In-Depth Look At Video Codecs

johnsee writes "Atomicmpc has an incredibly in- depth look at a wide range of video codecs. It looks not only at their inner workings, but also shows the quality produced by each at a variety of settings and situations."

Comments

Re:so which one wins?

[datapharmer]

Apparently some people have no sense of humor. BTW I am back.

For those not wanting to read the article:
Rated best to worst with default settings
Low Bitrate go with XVID, DIVX, h.264, WMV
Medium: XVID or h.264 depending on lighting and motion, WMV, DIVX
High: h.264, WMV, XVID, DIVX

Re:The description of DCT is pretty funny

[Rui del-Negro]

And so you should describe it as "dividing numbers by two and then multiplying them again"...? In other words, a "simple" description is preferable, despite the fact that it's completely wrong...? Hell, "dividing numbers by two" isn't even an accurate description of quantization, let alone of a DCT.

I think I made a pretty decent job of explaining what "frequency space" is, and why it can be used to improve compression, here:

http://digitalproducer.digitalmedianet.com/article s/viewarticle.jsp?id=109739-2

(scroll down to "The transformers")

It also explains why DCT isn't a form of compression per se, it simply makes it possible to use quantization in a way that does not affect quality as much as it would in "pixel space".

Several "non-techies" have read that and, although they realised the transform itself is not something trivial, they understood what it did and what it was used for. Something that you can't really say about the Atomic article (or its author).

Re:AVP beats ASP, no surprise.

[JohnnyLocust]

I've had some guys at my work try to tell me that H.263 = MPEG4. It actually got quite nasty. I recognize their are similarities, but I do not believe they are the 'exact same'.

H.263 is a part of the entire MPEG4 specification (as is H.264).

ie the following statement is always true:
H.263 is always MPEG4

However the the folloing statement is not always true:
MPEG4 is always h.263

My evidence is that the video cards we use have Mpeg4 hardware encoders

Not true at all. There are some hardware MPEG4 encoders on the market, but it is for the most part, not included in modern GPUs. For decoding purposes, portions of the h.263 (IDCT to be exact) has been implemented in hardware on video cards for quite sometime. However, combined with programmable shaders, a good deal of h.263 decoding can be greatly accelerated by most modern GPUs (nVidia's PureVideo DirectShow codec is an example of this). ATI's AVIVO XCode app does use a great deal of shaders to speed up the encoding process for several codecs. Even though it's been shoehorned to work with other GPUs, it was intended to work thier X1X00 line of video cards.