Why do most DivX rips look like crap?

[SunnyD]

Seriously...

I'm trying to figure this out. I haven't actually done any quality encodings myself yet, but I've been looking around trying to compare the different Codecs out there for file size versus quality, and I figured I'd try out some of the MPEG-4 setups out there.

So far I've tried DivX, XviD, and Apple's MPEG-4 implementations, and frankly, they all look like crap, yet tout that they all produce DVD/MPEG-2 quality playbacks.

I even went so far as to download (sigh) a couple of movies that utilize these various codecs - including one of the DivX titles that was about 1.2gig. I was thinking that it was the fact that people are trying to fit things onto 1 CD that they were sacrificing quality for space, but that wasn't quite the case.

Is this simply a matter of people not knowing how to setup the encoders properly, or is it really a case of "size versus quality" issues that I am seeing, or are these MPEG-4 compressors just blowing alot of hype?

I've got alot of home movies I'd like to put on disc, but if what I'm seeing is the only quality I'm going to get, I think I'll leave them on tape.

Any insight is appreciated.

 

[Mark R]

Most people set the bit rate far too low.

For a DVD resoluion video (720x576x25/720x480x30) MPEG-4 Advanced simple profile really needs about 2.5 - 3 Mbps - at that rate a typical movie will need about 2 GB.

Also a lot of people encode using DivX (freeware), or Quicktime which only use the simple profile (not advanced simple profile). The more advanced encoders are needed for the advanced profile. The other problem is that the codecs (particularly divx and xvid) have a number of 'optimisation' options which can acceelerate encoding (but at the cost of significant quality).

 

[rbV5]

Is this simply a matter of people not knowing how to setup the encoders properly, or is it really a case of "size versus quality" issues that I am seeing

Its both. Most DivX rips "may" look like crap(I haven't seen most of them), but good Divx rips look good...real good. Capturing your home movies is what will make or break your encodings. Garbage in>Garbage out.

 

[Looney]

No idea... maybe it's what you're downloading. I have over 200+ rips, and they're all excellent quality. Certainly better than the best VHS.

 

[SunnyD]

Originally posted by: Moralpanic
No idea... maybe it's what you're downloading. I have over 200+ rips, and they're all excellent quality. Certainly better than the best VHS.

Well, for example - I grabbed SW:Episode 1 for comparison's sake to DVD yesterday (which I have). I figured this would be a "typical" rip, commonly used settings etc. Right from the beginning of the picture - not running fullscreen (so native resolution) - I'm seeing compression artifacts, a very pronounced MPEG blockiness (I've seen this is DVD's too, but not this bad), very coarse edges on sharp objects, really bad color balancing (washed out), and a relative LACK of detail on alot of scenes. I'm certain this was a DVD rip as well, since I couldn't see any of the usually motion-picture screen artifacts (you know, dust on the film and such). For all intents, if I were to compare this DivX rip to VHS tape (and I'm using Digital-8 tapes to master from which are a hell of a lot nicer than VHS), I would be extremely pleased with VHS quality over DivX. The file size was around 800meg as well, so again, I was thinking this was typical.

But now that I know what the masses are using DivX and MPEG-4 for and how they're using it, I suppose I had better look into some of the more advanced options then.

 

[SunnyD]

Originally posted by: Mark R
Most people set the bit rate far too low.

For a DVD resoluion video (720x576x25/720x480x30) MPEG-4 Advanced simple profile really needs about 2.5 - 3 Mbps - at that rate a typical movie will need about 2 GB.

Also a lot of people encode using DivX (freeware), or Quicktime which only use the simple profile (not advanced simple profile). The more advanced encoders are needed for the advanced profile. The other problem is that the codecs (particularly divx and xvid) have a number of 'optimisation' options which can acceelerate encoding (but at the cost of significant quality).

Oh yeah, what other encoders are there out there anyway? The more "advanced" ones that is...

 

[THUGSROOK]

i use divx 503 pro and i can assure you my encodes dont look like crap
(approx 2000 VBR, 2pass, 2cd rip, QP, GM, BDE on)

MOF youd be hard pressed to tell they werent dvd, even @ full screen.

practice makes perfect

 

[Mark R]

I've tried Xvid, Mpegable and sorenson - all support the advanced simple profile (the main addition in DivX Pro). Quicktime, mpegable and sorenson also all support the creation of .MP4 files (the industry standard file type for MPEG4 data).

XVid and DivX (free/pro) are also both limited in that they don't support MPEG4 audio which is significantly better than MP3 and therefore cannot produce .MP4 files. DivX pro will generate .MP4 files but they use a different audio codec, and therefore are not compatible with other software. Similarly DivX will not play standard .MP4 files.

The upcoming Nero digital codec is supposed to be the first full MPEG4 codec with additional more complex video profiles and support for high complexity MPEG4 audio.

 

[SunnyD]

Originally posted by: Mark R
The upcoming Nero digital codec is supposed to be the first full MPEG4 codec with additional more complex video profiles and support for high complexity MPEG4 audio.

