Divx/Xvid quality

[Jeff7181]

How much can you compress a DVD before the quality loss is obvious? In other words... how small do you make your Divx/Xvid files? 700 MB? 1 GB? 2 GB?

 

[Lonyo]

700MB seems just about OK, but obviously the bigger the better.
And it depends on the length of the film too. 45 mins is fine at 350MB, so 1 1/2 hour film is OK at 700MB, but something like LoTR would obviously not be as good (being longer).
Either 1x700MB for shorter films, or maybe 1~1.4GB (2x700MB) for bigger films seems to be the standard.

(This is from my experience watching films on a 19" CRT at fullscreen using WMP).

 

[Jeff7181]

Anyone else wanna share their personal preference? How bout you media center guys? How small do you make movies that you've ripped?

 

[Excelsior]

Id say, for an average size movie, 700MB is perfectly fine if you don't require the absoulte best quality. It looks great to me, at least on the TV coming from my computer. But what Lonyo said is good.

 

[OvErHeAtInG]

Ten megs a minute (including MP3 audio) would be high quality (not far short of DVD) for a typical piece of video with plenty outdoors or motion going on. As little as 5-6 (MB/min) would work for TV shows or something which are generally indoor shots of people talking, which MPEG4 handles nicely. But you're asking "before quality loss is obvious"; quality loss will always be obvious. If you want DVD quality just watch from the DVD. There are also LOTS of other variables, again films are less compressible, because of film grain, outdoors action.

 

[BlueWeasel]

I usually try for at least a minimum bitrate of about 1000 when converting to Divx, but that's almost impossible when trying to fit a single 90min or so movie on a 700mb CD.

I converted all 3 LOTR movies to Divx and fit all 3 movies on a single DVD+R....it actually looked pretty good, but I could see some defects.

 

[Munky]

Here's how it works: The image quality depends on 2 things -

1. Bitrate
2. Resolution

Each frame in a movie is composed of a fixed number of pixels, and has only so many bits to store that information. With compression, each pixel in a frame only gets so many bits to store color information, and if you lower the bitrate too much, a good portion of that information will be lost. To fix this, you can either increase bitrate, or decrease resolution. Increasing the resolution will only make things worse.

Obviously you want to have as high resolution as you can, and that means also keeping the bitrate high enough. So, when I encode divx movies, I use a bitrate calculator (there are many available for free, I even wrote one myself), to find what's the highest bitrate I can have to make a movie of a certain length fit a certain size. If the movie is longer, you either have to increase bitrate or the size, depending on your priorities. Then, you find the maximum resolution you can reasonably use, and encode it like that. I don't remember the actual math, but it basically comes out to >= 0.20 (bits * pixel / frame). If you have less than that, then the image quality will suffer.

Here's a link to my old college website (can't believe it's still up), I have a bitrate calculator you can download, and that's the one I use.

Linky (in the freebies section)

 

[Haden]

I always keep AC3 sound, thus 700MB is not really an option. ~1.4GB is preferred, but depends on movie.

I'm using these suggestions when encoding.

 

[carlosd]

Minimun 1.4GB for a 90 minutes movie, great quality keeping AC3 sound.

 

[Goi]

Depends on what kind of display you're watching it on too. On a regular TV, I can't tell the difference between 700MB xvid rips and a DVD.

 

[kmmatney]

Originally posted by: carlosd
Minimun 1.4GB for a 90 minutes movie, great quality keeping AC3 sound.

I agree. Only use 700MB if you don't have a DVD burner. You will notice degradation at that size. If you have a DVD burner go for 1/3 of a DVD size, or around 1.5 GB.

 

[Bateluer]

Originally posted by: kmmatney

Originally posted by: carlosd
Minimun 1.4GB for a 90 minutes movie, great quality keeping AC3 sound.

I agree. Only use 700MB if you don't have a DVD burner. You will notice degradation at that size. If you have a DVD burner go for 1/3 of a DVD size, or around 1.5 GB.

Thats what I shoot mine for.

 

[tren001]

If you have a DVD burner, I'd say just use DVDShrink or something similar and do a compressed DVD backup, since DVD+/-Rs are so damn cheap nowadays. By do it this way, you can also play the disc in anything (because xvid setup DVD players are still pretty scarce). These kind of backups have basically identical quality to the originals.

If you do go with xvid encoding, 1.4g is probably the best, but even at that stage, you can see artifacts, especially in a dark scene, where you'll see "blocky" stuff.

