Videotape Formats


Analog and Digital

One difference between the formats that most of you may already aware of is the difference between digital tape formats and analog tape formats. Initially all of the videotape formats were analog. The first digital videotape format was D1 introduced by Sony in 1986. For nearly a decade digital videotape remained an issue only at the very high end of videotaping. But starting in 1995 with DVPRO, digital videotape has become a reality at the lower and middle levels of videotaping. So what is radically different between analog and digital tape? We won't go into detailed technical descriptions here. This is handled well at numerous other sites and can get pretty technical.

For our purposes here, it is sufficient to know that the primary difference is how the data is stored on the tape. In analog tapes the data is stored in an essentially uncoded format. In digital tape the raw data is stored as sets of zeroes and ones. The practical difference comes from the reading of the data. In analog tapes it is comparatively easy to misread data. If the brightness value at a point is nominally 67.4, the equipment may quite easily misread that as 67.3 or 67.5. Think of reading an analog clock with its large dial. You are likely to read the hours correctly but you have to guess a bit at the minutes. Someone else may read the same time slightly differently from you. Now look at a digital dial clock with its numbers spelled out. There is no mistaking the exact time. Someone else reading that dial will read exactly the same time as you. Getting back to our tapes, on the digital tape our 67.4 value has been encoded in a pattern of zeroes and ones. It will be very hard for any tape player to misread that number because there is only a pattern of zeroes and ones to read - a simple case of yes or no. A little bit of dust or wear on the tape head will not result in the misreading of the data. It will also be possible to copy that data exactly onto another tape or onto a computer disk. With analog tape, there is the possibility of some slight degradation each time the tape is copied. Our value of 67.4 may well become 66.8 after several generations of copying!

In practice degradation of data is most significant in the lower end analog formats, where a lot of data is stored on a small amount of often low quality tape. Thus if you copy your home VHS tape onto another VHS tape you will likely notice a marked decrease in quality. If you try to make a copy of a copy, the results will be very hard to view indeed! With higher quality formats this becomes less of a problem and by the time you get to professional formats such as Betacam SP multi-generational copies are not problem.

One problem with the lower end digital formats is that there is a need to compress the data before it goes on the tape. There is simply too much data to put on the small digital formats without throwing away some of the information in the picture. The three digital formats we will discuss here all use a 5:1 compression ratio. That is, they throw away 4/5 of the data in the picture. Now this may sound like the result should be a pretty poor low resolution picture. Actually that is not the case. The compression systems developed are very sophisticated. It is not a question of simply reducing the size of the picture or removing 4 out of every 5 data points on a regular basis. Much artificial intelligence is brought to bear on deciding how to compress a picture. There is no doubt however that not all subjects compress as well. Simple shots with large fields of uniform colours compress well. Very detailed areas with a lot of small details such as blades of grass or leaves in a tree don't do as well.

It is important to fully understand the differences between equipment using digital videotape and so-called "digital" equipment. The term "digital" is used for many things in video equipment. Some camcorders are labelled as "digital" because they have "digital" effects that could be applied to the recorded analog tape (e.g., strobe effects). Many camcorders also have "digital" zooms and "digital" image stabilisation. New videographers should be aware of this and not assume that because a piece of equipment says digital on it that it means it uses digital videotape!

 

Analog Tape Formats

 

VHS (Video Home System)

Everybody is familiar with the VHS format. This is the format that nearly all home VCRs today use. This format was introduced by JVC in 1976. There are fewer and fewer camcorders available in full size VHS format and we would not recommend doing any original taping in VHS format unless you are experimenting with equipment that you happen to have at hand. Quality of the footage is a serious concern with using VHS tape for footage acquisition.

The VHS format however is still very important in terms of distributing taped programs. The problem with the VHS format is that quality of the image on the tape is not really very good. This becomes a problem when you have what appear to be some great shots taken with a professional format machine and then duplicate it onto VHS. You may get a shock! Your finely detailed shoots of foliage may turn into a murky spinach soup. That bright red bird may bleed its red colour onto nearby objects. Recommendation: if you are considering distribution on VHS tape check carefully how your shots will look on VHS before you go too far.

