Getting subtitles onto the screen for any programme is not as straightforward as some might think. It is true that subtitling and captioning for prerecorded shows is considerably less pressured than for live events, with time available to correct text before it is encoded, inserted and, ultimately, transmitted. But when it comes to events that are happening at the time of subtitling, time is an enemy and accuracy an unforgiving pressure. Understandably, not all of the three main keyboard types, Phonetic, Velotype or QWERTY, used for subtitle creation are practical.

Regardless of whether the transcription of statements and event descriptions are for closed caption services or open caption services, it is the immediacy with which the text appears on the screen that is most important. It is not the same as teletext management, for example, which allows the writer time to enter the content management system to make the necessary grammatical or factual changes at any time.

Logically then, the absence of any opportunity for careful editing means the need for immediate accuracy is acute. The fact is, while the technical aspects of the subtitling process are generally uniform in their duration, the methods of creating the subtitles vary dramatically. In general, speed relates to either the ability of the typist creating the subtitles or the specifics of the method used. These methods can limit the production of words, though a very capable typist would be able to reach the highest rates.

Phonetic keyboards are specifically designed to allow the operator to follow the natural course of speech. To accomplish this, they are built, not to accommodate spelling but the phonetic sounds of a word, which effectively breaks even the longest word spoken to just three or four sounds. These can then be entered through a simple press of a key, just as with the normal typing method.

Since the operator is expertly trained to use this machine, speeds of up to 200 words per minute can be achieved. The phonetic codes are entered into the system and the computer software converts them into the everyday spelled version, which is then encoded into the broadcast to appear as subtitles or captions on the screen. Depending on the skills of the operator, the accuracy of this system can be between 75 and 95 percent.

The second method of creating subtitles is through Velotype keyboards, which construct words by recognising the syllables they have rather than the phonetic sound or specific letters. It is particularly difficult for the untrained operator to use, with a combination of keys needing to be pressed to create the syllable. However, with properly trained personnel, this system is amongst the most accurate, even without the presence of an inbuilt extensive dictionary.

Once again, the word efficiency of this system is heavily dependent on the abilities of the operator, but the highest word rate is around 140 per minute. While this rate is suitable to cover the speaking speed of most professional broadcasters, it can be slow for interviewees, for example, unaccustomed to speaking on air.

The third method is the use of a general keyboard commonly used by anyone who types an email or document, known as the QWERTY keyboard. Obviously, the operator needs to have a great deal of experience and skill in order to type words, error free, at speaking speed. However, the best performances will produce just 80 words per minute, making the use of this system limited.

Word shortforms, for example PM instead of Prime Minister, are often used to make up for the low word rate, though errors in words with unusual spelling inadequately covered by either the Phonetic or Velotype keyboards, are no longer a problem. However, despite such short cuts, this system is only suitable is if there is little spoken and only intermittently, with plenty of time for the typists to catch up on the statements.

Getting the subtitles on screen as quickly as possible creates real pressure, but whether it is for closed caption or open caption services, or even teletext services, the irritation that a viewer feels at reading poorly spelled, grammatically incorrect or confusingly structured sentences on screen will be high.

That, of course, is counterproductive, most likely driving viewers away. While teletext management allows correction, the need for close to perfect subtitling and captioning services is very real.