A list of Warner compression issues - High-Def Digest Forums
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Old 12-02-2007, 01:22 AM
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Default A list of Warner compression issues

I was starting to assemble a list of Warner titles with compression artifacts. Please if you find other examples post them and lets keep a running list of these issues.


So far I have the folllowing examples.

Superman Returns @ 37:18 to 37:21 and 37:57.
This is the aircraft scene with a lot of smoke and fast action. Both are difficult material for codecs and you can see quite severe macroblocking.

Swordfish @ 7:54 to 8:00
The opening explosion. Again this is a long sequence of fast action and somewhat difficult material. I am not sure if the deformed people are in the master or a product of the codec. The macroblock and to a lesser degree banding does appear a compression issue. This is also very soft but that could be a motion blur and part of the master.

Smallville D2, E1 @ 5:07 and 5:20
This is the opening credits sequence which has a lot of cuts. After each cut you usually see some compression issues. Those that are followed with fast action are the most offensive.
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Old 12-02-2007, 12:02 PM
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Superman Returns @ 37:18 to 37:21 and 37:57.
This is the aircraft scene with a lot of smoke and fast action. Both are difficult material for codecs and you can see quite severe macroblocking.
The only of these discs I still have is the HD DVD of Superman Returns. I checked these time codes on my LCD monitor, which is admittedly not my primary critical viewing display, but it's what I have available for quick reference.

So far, I don't really see it. There's a lot of artificial grain in that scene, which was added in post production by the director, but (at least on this monitor) no "severe macroblocking" stands out to me.

Have the gamma settings of your display been professionally calibrated? A bad gamma setting can cause blocking artifacts that shouldn't be visible on a properly calibrated display. I remember when I first bought my projector I saw severe blocking during the opening titles of Charlie and the Chocolate Factory, but after gamma calibration they went away.

Even if I were to stipulate that there were some pixelation there, what makes you certain that this is due specifically to the VC-1 compression, and not the digital cameras used to shoot the movie, a bad application of the digital smoke and grain, some dodgy CGI, or any number of other problems that could very well be present on the movie's DI (as the color banding seen later in the movie is)?

This is the problem with blaming every video artifact on the compression (and hence the lower bit rate ceiling available on HD DVD, which is your real implication). Without access to the original master, you have no idea where artifacts really come from. If you see artifacts, it's fair to criticize the disc for them, but it's not fair to lay the blame on the compression codec or disc format without absolute proof that they are the cause of the problem.
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Old 12-06-2007, 02:53 AM
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I have seen this on both my system and a calibrated system. I noticed the issue in both cases. I need to be clear, I am not being critical of VC-1, its doign a very good job given what it had to work with.

I am fairly certain that sceen is CG. That would rule out cameras. I cannot tell fro the image if they used Maya or another package but either way that quality of software simply does not generate these artifacts.

If they used an interm MJpeg step or lossy compressed frames as part of the production process that could have caused the image issues. Now the reason I believe its a compression issue is its a high movement, high noise scene. Those make it difficult to compress. When you compare the difficulty of the scene with the number of bits used, its well into the high loss range.

VC-1 and AVC have very different artifacts than Mpeg2. I don't think reviewers know how to spot them yet. If you take a film source with fine film grain and then compress it at low to medium bitrate you will lose much of the film grain. The image will not block (unless the codec completly breaks down), but it will appear "smooth" and "soft". The problem is as an end user its impossible to know when those were the intent (Dracula, The holliday) vs overcompresion (NIN).

If you read my comments carefully I did point out when I could not conclude an artifact was compression versus DI. I have never heard a director say they wanted blocking in their movie.

What I want is to end the free pass that the compression process gets in reviews. Noisy and Blocky should not be acceptable. Blury action scenes should also not be acceptable, though one would need to take care not to mistake motion blur for loop filtering.

I just find it shocking that the same people that notice black crush, deinterlace artifacts, and scaling issues can give this such an easy pass. Really, we should be holding HDM to a higher standard.



