How Will High Bit Rate VC-1 Compare to AVC

[PaulGo]

Now that Warner and other studios will be releasing higher bit rate VC-1 coded movies to take advantage of the greater bandwidth in the Blu-ray specification I wonder which codec will actually produce the best results. Is one codec superior to another or is it just a matter of preference?

I originally started this thread on AVS but because of Amir's ranting it got locked. I hope we can discuss this here.

http://www.avsforum.com/avs-vb/showthread.php?t=969782

There are some very good comments by Richard Casey - R&B Films who promised to produce a comparison Blu-Ray disc.

[PaulGo]

One thought from reading some threads on Doom9 and some other AVS threads. It seem Microsoft is reluctant to participate in these comparisons. I was trying to think as to why this might be. The most obvious answer is they have nothing to gain. VC-1 has good tools, but I was thinking about how and why it was created. It was created for lower bit rate applications, so perhaps it does not scale up to a higher bit rate as well as the latest version of AVC. So perhaps it cannot take advantage of the increased bitrate that Blu-ray has to offer.

Any thoughts on this?

[Sporty]

drmpeg kinda answered this, his thread would be a better place to ask also if you want more specifics

https://forum.blu-ray.com/showpost.p...25&postcount=8

[Mr. Hanky]

Originally Posted by PaulGo

I originally started this thread on AVS but because of Amir's ranting it got locked. I hope we can discuss this here.

I'm just glad you didn't blame it on me!

I got my "infraction pts" wings from that topic, btw.

[stockstar1138]

the high bit rate vc1 encodings i have seen (deja vu, shoot em' up) look every bit as good as an avc encoding. no need to care about how high the bitrate gets up if it produces the same quality image.

[BStecke]

Originally Posted by stockstar1138

the high bit rate vc1 encodings i have seen (deja vu, shoot em' up) look every bit as good as an avc encoding. no need to care about how high the bitrate gets up if it produces the same quality image.

I was going to mention Shoot 'Em Up as well. Supposedly this title was a test to see the response to high-bitrate (and Blu-ray specific) encodes. There was a thread regarding Shoot 'Em Up on AVS (don't know if it's the same one referenced above) about how Shoot 'Em Up, due to its specs, would be impossible to port to HD DVD.

Either way, as long as the quality is top-notch, I don't care what codec they use. If one takes up less disc space and allows for Uncompressed audio or more features (even though I hardly watch the features) where the other wouldn't, so be it. As long as image/sound quality isn't compromised, I don't care if they encode it with an Atari 2600.

[patrick99]

Originally Posted by BStecke

I was going to mention Shoot 'Em Up as well. Supposedly this title was a test to see the response to high-bitrate (and Blu-ray specific) encodes. There was a thread regarding Shoot 'Em Up on AVS (don't know if it's the same one referenced above) about how Shoot 'Em Up, due to its specs, would be impossible to port to HD DVD.

Either way, as long as the quality is top-notch, I don't care what codec they use. If one takes up less disc space and allows for Uncompressed audio or more features (even though I hardly watch the features) where the other wouldn't, so be it. As long as image/sound quality isn't compromised, I don't care if they encode it with an Atari 2600.

What I care about is getting bitrates in the mid 30's. Whether it's AVC or VC-1 they do it with, I don't care.

[Branden]

they are both excellent codecs and both can produce an excellent picture when encoded properly (even mpeg2 can look amazing if encoded properly and given enough bandwidth), but without a side-by-side comparison of each codec running at identical CBR from same source it would be difficult to conclusively say which is better.
with that said, it sure seems like VC-1 produces a softer image. but is that because AVC typically comes from BD exclusive studios that utilize the greater bandwidth while VC-1 typically comes from bit-starved HD-DVD ports, or because AVC is actually a superior codec?

i'm going to say that AVC is a barely superior codec simply because VC-1 was developed my M$, and every codec that M$ has ever made has been second fiddle.

