What is the defference between VC-1 and MPEG 4?

[Skillz5]

Is there a certain compression style which is better or does one produce better image quality than the other? I see some studios are in favor of certain formats. What is the difference? Can anyone help explain their preference?

Also PCM and Lossless...what is the difference?

[Slec]

Originally Posted by Skillz5

Is there a certain compression style which is better or does one produce better image quality than the other? I see some studios are in favor of certain formats. What is the difference? Can anyone help explain their preference?

Also PCM and Lossless...what is the difference?

Although there are differences between AVC and VC-1, a lot of people like to bag VC-1 because its a microsoft product. From what I've read, and I'm NOT any kind of expert, if a good authoring house were to use both on the same source, the results would be virtually identical...

PCM is a duplicate of the raw master track and is lossless. DTSHD-MA and TrueHD are essentially "zipped" versions of the PCM track. Therefore they are unzipped into PCM for the receiver to play... They should sound the same, but there are some proprietary things such as dialog normalization that can change slightly how a track sounds.

This Insider Thread is a good place to start. Posts 17 and 18 and onward...

[Skillz5]

Thank you very much, very informative. Any one else want to add anything?

[aygie]

I personally like AVC over VC-1. To me VC-1 titles have less colour depth and and often poor skin tones etc. AVC seems to keep the blacks nice and deep and still let other colours be bright and vibrant. From what i've seen (Disney, Sony, Fox) all of their top tier titles are AVC.

But it does always come down to whoever's doing the encode.

[Slec]

Originally Posted by Aygie

I personally like AVC over VC-1. To me VC-1 titles have less colour depth and and often poor skin tones etc. AVC seems to keep the blacks nice and deep and still let other colours be bright and vibrant. From what i've seen (Disney, Sony, Fox) all of their top tier titles are AVC.

But it does always come down to whoever's doing the encode.

+1.
I think VC-1 was being used mostly by dual format supporters, which led to single encodes for both formats... This tainted VC-1 out of the gate. Although reading 2theMax's comments from the above link, the newest version of VC-1 sounds pretty impressive...

[syncguy]

MPEG4-AVC was developed by ITU and VC-1 is a Microsoft initiative based on their WMV9 codec and has used SMPTE for standardisation. As I understand, ITU put more emphasis to get a better codec and ended up with a complex coding system which require more computational power, In contrast MS was concerned about complexity and made VC-1 simpler to implement even in mobile devices. For example, VC-1 could produce more interpolation errors as it uses fewer pixels for filtering in comparison to AVC. However, due to this reason AVC could be smoother than VC-1. AVC also supports deep colour (10 bits) and 4:2:2/studio 4:4:4 colour profiles to reduce amount of colour compression. (Blu-ray probably doesn’t use 4:2:2 and limited to 4:2:0). Initially, VC-1 didn't support deep colour, it was limited to 8 bits and 4:2:0 colour profile. I am not sure whether VC-1 has fixed this issue.

There are more differences as the focus of these two systems were different. I haven’t seen a perceivable (human factors) quality comparison of these two codecs. It is interesting to find out.

[Blu n Gold]

From what I understand as well, VC-1 cannot vary bit speed during the film, while AVC can. This allows for the movie to adjust to lighter and darker scenes along with more accurate color reproduction.

[Mr. Cinema]

Disney used VC-1 on Flightplan, Deja Vu, and Gone Baby Gone. I thought both of those looked great.

[syncguy]

Originally Posted by Mr. Cinema

Disney used VC-1 on Flightplan, Deja Vu, and Gone Baby Gone. I thought both of those looked great.

Okay. As long as the average bit rate is kept high as required, it will not show any issues. For example, mpeg2 will be okay if sufficiently high bit rate is used. Codecs will show the anomalies when they are staved without feeding enough bits. In principle, IMO, VC-1 may show issues before AVC when the bit rate is reduced.

However, as I indicated previously I haven’t heard of any controlled human factors experiments on this.