Need help on MPEG basics

Hello,I want to have some basic understanding about MPEG (sampling,encoding,etc.) but couldn't find a real good article.The best one I could find so far is this one: . But it also assumes you already have some knowledge before reading. For example,in the section "MPEG-2 Video" it draws a picture to show that a macroblock has 4 blocks of 8x8 pixels,however,soon after that it draws another picture to say that a macroblock has a stucture of 4 Y blocks and 1 Cb and 1 Cr blocks, so totally 6 blocks. I guess that I need to read some other articles before this one and hopefully, those articles wont suggest me to read this one first! Any help would be appreciated very much.

Hello, and welcome to the forum. I'm going to recommend the . Whether or not you happen to use DivX, or any other MPEG-4 codec, the guide has a great deal of information on Macroblocks, Quantizers, Motion Vectors ... available in four languages, and all with images that help describe these general MPEG technologies.

To speak to the particular point you raise: MPEG-2 and MPEG-4 ASP use a colorspace called "YV12". Essentially the luma channel (Y) is sampled every pixel, and the chroma channels (Cr, Cb) channels are sub-sampled by a factor of 2. This means for every 16x16 luma pixels you have 8x8 chroma pixels in each chroma channel, or 4 luma blocks, 1 chroma pair (1xCr block + 1xCb block), if you want to think of it that way.

chroma... luma... with my many posts i still dont know much. But I am slowly learning. Wondering when have I reached GURU status, but I must also admit, I think I'd probably be too lazy to read industry specs ... ;)

for mpeg 1 and 2 there is always of course. even has a F.A.Q. about colour spaces used etc etc etc. :)

Thanks a lot,everyone. Now I have so much to read. The Divx User Guide is really a great one for beginners and has far more than expected(I didn't see a document for MPEG1/2 like this).DigitAl56K gave me the hint to distiguish Pixel Macroblock and Sampling Macroblock.Koepi's one might be a bit too high level at this moment but will keep for future reference and dragongodz's link just includes everything(?) about MPEG and need more time to digest. As a newbie I am often stuck by some basic stuff,for example,it seems to me that there is no document to explain what exactly means for each digit in the expression of 4:4:4,4:2:2,4:2:0,4:1:1...,maybe some one could help me to figue it out. Thanks again.

There's a spot on the which is extremely helpful: If you click Show results as posts your search will show you only individual posts within threads. There is no need to wade through many different posts (or pages of posts) to find your keywords. You can restrict your post to a specific forum. You can just search thread titles if you wish, this is also helpful. And, if you want to find a page from one of Doom9's guides by keyword, has its own search: See my .sig?

I think we got waaaaay off topic ;)