Here's a question for those who really knows what goes on when we convert and compress video files. Say I'm ripping a DVD to XVID. I generally have a good idea what bitrate (or final file size) I want. My question is, having fixed the bitrate, does it matter what resolution I use? Is it best to just keep the native resolution of the DVD? Generally I have been reducing the width to 576 pixels but I've not been doing this based on any particular reason except that it seems like a good compromise. I play my files on multiple devices including an archos player (480x272 screen) and a 32" 720p LCD. And a related question... If I keep the native resolution during conversion ie. compress but not resize, is the conversion any quicker?
It's a good question and it does matter. If you set the resolution too high for a give bitrate, the quality will suffer. One method is to encode in AutoGK, set the file size and allow AutoGK to choose the resolution. Choosing the native resolution may be slightly quicker but it's wrong. Normally avi files are created with a pixel aspect ratio of 1:1, but this is certainly not the ratio used on the DVD, and has to accounted for.
Thanks for the reply. I'm using AutoGK more these days and only wish I'd found it two years ago when I started doing this stuff!
