TMPGEnc adds black margins (on sides) to converted DivX

[stinkybone]

I am trying to convert a divx movie to a vcd compliant mpg using TMPGEnc. But no matter what settings I use, the new vcd mpg has black margins on the left and right sides of the movie even though the original divx movie doesn't. when checking the properties of the original divx file they are as follows: Width 640, Height 480, 25 fps, data rate 119kbps, video sample size 24 bit, video compression "divxmpg4 v3".
the original divx movie has black borders on the top and bottom, but that is fine (since that's the way it's supposed to look), but the black borders on the sides don't show up until i convert it to an mpg.
from what i've read 25 fps means that it's decoded in PAL format, but i plan on burning the vcd mpg to a cd and playing on an NTSC tv (which normally run 29fps) so what should i do?. i am also wondering how i can make it fit on one cd once it's converted from a divx avi to a vcd mpg. it seems as though every minute of converted video takes up 10 MB of space, so that means that any movie longer than 80 minutes will not fit on an 80 minute cd (i've read that 80 minute cd's will hold an 800MB file and 74 minute cd's hold 740MB files). could someone with some experience please give me any helpful advice? thanks in advance.

[Ricardo]

I'll try my best to answer all your questions, though still reasonably new to this myself.

It sounds like when you convert from 640x480 to VCD resolution that the aspect ratio isn't quite the same and you've got keep aspect ratio the same set in TMPGEnc. Select just centre, instead of centre keep aspect ratio and it should cure your first problem.

Your frame rate problem - will your player handle PAL VCD's and play them to your TV? (I am in UK) and am able to play NTSC VCD's on my DVD player, so it's worth a try keeping it as it is.

You are right about amount of space on a VCD. The VCD standard doesn't use such stringent error checking as normal data CD, so you can get more on it. Use a bitrate calculator to help plan your bitrates to get the best compression - vs - quality for your CD.

You can download Sefy's templates if you want to mess about trying non-standard VCD's, but I found that my DVD player wouldn't touch them. Burn to CDRW (if your player will read them) to test out different settings. It'll save a whole lot of wasted CDRs.

Have fun experimenting.

[flaninacupboard]

hmm, do the black borders appear in the preview while encoding? i had a problem where media player would add black bars left and right on playback, but DVD deck played them no probs.

[kinneera]

The issue with the black bars is pretty simple...TMPGEnc is just trying to preserve the aspect ratio. VCD res is 352x240. If you double that, you get 704x480, NOT 640x480. Therefore, to preserve the aspect ratio, TMPGEnc has to fill in the extra 64 vertical lines with black space, thus a 32 pixel wide black space on either side of the video.

Frankly, I would recommend keeping it that way. Not preserving the aspect ratio will distort your picture when you play it back on a TV.

[Anonymous65]

In Tmpeg, you have to select the correct source ratio, and in your case, you might have to select 1:1 VGA to get the same look on TV as you get when playing the file on the PC.

[shochan]

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On 2001-08-24 16:27:04, kinneera wrote:
The issue with the black bars is pretty simple...TMPGEnc is just trying to preserve the aspect ratio. VCD res is 352x240. If you double that, you get 704x480, NOT 640x480. Therefore, to preserve the aspect ratio, TMPGEnc has to fill in the extra 64 vertical lines with black space, thus a 32 pixel wide black space on either side of the video.

Frankly, I would recommend keeping it that way. Not preserving the aspect ratio will distort your picture when you play it back on a TV.
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He is one hundred percent right they should go away on your tv so i wouldnt worry about that, but if they dont it is a minimal stretch which is easly adapted to.
just strait encode the 25fps as 29.97 fps. you will only notice it when it pans back and forth.

[Cart Wheel]

To obtain the correct aspect ratio, borders should not be added. Setting the source aspect ratio to 4:3 Display and using Full screen (keep aspect ratio) should correct the problem.
(Oh how I hate TMPGEnc deals with aspect ratios.)

-Cart
http://www.geocities.com/lukesvideo/index.html

<font size=-1>[ This Message was edited by: Cart Wheel on 2001-08-24 20:13:41 ]</font>

[kinneera]

Sure borders may need to be added to preserve aspect ratios. This is the whole point of letterboxing - preserving 16:9 widescreen aspect ratios on 4:3 aspect ration TVs. This Divx problem is just a variant of the same issue, albeit a less common one. Nonetheless, the borders that are produced should only be visible on the computer, not the TV anyway.

[Cart Wheel]

Borders would need to be added/removed only if the source 640x480 video had the wrong aspect ratio. Standard 352x240, 640x480, and 704x480 video all has the same amount of overscan. In other words, the same horizontal area of the source video is covered, but the higher resolutions simply have more detail in that area.