 

[JonathanYoung]

I use Gordian Knot to encode my Star Trek DVDs, and I set it on 1 CD (700MB) with 128kbit VBR mp3 sound. Each episode ranges from just over 300MB to 500MB, and IMO, they look exactly like the DVD. For movies, I'd say go for 2 CDs and burn them to a DVD-R. That's what I do with the 2-part episodes.

 

[uOpt]

I am thinking about making backups of my movie DVDs to DVD-R by putting the udf filesystem into a two-part RAID-0, then burn the raw device images of the two RAID parts on seperate DVD-R, in the end playing back by putting them into two drives, reassemble the RAID, mount the UDF filesystem and go.

Would suck to walk to a friend with a Windows box, though

 

[ng12345]

someone mentioned using dvd shrink ... you think that the compressed mpeg2 image is better than a compressed mpeg4?

the main difference i noticed with dvd shrink is that the picture becomes washed out... i'm not a videophile by any means but i could easily tell the difference between a dvd srhink copy and the original (i think it was at 70% compression)

with some movies nearing the 8gb mark, that yields almost 50% compression which yields a very nasty picture

i've just started with divx encoding so i'm trying to figure out the best resolution to shoot for also ... all this info is great

not trying to thread steal ... but does nayone know if there's any way that you can create a divx that preserves the dvd menus?

i've ripped my collection onto my 400gb hard drive at full quality mpeg-2, only to realize that 400gb is only good for about 45 dvds (not very helpful when i'm at 80+ dvds)

 

[Matthias99]

Originally posted by: ng12345
someone mentioned using dvd shrink ... you think that the compressed mpeg2 image is better than a compressed mpeg4?

Almost certainly not; MPEG-4 at the same bitrate/res should be considerably better than MPEG2.

I've just started with divx encoding so i'm trying to figure out the best resolution to shoot for also ... all this info is great

Generally speaking, I think you get better results if you keep the full resolution (720x480 for DVDs) and lower the bitrate accordingly. This way you're more or less just doing temporal compression, and not resampling the frames to a lower resolution (which can introduce its own graphical anomolies).

not trying to thread steal ... but does nayone know if there's any way that you can create a divx that preserves the dvd menus?

Not really. The DVD spec doesn't officially support DivX video compression.

i've ripped my collection onto my 400gb hard drive at full quality mpeg-2, only to realize that 400gb is only good for about 45 dvds (not very helpful when i'm at 80+ dvds)

Yeah... maybe you should have thought of that when speccing out your disks?

Personally, I think a "1-hour" (actually ~45 min. of video with commercials editied out) TV show looks decent on a 700MB CD-R. That's about 2Mbps. A 2-hour movie would be about 2GB at that bitrate.

 

[render]

1.5GB per movie since a DVD burner is so cheap.

 

[Gurck]

Highly dependant on movie length, and of course whether you require ac3 (5.1 channel) sound or if mp3 is good enough for you. Quality loss is noticeable if I'm really looking for it a few feet from my 19" CRT at 90+ minutes, noticeable from ~10 feet at 120+ minutes (but plenty tolerable), and becomes a bit much to put up with at 150+ minutes from 10'. This is with 96kb mp3 audio using the divx pro 5.1.1 codec. Another :thumbsup: for Gordian Knot, btw.

 

[YOyoYOhowsDAjello]

Originally posted by: Goi
Depends on what kind of display you're watching it on too. On a regular TV, I can't tell the difference between 700MB xvid rips and a DVD.

:thumbsup: A lot of my stuff looked good on my 36" tv... not that I'm watching on a 76" screen, quality loss is a lot more apparent.

 

[JackBurton]

I do DVD>Divx rips with MP3 192kbps for audio, and I keep the res around the 640 mark which comes out to ~1.4GB and looks GREAT. Now the final output size will obviously depend on the legth of the movie too. But the above is typical for a widescreen ~2hr movie. And I put more emphasis on quality than file size.

 

[JonTom]

I am thinking about making backups of my movie DVDs to DVD-R by putting the udf filesystem into a two-part RAID-0, then burn the raw device images of the two RAID parts on seperate DVD-R, in the end playing back by putting them into two drives, reassemble the RAID, mount the UDF filesystem and go.

Thats a lot of work, no? Easier to buy the DVD again...

 

[otispunkmeyer]

i use DVD decrypter to rip the .vob files

i then use dr divx....encode to home cinema high quality (depending on size and res of movie) it can be anywhere between 800 and 1500 mb, i then play these on my Kiss DP-1000 divx certified DVD player, and on a TV (36 inch sony wega widescreen) you just cant tell the difference