I'm using VOC ConvertXtoDvd to convert and burn AVI and MKV files into DVD. It has many options to optimize output. You can select the video bitrate/audio bitrate and subtitles.
I uploaded setup and crack if you want it.
http://rapidshare.com/files/212078265/CXDVD.v3.0.0.7.F4CG.rar
please keep in mind that, AVI fle format is a wrapper only, video may have encoded with different kind of codac. For example, if you are trying to convert XDiv encored avi file to DVD (commonly use Vidx codac) There might be some quality losses. In Most DVD players, you can play Vidx encored AVI files (in data DVD) without converting to DVD format VOB files.