Hi, I am interested whats the right way to do DVD authoring from a command line? Let's assume I have an AVI format movie (some screncast I recorded) and want to make it from a command line into a DVD (layout).

Basically this question has 2 subquestions:
1. the best command to convert avi video to mpeg (both video and audio)
2. the best command for authoring dvd from a avi to mpeg converted mpg file which, after I burn disc, it will work on DVD players (testing on PC is not too reliable(?))

It would be handy also some good examples of dvdauthor.xml file (needed for dvdauthor) to see for a single video file.

I am not interested in GUI (though do not object to hear some suggestions too - tried KDENLIVE, Bombono DVD, DVDStyler, WinFF, kMediaFactory...) but in CLI commands as I want to automate process and use my old video files to convert to dvd and burn / store away.

the big question is do you want a menu on the dvd ?
if you do want menus and chapters and jump to scene then a gui based program is most likely needed

No, menu is not needed as long as it can be played on a DVD player without it.
I tried a couple of xml for dvdauthor and when I tried later to clone my generated DVD with CloneDVD program, it says something like "defected DVD structure".
So I was interested to see how others are doing it and see if I have some error or missing parameter in my procedure.
That is why I do not care for menus, background picture etc for now, just pure proper convert from avi to mpeg as DVD requires mpg format (and by the way video has sound and video so do I need to extract them separate and then mux later into one or?) and then correct dvd authoring.

Interesting enough, but all DVDs I made with GUI couldn't pass through CloneDVD program. Its a Windows program so just forget it I mentioned, I am interested to do my job creating DVD on Linux properly first with terminal only.

Also, is Xine confident as a "DVD player emulator"?

sorry cant help with how to convert an avi to a playable DVD on a set top player, but for Linux desktop DVD playback of either avi or mpeg, or many other formats yes Xine works well.

i have also used VLC and on my media computer (a Raspberry Pi connected directly to my TV via HDMI) i use xbmc as my media player.

I used "devede" but it is GUI based and great for authoring & making menus but I'm sure you can skip the menu creation part. As far as converting try avconv. I used to use ffmpeg to convert various media formats but I guess it's soon deprecated and avconv is replacing it.

Try:

It has a sh*t ton of options so read the man page for relevant parameters.