a DVDShrink novice question about artifacts

[phædrus]

I have started to use DVD Shrink -- really I've used it for only about six weeks now, and in most cases just used it in re-author mode. Stripping out extras, or backing up single layer discs, normally I don't use compression. Since I am very picky about video quality, I probably won't be using this program to do extreme or even medium compression. In most cases, I expect I'll be at 90% or better.

No method of compression is perfect. I'm not very experienced with transcoding -- obviously, as I have rarely used transcoding so far. So what kinds of artifacts should I look for to guage the effects of my transcoding settings? I searched for the keyword "artifacts" and came up with some ideas. One member said that DVDShrink produces macroblock artifacts, whereas CCE tends to produce blurring and mosquito noise. (I've used CCE for making SVCDs with DVD2SVCD, so I know what he is talking about there. And from DivX work I am familiar with the appearance of macroblocking.)

I know others have talked about bad results on high motion scenes with more severe compression ratios in DVDShrink, but I wasn't clear whether this was macroblocking or blurring. Both? Either?

Usually I watch DVD backups on a computer monitor -- so normally I can clearly see any artifacting that does occur. Is there anything else I should be on the lookout for besides macroblocking? (Maybe it is a kind of pathology to scrutinize my backups to see every flaw, but I do want to understand exactly what visible effects the compression is having, even if they are minor.)

[mrbass]

do a backup using 60% compression (force it) on a dark movie and yeah you'll see some macroblocks. People with 60" HDTV shouldn't even be considering backing up as they'll see it most likely. Then again not sure if they've even be satisfied with DVD quality. My sister got that cox HD recorder back in June of last year. She kept it for about 3 weeks before just getting a regular one. I don't know how she can watch regular TV on her HDTV though. It reminds me when I hooked my dreamcast up through S-VIDEO then suddenly Soul Calibur didn't look so smooth around the characters. More bright and vivid yes but developers were counting on the bluriness to blend the characters with the background.

[spruceland]

Remember to check the deep analysis box for better quality, too.

[writersblock29]

@phædrus

Sounds like you already know what to look for in judging video quality in a DVD encode: many of the artifacts you saw in Divx encoding are pretty similiar to what you'll see in a poorly-compressed DVD backup. Like MRBASS stated, many see artifacts in original studio DVDs if both their equipment and eyesight are of high caliber. But I thought I'd share what I've noticed between the methods of transcoding (DVDShrink, Recode, DVD2ONE) and re-encoding (CCE, ect).

'Shrink works by filesize reduction, whittling away the existing bitrate on the original encode in order to make it all fit a -+R disk. While it does a pretty decent job in this regard, it has its limitations. For example, if you're backing up a DVD that's poorly compressed to begin with (such as in disks that are crammed with special features... often the main movie's quality is compromised to make it all fit), the artifacts already present become more pronounced -- sometimes if even only a 10% reduction is necessary. ON THE OTHER HAND, many studio movies are the reverse, being encoded with an extremely high bitrate with very few artifacts! Some of the SuperBit titles, for example. Those can sometimes be reduced quite a ways before you notice anything fishy on your copies.

Encoders completely re-encode the stream, using your original files as reference in creating entirely new projects. Many times, the artifacts some notice are actually present in the original streams (and sometimes blamed on the encoder, even though the encoder simply reproduced what it saw on the original stream). A rule of thumb I use is this: If the total project is less than three hours and doesn't have ridiculas amounts of audio streams, I can usually count on good to decent quality by re-encoding. In fact, movie-only encodes with only the Dobly 5.1 stream, 99% of the time, have very little noticable difference from the original to my eyes. Now that's not saying that they're perfect, crystal-clear, copies with HD definition, mind you. Just faithful to the originals.

Notice my above statement, however: "TO MY EYES." Quality's subjective, and what thrills your neighbor might aggrivate you. I know trial and error is frustrating, but it really is the only way for you to find what works best for what you want to do.

Hopefully, though, this gives you some ideas! Good luck!

[phædrus]

writersblock, thank you for your thoughts. Yes, I think I see what you are talking about. A poor original makes for an even poorer copy -- I had noticed some artifacts on the original of Aimee Mann's recent concert DVD, and those problems seemed more pronounced on the copy, though most shots looked absolutely smooth and sharp. On the other hand, I was backing up the Extended Edition Lord of the Rings discs, which are very high quality to begin with -- virtually no artifacts at all, and I see no problems with the backups that I can attribute to transcoding.

While we're on the subject, there is a particularly odd artifact of compression that I've noticed, and I wondered if anyone else knows what causes it. The pilot episode of the X-files in the first season box set is a particularly good example of this one. What it looks like is that foreground and high-motion objects appear to have natural motion, but backgrounds appear to shift abruptly, as if the foreground, in-focus people or objects are running at the normal 24 frames/second, but the background motion is a little jerky, maybe more like 8 frames/second. This phenomenon is more visible if there is cloud or fog or smoke in the background. The fog/smoke will not "flow smoothly" but rather it seems to move in little jumps, even though foreground motion in the frame seems utterly normal.

