MeGUI/Computer movie files/Subtitles

SRT
SubRipText. Made a while ago by a frenchy, it is a very basic text based subtitle format. Allows for simple hex coloring, bold and italic flags. It is a very bare simple format, however, it does allow the user to select a font, font size, or override the font color/outline during playback, Assuming VSFilter is used to play the subs.

Code sample (thank you wikipedia): 1 00:00:20,000 --> 00:00:24,400 In connection with a dramatic increase in crime in certain neighbourhoods,

SSA
SubStation Alpha. A rather old format which was developed out of the need for a powerful digital subtitle format, it was used extensively by fansubbers. Development ended with SSAv4 many years ago upon the disappearance of the developer and was succeeded by ASS (SSAv4+). Allows lots of cool stuff, including: Style and Code sample: Style: Default,Arial,40,16777215,16777215,16777215,-2147483640,-1,0,1,1,1,2,30,30,25,0,0 Dialogue: Marked=0,0:25:50.40,0:25:53.06,*Default,Comment,0000,0000,0000,,Kakarrot-o!!
 * Defining bold, italic, font type, font size, font color, font encoding type, and alignment (very basic positioning) of the text.
 * Styles are used to easily group together lines of text to use the same "style." They specify all of the above as well as outline width, shadow depth, outline/shadow color, and margins.
 * Basic karaoke effects.
 * Because each line has its own timestamp and positioning is allowed, multiple lines of text can be shown on screen

ASS
AdvancedSubStation Alpha, which is referred to as SSAv4+ in the specifications of the format, is where the major improvements were made. Most people do not realize the difference between SSA and ASS because the same filter, TextSub/VSFilter, has been the prime renderer of the format. As such, override codes which are ASS only can be used in a SSA script when rendered by TextSub/VSFilter. This among other things has lead to a large blurring of the two formats. However the documentation of SSA as well as the ASS revisions can be found here. Since the developer of SSA disappeared, the primary uses of the format was anime fansubbing. However many of the fansubbers needed the format to grow even more powerful, and thus SSAv4+ was proposed which then became known as ASS. The following advancements over SSA were made:
 * Can define the text for underline, strikeout, border width and shadow depth (only available in styles before), blurred edges, font scaling in the x and y axis, define spacing between letters, rotation of text, outline and shadow colors (only available in styles before), and alpha transparency.
 * Huge assortment of functions which allow for the font to be transformed over time through styles or override codes, movable text, exact pixel positioning, define the origin of text, and fading.
 * Karaoke is rebuffed, somehow
 * Styles are updated for the new options

There were also a few other parts of the SSA/ASS documentation which just never implemented into VobSub/VSFilter. The only one to note is embedded pictures. Which would essentially cross the barrier of text and image based subtitles in one format. However this never came to be.

Style and Code sample: Style: Batou,Century Gothic,28,&H00C0C0C0,&H00000000,&H00000000,&H7F000000,0,0,0,0,100,100,0,0,1,1,1,2,10,10,10,0 Dialogue: 0,0:13:00.11,0:13:03.77,Batou,,0000,0000,0000,,Both our faces aren't meant for mirrors.

VobSub
The name should be taken literally as to where these subtitles come from. VobSub is the name of the format for bitmap subs after they have been extracted from a VOB, Video Object file, on a DVD. The application which extracted the subtitles was also called VobSub (now known as VSRip) was developed by Gabest. VobSubs consist of an .idx file (the index of starting timestamps, colors, and other basic info) and a .sub file (which contains the bitmap pictures for the subtitles themselves). Unlike SRT, SSA, ASS, and TTXT which are Text based formats VobSubs are image based, and thus usually somewhat larger.

Index code and bitmap sample: timestamp: 00:18:40:752, filepos: 0000aa000

TTXT
MPEG-4 Timed Text. Based off the subtitle format created by 3GPP (in which case they are exactly alike). Looks a lot like XML madness. Of interest is the fact that it seems a line must defined for all times, meaning when there are no subtitles to be displayed, a blank line must be inserted. Sample: Please excuse me.