S-Video. No seperate CC stream with 1080i, however.

This has me thinking. I had thought that the "downsample" performed in the sat box was geared to producing the same output, no matter what the input source. Interesting that the highest-res source setting does not include the Line 21 CC stream. I wonder if the space is used for extra video data, perhaps some type of Macrovision, or if this is just some meaningless glitch.

Also, am on a roll here as I just succeded in capturing the AC-3 thru the SPDIF for the very first time, used the Besplice trick and got valid files, two tests and one full Enterprise episode. Now to synch this with Video, that should be fun.

[manono]

Hi-

Along these same lines, is there any similar way to determine actual resolution? Both screencaps are technically 720x480, but clearly one is less detailed than the other. Just as both are technically 16:9, but one really isn't.

The true 16:9 Hi-Def anamorphic cap has a third more resolution than does the widescreen 4:3 Sci-Fi channel cap. All that extra black encoded with the 4:3 image cuts into the resolution of the actual video. This page will help explain it:

http://www.thedigitalbits.com/articles/anamorphic/anamorphic185demo.html

and this:

http://gregl.net/videophile/anamorphic.htm