What Are Subtitles?


Subtitles refer to text derived from either a screenplay or transcript of the dialogue or commentary in television programs, video games, films, and the like, usually displayed on the screen.

They can either be a form of a written rendering of the dialogue in the same language, with or without added information to help viewers who cannot understand the spoken language.

In addition, it helps viewers who are deaf or who have accent recognition problems to follow the dialogue.

Nowadays, it is easy for the subtitlers to access each individual frame of the video instantly because they work with specialized computer software and hardware.

This specialized computer allows the subtitlers to create the subtitle and also decide where each subtitle should appear on the screen of the device.

For cinema film, the task of showing subtitles is traditionally done by separate technicians.

Today, the specialized computer software that is used by subtitlers makes it possible to generate a subtitle file containing the actual subtitle and position markers.

The position markers indicate where each subtitle should appear and disappear.

These markers are usually based on film length (measured in frames and feet) if the subtitles are to be used for traditional cinema film.

It can also be based on timecode if it is a work for electronic media (for example, DVD, Video, TV).

The following are several ways to add the finished subtitle files to the picture:

  • Enclosed in the vertical interval and later superimposed on the picture by the end-user with the help of a decoder built into the TV or  an external decoder (closed subtitles on TV or video);
  • Directly into the picture (open subtitles);
  • Or converted (rendered) to BMP or TIFF graphics that are later inlaid on the picture by the end user’s equipment (As part of a DVB broadcast or closed subtitles on DVD).

Individuals can create subtitles using freely available subtitle-creation software like MovieCaptioner for Mac/Windows, Subtitle Composer for Linux, Subtitle Workshop for Windows.

Then the subtitles entrenched them onto a video file with programs such as VirtualDub. The VirtualDub program then works in connection with VSFilter which could also be used to display subtitles as softsubs.

The softsubs are supported in many software video players.

Categories of Subtitles


The narrative subtitles are most commonly used to translate a film with one spoken language and the text of a second language. Narrative subtitles are the most common type of subtitle in which spoken dialogue is displayed.

Hearing Impaired subtitles

They are sometimes abbreviated as SDH or HI. The hearing subtitles are intended for people who are hearing impaired.

The hearing subtitles provide information about music, off-screen speakers (e.g. when a gunshot is heard or a doorbell rings), and environmental sounds.

In other words, the hearing impaired subtitles point to the sources and the kinds of sounds coming from the movie.

These sources and kinds are usually put inside brackets to delimitate it from actors’ dialogues.

For example: [mysterious music], [sound of typing on a keyboard],  [woman screaming], [glass breaks].

Forced subtitles

The forced subtitles are common in movies, and it only provides subtitles when the characters speak a foreign or alien language, a flag, or a sign. 

It also provides subtitles when other text in a scene is not translated in the dubbing process and localization.

These can be certain time/location identifiers, dialogues, textual graphics, etc. which aren’t explained via the audio.

For instance, In Steven Spielberg’s Amistad, the dialogue of the Spanish slave traders is being subtitled, while African languages are left untranslated.

Content subtitles

These subtitles are a North American Secondary Industry (non-Hollywood, which are often low-budget) staples. The content subtitles add content dictation that is missing from a dialogue or filmed action.

Most times, there are general low-budget allowances in such films, making it is often more practicable to add the overlay subtitles to fill in the information.

They are most commonly seen on Canada’s MapleLeaf films as optional subtitles and on America’s Maverick films as forced subtitles.

Content subtitles also appear at the end of a film, for example, Gods and Generals, and at the beginning of some higher-budget films, for example, Star Wars.


Titles are a category of subtitles that is typically used by dubbed programs, and it provides only the text for any untranslated on-screen text. They are most commonly seen as forced subtitles.

3D subtitles

This category of subtitles combines the standard subtitle position along the X and Y-axis of the picture, with a third position along the Z-axis. The third positioning allows the subtitle to “float” in front of the 3D image.

This option is available in 3D Blu-ray releases and in Digital Cinema.

Types of Subtitles

Subtitles are known to exist in two forms:

  • Open subtitles: These are “open to all” and cannot be turned off by the viewer;
  • Closed subtitles: These are designed for a certain group of viewers, and can usually be turned on/off or selected by the viewer. For example, being Teletext pages, DVB Bitmap subtitles, DVD/Blu-ray subtitles, U.S. Closed captions (608/708).

While sharing content, subtitles can appear in one of three(3) types:

Hard subtitles

This type of subtitles is also known as open or hardsubs subtitles. The hard subtitle text is irreversibly merged in original video frames, and so no special software or equipment is needed for playback.

Therefore, complex transition effects and animation can be implemented, such as karaoke song lyrics using various fonts, colors, animation, sizes (like a bouncing ball), etc. to follow the lyrics.

Nevertheless, these subtitles cannot be turned off unless the original video is also included in the distribution as they are now part of the original frame.  

As a result of this, it is impossible to have several variants of subtitling, such as in multiple languages.

Pre-rendered subtitles

They are also known as closed subtitles. Prerendered subtitles are used on Blu-ray and DVD (though they are contained in the same file as the video stream).

They are separate video frames that are overlaid on the original video stream while playing.

It is possible to have multiple language subtitles and switch among them or turn them off, but the player has to support such subtitles to display them.

Besides, subtitles are usually concealed as images with a number of colors and minimal bitrate; they usually lack anti-aliased font rasterization.

Besides, changing such subtitles is hard, but special OCR software, such as SubRip exists to convert such subtitles to “soft” ones.

Soft subtitles

They are also known as closed subtitles and softsubs. They are separate instructions, usually a specially marked-up text with timestamps to be displayed during playback.

Soft subtitles require player support. Also, there are multiply incompatible (but usually reciprocally convertible) subtitle file formats.

Softsubs are relatively easy to change and create, and they are usually used for fansubs. Text rendering quality can fluctuate depending on the player but is usually higher than prerendered subtitles.

Also, some formats introduce text encoding troubles for the end-user.  These happen if different languages are used simultaneously, for example, Asian and Latin scripts.

In other arrangements, digital video subtitles are sometimes called external and internal.

They are called external if they are distributed as a separate file (that is less convenient, but it is easier to edit/change such file).

Also, if they are embedded in a single video file container along with video and audio streams, we can call them internal.

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