La vélotypie utilise les principes de l’écriture syllabique. Deux opérateurs travaillent en simultané. Le premier opérateur écoute l’émission et synthétise le texte. Le second opérateur saisit le texte en frappant simultanément plusieurs touches d’un clavier vélotype afin de produire une syllabe. Afin de vérifier le texte ainsi produit, la ligne saisie n’est envoyée qu’après la saisie de deux autres lignes. Efficace, cette méthode demande un apprentissage poussé avant d’être bien maîtrisée et induit un léger décalage du sous-titrage en raison de l’envoi de la ligne de sous-titres à l’écran une fois les deux lignes précédentes validées. La vitesse de cette technique reste cependant limitée à 150 mots/minute.
http://fr.wikipedia.org/wiki/Sous-titrage_en_direct

Communication Access Real-Time Translation (CART) stenographers, who use a computer with using either stenotype or Velotype keyboards to transcribe stenographic input for presentation as captions within 2-3 seconds of the representing audio, must caption anything which is purely live and unscripted,[1] however, the most recent developments include operators using voice recognition software and revoicing the dialog. Voice recognition technology has advanced so quickly in the United Kingdom that about 50% of all live captioning is through voice recognition as of 2005.[citation needed] Realtime captions look different from offline captions, as they are presented as a continuous flow of text as people speak.[1]
http://en.wikipedia.org/wiki/Subtitle_(captioning)

Velotype is the old trademark for a type of keyboard for typing text known as a syllabic chord keyboard, an invention of the Dutchmen Nico Berkelmans and Marius den Outer. The current tradename is Veyboard. Veyboard is a Dutch company.

Contrary to traditional QWERTY type keyboards, on which a typist usually presses one key at a time to create one character at a time, a Veyboard requires the user to press several keys simultaneously, producing syllables rather than letters.

A practiced "veyboarder" can produce more text than on a traditional keyboard, as much as 200 words per minute, double the rate of a fast traditional typist. Because of this, Veyboards are often used for live applications, such as subtitling for television and for the hearing impaired....
http://en.wikipedia.org/wiki/Velotype