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Originally Posted by Josh Z View Post
The only of these discs I still have is the HD DVD of Superman Returns. I checked these time codes on my LCD monitor, which is admittedly not my primary critical viewing display, but it's what I have available for quick reference.

So far, I don't really see it. There's a lot of artificial grain in that scene, which was added in post production by the director, but (at least on this monitor) no "severe macroblocking" stands out to me.

Have the gamma settings of your display been professionally calibrated? A bad gamma setting can cause blocking artifacts that shouldn't be visible on a properly calibrated display. I remember when I first bought my projector I saw severe blocking during the opening titles of Charlie and the Chocolate Factory, but after gamma calibration they went away.

Even if I were to stipulate that there were some pixelation there, what makes you certain that this is due specifically to the VC-1 compression, and not the digital cameras used to shoot the movie, a bad application of the digital smoke and grain, some dodgy CGI, or any number of other problems that could very well be present on the movie's DI (as the color banding seen later in the movie is)?

This is the problem with blaming every video artifact on the compression (and hence the lower bit rate ceiling available on HD DVD, which is your real implication). Without access to the original master, you have no idea where artifacts really come from. If you see artifacts, it's fair to criticize the disc for them, but it's not fair to lay the blame on the compression codec or disc format without absolute proof that they are the cause of the problem.
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Old 12-06-2007, 03:28 AM
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I am fairly certain that sceen is CG. That would rule out cameras. I cannot tell fro the image if they used Maya or another package but either way that quality of software simply does not generate these artifacts.
I think you missed something that Josh pointed out. Something directors like to do a lot these days is add a film grain effect to their film in post production to give it a more filmlike look since today's processing techniques leave a completely grainless picture most of the time. Also, it just so happens that SR was digitally shot and judging from the look of it, Singer tried to make it look as much like film as possible. Some directors like the look of that grain and they put it in there intentionally and then some people run around forums saying it's because Blu-ray has crappy PQ or it's because of HD DVD's bandwidth ceiling or VC-1 or any other new kind of FUD the kids spread these days.

There are quite a few discs out there that get bad marks for grain when it is precisely the director's intent. There's a chance it could be due to the codec, but there's also a good chance that it's not.

Hope I got through to you a little better than Zyber did.
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Old 12-06-2007, 03:52 AM
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I do know the difference between film grain and compression issues. If you have looked at the scene I would love another opinion. I don't see grain, not like the typical titles like the opening of Casino Royale, Rocky, or Miami Vice.

Its possible that it was grain before compression and the codec just choked on it. Either way what came out on the other end is not what I expect was fed to it.

I do have a serious question. Why are you so eager to dissmiss compression issues?

BTW: AVC has a built in film grain simulator for the purpose of reproducing grain in difficult scenes and conserving bandwidth.

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Originally Posted by polyh3dron View Post
I think you missed something that Josh pointed out. Something directors like to do a lot these days is add a film grain effect to their film in post production to give it a more filmlike look since today's processing techniques leave a completely grainless picture most of the time. Also, it just so happens that SR was digitally shot and judging from the look of it, Singer tried to make it look as much like film as possible. Some directors like the look of that grain and they put it in there intentionally and then some people run around forums saying it's because Blu-ray has crappy PQ or it's because of HD DVD's bandwidth ceiling or VC-1 or any other new kind of FUD the kids spread these days.
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Old 12-06-2007, 11:23 AM
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I am fairly certain that sceen is CG. That would rule out cameras. I cannot tell fro the image if they used Maya or another package but either way that quality of software simply does not generate these artifacts.
I'll have to pull out the disc again, but the first time code you gave was a live action shot of Lois inside the plane, wasn't it?
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Old 12-06-2007, 12:15 PM
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I'll have to pull out the disc again, but the first time code you gave was a live action shot of Lois inside the plane, wasn't it?
I was refering to the portion outside the plane. The smoke and fire are clearly CG. Yes the inside of the plane looks like normal filming.
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Old 12-11-2007, 04:01 AM
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Another issue, Goodfellas @ 44:34. Look above the painting for severe blocking and resulting crawling.