[PaulGo]

Originally Posted by Branden

they are both excellent codecs and both can produce an excellent picture when encoded properly (even mpeg2 can look amazing if encoded properly and given enough bandwidth), but without a side-by-side comparison of each codec running at identical CBR from same source it would be difficult to conclusively say which is better.
with that said, it sure seems like VC-1 produces a softer image. but is that because AVC typically comes from BD exclusive studios that utilize the greater bandwidth while VC-1 typically comes from bit-starved HD-DVD ports, or because AVC is actually a superior codec?

i'm going to say that AVC is a barely superior codec simply because VC-1 was developed my M$, and every codec that M$ has ever made has been second fiddle.

I guess it goes with Amir's "good enough" philosophy.

[PaulGo]

Originally Posted by Mr. Hanky

I'm just glad you didn't blame it on me!

I got my "infraction pts" wings from that topic, btw.

What the heck happened? You can PM me if you don't want it public. I really can't stand the way Amir talks down to people and tries to intimidate them. Also if he can't have his way he just throws a fit and goes into a temper tantrum. He has the emotional capacity of a five year old.

[BStecke]

Originally Posted by patrick99

What I care about is getting bitrates in the mid 30's. Whether it's AVC or VC-1 they do it with, I don't care.

I would care more about watching the movie than the bitrate meter, but that's just me . . .

[patrick99]

Originally Posted by BStecke

I would care more about watching the movie than the bitrate meter, but that's just me . . .

That's the sort of comment I am used to hearing at AVS. . .

[Zixxer]

so we are going to have a bit rate war too?

[w_tanoto]

I'm just wondering.... does VC-1 equal to WMV, or is it different kind?
I know AVC is MP4

I use WMV as my standard in my laptop for video, MP4 in iPOD, PS3 and PSP. MP3 for music everywhere

[Neo65]

VC-1 can look good at high bitrates. AVC look good at high bitrates.

Averate bitrates is mainly meaningless as many movies have simple segments that don't take that many bits to encode, drama and romance with soft filters take very little bits to encode well. Peak (or max) bitrates is what it's all about. Since a lower max bitrate lowers the headroom on a successful encode and increases the need to go back to play with the segments that are flagged to have problem meeting that limit.

Very complex scenes with high entropy content (say leaves, trees, rainfall, panorama of battles) if the camera is in focus and the scene itself is not out of focus require many bits even to encode the stills, but the motion vectors can make subsequent frames after the complex ones take very little bits since you can just say each macroblock in subsequent stills are same as the reference frame.

Where you need high bitrates is the complex frames that are high motion, ie: the frame itself is very complex, and there are a lot of moving parts. Slow movement or pans are more noticeable to many people, but in terms of overall quality of encode, rapid motion is where the worst artifacts can show up even as the fast motion itself hides them from 'most' eyes.

Where VC-1 and AVC come in is that the compression artifacts created when you run out of bits can be hidden --- smudged away by what are known as in loop filtering. These filters typically work on the boundary of macroblocks and subblocks to hide block artifacts. For VC-1, the operations are in two blocks known as "overlap smoothing" and "in loop filter". For AVC, they are all in the block known as "deblocking filter".

The question of hunting for compression artifacts is an interesting one as there is a wide range of how artifacts can be present. Even when talking about "visible" artifacts is a subjective question, since being visible requires a person, and a display, meaning is an artifact visible for this one person on this one display, or even on this group of people for one display.

Subjective testing on video quality are typically done with normal people because the video experts (golden eyes) are particularly good at picking out flaws and can be pesky to people who want to push extreme low bitrate agendas. But even golden eyes will have difficulty at quickly telling any arbitrarily encodes apart quickly, they need a long time and would rather give you their materials to encode (materials they are already very familiar with).

But if the question comes to presence of artifacts, that's a very simple one to determine, since I can point out some very obvious flaws in many HD DVD and BD movies.

For a comparison of lower and higher bitrates of VC-1. Nature's Journey is my favourite, even if the original does not appear to be as sharp as I hope, it has some very clear difference. If you go to AVS and checkout Xylon's thread on this, I gave difference maps of the two encodes. In one particular interesting comparison, we see that there are grid patterns in the sky. Once you know where to look and you see the grid patterns (presumably from application of overlap smoothing or in loop filtering), you can go back to the still image and find the subtle grids on a good TV, but without seeing the grids, it would be very difficult to find them.

