What is the necessary file structure for a DVD to be playable?

"In a technical sense, the VIDEO_TS folder already contains the video data in DVD format. A Video DVD is the contents of this VIDEO_TS folder burned onto a DVD+/-R disc in a hybrid ISO9660+UDF filesystem. As Steve Rowe has mentioned, Video DVDs use UDF v1.02.

See Doom9's DVD Structure article for details of the filetypes. When burned as a Video DVD, the files in the VIDEO_TS folder are layed out on the disc in a particular order. For example (notice the files are not layed out in alphabetical order):

VIDEO_TS.IFO -- VIDEO_TS.* is the first play item
VIDEO_TS.VOB
VIDEO_TS.BUP
VTS_01_0.IFO -- VTS_01 is the first title set
VTS_01_0.VOB -- the _0.VOB is the title set's menu
VTS_01_1.VOB -- the _[1-9].VOB is the title set's video content
VTS_01_2.VOB
VTS_01_0.BUP
VTS_02_0.IFO -- IFOs contain navigational information
VTS_02_0.VOB -- VOBs contain Video, Audio & Subtitle streams
VTS_02_1.VOB
VTS_02_0.BUP -- BUPs are backup IFOs

Many data burning utilities can create Video DVDs, but you need to make sure they don't try to burn as a data DVD -- data DVDs won't necessarily lay out the files in the proper order, and may use the wrong filesystem for the disc.

If you have the mkisofs command available (in the Terminal on MacOSX and Linux, or Windows with Cygwin), or the hdiutil command on OSX, you can make a ready-to-burn ISO with one of the following commands (source):

# INPUT_FOLDER is the folder that contains the VIDEO_TS

mkisofs -f -dvd-video -udf -V VOLUMENAME -o OUTPUT.iso /path/to/INPUT_FOLDER

hdiutil makehybrid -iso -joliet -udf -udf-version 1.02 -default-volume-name ""VOLUMENAME"" -o OUTPUT.iso /path/to/INPUT_FOLDER

The output ISO file can be burned with any burning utility program."

"A top level AUDIO_TS, though not used, is mandatory.

Alternatively you can use DVD Imager (up to Leopard) for creating a DVD image that you can burn on a DVD with Disk utility. Internally, it uses mkisofs (not available on Mac OS X but shipped with DVD Imager in its resources subfolder - ctrl-click on DVD imager icon and choose ""show contents of packet"") with a command line similar to this one:

mkisofs -dvd-video -udf -o dvd.img dvd/"