What causes artifacts?

[Skunk]

I have been using DVD-RB for some time now and am rather pleased with the results I get in most cases. Every now and then though I get some artifacts/pixelation in the final DVD. I defrag before every rebuild, as I hear it can cause such problems. The thing that gets me is that I can run the encode again under the same circumstances and I get a good copy.

What I am wondering then, is exactly what causes these artifacts and how can I prevent them? Any ideas would be appreciated.

EDIT - Every so often I will get artifacts in a different place on the second rebuild. I have found that I can combine the .M2V files from both projects to make one good copy before rebuild.

[jdobbs]

I think something is amiss, probably memory -- possibly disc, on your system.

[jptheripper]

if the are on the disk, i question the media or the burn. COmbining m2vs does not change the content, and therefore cannot remove artifacts

[on30trainman]

I have an interesting experience with artifacts/blockiness in burnt DVDs. When RB RC1.0 came out and was packaged with HC 0.15 I ran Friday Night Lights thru it and burnt a DVD using Ridata -R 8X media. The result was very noticeable blockiness throughout the movie when viewed with my KOSS KD365. When viewed on the computer there was no blockiness at all. I then reran the encoding with RB and HC 0.14 and burnt on another Ridata DVD. There still was some blockiness on the KOSS but not nearly as much. I actually reported this to jdobbs (but referring to a different movie I had also run) - also some others seemed to be having more trouble with the artifacts/blockiness using HC 0.15.
Last week I bought a second DVD player (Sony DVP-NS41P) just to be able to run quality comparisons in parallel. Played FNL encoded with HC 0.15 on the Sony and saw no blockiness at all. I was really surprised by that. Tried the disk in the KOSS again - blockiness was there. The KOSS player is about two years old - maybe it is aging and not playing as well. I have a two year replacement warranty on it with Sears (cost $8 or so) - maybe I will return it for replacement.
If the blockiness is only occuring on your standalone, and not when played on the computer, it could be the player and/or media causing it. Just reburning the same encode on a new disk might move the blockiness to different spots. I usually use Fuji brand TY media, but wanted to use up some Ridata. But I never have had problems with the Ridatas. BTW, am now using CCE Basic - maybe I should try FNL with that encoder.
jdobbs - keep up the good work with DVD-RB. Thanks

Steve W.

[jptheripper]

if the blockiness is not there on any one player, be it pc or standalone, then its the media. If the encode comes out clean on a single player the encode is good, in general

[hutch1711]

if the blockiness is not there on any one player, be it pc or standalone, then its the media.
:stupid: I'm not sure what you're trying to say here. :confused:

[jptheripper]

im trying to say that data is data, if its fine in one place, then its there (correct) on the disk.

The only option for blockiness are its out of spec and one player is more tolerant of it (which is possible but unlikely) or that the reader in one player is more tolerant of cheap/bad media (a much more common cause, in my experience).

[jdobbs]

The important factor is that when the software is presented the exact same data with the exact same options it processes it in the exact same way with the exact same result. So if the result changes between one run and another there has to be an external factor. It could be memory, disc, media, burner, or even player.

[rail grinder]

before i burn the final dvd i always test out the "pure" data by skimming through the final compilation with power dvd. after after everything's been rebuilt to vobs i fire up power dvd and "open dvd files on hard disk drive" or if i've compiled an image, i mount it and open it with power dvd.

at this point, if there's artifacts or macroblocks from the pure rebuilt data, i reencode with different settings. if not, i compare it again to the original source to see if there's room for improvement. otherwise i start burning away.

if i verify it this way i can be certain that the data itself is all hunky-dory and that all other factors would cause blockiness, ie. age and quality of standalone, media quality, burn quality, optical drive reading quality, etc...

[Skunk]

if the are on the disk, i question the media or the burn. COmbining m2vs does not change the content, and therefore cannot remove artifacts

The blockiness appears in the M2V files created by the encoder, whether it be Procoder or HC (I use them mostly) so it is definitely a problem with the encode itself. I have had good results combining the M2Vs from 2 projects though. Thats why I'm so confused, you see?

I'm just a perfectionist and have re-encoded a movie 3 or 4 times just to get a perfect copy. I dont mind if thats what it takes, but damnned if I dont want to save some time along the way. This happens on maybe one of 20 or 30 DVDs I backup so its not too bad I guess, just wondering if I could pinpoint the cause.