Weird Xvid problems with Gknot...please read

[totn00b]

i followed the xvid guide here at doom9 to encode a 1 hr 56 mins long movie on 2 discs with ac3 sound

here's what happened on 2 pass encodes

1. enabled lumi masking, chroma motion..resolution 672 x 288....bits/pixel = 0.261....IVTC on..final filesizes after muxing ac3 audio were 699 mb and 369 mb

2. nothing enabled in advanced options..resolution 704 x 304..bits/pixel = 0.239....IVTC on..final filesizes were same as 1.

3. nothing enabled...RESOLUTION 640 x 272..bits/pixel = 0.29..IVTC on..final filesize was PERFECT..1.36 gb

wt hell is going on here? using koepi 06-24-2003 build...how can i make a higher res rip?

[manono]

Hi and welcome to the forum-

When strange things like that happen, it's frequently a good idea to hit "Load Defaults" in the XviD Configuration screen and reenter settings. In the Global Tab make sure that you don't have "Packed Bitstream" checked. Here's a brief guide they made as a sticky in the XviD Forum:

http://forum.doom9.org/showthread.php?s=&threadid=53136

In there you'll find a link to snowbeach's excellent and very detailed guide. Perhaps there'll be something in one place or the other that will clue you to an incorrect setting you might have.

Other than that, if you still have it, you might post your log file from one of the encodes that didn't work for you.

[silver_cpu]

I'm not quite sure what you're getting at here (the stats you are giving don't have enough context for me to go on really), but I'm going to take a shot. Please at least glance at each point, especially the end.

First off, how many bits per pixel are you trying to achieve? Run a compression test, and tell us what the suggested bpp is. This is different for every movie, but if you use quality=100 for the test, you should get a good estimate. Make sure that you use the same settings in the real encoding as you do in the test.

As you increase the resolution, you can either increase the bitrate, or lose bits per pixel. Obviously, as the number of pixels increase, fewer bits can be allocated to each unless there are more bits to go around. However, this does not change the fact that the end video will be the same size as any other video encoded at the same bitrate. It will just have poorer quality if there are too many pixels for the encoder to support at given bitrate.

Also, some features in Xvid are likely to give you better compressability. Luminance masking tends to help with this, but can give odd artifacts in some parts of some material. It really depends on the material, and how discerning you are about quality.

I also suggest that you compress the AC3 file down (MP3 is actually a great choice, I doubt you'll notice the difference while you're watching), you're going to lose an enormous amount of space to it if you don't. Of course, if you want to retain the 5.1 sound, you don't have many choices other than to keep it, and spread the movie to two discs (which I'd advise anyway for a movie reaching 2 hours or more, unless it's very compressible).

I have noticed that in two passes, Xvid often will give an inappropriate file size for the video in 2-pass mode. I am unsure why this is, but it happens more often than not. For instance, most of my movie encodes go on one disc. I often get completed files (with muxed audio and video) of 500-600MB, instead of the 700MB I asked for. Sound rediculous? You bet it is. But unless the Xvid team figures out what's going on, we'll just have to settle with it. I've noticed the same problem in 2-pass DivX encodes, but the problem seems to go away if I use 3 passes instead of 2, which really doesn't make any sense to me.

[totn00b]

Originally posted by silver_cpu
I'm not quite sure what you're getting at here (the stats you are giving don't have enough context for me to go on really), but I'm going to take a shot. Please at least glance at each point, especially the end.

First off, how many bits per pixel are you trying to achieve? Run a compression test, and tell us what the suggested bpp is. This is different for every movie, but if you use quality=100 for the test, you should get a good estimate. Make sure that you use the same settings in the real encoding as you do in the test.

As you increase the resolution, you can either increase the bitrate, or lose bits per pixel. Obviously, as the number of pixels increase, fewer bits can be allocated to each unless there are more bits to go around. However, this does not change the fact that the end video will be the same size as any other video encoded at the same bitrate. It will just have poorer quality if there are too many pixels for the encoder to support at given bitrate.

Also, some features in Xvid are likely to give you better compressability. Luminance masking tends to help with this, but can give odd artifacts in some parts of some material. It really depends on the material, and how discerning you are about quality.

I also suggest that you compress the AC3 file down (MP3 is actually a great choice, I doubt you'll notice the difference while you're watching), you're going to lose an enormous amount of space to it if you don't. Of course, if you want to retain the 5.1 sound, you don't have many choices other than to keep it, and spread the movie to two discs (which I'd advise anyway for a movie reaching 2 hours or more, unless it's very compressible).

I have noticed that in two passes, Xvid often will give an inappropriate file size for the video in 2-pass mode. I am unsure why this is, but it happens more often than not. For instance, most of my movie encodes go on one disc. I often get completed files (with muxed audio and video) of 500-600MB, instead of the 700MB I asked for. Sound rediculous? You bet it is. But unless the Xvid team figures out what's going on, we'll just have to settle with it. I've noticed the same problem in 2-pass DivX encodes, but the problem seems to go away if I use 3 passes instead of 2, which really doesn't make any sense to me.

i have an optical output and a 5.1/dts receiver so i can tell the difference between dd and mp3

it's just weird that it's fine for 640 x 272 but totally hosed for higher res..i'm going to check out that guide that manono posted

[cult]

I have a small suggestion for you.Dont use lumi masking,its buggy,read the newbies settings in xvid forum