Telecine - History of Telecine

History of Telecine

With the advent of popular broadcast television, producers realized they needed more than live television programming. By turning to film-originated material, they would have access to the wealth of films made for the cinema in addition to recorded television programming on film that could be aired at different times. However, the difference in frame rates between film (generally 24 frames/s) and television (30 or 25 frames/s) meant that simply playing a film into a television camera would result in flickering when the film frame was changed in mid-field of the TV frame.

Originally the kinescope was used to record the image from a television display to film, synchronized to the TV scan rate. This could then be re-played directly into a video camera for re-display. Non-live programming could also be filmed using the same cameras, edited mechanically as normal, and then played back for TV. As the film was run at the same speed as the television, the flickering was eliminated. Various displays, including projectors for these "video rate films", slide projectors and film cameras were often combined into a "film chain", allowing the broadcaster to cue up various forms of media and switch between them by moving a mirror or prism. Color was supported by using a multi-tube video camera, prisms, and filters to separate the original color signal and feed the red, green and blue to individual tubes.

However, this still left film shot at cinema frame rates as a problem. The obvious solution is to simply speed up the film to match the television frame rates, but this, at least in the case of NTSC, is rather obvious to the eye and ear. This problem is not difficult to fix, however; the solution being to periodically play a selected frame twice. For NTSC, the difference in frame rates can be corrected by showing every fourth frame of film twice, although this does require the sound to be handled separately to avoid "skipping" effects. A more convincing technique is to use "2:3 pulldown", discussed below, which turns every second frame of the film into three fields of video, which results in a much smoother display. PAL uses a similar system, "2:2 pulldown".

In recent decades, telecine has primarily been a film-to-videotape process, as opposed to film-to-air. Changes since the 1950s have primarily been in terms of equipment and physical formats; the basic concept remains the same. Home movies are video tapes of films that used this technique, and it is not uncommon to find telecined DVDs where the source was originally recorded to videotape. The same is not true for modern DVDs of cinematic films, which are generally recorded in their original frame rate — in these cases the DVD player itself applies telecining as required to match the capabilities of the television receiver.