 

S-VHS (Super VHS)

Super VHS is a marked improvement over VHS. The signals from the camera are handled differently, with colour and brightness being split up, and result in improved colour rendition. The tape is similar in size to the VHS tape cassette. S-VHS tape cannot be played in a VHS machine. S-VHS is a common format for use on non-broadcast video projects and is sometimes used for broadcast video in smaller stations. There are a number of good industrial level camcorders in the S-VHS format, both single piece and two piece, (e.g., the Panasonic Supercam, the JVC GY-X2B, and the JVC GY-X3) in the under $10,000 price range.

 

VHS-C and S-VHS-C (Compact VHS and S-VHS)

These are smaller cassettes than VHS and SVHS that only hold 30 minutes (sometimes 40 minutes) of tape in regular play. They were created to allow for smaller camcorders. VHS-C tape can be played in regular VHS machines using an adapter. Most camcorders using VHS tape are actually VHS-C machines. There are few S-VHS-C camcorders currently available.

 

8 mm

8 mm is a consumer format introduced in 1983 that uses a much smaller tape size than VHS. The tape is only 8 mm wide and .55 to .4 mm thick as compared to the 13 mm wide and .8 mm thick VHS tape. This means that a cassette holding up to 2 hours of tape at regular play is only 2.5 by 4 inches (6 by 9.5 cm). Compare that to the VHS cassette at 4 by 6 inches (10 by 16 cm). With miniaturisation however there come problems. Eight mm tape is much more delicate and prone to defects than VHS tape. These defects often take the form of "dropouts", horizontal streaks on the picture when played back. These defects are caused by physical defects on the tapes or dust. In terms of quality, 8 mm is roughly similar to VHS. Like VHS, it is not recommended for shooting nature footage.

 

Hi8

Hi8 does for 8 mm what S-VHS does for VHS. There is a marked improvement in picture quality. There have been some good industrial level camcorders in Hi8 format (e.g., the Sony EVW100 and the Toshiba TS200) but these have apparently been discontinued by their manufactures in favour of the more recent digital formats. Used Hi8 industrial level camcorders are still readily available and there are many new consumer level Hi8 camcorders still available (in the $1,000 to $2,000 range). The Canon L1 and L2 line (now discontinued) has been important for nature videographers. These camcorders were the only inexpensive Hi8 camcorders taking interchangeable lenses.

 

3/4" - U-Matic

This is an old format introduced in 1971 but it is still used by some videographers who have been using the format for a long time. It can produce good quality video and 3/4" decks are still commonly available in duplicating houses. However, there is little reason for somebody just starting into nature videography to get into this format given the technical advantages of some of the other more recent formats.

 

Betacam and Betacam SP

Betacam is a Sony product first introduced in 1982. It is currently geared for broadcast use, although there have been some less expensive models destined more for industrial use. Betacam, MII and the digital formats discussed, use a different way of handling colour information than the preceding formats. Basically the colour information from the picture is broken into three channels (one each for red, green and blue information). Formats which handle colour in this way are known as component formats in opposition to the composite formats discussed previously.

Suffice it to say that the pictures you will get using a Betacam system (or other component format) will generally be markedly superior to those you would get using any of the preceding formats. Colours in particular come out looking much more vibrant and objects appear three-dimensional. Note that this does not mean that using a Betacam system will ensure that you get good shots! If you don't know how to use the system well, you will still end up with poor shots. Also remember that under certain conditions, e.g., well lit close ups, S-VHS and Hi8 shots may be hard to distinguish from Betacam shots. The superiority of Betacam shots comes partly from the technical aspects of the tape format but also in large part because of the use of superior optics and other camcorder and VTR components (and generally better operators!).

The difference between Betacam and Betacam SP, introduced in 1986, is in the tape. Betacam SP uses a metal tape and is an improvement over Betacam.

Betacam cassettes are large. Ninety minute cassettes measures 5.5 by 10 inches (14 by 25 cm). Typically Betacam field units (camcorders or dockable decks) handle only smaller cassettes with shorter lengths of tape (30 minutes and less). These smaller cassettes are 4 by 6 inches (10 by 16 cm) in size.

Betacam SP is still the de facto standard for professional broadcast videotaping, partly because of the large number of units out in the professional videotape community. Some authors assume that over 90% of all professional videotaping is done using Betacam and Betacam SP.

