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Telecine ( or ), or TK, is the process of transferring film into video and is performed in a color suite. The term is also used to refer to the equipment used in this post-production process.
(2025). 9780240807515, Focal Press. ISBN 9780240807515
Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as , video cassette recorders (VCR), DVD-Video, Blu-ray or . Initially, this allowed television broadcasters to produce programs using film, usually 16-mm stock, but transmit them in the same format, and quality, as other forms of television production. Furthermore, telecine allows , television producers and working in the film industry to release their productions on video and allows producers to use video production equipment to complete their filmmaking projects.
Within the film industry, it is also referred to as a TK, TC having already been used to designate timecode. Motion picture film scanners are similar to telecines.
The kinescope was used to record the image from a television display to film, synchronized to the TV scan rate. The film could then be shown directly into a video camera for retransmission.Pincus, Edward and Ascher, Steven. (1984). The Filmmaker's Handbook. Plume. p. 368-9 Non-live programming could also be filmed using the kinescope, 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, 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 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, requires a change that is rather obvious to the eye and ear. The simple solution is 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. This solution does require the sound to be handled separately. A more advanced 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 slightly smoother display. PAL uses a similar system, 2:2 pulldown. However, during the analog broadcasting period, the 24 frames per second film was shown at a slightly faster 25 frames per second rate, to match the PAL video signal. This resulted in a fractionally higher-pitched audio soundtrack, and resulted in feature films having a slightly shorter duration, by being shown 1 frame per second faster.
In recent decades, telecine has primarily been a film-to-storage 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 originally on film may be transferred to video tape using this technique.
Theatrical features originally photographed at 24 frames per second are shown at 25 frames per second. While this is usually not noticed in the picture, the 4% increase in playback speed causes a slightly noticeable increase in audio pitch by about 0.707 semitones. This can be corrected using time stretching algorithms, which speed up audio while preserving pitch.
2:2 pulldown is also used to transfer shows and films photographed at 30 frames per second, like Friends and Oklahoma! (1955), to NTSC video, which has ≈59.94 Hz scanning rate. This requires playback speed to be slowed by a tenth of a percent.
The term pulldown comes from the mechanical process of pulling (physically moving) the film downward within the film portion of the transport mechanism, to advance it from one frame to the next at a given rate (nominally 24 ). This is accomplished in two steps. The first step is to slow down the film motion by NTSC's ratio to (≈23.976) . The difference in speed is imperceptible to the viewer. For a two-hour film, play time is extended by 7.2 seconds. If the total playback time must be kept exact, a single frame can be dropped every 1000 frames.
The second step of the 2:3 pulldown is distributing cinema frames into video fields. At 23.976 , there are four frames of film for every five frames of 29.97 video:
These four film frames are stretched into five video frames by exploiting the interlaced video nature of 60 Hz video. For every video frame, there are actually two incomplete images or fields, one for the odd-numbered lines of the image, and one for the even-numbered lines. There are, therefore, ten fields for every four film frames, which are called A, B, C, and D. The telecine alternately places frame A across two fields, frame B across three fields, frame C across two fields and frame D across three fields. This can be written as A-A-B-B-B-C-C-D-D-D or 2-3-2-3 or simply 2–3. The cycle repeats itself completely after four film frames. A 3:2 pulldown pattern is identical to the one described above except that it is shifted by one frame. For instance, a cycle that starts with film frame B yields a 3:2 pattern: B-B-B-C-C-D-D-D-A-A or 3-2-3-2 or simply 3–2. In other words, there is no difference between the 2-3 and 3-2 patterns. In fact, the 3-2 notation is misleading because according to SMPTE standards for every four-frame film sequence the first frame is scanned twice, not three times., page 430
The above method is a classic 2:3, which was used before frame buffers allowed for holding more than one frame. The preferred method for doing a 2:3 creates only one dirty frame in every five (i.e. 3:3:2:2 or 2:3:3:2 or 2:2:3:3); while this method has slightly more judder, it allows for easier upconversion (the dirty frame can be dropped without losing information) and a better overall compression when encoding. The 2:3:3:2 pattern is supported by the Panasonic DVX-100B video camera under the name "Advanced Pulldown". Note that just fields are displayed—no frames hence no dirty frames—in interlaced display such as on a CRT. Dirty frames may appear in other methods of displaying the interlaced video.
This method was born out of a frustration with the faster, higher-pitched soundtracks that traditionally accompanied films transferred for PAL and SECAM audiences. A few motion pictures are beginning to be telecined this way. It is particularly suited for films where the soundtrack is of special importance.
Also, other patterns have been described that refer to the progressive scan frame rate conversion required to display 24 video (e.g., from a DVD player) on a progressive display (e.g., LCD or plasma):
Mainframe Entertainment used a novel process for its TV shows. They are rendered at exactly 25.000 frames per second; then, for PAL/SECAM distribution, ordinary 2:2 pulldown is applied, but for NTSC distribution, 199 fields out of every 1001 are repeated. This brings the refresh rate from 25 to exactly , or ≈59.94, fields per second, with no change whatsoever in speed, duration, or audio pitch.
PAL material in which 2:3 (Euro) pulldown has been applied suffers from a similar lack of smoothness, though this effect is not usually called telecine judder. Effectively, every 12th film frame is displayed for the duration of three PAL fields (60 milliseconds), whereas the other 11 frames are each displayed for the duration of two PAL fields (40 milliseconds). This causes a slight hiccup in the video about twice a second.
Reverse telecine is crucial when acquiring film material into a digital non-linear editing system since these machines produce edit decision lists which refer to specific frames in the original film material. When video from a telecine is ingested into these systems, the operator usually has available a telecine trace, in the form of a text file, which gives the correspondence between the video material and film original. Alternatively, the video transfer may include telecine sequence markers burned in to the video image along with other identifying information such as time code.