Is there a specific name for this artifact of compression? I assume that it is due to the encoder originally used to encode the DVD from the original source material. Is that something that the one who originally compressed the DVD can control with different settings on his compression program, whether CCE or something else?

[bloodrush]

I've noticed that too, especially with TV discs because they cram so many episodes onto one dual layer DVD, going to a single layer DVD uses too much compression. I had this problem with Steven King's The Stand. I noticed if I used Smooth or Max Smooth it seems to minimize this problem. Of course the best way is to just reauthor and use more DVD's with fewer Episodes on them, but I hate lots of DVD's all over the place. It comes down to a preference for quality or fewer DVD's. Your choice...

[phædrus]

just to clarify, bloodrush, I am talking about artifacts that are already there in the original. Specifically, with the X-files disc I was talking about, it is a dual layer disc with four episodes. There ought to be enough data available to make a smooth-looking picture. I guess they just had poor encoding skills.

(The other episodes in season one are not as much of a problem -- but the pilot episode looks fuzzy and also has that slightly jerky background problem in quite a few scenes. Too bad, too, because the pilot was a good episode. I suppose if I was a fanatic, I might try to find the 12-inch laserdisc version of the pilot, and record it with a standalone DVD recorder. I bet it would look better than the DVD. The X-files laserdiscs were excellent quality.)

[writersblock29]

@phædrus

I'll have to check out the X-Files disk, but I get the feeling I know what you're talking about. Scenes involving fire sometimes look tacky on some disks, as well. With enough added bitrate to the original, smoke, fire, fog, ect. tend to compress rather well. But if the original disk in question is one that's crammed-full (limmiting the bitrate of the titleset to a low level) or simply poorly-compressed, we start to see just how an encoder works. Encoders set to VBR attempt to use more bitrate for busy scenes -- where there are a lot of differences between frames -- while using far less bitrate for low-action or low-detailed scenes. Fog's tricky because of its low level of detail, and the fact that the motion of the fog is mostly on the outlines of the clouds as opposed to throughout its mass... make sense? Objects (or people) in the foreground tend to be in sharper focus, which demands more detail on them per frame -- coupled by the fact that either they or the camera are moving... changing the information the encoder needs to represent from frame to frame. Sometimes you'll notice pixel crawl on walls behind characters, while the characters themselves are sharp and clear. Give the orignal encoder enough bitrate, and this doesn't happen (or at least, is minimized). Limit this bitrate, and the encoder has to make a decision what to do with its budget; detail and motion tend to win out. Limit the bitrate yet again with a transcoder... and the original artifacts become more apparent (along with a few new problems, if the original was already on thin ice to begin with) on your copy. There are other factors involved that are probably better explained by those more knowledgable, but this ought to give you a bit of an idea. Again, I'll have to check out that eposide, but I'd imagine that this is what you're witnessing.

Poor original, poor copy!

Like BLOODRUSH said, you could try using Shrink's "Smooth" or "Max Smooth" settings, which will more evenly distribute the removed bitrate between frames. You'll lose some of the picture's overall sharpness, but it might help to reduce these artifacts. Or, jump over to the DVD Rebuilder section and try your hand at encoding; Setting up Rebuilder involves a dance step or two, but the ease of use to the program itself easily rivals most of the transcoders. Again, encoding won't remove artifacts present on the original, but in most cases you can put more content on a DVD-+R with better quality than a transcoder can provide. Then you'll always have a choice: DVD Shrink for when you don't have much to shave and need a quick(er) solution, or DVD Rebuilder for those large, messy, jobs. You can even use DVD Shrink (set to "no compression") to create movie-only projects which you can process using DVD Rebuilder and have the piece of mind from knowing you used the best availible method for preserving quality.*

*The PRO version of DVD Rebuilder already has a "movie-only" function built right into it.

Lots of choices!

[dwflo]

I would like to get my 2cents in here about artifacts with DVDShrink.
Now that I have a HDTV, these things stick out like a sore thumb. But, I do have to give credit to the creater of DVDShrink, seeing he also created Nero Recode.

Just did a movie only copy of Battlestar Galactica-The Mini Series. Shrink did an okay job, but viewing on my Sony HDTV was rather unpleasent. Did the same movie only with Recode...WOW, what a difference. They both reduced a 3hour video at 54%, but the quality of Recode was remarkable, there were no artifacts.

Since I paid for the Nero Suite, It seemed plausable to use Recode, with DVD Decrypter. I realize that Shrink is not supported at the moment, but Recode is, so why not make use of it!

Don't get me wrong, Shrink is the only backup I have used, and still recommend it for free software. But I must say Recode has come a long way to. My hat goes off to Mr. "Shrink" for his fine work. If DVDShrink was payware, then I would be a customer. Why do think I purchased Nero? Recode of course!!!

