Update: Answer is NO!! Yay!...DVD Shrink v2.3+: Is there a color desaturation issue?

[JFerguson]

I wanted to continue this discussion in a new thread, as it was kind of buried/off-topic in this other thread here:


DVD shrink 3.0 final info... (http://forum.doom9.org/showthread.php?s=&threadid=59333)


See the tail-end of it for discussion. SirCentipede is seeing color desaturation issues and I saw it mentioned by a couple of other users in the "DVD Shrink 3.0 Beta 3" thread here.


Anyways, I ran Dark Blue R1 (Kurt Russell cop flick) through DVDShrink v3.0 Beta 3 and InstantCopy v7.xx. Using PowerDVD, I took 28 snapshots of the original and 28 snapshots from Shrink (chapter points). I haven't done anything with the InstantCopy image yet -- read on.

I slide show flipped between them using ACDSee Classic and couldn't see any differences. I even zoomed in like 20x and still couldn't see any differences.

So then I loaded up both sets of snapshots into Beyond Compare 32 and did a binary compare of them. The original snaps and the Shrink snaps (90%) were completely identical.

Is that weird? Or, not??

To doublecheck, I loaded up both (original and Shrink) into PowerDVD and snapped a shot off the opening MGM sequence and one more from a chapter point. I fully compressed the opening MGM sequence in Shrink.

Did another binary compare -- the opening snapshot was unequal (as expected), but the chapter snaps were indeed equal.

So, I didn't see any color desaturation issue. But, naturally, I'm still curious...

[luphy]

Was your movie PAL or NTSC?

Also, when you said binary comparisons were identical between the
still images for Shrink and IC7 - are you saying the images were
exactly identical bit for bit? Surprising that would be the case
as I would have thought each program would transcode somewhat
differently.

[JFerguson]

Movie is NTSC.

And yes, they are bit for bit identical. That might be a byproduct of PowerDVD and the low compression rate I used. There's certainly a couple of factors at play here.

I'm running it through DVD Shrink again. One of my titles that I stripped gave an Out of bounds error in InstantCopy, so I fixed that (it was minor), and I'm gonna run it through DVD Shrink once more...

[mrbass]

I simply haven't seen it (My eyes are a by-product of lasik eye surgery so who knows)...I only do NTSC. So is this a PAL only issue or only for people who have artificial eyes like me?

[SirCentipede]

To show what I got during my comparisons, I've finally found a place to load my still-frames up.

All of them where taken of the opening sequence of 24, Season 1, Episode 1 (RC2, Pal) and I captured them with WinDVD 4.5.

Pls don't look at pixelization or blocks as i had to compress the bmp-files (1,68 MB) to jpeg as the host where i put the stills only allows max. 100kb for file-upload.

The colours are roughly the same as in the bitmaps:

Original DVD:
http://www.beepworld.de/memberdateien/members46/digglah/24original.jpg

DVDshrink 3.0 beta 3 compressed at ca. 60%:
http://www.beepworld.de/memberdateien/members46/digglah/24shrink3.060.jpg

DVDshrink 3.0 beta 3 "no compression":
http://www.beepworld.de/memberdateien/members46/digglah/24shrink3.0100.jpg

DVDshrink 2.3 "no compression":
http://www.beepworld.de/memberdateien/members46/digglah/24shrin2.3100.jpg

IC7 compressed:
http://www.beepworld.de/memberdateien/members46/digglah/24ic7.jpg

Maybe my test-setups are flawed, maybe this is a PAL issue, but I hope these pictures show what I'm talking about and people can visualize what I'm aiming at.


P.S.: If anybody is interested in the original bmps, pls pm me or show me a place where i can put them up.

[DVDRFreak]

Same issue here.

DVDshrink seems to flatten the colors. Hope it will be fixed in the final. For now I will use Recode or CCE to do my backups.

[ghaynes]

Can someone post NTSC screen captures to see if there is a desaturation problem? I'm just wondering if this is a PAL only issue or not.

[JFerguson]

Originally posted by SirCentipede
Maybe my test-setups are flawed, maybe this is a PAL issue, but I hope these pictures show what I'm talking about and people can visualize what I'm aiming at.



Wow, there's no debate with those snapshots. I did my second run against Dark Blue NTSC last night at 90% and the 28 snapshots I took were again bitwise identical.

I'll try another movie today...

[daehkcid]

http://www.angelfire.com/moon/daehkcid/PDVD_019.BMP
http://www.angelfire.com/moon/daehkcid/PDVD_021.BMP

Matrix NTSC DVDShrink'ed 87%.

