2.2 Content media

2.2.1 Analog mode: Video

 

Analog video may be an inexpensive format, but because of the way that the data and signals are processed, it can also be unstable. Philippe Bellaïche describes the analog signal as “[...] a signal whose value continually changes over time. It is subject to distortion during processing and is often further hindered by an additional noise component during filming or transmission.” [1] The analog signal therefore has the major drawback of being very fragile; each time analog video is played or processed, noise interference is invariably superimposed on the wanted signal, altering its quality. Moreover, because dedicated circuits cannot work in a perfectly linear fashion, the data is always somewhat altered when the signal is processed. The signal is stored on a magnetic tape, which is itself subject to deterioration caused by its storage conditions and the effects of time. Combined, these circumstances only worsen and quickly weaken the quality of the signal as successive tape generations are made.

As a rule, for both the analog and digital format, the wider the magnetic cassette tape, the greater its resistance to creasing and other physical damage.

The VHS medium is an analog system designed for household use. This video format was primarily used for video art in the 1980s and is still used as viewing copies. [2] The VHS format was, however, not created with a long lifespan in mind. Other professional analog formats, such as Betacam SP (1987), were designed to deliver a very high-quality image and can even be used as an archiving format. Hi8 (1989) is the most recent analog format.

 

VHS and S-VHS

 

VHS cassette players and recorders are still used, although mainly on a household level. However, their use is waning as DVD distribution of popular films increases. S-VHS (Super-VHS) offers a superior image to standard VHS tapes as well as other technical advantages: VHS cassettes can be played on S-VHS machines, but S-VHS recordings cannot be played on standard VHS machines. Users can also select from among a variety of speeds to record on S-VHS cassettes. Essentially, S-VHS is an improvement over VHS; the bandwidth increases from 3 to 5 MHz, boosting the horizontal resolution to 400 lines (250 for VHS). Also, unlike VHS, chrominance and luminance are processed separately. VHS, used initially as a camera format (master tape) by artists, was subsequently used for distribution (viewing copies). In both the art and education sectors, this format was largely replaced by digital video during the 1990s. [3]

 

Because VHS has been in use in North America since 1977, it is not unusual to find cassettes that date back more than 25 years. Determining the age of a cassette can help in assessing its condition, and conservation activities should therefore take into account a cassette’s age and condition. For older tapes, migration to more recent formats (remastering) is likely inevitable. Cleaning may be required before the transfer is conducted. When migrating from standard VHS, it is recommended that an S-VHS video recorder be used for the transfer, as it includes an S-video output (unlike VHS, which offers only a composite output). The S-video output transmits C (chrominance) and Y (luminance) signals separately, while the composite output mingles the two signals together, the S-video thus allowing for a transfer truer to the original.[4]

 

8 mm (video 8) and Hi8

 

The 8 mm format (1985) was Sony’s response to VHS; its small cassette allowed it to be easily used in more compact camcorders. The Hi8 format (1989) was used extensively until the 1990s but has since become obsolete. [5] However, Hi8 cassettes are still available on the market. The relative and overall quality of 8 mm is comparable to VHS, while that of Hi8 is closer to S-VHS. [6] Technically speaking, the leap between 8 mm and Hi8 is similar to that between VHS and S-VHS. [7] The Hi8 format can also be played on a more recent Digital 8 player, but digital formats, such as the MiniDV, have taken over much of the Hi8 market. Like the 8 mm format, Hi8 was developed for the general public. Use of Hi8 in the industrial and education sectors gradually diminished as digital formats designed for the general public became more popular. However, the format remained widely used by artists during most of the 1990s, with the low cost of Hi8 (compared to digital formats) no doubt contributing to its popularity.

