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View Full Version : AutoGK 1.05beta & DivX511 - pixel artifacts (incl. test files)


Data
12th March 2004, 18:16
update#1: occurs in 1.05beta & 1.0 (older versions not tested)

update#2: I've added input files (3mb), with which you can recreate the problem. Can someone *please* test it too and report back in this thead? Thx in advance!
The files are on http://mitglied.lycos.de/datasoong/tng.html
Please ignore the first and last frames, as they might be damaged, due to vobSplitting) To recreate the prob. use the default settings in AutoGK and the option "target quality" (i.e. 75% or 90%, etc).
[plz. also note update #3 bellow]


Complete problem description:

I've got strange artifacts in some scenes when I use AutoGK with the DivX setting. It only happens with DivX (in my case 5.1.1 std), with XviD this doesn't accour.

Here are screenshots taken out of an encoded avi. (in this case Star Trek TNG Pilot episode converted from the RC-2 PAL DVD / scene: when the ship goes to warp at the end of the famous intro sequence).

( screens alternatively on http://mitglied.lycos.de/datasoong/tng.html )

DivX 5.1.1 encoded:
http://mitglied.lycos.de/datasoong/DivX511.jpg

XviD encoded:
http://mitglied.lycos.de/datasoong/xvid.jpg

Only one frame is affected in this scene (the other frames look fine).

I've noticed those same artifacts several times in this avi file, mostly they occur when the camera view changes (i.e. you look at person A / now they show you the perspective from person A / and in between those two [the transition] sometimes 1 frame has this strange pixelization)

When encoding the avi externally (i.e. with a default DivX certified profile) this does not happen. It must be an encoding in AutoGK that causes this.

I used the quality in % setting in AutoGK (90%, 100% - didn't make any difference) I also tried using the other matrix (not the ESS compatible one), same result. With this single-pass encoding it always seems to happen. (also tested on 2 different computers :-))

update#3: I've noticed one strange thing: When using custom size (MB) and entering a size that is larger than what the file would have normally been at 100% quality encoding, there are no artifacts! (i.e. the 100% quality file was 133megs after first encoding; one now encodes again, this time to forced 200megs -result: perfect file without pixel artifacts) [but this can hardly be the answer for this problem :D]
Btw., when using "maximum quality, unlimited size", the problem also doesn't seem to occur. But it's strange that with XviD everything works file (in any quality/size setting) and with DivX one would have to use this "maximum quality" setting [and not even a manual quality level of 75% to 100% works without this problem]

PS to dev team: AutoGK ist clearly the best program I've ever seen for direct VOB->AVI conversion. Incredable job!

colordog
13th March 2004, 01:10
I'm definitely not sure, but this might be the infamous 'DivX 5.1.1 decoder deblocking" error. Basically, I think there was a problem in their first installer system that affected decoding. If you installed your version of 5.1.1 before the last week of Feb, download the new installer (still version 5.1.1) and then play the movie again to see if that's the issue.

More here:
http://forum.doom9.org/showthread.php?s=&threadid=71706
and history here:
http://forum.doom9.org/showthread.php?s=&threadid=66226

Again, I dunno if that's really the problem...

Data
13th March 2004, 03:04
Hello colordog,

I've upgraded to the suggestion version, but I'm still getting the same strange artifacts. I'm affraid they're "burned" into the movie during encoding and aren't a result of faulty playback.
(I get the same distortions at the exact same frame when using other decoder filters like ffdshow, etc. - but only for the AutoGK DivX encoded files)

Non the less, thanks a lot for your input.

update: I've also tried encoding the video again, with AutoGK (this time 1.05beta) and this latest DivX 5.1.1 version - still the same result (also at the exact same frame) :(

The video looks fine when encoded externally in DivX 5.1.1 (single pass, no matter what options I choose [I tried lots of variations]) - I can't recreate these pixel artifacts outside of AutoGK.

Data
19th March 2004, 16:01
Can anyone please test this too? I've provided test input files (and this thread also took many hours to "compile"). It would be a shame if all of this time was wasted without anyone else even testing it. [this thread has 238 views and only one external reply :(]

And if there is indeed a problem with AutoGK & DivX encoding (maybe it only happens with PAL sources, I don't know) it would be a shame if the problem went unnoticed :(

I have this issue frequently, in several encoded episodes, (i.e. when there's lightning, camera cuts, etc.)

Thx for your help!

len0x
19th March 2004, 18:12
Well, it turned out its a b-frames problem. I did two simple encodings outside of AutoGK and got the same output with bframes and clean picture without them. I cannot really disable b-frames completely, so there is no solution for this...

P.S. This problem doesn't exists in two-pass encoding, just quality based mode...

Data
19th March 2004, 18:27
Hi len0x,

thanks a lot for taking the time to test this. It's too bad it's not solvable in AutoGK :(

How do programs like Dr.DivX solve it (there even in single pass mode such a problem doesn't occur)?

I'm not guite sure about it not occuring in two-pass mode, I'm going to re-test that. (I think in this small test input file that was the case, but with bigger files I also had these problems in 2 pass mode, but I'm not sure - so I'll recheck and get with the results)

PS: I'm glad I haven't seen it occur in DivX mode at all (so far :))

len0x
19th March 2004, 18:36
Originally posted by Data

How do programs like Dr.DivX solve it (there even in single pass mode such a problem doesn't occur)?


if you're using home theatre profile then b-frames are disabled there - if you remove profiles you should see that in Dr.DivX as well...
(or alternatively it can be that profiles disable quality based ancoding at all, so one pass is only bitrate-based and problem may not occur there...)

Data
19th March 2004, 18:41
I hadn't used the default profiles in divx, I went into the advanced options, manually set it to single pass, increased the resolution and tried all sorts of options. I was unable to recreate the problem there so far.

len0x
19th March 2004, 18:43
Its definitely b-frames. Even profiles and bitrate pass worked fine for me. Just with b-frames I get garbage...

P.S. bframes are hidden in the profile window of divx codec settings

Data
19th March 2004, 20:15
Well if bframes are hidden in the settings alltogether, there's no way for me to test the option (I still haven't found anything remotely close to "bframes" there ;)

By the way I retested the thing about two-pass in AutoGK. It also happens there, I've uploaded a new test input file:
http://mitglied.lycos.de/datasoong/input2.html

It's a different section of the orignal VOB file. (and this time a bit longer).

The interesting thing is that:
a) The pixel artifact problem occurs at a different frame here (even though this file is a part of the exact same original vob file that the first input test file also was)
b) it also happens when using two-pass (i.e. try custom size: 2mb in AutoGK)

Here are the screens of my encoded AVIs

Single pass, full quality (100%):
http://mitglied.lycos.de/datasoong/100_percent_single_pass.jpg

And two-pass, 2MB:
http://mitglied.lycos.de/datasoong/2mb_two_pass.jpg

Very strange ;)