Re: Bitrate

Never ever use CBR if your average bitrate is below 8Mb/s unless max quality is not most important. If you don't choose VBR multi-pass you will lose some quality. Exception potentially is a slideshow (except for transitions) but extra cost of MPEG2 SD VBR is really cheap nowadays.

The average bitrate obviously decides the file size. Don't forget as mentioned that you'll have to add little bit of overhead for DVD menus. Look for a calculator that adds video + audio (I assume the bitrate calc referenced above allows you to enter AC3 bitrates).

For 1:30 video and 192Kbs AC3 audio you end up at around 6Mb/s as mentioned (max I'd set at 8Mb/s and min depends but typically 3-4Mb/s for most videos). I also would not exceed 8Mb/s for video. I've seen cases where it caused stutter in some DVD players (with self-burned DVD's).

For best DVD compliance use AC3 audio always with 48KHz and either 192Kbs or 224Kbs works (officially bitrates between 32-1536 are supported).

The 384k bitrate is commonly used for 5.1 channels (and often commercial DVD's are 448Kb for 6 channels).