 

Hi8 cassettes are made with narrow tapes that have been stretched. The shortest tapes – 30 and 60 minutes – are more resistant than those that are longer. [8] Users have reported dropouts (loss of signal) not long after the first recording. [9] Cassettes with tapes made using metal evaporated technology are showing problems with durability. [10] While this format is relatively recent, it is fragile and appears to have a rather short lifespan. Migration to more recent formats (remastering) is therefore recommended and should be done as soon as possible. Much as with the VHS/S-VHS pairing, it is preferable to migrate 8 mm cassettes with a Hi8 recorder, as the latter is equipped with an S-video output, which separates the chrominance and luminance signals.

 

Videodisc (laser disc)

 

The videodisc is the only analog format that uses optical scanning technology similar to the DVD and CD. Artists used the videodisc despite their inability to record on it. However, during the 1980s and 1990s, videodiscs found their way into the museum environment as exhibition copies. Prior to the arrival of the DVD, the videodisc was considered a good format for presenting a work, as it was not susceptible to wear and tear, despite its sensitivity to scratches. Because it is obsolete and has been subject to problems associated with the delamination of its metallic oxide coating, it is recommended that it be migrated to other formats. The work Royal Canadian Mounted Police (1989) by Nam June Paik is presented using a videodisc. The medium is problem-free for now, but once it becomes no longer possible to use, the work will be presented with a DVD.

 

Betacam and Betacam SP

 

The Betacam (1983) and Betacam SP (1987) formats [11] were developed for the industrial and educational sectors and for professional markets. Betacam SP, a later generation of Betacam, was the industry standard in broadcast television for more than 15 years. [12] Betacam SP was also used for master tapes by commercial and independent producers as well as by artists. It was adopted as an exhibition format by artists and as a collection format for independent media distributors. Betacam SP was also used to make preservation copies.

 

Even after the entry of digital to the broadcast business, Sony continued to sell its Betacam SP video recorders until recently. [13] Betacam cassettes can be played on Betacam SP players, but tapes recorded on Betacam SP cannot be played on standard Betacam machines. The more recent players in the Betacam family, such as digital Betacam devices, can also play Betacam SP tapes. Betacam cassettes are available in two formats: large (L) and small (S). The cameras accept S cassettes, while the video recorders can accommodate both S and L formats.

 

The design of Betacam formats and players has made them extremely robust, and as they continue to be used in the television industry, it is still possible to maintain them. However, Betacam faces the same risk of loss of signal due to the fragility of the tape itself. The obsolescence of the Betacam format will not be a problem as long as more recent models, such as Betacam digital video recorders, offer backward compatibility with analog Betacam formats. Given the image quality it produces and its robustness, the Betacam SP format is considered the best analog format.

 

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[1] “[…] un signal dont la valeur varie avec le temps de manière continue. Il est sujet à la distorsion lors de son traitement et est souvent dégradé par une composante de bruit venant s’ajouter à lui au cours de son enregistrement ou de sa diffusion.”

Philippe Bellaïche, Les secrets de l’image video (Paris: Eyrolles, 2007), 214.
[2] Keep Moving Images. Preservation information for artists working with the moving image, "Video: Formats", http://kmi.lux.org.uk/video/formats.htm.
[3] For more information on format specifications: Mona Jimenez and Liss Platt, Videotape Identification and Assessment Guide, http://www.arts.state.tx.us/video/pdf/video.pdf.
[4] S-video cable carries the luminance (Y) and chrominance (C) signals separately. In the composite mode, signals are mingled with one another when transmitted, which often leads to intermodulation and interference problems, a rare occurrence with S-video.
[5] Sony, "Hi8", http://www.sonystyle.com/.
[6] The Hi8 format is of slightly higher quality than the S-VHS format.
[7] Like the VHS and S-VHS formats, the Hi-8 format is an improved version of 8 mm technology.
[8] Mona Jimenez et Liss Platt, op.cit., 21.
[9] Ibid.
[10] Ibid.
[11] Philippe Bellaïche, op.cit., 357-358.
[12] "Betacam", Wikipedia, http://en.wikipedia.org/wiki/Betacam.
[13] Mona Jimenez and Liss Platt, op.cit., 18.

 

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