But this says nothing about the reason why the grid patterns were there. It could be the in loop filter, it could be overlap smoothing, or it can simply be operator error as that one frame happen to show up in a segment that ran out of bits and had to use higher quantization. Who knows? But you can't dispute that there are grid artifacts there.

Does that mean that the grid artifacts visible on one frame on the lower birate encode of Nature's Journey don't matter if it is hard to see? Now that there is an interesting question.

[Mr. Hanky]

Originally Posted by PaulGo

What the heck happened? You can PM me if you don't want it public. I really can't stand the way Amir talks down to people and tries to intimidate them. Also if he can't have his way he just throws a fit and goes into a temper tantrum. He has the emotional capacity of a five year old.

Not to deviate from this topic any further, but what you see at AVMS is essentially the gist of it (no knock down drag out scuffle, but evidently certain individuals couldn't have their way and then stormed out). Amir took his ball and left, and then Mark Reuben pulled the plug on the topic. Here's the "citation" I got from the mods:

You have received an infraction at AVS Forum
Dear Mr. Hanky,

You have received an infraction at AVS Forum.

Reason: Attacked another member
-------
there is no need to attack: if this continues you will be asked to leave AVS
-------

This infraction is worth 3 point(s) and may result in restricted access until it expires. Serious infractions will never expire.

Original Post:
http://www.avsforum.com/avs-vb/showt...php?p=12953060
Quote:
All of a sudden, proving the compression prowess of vc-1 isn't worthwhile? Sub-10 Mb/s encodes would seem to be where the "rubber hits the road"- a meaty challenge, so to speak. No reason to skip out on such a challenge, unless you are assured a stunning victory will be implausible. If it doesn't apply well for optical hdm, it sure hits head on with MS's digital download initiatives. Let's be real here- you had every reason to participate, if it was truly your goal to quantify the compression superiority of vc-1. If that "superiority" was not to become evident in such a competition, then we have every reason to suspect that not participating is the tactically correct manuever from a PR standpoint.
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All the best,
AVS Forum

[Swede]

Originally Posted by BStecke

I would care more about watching the movie than the bitrate meter, but that's just me . . .

If we knew that all new movies were optimized to utilize the capacity of blu-ray we wouldn't have to

That said, I hardly ever look at the bitrate meter, but I DO care about Studios using the full potential of blu-ray's capacity for maximum PQ & AQ

[reiella]

Originally Posted by Swede

If we knew that all new movies were optimized to utilize the capacity of blu-ray we wouldn't have to

That said, I hardly ever look at the bitrate meter, but I DO care about Studios using the full potential of blu-ray's capacity for maximum PQ & AQ

By the same token, just because the bit-rate is higher, doesn't mean the image is benefiting from the increased bandwidth.

The metrics facilitate the result, and the result should be what we care about, not the factors going into it.

[patrick99]

Originally Posted by reiella

By the same token, just because the bit-rate is higher, doesn't mean the image is benefiting from the increased bandwidth.

The metrics facilitate the result, and the result should be what we care about, not the factors going into it.

When I see that a high bitrate has been used, I know that any shortcomings I may see in the image are not a result of insufficient bitrate. When I see that a low bitrate has been used, I don't know whether any shortcomings I see in the image are a result of shortcomings in the source material or insufficient bitrate. And please do not tell me I should trust the people who are putting out the disc to make the right decision as to what bitrate to use for the material.

[reiella]

Originally Posted by patrick99

When I see that a high bitrate has been used, I know that any shortcomings I may see in the image are not a result of insufficient bitrate. When I see that a low bitrate has been used, I don't know whether any shortcomings I see in the image are a result of shortcomings in the source material or insufficient bitrate. And please do not tell me I should trust the people who are putting out the disc to make the right decision as to what bitrate to use for the material.

But you'll trust the people who are putting out the disc to actually utilize the supposed bandwidth?

[ Add / Edit ]
And quite the point, do you look for shortcomings on the film when you notice that your PS3 says "VC-1 14mbps", or do you look for the "VC-1 14mbps" after seeing shortcomings?