First off, is mpeg-4 a more advanced version of the original mpeg-2 codec (found on DVD-video) as AAC is a more advanced version of MPEG-1 layer 3 or is it a "high-efficiency" version of the original MPEG-2 codec like AAC+ is to AAC?

That may sound very vague. Alright, for a fixed resolution and bit rate is MPEG-4 always superior or is the original MPEG-2 codec (distinguished from the new MPEG-2 codec used on Blueray which is more like a virtual MPEG-3) superior once the bit rate is high enough?

MPEG2 on blueray is not a virtual MPEG3, its just MPEG2 nothing new about it.

MPEG4 and MPEG2 are not closely related (MPEG4 is not just an extension to MPEG2, like MPEG2 is for MPEG1) and within the MPEG4 standard you have two completely incompatible video standards: MPEG4 part 2 (ASP) and MPEG4 part 10 (AKA h264/AVC, will be used on Blueray/HD-DVD).

As for you question, with no bit rate constraints both (or all 3) standards are equal.

Oh. Someone else had said that Blu-ray was going to be extra layers on the mpeg-2 standard. And it still sounds like a "virtual mpeg-3" in that I've been told they were originally going to create a separate mpeg-3 standard for it but decided to add extra layers to an existing standard.

And I asked about holding the bit rate and resolution constant. From what you've said I suppose mpeg-4 layer 2 is always better than mpeg-2 if they both have the same bit rate and resolution?

I think you heard wrong there. The MPEG2 is the same as found on DVDs, only the Blu-Ray standard will allow for higher levels than can be used for DVD (I assume). There certainly is (or has been) no talk about an MPEG3.


And encoded from the same source, yes.

You need to clarify: Are you speaking about audio or video? What do you mean by "mpeg-4 layer 2"?

i hoped he meant mpeg4 part 2, thus video... and I'm not sure what the resolution of an audio file is... sampling rate?

Well, why isn't there an mpeg-3 standard? Why'd the skip it over?

And I thought "layer" and "part" could be used interchangeably.

MPEG naming conventions baffle me too. There's also a MPEG7 and MPEG21 without having the in betweens. No idea why it is like that.

There was an MPEG-3 working group, focusing on high definitions moving pictures (ie HD video). In the early stages, it appeared that the MPEG-2 standard would be able to handle high definition video, so MPEG-3 was cancelled.

MPEG-7 and MPEG-21 are not related to compression.

this is very source-dependant, as manono said here
http://forum.doom9.org/showthread.php?p=636742#post636742
"But grain/noise is very hard for MPEG-4 to compress and is, in my opinion, one reason why it still isn't as good as MPEG-2."

and as i recently said here
http://episteme.arstechnica.com/groupee/fo...31#452000016731

so, depending on what you encode, pick your codec. i say i couldn't find a mpeg4pt2 codec for my tv-caps that i was totally satisfied with. this is not to say mpeg4pt2 codecs look too bad with my sources (i clean my sources prior to encoding)...just that I wasn't _fully_ satisfied.
with cinema craft encoder i am. fully.

the peak codec performance on a completely clean sources and high bitrates would be interesting subject but i think less people would notice any difference.
but some differences would be apparent: for example, xvid and divx will have "floating walls" even on rather high bitrates. mpeg2 will have blocking on fade-outs, and simillar.

i'm surprised to see stephan is so sure about mpeg4 always being better than mpeg2: he's usually very sceptical about judging video quality in general...heh...
i can post plenty of clips where mpeg2 beats mpeg4. on same bitrate.


nothing in video compression is certain.

the stuff is like this; only the proprietary codecs can be compared "for certain". with mpeg, one mpeg2 encoder may look excellent, and another may look very poor.
so we can't say for sure "mpeg2 is such" or "mpeg4 is such".
we can only say "i have such feelings about this implementation of mpeg2 (or mpeg4)".

i do wonder if they will really support wmv9?

VC-1 is mandatory too, so yes. (only the video standard, not the container or audio codec, although chances are a number of player will support those too).