Converting the videos is easy enough. ffmpeg is the tool to use:
$ ffmpeg -i yourfile.avi -target pal-dvd -aspect 4:3 output.mpg
You can use any format for input that your ffmpeg is compiled to support, so this works just as well for Youtube and Google Videos that you cannot find the mpgs for:
$ ffmpeg -i youryoutubevid.flv -target pal-dvd -aspect 4:3 output.mpg
The problem with making your DVD is the actual authoring process. I've been using
ManDVD with some success, although it seems to be slightly incompatible with modern ffmpegs (make sure to add a menu sound file, as ManDVD fails to instruct ffmpeg correctly to make a silent one to multiplex in), and can be frustrating to use: no working project save, for example. It will author and burn disks, but sometimes, if you're using ManDVD or another tool, the process will fail after the creation of the authored content in AUDIO_TS AND VIDEO_TS directories. If that happens, you can do this:
$ growisofs -dvd-compat -Z /dev/dvd -dvd-video .
That will burn you a new, properly authored DVD if you run it from the directory where your VIDEO_TS directory resides.
As far as the authoring goes, what we need is a
simple frontend to
dvdauthor which will create an XML document and design the titles, menus and masks nicely. I
know that I could make all the menu files in the GIMP, but I just don't have the time. I want a simple, templates-based approach. I'm happy to do all the file conversion, up front, and I'm happy to use cdrecord or growisofs to handle the burn. I need help with the DVD authoring, that's all.
Let's stop this from being a compatibility crap-shoot, and get a process that produces consistent, standards-compliant DVD content into order, without loads of scripting.
Edit
Ok, maybe I was ill-informed. I'm trying
VideoTrans at the moment. It seems to be making a consistent and quite sophisticated menu system for the four videos I want to turn into a DVD. I'll see what the results are like.