muted. Television and video For live programs, spoken words comprising the television program's soundtrack are transcribed by a human operator (a speech-to-text reporter) using stenotype or stenomask type of machines, whose phonetic output is instantly translated into text by a computer and displayed on the screen. This technique was developed in the 1970s as an initiative of the BBC's Ceefax teletext service. In collaboration with the BBC, a university student took on the research project of writing the first phonetics-to-text conversion program for this purpose. Sometimes, the captions of live broadcasts, like news bulletins, sports events, live entertainment shows, and other live shows, fall behind by a few seconds. This delay is because the machine does not know what the person is going to say next, so after the person on the show says the sentence, the captions appear. Automatic computer speech recognition works well when trained to recognize a single voice, and so since 2003, the BBC does live subtitling by having someone re-speak what is being broadcast. Live captioning is also a form of real-time text. Meanwhile, sport events on ESPN are using court reporters, using a special (steno) keyboard and individually constructed "dictionaries." In some cases, the transcript is available beforehand, and captions are simply displayed during the program after being edited. For programs that have a mix of pre-prepared and live content, such as news bulletins, a combination of techniques is used. For prerecorded programs, commercials, and home videos, audio is transcribed and captions are prepared, positioned, and timed in advance. For all types of NTSC programming, captions are "encoded" into line 21 of the vertical blanking interval - a part of the TV picture that sits just above the visible portion and is usually unseen. For ATSC (digital television) programming, three streams are encoded in the video: two are backward compatible "line 21" captions, and the third is a set of up to 63 additional caption streams encoded in EIA-708 format. Captioning is modulated and stored differently in PAL and SECAM 625 line 25 frame countries, where teletext is used rather than in EIA-608, but the methods of preparation and the line 21 field used are similar. For home Betamax and VHS videotapes, a shift down of this line 21 field must be done due to the greater number of VBI lines used in 625 line PAL countries, though only a small minority of European