What Are I Frames, B Frames, ect.

[Tom Saurus]

I am new at making DVD's. My ATI MMC allows me to chose I frames or not. When I don't select that I have option of various A or B frames. Could someone explain what these different frames mean?

I notice a dimishment in the quality of the video when I play back a just I Frame video file in WinDVD. Why would this be?

I like to grab still pictures for various reasons by using WinDVD and the image quality is important to me. I thought I frames would be better for editing and such, but does it dimish the quality of the video? What are the advantage and disadvantages of these different types of frames.

Is there a better free program out there that is better at grabbing still frames then WinDVD. When I used to capture AVI's I liked how Virtualdub would all me to get to the exact frame I liked and grabbed a picture and paste it right into my picture editing program.

Does Tmpeg have a frame grab feature built in? If it did that program would be just about perfect?

Thanks in advance for any advice you can give.

[bugster]

Look here and here

I-Frame only mpegs will be large file size or low bitrate so poor quality as compression is less.

[Tom Saurus]

Thank you for the information. It was kind of you to direct me to where I could find the answer to my question.