Of course, if the source video does have an incorrect aspect ratio (which is very possible), then some alteration of the borders would be needed.

-Cart
http://www.geocities.com/lukesvideo/index.html

[kinneera]

Your argument doesn't make any sense given that resolution is just a way of defining aspect ratio. 640x480 is the same aspect ratio as 320x240, with double the pixel information per unit of area (this can also be thought of as pixels that are half the size, thus finer detail). The same applies for 704x480 vs. 352x240. But 640x480 and 704x480 are NOT the same aspect ratio when displayed on the exact same display device. 704x480 will look squished on the square pixels of a computer screen and correct on the rectangular pixels of a TV. The same applies in reverse for 640x480. So what this means is that for the video to look correct on one device, it is going to have to have a border present on the other. If you choose the TV resolutions, such as 704x480, TMPGEnc is going to generate that border so that your video looks correct on a computer monitor. This is proper behavior. The borders will NOT appear on your TV, because the 640 pixels describing the actual video will stretch to the appropriate width on the TV and the borders will be shifted off the edges of the screen. If you choose a computer resolution, such as 640x480, the borders will not be present on your computer, but will be on the TV (or the playback device will simply stretch it to match, in which case you get distorted video).

[Cart Wheel]

What I'm saying is this:
If you resize three standard 352x240, 640x480, and 704x480 videos to the same resolution (say 320x240), the amount of borders on the edges of the video will be identical.

A television does not have rectangular pixels. In fact, it does not have pixels. Horizontally, the signal is analog and is not divided into pixels.

In general, a DVD player simply scales the video such that the output has a 4:3 frame aspect ratio. This means that 640x480 video and a 704x480 video would both be scaled to fill the entire screen. If you were to view both videos prior to scaling on a square pixel device, the 640x480 video would look more squished. However, because of the DVD player's scaling, both would have the same aspect ratio on the output. (And neither video would have had borders added or removed.)

-Cart
http://www.geocities.com/lukesvideo/index.html

[kinneera]

We are basically making the same argument, but disagreeing on the details of how each playback device handles it.

Just to get it out of the way, when I say rectangular pixels on a TV, it's an analogy that serves to provide a reasonable standard for comparing (I'm not the first to use this analogy).

You are correct about DVD playback, but you got it the computer playback part backward. The 640x480 is what would look correct on a square pixel device, not the 704x480. And of course, the DVD player's scaling would make 640x480 look slightly stretched. Really, it's comparing the uncomparable. All I was really trying to say is that as long as you set the source aspect ratio in TMPGEnc to whatever your source video actually is, and set the output aspect ratio to whatever you want it to be - most likely 4:3 - and select Full Screen Keep Aspect Ratio, it's going to do it correctly. It will look correct on PC and TV.

And yes, this means that you can select a source aspect ratio like 16:9 and TMPGEnc will process (and automatically letterbox) it correctly to work on a 4:3 playback device. Your source aspect ratio doesn't just have to be 4:3.

The quick summary:
1. Set source aspect ratio to whatever your source video ACTUALLY is
2. Set output aspect ratio to what you want it to be
3. Make sure Full Screen Keep Aspect Ratio option is selected

TMPGEnc will produce the video correctly and this discussion isn't necessary.

[shochan]

if you dont like the borders on the side go to the advanced tab and do a little clip frame(set the aspect ratios lke thaty said) and clip out the black borders and take a little off the top and bottom till it reaches the 352x240. who really even cares if it stretches were talkin about a few lines.

[Cart Wheel]

I apologize for not being clear. A square pixel 640x480 video will have the correct aspect ratio for viewing on a monitor. What I was trying to say was that *relative* to the 704x480 video, it will look squished (also on a monitor). A better way to say this is that the 704x480 video will look stretched in comparison to the 640x480 video.

To understand the aspect ratio of a 704x480 video, let me use an analogy. Let's say you have a 640x480 JPEG image. If you resize it to 704x480 via Photoshop, you will see the image image, but it will be stretched horizontally. The same is true for video. The only difference is that instead of interpolating the added pixels, capturing in 704x480 obtains extra detail from the source video.
If you resize the 704x480 image to 640x480, it will have the same aspect ratio as the original 640x480 image. The same is true when playing the video on your TV. Both the 640x480 and 704x480 videos are resized to a 4:3 frame size. (If a TV used pixels, that would be like resizing both videos to 640x480.) Thus, the output videos on the TV have the same aspect ratio, and no borders are added/removed.

I agree with your summary, but you have to make sure you understand exactly what the source aspect ratio really is.

-Cart
http://www.geocities.com/lukesvideo/index.html