What are the Xvid resolution rules????

[kastro68]

Am i the only one experiencing resolution problems with the Xvid codec?

I am not sure if this is a bug or not, but with some resolutions i choose there is a diagonal problem.

Someone once told me that I should stick with multiples of 16. So far all resolutions that are multiples of 16 have worked for me. However I found this rule toooooooooooooooooooooo restrictive.

I have found that some resolutions that are not multiples of 16 work fine without the diagonal problem.

IS THIS A BUG? Or am i required to do a test encode each time to check if the chosen resolution will work fine?

[MaTTeR]

Not sure. I've always followed multiples of 16 rule using Gknot and never experienced this problem your seeing. This gives me plenty of flexibility:)

[kastro68]

But does using a multiple of 16 leave you with an aspect error of zero each time?

[Ripe73]

But does using a multiple of 16 leave you with an aspect error of zero each time?

Use smartcrop all

[MaTTeR]

Originally posted by Ripe73


Use smartcrop all
Yep, smart crop all gives me 0.

[kastro68]

But won't using smart crop all chop off non black borders too!

And there is still the issue of chopping off black borders off mpeg or vcd files.

[kastro68]

ie... it will chop off parts of the movie

[MaTTeR]

In all of my encodes, smart crop all just chops a few pixels on each side. Please tell me you don't notice this. LOL

[Ripe73]

Or buy the DVD:D

[kastro68]

It still doesn't solve the problem of converting a format like mpeg or VCD inTO Xvid...black borders take up space

[MaTTeR]

I dont encode to VCD so I'm not familiar with that process. I don't understand what black borders your talking about taking up space. In Gknot you simply crop down the black borders using the pixel method, then select smart crop all. No black borders exist in this method. How does VCD differ in this regard?

[kastro68]

Sometimes I have to convert VCD files into Mpeg4 so i could fit in more eps per cd...only ppl stingy on CDs would understand.

VCD format sometimes has black borders. Ideally i would like to chop off these black borders so that the Xvid encode does not have any black borders.

AND when i chop off these black borders, the resolution may no longer be a multiple of 16.

[Foo]

@ Kastro

I'd agree that this is a big problem, but I haven't noticed it lately. I did something at 640x344 the other day, so I'll have to watch it all the way through to see if there are any errors, but my spot checking didn't show any. People please stop simply suggesting a "smart crop all" when he is asking about a real potential drawback :D. Some people don't want to loose 20 pixels of the horizontal ;). A forced multiple of 16 is a pain, and isn't close enough AR wise (at least to my eyes) at certain target resolutions. An 8x or 4x restriction would probably be okay :). However, I must ask, are you using the DivX FourCC or the Xvid one?

foo

[kastro68]

Originally posted by Foo
However, I must ask, are you using the DivX FourCC or the Xvid one?

foo


If possible i would prefer using the DivX FourCC because i like the post processing and brightness control. However, recently I have been using the Xvid FourCC quite frequently.

This is because the DivX FourCC doesn't work that well for Xvid encodes where either Modulated or Mpeg quantizaton has been used. I have experienced cases where there was a green grid that appears over the video image that progressively gets darker as it approaches a keyframe, this occurred when I was using the modulated quantization. I have even seen bleeding from the right edge where I cut off a black edge from a vcd video clip, even though I used H.263 quantization. None of these problems occurred when i changed the FourCC to Xvid.

However the diagonal problem occurs with both the DivX FourCC and the Xvid FourCC.

What I find interesting is that some resolutions that are not necessarily a multiple of 16 work, while others may not. It isn't really a big deal for me to do a cbr test to see if the resolution i chose was feasible if I was just encoding a single movie.

BUT, it is a lot of work when you want to convert heaps of music clips to Xvid. Once I queued 15 or 16 clips in Virtual Dub only to find that they turned out black and white with a diagonal running from the bottom left to top right.

Also of interest is the fact that divX 4.12 can run at any resolution I threw at it so far [using sensible resolutions that are not too small or too large]. So I think that it is possible to fix the resolution requirements of Xvid.

Ja ne

[-h]

Just to wrap this thread up, yes MPEG4 fully supports resolutions which are not a multiple of 16. I will look into why things are going wrong.

-h

[duartix]

For those people using a multiple of 16 resolution please read this post:

http://forum.doom9.org/showthread.php?s=&threadid=18277

and then post your tests please.

[LotionBoy]

I just dropped a whole bunch of tests there. mod16 resolutions are looking really poor compared to mod32. Now someone just needs to explain the math that causes this.

LotionBoy

[kastro68]

@LotionBoy

Didn't someone already explain this in great detail...can't remember which post it was in though.

[duartix]

@kastro68:
Can you please search the board and tell us where?
I'm really insterested in this subject.

Thanks.

[kastro68]

I tried going back to search for the post, and it appears that it is not entirely relevant...sorry about that, my mistake, again.

I am currently trying to keep a really low profile at the moment, after a very embarrassing incident one or two days ago. :P


But if you ask -h I'm sure he'll give you a good lecture about it. :)


Ja

[Teegedeck]

It might be good to keep an eye on this thread, too:
http://forum.doom9.org/showthread.php?s=&threadid=18277

[Franko30]

Originally posted by Teegedeck
It might be good to keep an eye on this thread, too:
http://forum.doom9.org/showthread.php?s=&threadid=18277

Parrot indeed :D

(it's the same thread duartix mentioned a few posts back).

But: Interesting findings!

Frank

[Teegedeck]

Originally posted by Franko30


Parrot indeed :D

(it's the same thread duartix mentioned a few posts back).

But: Interesting findings!

Frank

I'm happy if I can keep you entertained! ;)