When a DVD disc is placed into a standard DVD player, the player looks for a directory or folder
named VIDEO_TS (Video Title Sets). For maximum compatibility, the name of this folder is expected
to be in all capitals with no lowercase letters. Older DVD players also look for the additional
folder AUDIO_TS (Audio Title Sets). Many modern DVD movies contain only the required VIDEO_TS folder.
If the VIDEO_TS folder is not present or cannot be read, most player displays a short error message
such as "No Disc" on the screen.
Once the VIDEO_TS folder is located, the DVD player makes an attempt to read the contents of the
VIDEO_TS.IFO file in this folder (IFO stands for "Information"). This file contains required
information and data structures to instruct the player how to play back the inserted disc. If this
file is missing or it cannot be read for any reason, the DVD player makes another attempt to read
the alternate file VIDEO_TS.BUP (BUP stands for "Back up"). When a DVD disc is created, authoring
software creates the file VIDEO_TS.BUP as a backup copy of the VIDEO_TS.IFO. If both the VIDEO_TS.IFO
and VIDEO_TS.BUP files cannot be read or accessed, most DVD player again displays the short error
message such as "No Disc" on the screen.
In a nutshell, the DVD player looks for a data structure called VMGM_MAT that must be present in
the file VIDEO_TS.IFO. This data structure contains another structure called the First-Play PGC
that has the start-up information. In this provided project, the First-Play PGC instructs the DVD
player to read another data structure called VTSI_MAT that is present in the file VTS_01_0.IFO.
VTSI_MAT contains information regarding how to play back the title.