The name VTS_01_1.VOB follows a strict hierarchical naming scheme required by DVD players to identify and play content correctly:
Groups related content together. A single DVD can have up to 99 title sets. VTS_01_1.VOB
Identifies this as the first title set on the disc (usually the main movie). The name VTS_01_1
A VOB file is a specialized container format based on the . It acts as a wrapper that "multiplexes" several streams of data so they can be played back in perfect synchronization: Video: Typically encoded in MPEG-2 format. VTS_01_1.VOB
Contains internal timing data that helps a DVD player jump to specific chapters or handle multi-angle footage. 2. Understanding the Naming Convention
Stored as "subpictures" that are overlaid on the video stream.