It is also possible, but more difficult, to perform reverse telecine without prior knowledge of where each field of video lies in the 2:3 pulldown pattern. This is the task faced by most consumer equipment such as line doublers and personal video recorders. Ideally, only a single field needs to be identified, the rest following the pattern in lock-step. However, the 2:3 pulldown pattern does not necessarily remain consistent throughout an entire program. Edits performed on film material after it undergoes 2:3 pulldown, e.g. in NTSC format, can introduce jumps in the pattern if care is not taken to preserve the original frame sequence. Most reverse telecine algorithms attempt to follow the 2:3 pattern using image analysis techniques, e.g. by searching for repeated fields.
Algorithms that perform 2:3 pulldown removal also usually perform the task of deinterlacing. It is possible to algorithmically determine whether video contains a 2:3 pulldown pattern or not, and selectively do either reverse telecine (in the case of film-sourced video) or simpler deinterlacing (in the case of native video sources).
The problem with flying-spot scanners was the difference in frequencies between television field rates and film frame rates. This was solved first by the Mark I Polygonal Prism system, which was optically synchronized to the television frame rate by the rotating prism and could be run at any frame rate. This was replaced by the Mark II Twin Lens, and then around 1975, by the Mark III Hopping Patch (jump scan). The Mark III series progressed from the original jump scan interlace scan to the Mark IIIB which used a progressive scan and included a digital scan converter (Digiscan) to output interlaced video. The Mark IIIC was the most popular of the series and used a next-generation Digiscan plus other improvements.
The Mark series was then replaced by the Ursa (1989), the first in their line of telecines capable of producing digital data in 4:2:2 color space. The Ursa Gold (1993) stepped this up to 4:4:4 and then the Ursa Diamond (1997), which incorporated many third-party improvements on the Ursa system.Holben, Jay (May 1999). "From Film to Tape" American Cinematographer Magazine, pp. 108–122.
In a line array CCD telecine, a white light is shone through the exposed film image into a prism, which separates out the image into the three primary colors, red, green and blue. Each beam of colored light is then projected at a different CCD, one for each color. The CCD converts the light into electrical impulses which the telecine electronics Modulation into a video signal which can then be recorded onto video tape or broadcast.
Philips-BTS eventually evolved the FDL 60 into the FDL 90 (1989) and Quadra (1993). In 1996 Philips, working with Kodak, introduced the Spirit DataCine (SDC 2000), which was capable of scanning the film image at HDTV resolutions and approaching 2K (1920 Luminance and 960 Chrominace RGB)1556 RGB. With the data option, the Spirit DataCine can be used as a motion picture film scanner outputting 2K DPX data files as RGB. In 2000 Philips introduced the Shadow Telecine (STE), a low-cost version of the Spirit with no Kodak parts. The Spirit DataCine, Cintel's C-Reality and ITK's Millennium opened the door to the technology of digital intermediates, wherein telecine tools were not just used for video outputs, but could now be used for high-resolution data that would later be recorded back film out. The DFT Digital Film Technology Spirit 4K/2K/HD (2004) replaced the Spirit 1 Datacine and uses both 2K and 4K line array CCDs. DFT revealed its new scanner, Scanity, at the 2009 NAB Show. DFT Scanity The Scanity uses time delay integration (TDI) sensor technology for extremely fast and sensitive film scans.
An array of high-power multiple red, green and blue LEDs is pulsed just as the film frame is positioned in front of the optical lens. The camera sends the single, non-interlaced image of the film frame to a digital frame store, where the electronic picture is clocked out at the selected TV frame rate for PAL or NTSC or other standards. More advanced systems replace the sprocket wheel with laser or camera-based perf detection and image stabilization system.
As digital intermediate post-production becomes more common, the need to combine the traditional telecine functions of input devices, standards converters, and color grading systems is becoming less important as the post-production chain changes to tapeless and filmless operation.
However, the parts of the workflow associated with telecines still remain and are being pushed to the end, rather than the beginning, of the post-production chain, in the form of real-time digital grading systems and digital intermediate mastering systems, increasingly running in software on commodity computer systems. These are sometimes called virtual telecine systems.
For most 24 cameras, the virtual 2:3 pulldown process is happening inside the camera. Although the camera is capturing a progressive frame at the CCD, just like a film camera, it is then imposing an interlacing on the image to record it to tape so that it can be played back on any standard television. Not every camera handles 24 this way, but the majority of them do.
Cameras that record 25 (PAL) or 29.97 (NTSC) do not need to employ 2:3 pulldown, because every progressive frame occupies exactly two video fields. In the video industry, this type of encoding is called progressive segmented frame (PsF). PsF is conceptually identical to 2:2 pulldown, only there is no film original to transfer from.
All of these coding methods are in use to some extent. In PAL countries, 25 formats remain the norm. In NTSC countries, most digital broadcasts of 24 progressive material, both standard and high definition, continue to use interlaced formats with 2:3 pulldown, even though ATSC allows native 24 and 23.976 progressive formats which offer the greatest image quality and coding efficiency, and are widely used in motion picture and high definition video production.
NTSC DVDs are often soft telecined, although lower-quality hard-telecined DVDs exist. In the case of PAL DVDs using 2:2 pulldown, the difference between soft and hard telecine vanishes, and the two may be regarded as equal. In the case of PAL DVDs using 2:3 pulldown, either soft or hard telecining may be applied.
Blu-ray offers native 24 support, allowing 5:5 cadence on most modern televisions.
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