Normal Overlay Graphic Subtitles and 16:9
Overlay graphics that you use for subtitles on 16:9 tracks must be anamorphic (horizontally
compressed) to display properly when viewed on a 16:9 monitor. If you use nonanamorphic
graphics for the subtitles, they will appear horizontally stretched when viewed on a 16:9
When a 16:9 track with a graphic subtitle plays on a 4:3 monitor, the entire graphic
appears, whether you use the letterbox or pan-scan mode. If you used an anamorphic
graphic for the subtitle, it will appear horizontally squeezed when viewed on a 4:3 monitor.