Is THIS what you're referring to?

Also, is there a single codec out there that will play all MPEG-4 based files (DivX, XviD, Quicktime, and real MP4)? Or do I need to have each individual codec installed...

 

[Mark R]

Is <a class=ftalternatingbarlinklarge href="http://www.nero.com/en/index.html#c1040045686586" target=new><FONT face=Tahoma color=#000080>THIS</FONT></A> what you're referring to?

That's not it. That is just the MPEG4 (AAC) audio codec. I'm not sure if it is a complete implementation of MPEG4 audio.

As for video codecs - well, it's a mess isn't it. With .AVI files, the file header specifies which codec should be used - if you don't have the exact codec, then media player will complain and refuse to play. It is possible to hack this both during encoding and also afterwards, but it doesn't always work, because DivX and XviD have different bugs.

I've had little trouble getting files encoded with the basic features of XVid to play back with DivX, or indeed vice-versa. With the advanced features (global motion compensation, B frames, and Quarter-pixels) - strange things often happen.

I've not tried the mpegable avi encoder, and sorenson won't encode to AVI (although it will encode MPEG4 video in WMV files).

Essentially, if you want to play all MPEG4 files then you need almost all the different players. Media player won't attempt to use another, if it can't find the exact one for a particular .AVI. DivX's MP4 player won't play .MP4 files encoded by a proper encoder. Quicktime has only very limited playback support.

Mpegable's mp4 player, has at least played every mp4 file I've thrown at it without fuss - it's also much, much faster than quicktime.

Mpegable's AVI codec is quite happy playing XVid and DivX 5 files with the appropriate hacking. Similarly, both xvid and divx are quite happy playing the files (when appropriately hacked).

 

[SunnyD]

Whoa, all that just confused me even more.

You're saying that various players won't play with different codec's right? So far I haven't had any issues with Media Player playing both DivX and XviD, and MPEG4 AVI's. I have Quicktime installed, so that takes care of the rest pretty much. So anyway, is this what you're alluding to? Am I going to see problems in the near future?

Thanks for all of this info, this is getting pretty interesting.

 

[Looney]

No, different players won't affect quality... it's the codec.

Don't know what to tell you, you'll probably downloading crappy encoded movies. Like i said, i have hundred of movies and tv shows encoded, and all of mine are better than VHS quality.

 

[bedrocked]

the reason why most of the ones u download are not 'up to par' is because there is a standard among the groups who do xvid/divx to keep it to no bigger then 2cd, preferably 1. like was mentioned above a good quality divx would take 3cds for a typical movie.

 

[Ogo]

Try watching the movies through your TV out, once I did that my movies looked 10x better than on my monitor. Only the crappiest rips had the "squares" noticeable on the 32 inch television.

 

[lung]

like was mentioned above a good quality divx would take 3cds for a typical movie

Whatever. I have ripped several movies to single cd divx and they look pretty damn good. Although, the ones that work on one cd and still look good are no longer than 90 minutes. Personally I have gotten away from divx anyways since I would rather spend the little bit of money on the dvd and get the better quality as well as not having to swap discs.

 

[elkinm]

Use 2 pass encoding with something like Xvid. Divx 5 is alomst as good but not quite. If you have time though, the new n-pass encoding is better but requires several passes to beat xvid im my opinion. I noticed that a 1 and a half hour movie easily fits on a 700 MB CD. I have downloaded files like this but they still looked bad which basicly means that a poor codec was used like divx 3 or only one pass was used. Pypicaly anything xvid I downlod looks just about perfect with hardly any diference from the DVD but divx is usualy worse. Also, when I download, I usualy get some small corruption so usualy some pixilation or color distortion occurs in the movie from this. Any movies that I tried encoding myself look nearly perfect.

Also xvid and divx are logarithimc in size. What I mean that encoding a small size 500 MB file to 100 MB xvid file will see much more quality degredation then converting a 5 GB file with far greater resolution to 1 GB assuming same length file. So it seems that some minimum data is need for a perfect encode but after that little extra is needed for larger resolutins. I think that is strange that I can achieve a 5x compression ratio on DVD MPEG-2 files with practicaly no quality loss but with smaller 200 MB files I cannot get 2x compression with little quality loss.

Since the AC3 takes up more room, encoding moovies with AC3 audio takes up slightly more room then with MP3 so I encode to 2 CDs up to 2+ hours. Only for movies longer then 2.5 or 3 hours would I use 3 CDs even with AC3 and that would give me excelent quality but little compression.

Edit, and best of all, now none of the imabes for the buttons and icons are removed by IE6 SP1. Don't know why IE still has that bug but I am happy that I can see everything once again.

 

[Goi]

DivX, Xvid and other MPEG-4 compressors are actually better than MPEG-2/DVD, but the problem is, most of the stuff you see out there are DVD rips. Its taking a compressed MPEG-2 file and compressing it again with another lossy compressing engine - MPEG-4. As good as MPEG-4 is, it can never match its source, much less exceed it. Because of this, obviously DVD rips are gonna look worse than the actual DVDs!