![]() They're generally referred to as either VobSub or IDX + SUB (IDX/SUB) subtitles. SUB and additional information in another file with an extension of. In fact, VobSub basically just re-packages the images from the DVD into a file that has the extension of. VobSub Subtitles VobSub subtitles have become very common because it's easy to get them from DVDs. AVI was/is the most common container for MPEG-4 ASP video encoded with codecs like DivX and XviD, and was also the format first added to DVD players for MPEG- support. While AVI files can't contain graphic subtitles, they can have text subtitles. Perhaps the biggest reason for the widespread development of text-based subtitles is their use in AVI files. But if you happen to belong to the small minority with a need to make subtitles you'll have to at least start with a text-based format. Creating subtitles isn't exactly something most people have the inclination (or time) to do. Since editing a text-based subtitle can generally be done with even a simple text editor like Notepad they're the easiest to modify and by far the easiest to create yourself. The Big Advantage to Text The important thing about any text-based subtitle format is that you do have the ability to edit subtitles easily. Still, there are times you need to understand the difference and know which you have or need. It's not necessarily important to understand how either type of subtitles work, or why a particular application uses one or the other. These images are put over the top of the video frame when displayed. Much like the way characters on older text-based computer interfaces, they're actually just a collection of dots on a grid. They're actually encoded as raster graphics. As a matter of fact subtitles on DVDs aren't actually text. Although it's normal for all subtitles to start out this way, that doesn't mean that's how they're stored. Since text is also some of the easiest data to store and compress it makes sense to store subtitles as simple text files or a text stream within a video file. Images Most subtitles consist purely of text characters. Then we'll take a look at three specific subtitle formats VobSub, SubRip, and SubStation Alpha. First we'll be considering the difference between image and text based subtitles. But we'll still be considering two categories. For our purposes we'll be focusing on subtitles that exist as separate streams in a video container, or even separate files entirely. They can be hard coded or separate streams, depending on whether they're encoded as part of the video or simply muxed into the same container. They can be mandatory or selectable, depending on whether they can be turned off. ![]() Subtitle Categories There are many ways to categorize subtitles. With a little bit of reading it becomes easy to figure them out. Ironically, for most people subtitles are much easier to grasp than other multimedia elements. Even they're found on nearly every DVD, with the complexity of dealing with video, audio, and menus it's common for people to leave them for last, and often they get ignored completely. ![]() There is no information about end time.Subtitles may be the least understood aspect of digital video. In the Square Bracket Time Code format each subtitle text is preeceeded by a line that includes the start time inside square brackets. Nevertheless, XML is still used by applications and SOAP based web services Since the advent of JSON, however, it has lost the advantage to the more simple nature of JSON. It is part of the W3C standard.Įxtensible Markup Language (XML) is a widely used language that was once the de facto standard for data interchange between applications. WebVTT (Web Video Text Tracks Format) is a subtitle file format used by HTML5 compliant browsers to render timed text. TTML is a subtitle file format previously called Distribution Format Exchange Profile and is a W3C standard. SubViewer Sub is a subtitle format used by DivX media Player. Spruce Subtitle File is a less known subtitle format that was created by Spruce Technologies and used in DVD Studio Pro SSA is a subtitle file format generated by the Sub Station Alpha software. It uses Frame Rate to mark the timing of subtitles. MicroDVD Sub is a subtitle format used by the MicroDVD Player. Video players show the subtitle on the screen when the video is within this period. A time range (start to end) precedes each line of subtitle. SRT is a subtitle file format generated by the SubRip software. Lines of songs are preceded by the time when they appear in the song. LRC is a lyrics file format introduced by the program Lyrics Displayer. The VTT Range format has start and end time codes without serial numbers and newlines between subtitle items In the multi-line short time format the start time code exists in a line above the subtitle.
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