DVD Flick is a great and easy to use open source software for making simple DVDs. It accepts various input formats, such as AVI, FLV, MKV, MP4, MPG and even HDMOV (QuickTime HD). This guide will mainly focus on DivX/XviD AVI input files, although it will work for pretty much any of the formats that DVD Flick accepts.
DVD Flick has a built-in burner, but if you prefer not to use it and to test playback first prior to burning, then a DVD folder or ISO output is available (if you choose these latter two options, please make sure you know how to burn these files to make a DVD, as this guide will not cover it).
For this guide, we will also use GSpot in order to find out certain details about our input DivX/XviD files (actually just the framerate), so it is not strictly necessary if you already know these details. All you need to do to install GSpot is to download it and extract the contents to a folder on your computer.
Step 2: Inputs
Before you load your inputs into DVD Flick, it is best to make sure that these input files are all of the same system (PAL or NTSC or NTSC-Film). As a rule, files that are 23.976, 24 are NTSC-Film. 29.97 or 30 frame per second are NTSC. While PAL video is at 25 FPS. Multiples of these framerates (eg. 15 FPS and 60 FPS => NTSC) are sometime used as well. For AVI files, the best way to check for the framerate is to use GSpot. You can actually get this information within DVD Flick, but only after loading in the files, which makes it harder to plan out ahead your projects.
Start GSpot and from the "File" menu, select "Open" to load in your AVI file. GSpot will scan the file and show you the framerate in the "Frames/s" area (marked in red in the screenshot below). Repeat this for all your AVI files to make sure they are all either NTSC, NTSC-Film or PAL. Mixing different types of video files (eg. mixing PAL and NTSC) will mean unsmooth video or other artifacts.