Btw, I did notice the dojo kungfu scene to be a little lite on the yellow on my TV. I'll check again tonite with the original DVD to see if it's a yellow problem or a PAL problem. I hope's its the latter :P

Stil, try to guess which one is the original source and which is the shrinked one - see if DVDShrink is doing a good job :)

[SirCentipede]

I just read a thread by quantum on how to compare single frames of movies compressed by different transcoders:

http://forum.doom9.org/showthread.php?s=&threadid=58808

It made me curious: I downloaded virtualdub and did my tests from scratch again:

I did the some frames of 24, Season 1, Episode 1 (RC2, Pal) with DVDshrink 3.0 beta3 at compression ratio 50% and at no compression and compared the results in virtualdub to the original.

And i couldn't believe my eyes. THE SATURATION of the original and of both the DVDshrink transcoded movies IS THE SAME.

After that i did it with WinDVD again, because i thought i screwed it up the first time i did it with WinDVD: But again i got differently saturated Pictures.

:confused: :confused: :confused:

hmmmm!?

Then i downloaded PowerDVD, in order to see if it is an issue of WinDVD or Software DVD Players in general: To my surprise Power DVD showed exactly the same saturation levels in both the original and the transcoded versions.

To sum it all up:

PERSONALLY I DON'T THINK THERE IS A SATURATION ISSUE WITH DVDSHRINK ANYMORE.

Sorry for making such a fuss about it, i judged only by using WINDVD, because i haven't had other programms to compare my Backup-Results.

I hope this issue is now settled, so that everybody will use DVDshrink again without fearing to get less saturated movies.

[Erik_Osterholm]

I have to agree with SirCentipede.

First of all, read through the post. There may be no need to view the screenshots below, if you trust that they are identical.

Anyway, at first I was quite distraught with the color saturation problem, so I did some more tests. I used VirtualDubMod and grabbed a bitmap of the same frame (adjusted for studio logos, which I had stripped).

http://xrl.us/pex

and

http://xrl.us/pey

The titles of the expanded URLs should be self-explanatory. I was puzzled, because they were identical, however when I had run them through Zoomplayer (using WinDVD's directshow decoder) there had been very obvious saturation.

I did a little more testing and think I have discovered the problem. Everyone who saw color saturation problems: did you have two instances of your software open at the same time? In other words, you were decoding and displaying side by side? If so, try this trick. Try opening the DVD Shrink'd DVD first and then the original. I suspect that the original will appear to have color saturation. I believe the problem stems from the fact that only a single overlay will be used (at least by WinDVD) and if a second instance of the decoder is opened, it will have to use an alternate display mode (something where it manually decodes and displays in Windows). The problem doesn't appear to lie with DVD Shrink at all.

[daehkcid]

Hahah cool. :) I used PowerDVD :)

[SirCentipede]

Lucky u....:)

[mrbass]

lesson is..
1) view on TV (original vs. backup)
2) try another backup program, same movie
3) do what you did and try another version or another dvd software player.

well at least we now know. I wonder you said windvd 4.5 if it's not detecting it's not an original CSS dvd and thus modifying colors to make your 'home video' look better. Don't you love when programs take over and do-it-all-for-you...just like lovely windows xp.

[JFerguson]

Updated the title. Glad to hear we figured it out... :)

[SirCentipede]

@mrbass

LOL....my 'home video', I wish they would look only a fraction like that...:D :D :D

btw your post let me recognize what the difference between the dvdShrink stills and the original or IC7 stills was:
I played the DVDshrink movies in file mode in WinDVD, the original and the IC7 movie i had as iso-files in Daemon Tool.

[quantum]

Glad to hear it's not a DVDShrink issue. The software players can and do make changes to the frames, which is one of the reasons I've been pushing my technique for comparing the transoders (http://forum.doom9.org/showthread.php?s=&threadid=58808)

I'm glad it helped SirCentipede.

[dvdshrink]

I'm glad to hear it too!

MPEG-2 video is encoded in the YCrCb colorspace and although it is possible that a transcode engine could desaturate the image, it is more likely a result of your software player's YCrCb to RGB conversion algorithms.

If one player window is doing this conversion with a hardware overlay, and the other with some alternative software algorithm, then you may see a difference... as verified in this thread.

An interesting compression option would be to remove all CrCb data from the source video - the output would be luminance only and could be offered as a "grayscale" alternative to still pictures :-)

Except, as an afterthought, the compression would not be very high: DVD MPEG-2 video devotes 2/3 bandwidth to Y, only 1/3 to CrCb.