subtitling dictionary

Subtitling Dictionary

Here you can find explanations to the most common words and terms used within subtitling.


Asynchronous Serial Interface, or ASI, is a streaming data format. Normally it carries a number of MPEG Transport Streams. Fixed data rate at 270 Mbits/s.

Automation system
Control system for the complete TV station or playout center. The Cavena Subtitle Transmission Control, STC, interfaces to the automation system. The Cavena STC has interfaces to all common automation systems on the market.


Same as invision, subtitles burned onto the video, part of the video film. Read more about burn-in subtitles.


Character Set
The national character set is of vital importance – an incorrect character in a subtitle is very disturbing to the viewer, since he/she reads the subtitles subconsciously. All types of characters and accents etc. must therefore be supported.

Closed subtitles and Closed Captioning
Closed captioning, American wording or closed subtitles, European wording, is subtitling that exists as data in the transmission. The viewer can choose to display the subtitles or not. Transmission formats include Line 21 (US standard), Teletext and DVB subtitling (European standards). There are also some proprietary formats.

The Cavena Cimpress is a 1 RU video subtitle keyer for inserting open or teletext subtitles into broadcast applications in a digital video environment.

Compensating for missing frames
Cavena proprietary technology compensates for missing frames and can handle any video format. The low resolution video that the translator works with may be one minute shorter compared to full resolution video tape.


Digital Video Broadcasting. The DVB group has put together a number of standards for Digital Video Broadcasting.

DVB Teletext
This is the standard for wrapping EBU teletext into a DVB signal. An IRD can decode and display this data or re-insert into VBI for the TV to decode. Today it is the most common method for multi-lingual subtitling in DVB transmissions in Europe.

DVB Subtitling
Early entrances to this field use proprietary formats for the subtitle data. Today, most manufacturers adhere to the DVB standard. This standard allows for several methods of transmission of subtitles. DVB – (Character coded), DVB – (Subtitling bitmap), DVB – Teletext, (In the US possibly DVB – Line 21). Using the DVB subtitling standard with bit maps, the broadcaster has full control of the appearance of the subtitles. Fonts, sizes, colour and anti-aliasing is then defined by the broadcaster.


EBU Teletext
This has long been the standard format for hard of hearing subtitling and multi-lingual subtitling in Europe.

Short for End Of Message, commando from Automation to the Cavena STU.


Subtitles can be displayed using different fonts. Although they must be highly legible, the subtitles should distract as little as possible from the picture. Accustomed subtitle readers will absorb the information in the subtitles subconsciously. They will not normally perceive the subtitles as disturbing to the picture. Line 21 and Teletext have to rely on built-in decoder fonts in the TV or STB.


Short for General Purpose Interface. Simple control interface, can be used for cueing equipment.


HDTV is short for High Definition TV. Different formats for HDTV do exist. In general 720-lines and upwards is defined as HDTV.


Meaning subtitles are keyed on to the video prior to or during the transmission. This can be done for analogue as well as digital SD and HD signals. Also referred to as burn-in subtitles.

Integrated Receiver Decoder. Has both demodulator and decoder for “par example” MPEG-2, can be integrated in the TV or part of the set-top box.


Line 21
The US standard for closed captioning uses Line 21 of the VBI-lines for transmission. The data rate is low and allows for recording and playback on a consumer VCR. A decoder/character generator combination in a set-top box or in the TV is used to display the captions.


Short for Motion Pictures Experts Group. Compression standard for video.

Multiplexer, Number of digital video channels “muxed” or joined into one single transmission stream.

Multilingual Subtitling
Using teletext, DVB subtitling or similar methods, several languages can be transmitted simultaneously on one channel. The subtitles can be displayed in the selected language using either a decoder and character generator at the head end of a cable TV system, at a local TV transmitter, or in the viewer’s decoder (teletext, DVB etc.).


National Television Systems Committee. Advisory group for television standards in America.


Short for Operational Practice-47, an Australian standard for handling subtitling data in the vertical ancillary space, applicable for HD-SDI signals.


Short for Phase Alternating Line. Analog coding for television used in Europe and many other parts of the world.

Short for Packet IDentifier. A field to name different transport packages.

Short for Program Clock Reference. “Clock” is not fully correct, it’s a counter used to synchronize video and subtitles.


Reading Speed
Since the viewer is busy watching and listening to the programme, only part of his time is spent on reading, and his reading speed is therefore low. The use of a font with good legibility helps.


Short for the Cavena Subtitles Archive Management System

Short for Standard Definition TV. Digital TV with less lines than 720.

Short for Simple Network Management Protocol.

File ending to EBU subtitling data exchange format (Format specification N19).

Subtitling is translation and condensed interpretation of the dialogue displayed as text overlaid on the video picture.

Serial Digital Interface. Interface/signal protocol to carry uncompressed video. For SD it’s 270 Mb/s and HD it’s 1.485 Gb/s and for 3G it’s 2.97 Gb/s.

Short for Start Of Message, command from automation system to Cavena STU.

Short for the Cavena Subtitle Transmission Unit.

Subtitle formats
Refers to how the subtitles are presented on the screen or how they are brought to the screen. Can be open or closed, i.e. in-vision or part of any DVB format and so on. Not to be confused with subtitle file formats, which is the format in which subtitles are produced, it can be CIP, 890, S95 and so on, there are multiple formats and they can all be quality checked and converted by the Cavena Toolbox.


Teletext Subtitling
Teletext is transmission of data information in the blanking interval of a video signal. The data is read by a decoder in the receiver and displayed with a simple built-in character generator. The readout is controlled by the viewer, who can select his preferred language among those transmitted.

The Cavena file conversation tool. Read more about Toolbox subtitle file converter.

Time code
A time code is a sequence of numeric codes generated at frame intervals by a timing system. Time codes are used extensively for synchronization, and for logging material in recorded media.

Transcode implies format conversion live, meaning going from one format to another format. And in this process the Cavena system handles the subtitles. Receiving the subtitles in one format and re-sending subtitles in another format. Read more about subtitle encoding and transcoding


Vertical Ancillary Data Space. Part of a digital transmission signal that is not displayed. The space is used for data not displayed on the TV screen. Plays the same role as VBI.

Short for Visual Display Unit, just a monitor or similar to look at.

Video Tape Recorder.

The vertical blanking interval (VBI), also known as the vertical interval or VBLANK, can be regarded as empty space used for teletext or any other data sent. The VBI was required for old type of TV sets with a cathode ray tube.

Short for Video On Demand.


Short for Windows Media Video.


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