Codec Question?


I dont think so.

To my knowledge XviD was the open version of DivX. But I may be mistaken. Dont take my words with importance.
 
There is a long and complex history to both...

DivX is (an implimentation of) MPEG-4
XviD is (an implimentation of) MPEG-4

Xvid is the open source continuation of where DivX left off (when it went commercial)
Or something to that effect.
 
MPEG stands for Motion Picture Experts Group. That group is responsible for developing the MPEG-1,2, and 4 specifications. After the MPEG-4 specification was created, it was up to others to actually implement them into a useable form.

Microsoft was one of the first companies to use the MPEG-4 ideas in a video codec, which could be placed in an .avi container. These were called the MS MPEG-4 V1 and V2 codecs. Microsoft also developed a MS MPEG-4 V3 codec, but they only allowed it to be put in the .asf container, which is crippled because there are liscensing restrictions to using the container. The DivX ;-) 3.11alpha codec is the MS MPEG-4 V3 codec hacked so that it can be used in an avi container. The DivX3 codec was the first popular implementation of MPEG-4 among internet "geeks", but its weakness was that it was technically illegal.

So, I believe it was some of the same programmers who released DivX3 also decided to develop their own MPEG-4 codec from stratch, which was named DivX4. DivX4 and the rest of the DivX codecs were all closed source. Soon after, an open source project was started called OpenDivx, which was an open-source MPEG-4 codec. I think OpenDivx was also reffered to as Project Mayo; although, they may be completely different. Out of OpenDivx spawned the XviD project.

A lot of times you will see disclaimers in XviD or OpenDivx programs etc. saying that it can only be used for educational purposes. This is because there are some patented elements in the MPEG-4 specification. Although everyone can see and use them, there are liscensing fees that need to be paid to the patent holders. It is similar to the free mp3 codecs like LAME. Mp3 is an abbreviation for MPEG-1/2/2.5 audio layer 3. There is a company called Fraunhofer that holds the patent to many techniques used in mp3, so any program that incorporates mp3 must pay Fraunhofer. LAME originally stood for Lame Ain't an Mp3 Encoder, and it wasn't to begin with. It was an education project with the goal of improving some of the algorithms in the mp3 specification. Since then, it has spawned into a full codec. But, from the LAME project, you won't find any useable codec binaries because it is illegal for them to distribute. So, some people take the freely available LAME sources and compile them into a useable binary, which is technically illegal if you live in a region where you would be required to pay liscensing fees and you are not useing it for educational purposes.

The XviD project is very similar, in those respects, to the LAME project. You will notice that if you go to the XviD projects homepage, http://www.xvid.org, you can't download a useable binary.

Now, there are many MPEG-4 codecs such as DivX, XviD, 3viX, and Nero Digital. Recently, there are many new, more advanced codecs based on the H.264 specifications, which is also called MPEG-4 AVC (Advanced Video Coding or something). Plain MPEG-4 is also similar to H.263.

I probably missed a few important points or got confused on others, but most of that should be right :) .
 
Well, I guess it probably isn't illegal for the projects to host the binaries themselves, but since they are founded on the idea that they are to be an educational project only, they don't want to give any authorites any reason to shut them down. If they hosted binaries, it might seem that they are just trying to distribute codecs without paying liscensing fees. That is also the reason some of the more popular ripping programs, etc. like CDeX don't come with the LAME .dll; you have to get it separately.

I don't see anything wrong with downloading a LAME .dll to use in, say, an audio editing program you are writing for your senior project in college. But, I doubt most people are using it for that.
 
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