What is the difference between AVC and VC-1?

[mainman]

I know AVC was developed by Sony, and VC-1 was developed by Microsoft.

What is the difference between the two, which is more efficient right now? I heard something about 14mbit/s, which one has this, or do theyy both have it?

And which codec does the majority of HD-DVD titles use right now?

Thanks.

[marzetta7]

H.264 was NOT created by Sony but by the Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG). VC-1 I believe was co-developed by Microsoft.

You can learn more about both here...

http://en.wikipedia.org/wiki/H.264

http://en.wikipedia.org/wiki/VC-1

What codec is better, I think that is still up to debate.

[mainman]

Originally Posted by marzetta7

H.264 was NOT created by Sony but by the Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG). VC-1 I believe was co-developed by Microsoft.

You can learn more about both here...

http://en.wikipedia.org/wiki/H.264

http://en.wikipedia.org/wiki/VC-1

What codec is better, I think that is still up to debate.

http://en.wikipedia.org/wiki/VC-1

Although widely considered to be Microsoft's product, there are actually 15 other companies in the VC-1 patent pool

Is Sony one of those 15 companies? Because I remember reading somewhere that Sony developed a codec (something) together with Microsoft.

[hmurchison]

Both are similiar in that they use modern compression techiques to improve quality at lower bitrate.

VC-1 is a bit easier to encode/decode than AVC.

Trying to discern any real substantive difference will require digging deep down into the nuts and bolts of the codecs.

[Shadowself]

Originally Posted by hmurchison

VC-1 is a bit easier to encode/decode than AVC.

I don't understand this statement.

Are you saying AVC is more compute intensive (requires more compute cycles) than VC-1?

Otherwise, once the codecs are written into software (in the case of software used to compress video media) or firmware (in the case of players decompressing the video for playback) it does not seem to me that one is easier than the other. The software/firmware does all the heavy lifting for you.

Additionally some computer companies have provided video chat capabilities using AVC on their systems for a few years (at least two generations of CPUs back) with no special hardware or firmware required so it does not seem to me that AVC can be very compute intensive.

[hmurchison]

Yes AVC is definitely tougher to encode (roughly 8x/4x the power needed for encode/decode versus MPEG2) there is no free lunch if AVC is used on a disc the processors involved will have to have enough power to handle the extra crunch.

Here's a great explanation of why

http://www.tvtechnology.com/features/news/n_AVC.shtml

"AVC is more complex and may ultimately offer the potential for higher quality and more efficient coding. VC-1 is less complex and therefore, presumably easier to implement efficiently," Goldman said.

Examples of specific differences between AVC and VC-1 include AVC's use of six-tap filters versus VC-1's use of four-tap filters. AVC uses an entropy scheme known as CABAC (context-adaptive binary arithmetic coding) that is computationally intensive and therefore expensive to implement. VC-1, by contrast, uses high-order entropy coding that is less complex and less expensive to implement.

http://broadcastengineering.com/mag/...avc/index.html

Practical AVC encoding and decoding solutions must overcome substantial technical challenges. SD AVC compression requires around 10 times more processing power than MPEG-2, and there is now a dearth of ready-made silicon solutions for professional AVC compression applications. HD encoding compounds the challenge.

VC-1 seems to be the easier codec to master discs to from what I've seen but I think that in the next 5 years we'll see AVC pull forward in the quality department. I expect Sony to be more of a AVC proponent. Hell they may be in the patent pool for AVC.

[AV_Integrated]

Originally Posted by Shadowself

The software/firmware does all the heavy lifting for you.

Computationally, for the highest quality video, the hardware requirements and the software requirements are huge. Software is pretty standard, but once a codec is developed, tweaking the nuances of it to generate the highest quality video possible for any given situation is phenomenally complex.

This complexity lends itself to typically being far less than real time for encoding unless you have an incredible amount of horsepower driving the hardware. While you may see cheaper encoders that can do half frame @ 15fps with so-so quality that work on many PCs, finding an encoder that can do full HD, at full HD quality, in real time requires over 4x that processing power at the very least - typically a great deal more.

Likewise the decode is heavily hardware intensive. If you go to Apple's website and look at their HD movie trailers, you will see if your PC is up to the challenge of their 1080p trailers. Many PCs aren't going to make the cut, while some will. I know that neither of my computers can do 1080p cleanly. So, while it is in the software to perform the decode, and the decode does happen, it doesn't happen in real time at 30 frames per second or more as demanded by 1080p video.

As I said - it is incredibly processor intensive.