Overall I have no idea how Peter gave this a 4 star. Its littered with noise (not grain) though it may have started as grain in the master. Overall its another good example of overcompresson at work.
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Old 12-15-2007, 12:16 PM
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I spent some more time with that scene in Superman Returns last night, this time on my primary projector. You ask why this "severe macroblocking" wasn't noted in the review. Probably because it's just not there. I saw nothing that could be described as severe macroblocking.

The first time code, which is Lois inside the darkened airplane, is pretty noisy. It's a low-light scene and the movie was shot with digital cameras. Noise is inevitable, and the director has also added artificial grain to a lot of the movie. No blocking, though.

The second time code takes place during Supe's rescue, where each shot lasts about 1/3 of a second. Even if there supposedly are artifacts there, they aren't visible during regular playback. Perhaps if I knew the precise frame to freeze on, but if that's really what it takes I don't consider this a valid complaint.

I still think this is a display calibration issue. During the Lois scene, if I walked directly up to the screen and cranked my contrast to absurd levels, the scene indeed looked pretty bad. Pulled back down to the proper calibrated level, it just looked a little noisy. At regular seating distance, the noise is indistinguishable from film grain.

You haven't told us what type of display you're using, or what "picture enhancement" features you have turned on. The problems most likely stem from there, not the disc.

Now, all that said, I don't love the Superman Returns disc. I think the movie's photography is hideous and the image is distractingly soft. I don't blame that on compression, though. That's just the ugly style that the director imposed on the movie.
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Old 12-18-2007, 04:34 AM
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I spent some more time with that scene in Superman Returns last night, this time on my primary projector. You ask why this "severe macroblocking" wasn't noted in the review. Probably because it's just not there. I saw nothing that could be described as severe macroblocking.

The first time code, which is Lois inside the darkened airplane, is pretty noisy. It's a low-light scene and the movie was shot with digital cameras. Noise is inevitable, and the director has also added artificial grain to a lot of the movie. No blocking, though.
I think what may be occuring here is we are using blocking to mean different things. I suspect, and tell me if I am wrong, that you are looking for the traditional mpeg2 style blocks. Those really do not appear. What I am seeing is what looks like it started as noise or grain (or a simulation of grain) and then was frequency quantized by the compressor. As a result the grain no longer looks like normal grain but a more blockish and visually invasive reproduction.


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The second time code takes place during Supe's rescue, where each shot lasts about 1/3 of a second. Even if there supposedly are artifacts there, they aren't visible during regular playback. Perhaps if I knew the precise frame to freeze on, but if that's really what it takes I don't consider this a valid complaint.
If you have time look at a couple frames. Start at 37:43 and go forward until they return inside the aircraft with a mans head on the left. For the 1st 8 frames of the inside shot you should be able to see banding/blocking effects on the mans face visible at any viewing distance. After a few frames the codecs is able to make use of the frame to frame coherency and recover and the artifacts dissapear.

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I still think this is a display calibration issue. During the Lois scene, if I walked directly up to the screen and cranked my contrast to absurd levels, the scene indeed looked pretty bad. Pulled back down to the proper calibrated level, it just looked a little noisy. At regular seating distance, the noise is indistinguishable from film grain.

You haven't told us what type of display you're using, or what "picture enhancement" features you have turned on. The problems most likely stem from there, not the disc.
I have seen the disk on two different displays. One was on a very good crt based projector. I believe the CRT had been calibrated. Today I am using a 37" westinghouse LCD. Not the best display but not terrible (except black level). I have not had it calibrated but did have an av expert very familiar with setup calibrate it for me. It is true that the lcd makes some artifacts more noticable, but since I saw this on both displays I tend not to assign blame there. Also note I don't see these same things in other disks.

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Originally Posted by Josh Z View Post
Now, all that said, I don't love the Superman Returns disc. I think the movie's photography is hideous and the image is distractingly soft. I don't blame that on compression, though. That's just the ugly style that the director imposed on the movie.
Agree, but I think the style does display the problems of attempting to overcompress a noisy source.
.
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