svcd letterbox

[RiDaH22]

i recently asked a question about about widescreen svcds. i came up with the answer: encode my video in letterbox. when i did that it didn't keep my video in widescreen it turned it into a square video. please help me get my movie into 4:3 aspect ratio but still keep widescreen at the same time.

[Vejita-sama]

You can't have a DAR of 4:3 and 16:9 at the same time, it's one or the other. A little more info would help, it appears that you have a widescreen TV, a 16:9 video source and want to make a SVCD that will play correctly (ie. preseves 16:9 DAR) on your widescreen TV.

If so here's how it works. X(S)VCDs have a DAR of 4:3 only. So you can't make a SVCD with DAR of 16:9. But you can make an xSVCD with a DAR of 16:9. SVCDs do not support anamorphic video. But some DVD players will play anamorphic SVCDs anyway (you'd have to check your DVD player to know it varies).

Normally if you want to convert a 16:9 source to SVCD, you would letterbox it (as SVCDs have a DAR of 4:3).

Q: what happens when you play a 4:3 source on a widescreen TV?
A: the tv adds black bars to the left/right of the video to maintain the 4:3 DAR.

Hence, if your 4:3 video is letterboxed you'll get the black bars on the left/right AND the top/bottom (encoded as part of the video). From your above description I think that this is what happened.

As for how to fix this (make a 16:9 or anamorphic SVCD) we need to know more info: video source, programs used to encode, settings, etc.

[RiDaH22]

my video source is widescreen of course with a resolution of 640x360 and NTSCFilm if that is a factor in this but i do NOT have a widescreen tv just a widescreen video. thanks for helping me

[Nitemare]

What is your source video? An AVI file? What encoder are you using? TMPEG?

If so, set your source aspect ratio as 1:1 [VGA] and set the video arrange method to Full Screen [keep aspect ratio]. That's it!

If you're letterboxing and frameserving with Virtual Dub to another program, make sure the program you're using to encode has the source aspect ratio set to 4:3... this is what the letterboxing in Vdub does for you...makes it 4:3...assuming it is sized correctly in the first place.

What are you watching the finished product with? SVCD output is 480x480 (square video) with a 4:3 DAR. Your TV and most DVD software will display this correctly. Media player ignores the 4:3 DAR and displays square video. This is normal.

Maybe none of this applies? If we haven't stumbled across the answer here then more info is really needed to troubleshoot this problem. Good luck!

[RiDaH22]

yes the source file is avi and the i am encoding with tmpeg

[gonzalimator]

Hey RiDaH22,

Are you aware that SVCD's are 480x480? That's a square. (not meaning to insult you, just being matter-of-fact) Maybe what you need to do is custom resize your source when you encode to SCVD, so that when it plays through your DVD player it will be resized to the correct aspect ratio.

Here's what I would do:
figure out the aspect ratio - 640÷360=1.777777778 this is 1.77:1

If we think about the final destination resolution (720x480 DAR-that's on a TV) you can see that the horizontal resolution is the only difference between DVD and SVCD. So, we need to calculate what your movie's resolution should be at full screen first, then we can see what the vertical res should be. Knowing that a DVD player that supports SVCD will stretch the horizontal and not the vertical res, that should work. One more thing. I should point out that 720x480 is not 4:3. On a TV screen it is, but not on a computer monitor. 4:3 is what we want, but we should need to adjust for this discrepancy.

Here's some more math:
4:3 ratio demands that a movie 720 pixels wide be 540 pixels tall(720÷1.33=540)
But for a TV we know that it should 480 pixels tall when the hizontal res is 720. 480 is 88.89% of 540. We need to figure out the vertical res first as if it were full screen, then multiply that figure by 88.89%

Example:

640x360 would be 720x407. (720÷1.78 aspect=407 vert res)
multiply 407 by 88.89% = 362 (this accounts for the TV)
the custom resize for this film for SVCD should be 480x362

Some people say that your res (horizontal or vertical) should be a multiple of 16 for VCDs. If this necessary for a custom resize (I don't think it is because the final res of the mpg will be multiples of 16, 480x480) then take that vert res number and divide it by 16. If it's not a whole number but somewhere between, round up or down, whichever is closest. Then multiply by 16 to get the vertical res again. 362÷16=22.625 so that's closer to 23. 23x16=368, so if you want, make your resize 480x368.

So.... if you use TMPGEnc, when you are encoding the mpg for SVCD authoring, go to Settings. Under the Video tab make the res 480x480. Under the Advanced tab, set the Video arrange Method to "Center (custom size)". Fill in the values to 480x362 or 480x368, whichever.

Hope that helps.

I double-checked my math against FitCDs resize function and it spat out 480x368, so I can't be too far off with my logic.

[Vejita-sama]

Nitemare nailed it. Since your source is DivX set the "source aspect ratio" to 1:1, set the up put to 4:3 NTSC TV, and under video arrange method choose "full screen keep aspect ratio." TMPGenc will then letterbox (and center) the video for you.

It might be a good idea to read up more on DAR (and maybe anamorphic DVDs as well). Take a look at:

http://www.doom9.org/aspectratios.htm

http://www.thedigitalbits.com/articles/anamorphic/aspectratios/widescreenorama.html

Basically there are three DAR (display aspect ratios) you need to know:

1:1 PC video
4:3 Standard TV
16:9 Film (and widescreen TV)

Under the 16:9 flag you'll find a few ratios:

1.85:1 academy flat
2.35:1 anamorphic wide screen
1.77:1 widescreen TV

ALL pc video SHOULD have a DAR of 1:1. So if your source is divx set source aspect ratio to "1:1 VGA". It might have started as 4:3 or 16:9, but if it's (correctly encoded) pc video it's now 1:1

[RiDaH22]

whoa thanks and imma write that math down alot of shit to rememer