help getting perfect quality vids

[chrome]

sometimes i can make virtually perfect backups of my dvds to divx or xvid, but other times, they come across VERY badly... ive tried using both codecs but they usually come out the same nasty blurry mess. hopefully someone knows the problem im talking about (the video is unclear, colours run together, its blurry, generally looks NASSSTY)

is there something i could be doing in gordian knot to help? when i go to make the avs file, theres lots of options there that i dont USUALLY mess with... for instance, the noise filter, would this help? also i see resize filter (bilinear, soft, neutral, sharp, simple) can someone tell me what this does? (ive seen it mentioned a few times, but no real explanation of it.)

also, is there some filter i can use to get these "problem" movies looking perfect? ive never really touched filters before, but im guessing its something im going to have to get in to...

thankyou in advance

[manono]

Hi-

I'm sure that there are lots of followup questions that could be asked, as you haven't given near enough information to reliably help you. But for starters; are you making these always for 1 CD or for 2, or does it vary? Are you always using the same resolution, like 640x272, or does it vary? Which 2 codecs have you tried, maybe DivX5 and XviD? If so, are you using B-Frames, or not? As perhaps you know, different movies compress differently, and settings that work for one may not work for another. On the one extreme you have clean, relatively dark and relatively static movies that compress well. Just yesterday I did one like that, 128 minutes long at 640x272 for one CD and it turned out well (average quant=3.3). On the other extreme are noisy, long, bright and action packed movies that you struggle to fit on 2 CDs with decent quality. What kind of audio do you use, AC3 or MP3? Using AC3 allows less space for the video portion. If some of the movies that turned out poorly are well known ones, maybe name them and someone that has worked with them can give some tips. The best advice I can give without knowing more is to recommend running a Compression Test to get an idea of what the finished quality will be before doing the encoding. From the sound of it, you haven't been doing that.

You might post the log file from one of the bad movies, along with the .avs (after removing the lines beginning with "#").

[chrome]

ok, sorry, my bad.

i have tried both xvid and divx codecs, and the quality is still the same, so im positive the problem is not the codecs

the problem only happens when i encode for one cd (i must say though, sometimes i get perfect single cd rips, this problem only happens on SOME single cd copies), and as a general personal rule, anything under an hour and 30 mins, i can put on one cd, at between 608 to 640 res. if its an hour and 45 mins, i can still squeeze it on, at 576. if the time is longer, i go for 2 cds. single cd copies i only use mp3, never ac3 (only ac3 on 2 cd ones, and again, i dont have problems with 2 cd rips)

so, im sure the problem is not resolution or the amount of space im trying to compress the movie in to.

might it help if i posted a screenshot of the horrible quality im getting?

[manono]

Hi-

so, im sure the problem is not resolution or the amount of space im trying to compress the movie in to.

I wouldn't be so sure. I saw your thread in the XviD Forum, and that combined with your last post in this thread leads me to conclude that my first hunch was right; you're not giving some of your movies enough bitrate if you're getting a lot of blocks.

There's very little connection between the length of your movie or the resolution you use, and the number of CDs to use. It depends entirely on the compressibility of the movie. And I'll repeat, the best way to determine it's compressibility is to run a compression test before doing the encoding.

I'll give you an example. Do you know that girl surfer movie called Blue Crush (not my kind of movie; my daughter wanted it)? It's only 104 minutes long, but would look lousy done for 1 CD. Why? Because it's filled with all these surfing/rough water scenes. That kind of stuff is real hard to compress.

the problem only happens when i encode for one cd

That's a dead giveaway right there. If you were to reencode one of those bad 1 CD rips for 2 CDs, I bet the problems would disappear. Another thing you can try is to drastically limit the maximum quant allowed. But you didn't hear that from me. :) In addition, you'll need some experience to learn how to do that right. You can get oversized files if you don't know what you're doing.