[MSlv]

First of all, I never use re-author mode! I like to have the disc as close to the original as possible, with all content intact (menus+extras on disc 1).
The first time I used DVD Shrink I had AEM disabled, because I didn't know what it does... Of course, my first DVD backups didn't look that good... The I learned what AEM does, and did almost a dozen DVDs with Max sharpness. They looked better than those w/o AEM, but high motion scenes had lots of pixelisation when retio was too small (under 70%). I the found out that Recode was made by Shrink creator too, and I started using it instead (a nero cd came with my DVD burner). I must say the quality difference is big... Since then I only used Recode for shrinking, and the movies look almost as good as the original. I used Top gun for my first Recode test. I kept the original menus and all extras, with DTS and AC3 5.1 audio streams and just romanian subtitle. The movie had a compression ratio of 54%, but it still looked flawless, with no compression artefacts like macroblocks or pixelisation visible. I inspected the image closely on my 17" TFT and on my 113cm rear projection TV.

So that's about it. DVDDecrypter+Recode is all I use for now and the discs look great. Of course, I still have those DVD shrinked discs that don't look that good, but they're still watchable on big screen TVs...

[dwflo]

Originally posted by MSlv
First of all, I never use re-author mode! I like to have the disc as close to the original as possible, with all content intact (menus+extras on disc 1).

Normally I prefer to keep the complete movie, but Battlestar Galactica is 3hrs without any extras. There are a lot of extras on the disc, and I didn't want to compromise the quality. Had I done the full disc, I don't think the quality would have been as good.

[dragongodz]

Shrink did an okay job, but viewing on my Sony HDTV was rather unpleasent. Did the same movie only with Recode...WOW, what a difference.

obvious question here is what EAC setting did you use in dvdshrink and did you test it with any other setting ?

does recode have any settings besides turning high quality(or whatever its called) on ?

[MSlv]

You should always turn Deep Analisys ON and set AEC to Sharp(default). Or use Recode, which uses the best settings automatically.

Also, if you don't want to re-author a DVD which has lots of extras, you could compress the menu and the extras twice... Although this provides more space for the movie, the quality of the menus and the extras will suck, so you're better off reauthoring...

[dragongodz]

You should always turn Deep Analisys ON and set AEC to Sharp(default). Or use Recode, which uses the best settings automatically.

i dont know who exactly that was meant to be for but since dwflo said he saw a huge difference i am curious what setting he used and tried.

as for know what the settings ,the different EAC and deep analisys, does well actually i do know what they do. if you are getting lots of macroblocking etc then you should try changing to a smooth setting as that should help reduce that but you can lose a bit of picture sharpness. default is not always the best under every circumstance.

[MSlv]

Yes, you're right. There is no ideal setting, and you'd have to shrink a dvd 4 times and see which version looks best. The Sharp(default) setting works ok in most cases (for me at least), unless it requires too much compression, in which case the smooth options are useful to hide macroblocking.

But if you have the money to buy CCE (there are other illegal means to get hold of it), get Rebuilder. They all say it's the best when used with CCE, although I personally prefer transcoding to re-encoding, that's why I never used it.

By the way, what I meant with was you should always use it. Turning it off (like I did for my first shrinks) will only make the quality worse, not better.

[golftech]

Hi, so what program(s) should I use and how if I don't want any compression and keep everthing intact as I want max PQ because I use a 80" wide screen and CRT PJ and it would show poor copies very easily. Putting a movie on 2 discs doesn't bother me. Can I make no compression(perfect copies) still using 2 discs but getting rid of some of the extra crap.

Thanks for any tips.

[dragongodz]

you'd have to shrink a dvd 4 times and see which version looks best.

not the whole movie you wouldnt. you select just a section and set compression level to what it would be if doing the whole. saves a lot of time.

The Sharp(default) setting works ok in most cases (for me at least), unless it requires too much compression, in which case the smooth options are useful to hide macroblocking.

agree, sharp should be fine for the majority. since however we are talking about movies that show macroblocking at that setting then trying a different setting is the obvious thing to do.

But if you have the money to buy CCE (there are other illegal means to get hold of it), get Rebuilder. They all say it's the best when used with CCE, although I personally prefer transcoding to re-encoding, that's why I never used it.

with great free encoders such as QuEnc and HC there is no need to buy CCE Basic to try out DVD-Rebuilder. i definatly reccomend people try it with higher compressions and/or movies they are not happy with the results from a transcoder.

Putting a movie on 2 discs doesn't bother me. Can I make no compression(perfect copies) still using 2 discs but getting rid of some of the extra crap.

completely different question than what we are talking about. try

[golftech]

Sorry, I've tryed search but maybe I'm just using the wrong words.

Thanks

[mrbass]

Originally posted by MSlv
You should always turn Deep Analisys ON and set AEC to Sharp(default).

Couldn't agree more. Even since 3.2 came out with AEC I've never done a movie without it and of course Deep Analysis. Unless, of course, no compression is needed. Takes longer but it's well worth it. I really wish these were the default settings but if they were people would most likely complain how slow it is though.