[DaViD Boulet]

This is not an HD DVD versus BD debate. Both formats can and do use VC-1 and AVC video compression CODECs. Both are "advanced video" codecs and their use is studio-dependent since they both can acheive high quality and similar bit-rates.

However, Dan Ramer had noticed a trend that many AVC titles, on average look better than many WB VC-1 titles. The problem, of course, is that it's nearly impossible to know for sure what the original uncompressed master would have looked like to know how faithful the compression is being.

But in this review of Shrek three, there's a clue. He noticed that the special features looked better than the feature film... and only then did he check to see what video codecs were being used in each case:

http://www.dvdfile.com/index.php?opt...=6382&Itemid=3

Quote:

The film’s theatrical aspect ratio of 1.85:1 is presented in a very nice high definition transfer compressed with the VC-1 video CODEC. Something quite unexpected happened as I was reviewing this HD DVD. In my many email exchanges with readers who had problems with my assertions that AVC is superior to VC-1 and BD has the quality edge over HD DVD, I was asked to compare the same source material on two different formats, preferably compressed with two different video CODECs. Since Warner only compresses once for the storage capacity of the smaller capacity medium, it was not possible for me to make a meaningful comparison. But as I watched this disc’s supplements that contain film excerpts, I suddenly realized that the images in the supplements look better: sharper, more vibrant, more film-like. Only then was I motivated to check the transfers’ CODECs. This was, in effect, a blind test. I didn’t check the CODECs until I noticed a visible difference. I found that the disc’s producers opted for a VC-1 transfer for the feature film and AVC transfers for the supplements. I only wish that I had two copies of this HD DVD and that Toshiba didn’t force the stop mode when the HDMI connection is interrupted; under ideal circumstances, I would have liked to compare identical freeze-frames.

Now, this still doesn't offer conclusive evidence that the lesser-quality of the feature film is due to VC-1. It's possible that it was slightly filtered to aid in compression. I offer up an example of a film I reviewed here at HTF: The Incredibles on DVD. In that case, the feature film and bonus material was all compressed with MPEG2... yet the clips of the film in the bonus material was NOTICABLY sharper and more detailed than the feature film...which showed that the film had been "filtered" despite all its high praise. It's possible that's what we're seeing here with Shrek 3 as well, though the different video codecs being used in these two cases does invite some questions.

[Lou Sytsma]

My money would be on some sort of filtering being applied.

[RobertR]

I agree with Lou. It's like any other comparison: It's not valid unless you are CERTAIN that ALL variables are controlled.

[Shane Martin]

I think this debate about AVC vs VC1 has already been decided and the answer was No. Paramount encoded Flags of our Fathers in BR using AVC with a ridiculously high bit rate and encoded the HD version with VC1. The consensus as the time was no difference. If there was one, it's so indistinguishable by eye that it doesn't matter. The only people proclaiming they could notice a difference were blu ray people and you have to know some sort of bias was in place for sure.

The key is the efficiency of the codec, not the bitrate.

[Carlo Medina]

I lost the link, but there was a site out there comparing screenshots of the various HD codecs. In general it was apaprent that AVC or VC-1 was superior to MPEG-2, but comparisons between AVC and VC-1 discs were, in general, hard to distinguish. Most looked identical to my eyes.

[Jeff Adkins]

Quote:

Originally Posted by Shane Martin

I think this debate about AVC vs VC1 has already been decided and the answer was No. Paramount encoded Flags of our Fathers in BR using AVC with a ridiculously high bit rate and encoded the HD version with VC1. The consensus as the time was no difference. If there was one, it's so indistinguishable by eye that it doesn't matter. The only people proclaiming they could notice a difference were blu ray people and you have to know some sort of bias was in place for sure.

No, even some of the HD-DVD fans said there was a difference but not enough to for them to warrant the extra bandwidth.

My AVC titles seem to look more film-like and have more definition than the VC-1 titles I own. Both codecs can look spectacular, but on average the AVC stuff is superior IMHO.

[Marc Colella]

Quote:

Originally Posted by Jeff Adkins

My AVC titles seem to look more film-like and have more definition than the VC-1 titles I own. Both codecs can look spectacular, but on average the AVC stuff is superior IMHO.

I'm assuming you're comparing both codecs on the same title, otherwise you're comparing apples to oranges.

[troy evans]

Oh No, Now we're going to discuss codec differences instead of format differences. This should prove interesting.

[DaViD Boulet]

Quote:

I lost the link, but there was a site out there comparing screenshots of the various HD codecs. In general it was apaprent that AVC or VC-1 was superior to MPEG-2, but comparisons between AVC and VC-1 discs were, in general, hard to distinguish. Most looked identical to my eyes.

Still-frames aren't really ideal for comparing compression codecs bcs compression algorithms and bit-rates tend to reveal their artifacts/transparency during motion.

[DaViD Boulet]

Quote:

I'm assuming you're comparing both codecs on the same title, otherwise you're comparing apples to oranges.

Agreed.

But when you see trends between 100 apples and 100 oranges, though it doesn't point to any definitive conclusions, it does raise some legitimate questions.