[chrome]

my xvid post was about a different movie (2cd, mp3 audio, two towers) and with that movie i had a problem where it was somewhat blocky during action sequences, but during the slower bits, it was fine.

but i think your right about the other stuff. someone once said that some movies just WONT compress nicely on 1 cd. are you saying that im basically stuffed if i want to compress -some- movies onto one cd?

and yes i did notice when i aim for 2 cds instead of 1 for those problem movies, they turn out fine, but im sure there must be a way around it (far be it from me to discuss piracy, but in the interest of research only, ive noticed perfectly good single cd versions of some of my trouble movies im trying to encode for a single cd)

also, why are some scenes more difficult to compress? (like in your example) is it the motion involved?

oh, and ill have a look into that reducing max quant. deal, and try giving that a shot.

ive never done a compressibility test, i know where to do it, but if you could run me through exactly what to do/what it tells me/how the info is relavent/and what i do with the info i get, that would be a HUGE help. (its a lot to ask, but if you happen to know of a good write-up on the subject, you could point me to where thats at...)

also, when i go to make the avs file, i see "resize filter", could you tell me what exactly that means and what the options for that do?

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ok, im editing this post just to add this bit: had a look on doom9 for anything on compressibility test, and heres my understanding of it (if you could call it that), just let me know if i kinda get it or am way off:

when you do the test, your given the bits/pixel*frame info...which should give me a clue more or less, how many cds i should be putting the movie on... if im getting anything around or higher than .25, it should be on 2 or more, anything less or near to .17 should be fine on 1 cd?

so really, the ability to have a nice looking movie (compress it nicely) does not REALLY depend on the length of the movie, or even really the size of the original vob files), but rather the quality of the original movie?
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thanks for your help so far, by the way.

[jggimi]

In Doom9's Gknot guide (http://www.doom9.org/gknot-main4.htm), you'll find the compressibility test for Xvid described in Step 2. (http://www.doom9.org/gknot-main4.htm).

There seems to be an echo in here.

[manono]

Hi-

There seems to be an echo in here.

No kidding. Hehe. :)

chrome, have you read the XviD Encoding Tips (http://forum.doom9.org/showthread.php?s=&threadid=53136) sticky in the XviD forum? In there you'll find a link to snowbeach's excellent and very detailed XviD guide.

are you saying that im basically stuffed if i want to compress -some- movies onto one cd?

Depends on the quality that will satisfy you. But since the title of this thread is "help getting perfect quality vids", then I'd say yes, you're stuffed.

ive noticed perfectly good single cd versions of some of my trouble movies im trying to encode for a single cd)

If you're relatively inexperienced at knowing what to look for, they may look perfectly fine. Those guys have rules they have to follow about how many CDs for what length movie, and you don't. And there are lots of "tricks" you (and they) can use, and as you gain experience, you'll learn them. I've seen first pass sizes of over 5 GB for 100 minute movies at 512x384. Try and compress that down to 1 CD sometime.

also, why are some scenes more difficult to compress? (like in your example) is it the motion involved?

Yes, but motion isn't just Jackie Chan kicking ass (hard to compress). It might be water (The Abyss or Waterworld), or noisy and grainy movies (Saving Private Ryan). It might be a crowd scene. It might just be a full screen shot of tree leaves blowing in the wind. All are complex scenes that are difficult to compress. It's not just explosions and fighting scenes that are difficult to compress.

also, when i go to make the avs file, i see "resize filter", could you tell me what exactly that means and what the options for that do?

The different resizers give you varying degrees of sharpness and compressibility. In my opinion LanczosResize is the best and sharpest of the resizers. But you'll loose compressibility when compared to the other resizers. Then you have the different settings of the Bicubic resizers. And the most compressible and least sharp (and should almost never be used in my opinion) are Bilinear and Simple resize.

And you might try some of the denoisers available in GKnot or elsewhere to aid in making your difficult movies more compressible. Here's a list of what's available inside of AviSynth:

http://www.avisynth.org/index.php?page=FiltersByCategory

And here are almost all of the 3rd party filters:

http://www.avisynth.org/~warpenterprises/

Do not overuse temporal and spatial smoothers. But with light use they can help you considerably without obvious degrading of a difficult to compress movie.

if im getting anything around or higher than .25, it should be on 2 or more, anything less or near to .17 should be fine on 1 cd?

You're given that info when you open the .d2v. And as jggimi likes to say, those are guidelines to be used only until the results of the compress test are in. Then they go out the window, and you rely on what the compress test tells you to help you choose the resolution and number of CDs.