Sony has produced three levels of Betacam equipment. The BVW (broadcast) series is the high end series with corresponding price tags! A simple BVW series one piece camcorder costs over $40,000. The PVW (professional) series is less expensive than the BVW series and is frequently used for field acquisition. A PVW series two piece camcorder costs more than $20,000. The UVW series was introduced in 1993 as an industrial level series. The one-piece UVW100 camcorder weighs about 13 lbs (6 kg) and cost approximately $14,000 new (without lens) but can now be found used for approximately $6,000 to $7,000.

 

MII

MII, introduced in 1986, is Panasonic's answer to Betacam SP. All MII tape is metal. The 90 minute cassette at 4 by 8 inches (11 by 19 cm) is considerably smaller than the 90 minute Betacam SP cassette. However the dockable decks take only a small 20 minute cassette (3.6 by 5 inches - 9 by 13 cm).

Technically, MII is equal to or superior to Betacam SP, but Panasonic lost out to Sony in terms of public relations, customer support, and the promotion of its product. Today, although MII is still supposedly "in production", and in use by some major players such as NBC, it has to be considered a somewhat orphaned format. The Panasonic MII equipment has generally been priced considerably below the equivalent Sony Betacam SP BVW series equipment. In addition good deals may be available from Panasonic on new units and from dealers on used units.

Panasonic MII field equipment includes several small dockable decks usable with a variety of camera heads and some excellent portable decks.

We use MII for a lot of our taping and observers have consistently felt that the quality of the footage was better than Betacam SP footage. We selected MII because we were able to get an excellent deal on the equipment and build up a good field acquisition and editing system for considerably less than half of the cost of a comparable BVW Betacam SP set up. Be aware if you get into MII that at some point repairs may become an issue and that few duplicating facilities or clients are likely to have MII. Therefore you will probably have to copy your MII programs to Betacam SP at some stage.

 

Digital Tape Formats

Unfortunately there appears to be somewhat of a proliferation of digital tape formats. Often when neophyte videographers think of digital videotape they are thinking of DV or DVC, the consumer digital videotape format introduced in 1996. In addition there are related digital videotape formats using the same cassette size such as DVCPRO, DVCPRO50, and DVCAM. Then there are other digital tape formats using larger tape such as Digital S, Betacam SX, DS, Digital Betacam, D1, D2, D3, D6, and DCT. Most of these formats are not likely to be used by the starting nature videographer, if only because of price considerations, and we will restrict this discussion to the DV, DVCPRO, and DVCAM formats.

 

DV - DVC (Digital Videocassette)

This first consumer digital videotape format was introduced in 1996. The tape used for this format is quite small: 6.35 mm wide and 8.8 microns thick. A cassette with up to approximately 3.5 hours of playing time is only 3.5 by 5 inches (9 by 12 cm). Smaller cassettes with shorter playing times are also available. Like Betacam SP and MII it is a component format with separate channels for red, green, and blue. The data on the tape is compressed at a 5:1 ratio. This means that 4/5 of the data in the original image is thrown away. The quality that can be obtained from this format is close to the quality once expected only in broadcast quality systems.

Most camcorders for this format to date have been consumer to industrial level cameras, although obviously these terms start losing some of their meaning when talking about DV. Many of the initial consumer offerings are fairly simple one piece camcorders with non-interchangeable lenses. The smallest DV camcorders are very small and start at just under $2,000. One example of a very popular semi-professional DV camera is Sony's DVX-1000 ($4,200). A very exciting prospect for nature videographers is Canon's long awaited XL1 ($4,600), a digital successor to Canon's successful L1 and L2 line. There is a dockable DV format deck (the JVC BR-DV10) that can be mated to professional camera heads ($11,000 and up depending on camera head).

 

DVCPRO

DVCPRO was introduced in 1995 primarily by Panasonic. It is similar in most respects to DV except that the tape speed is twice that of DV resulting in reduced error rates. DV equipment cannot read DVCPRO tapes or record on DVCPRO tapes. However DVCPRO equipment can play back DV format tapes. Examples of DVCPRO camcorders are the Panasonic AJ-D200 ($9,400) or the Panasonic AJ-D700 ($22,000).

 

DVCAM

DVCAM was introduced in 1996 by Sony and can be considered as Sony's answer to Panasonic's DVCPRO. DVCAM and DVCPRO are not compatible. DVCAM is partly compatible with DV. Examples of DVCAM camcorders are the Sony DSR-200 ($6,400), essentially an upgraded VX1000, and the two piece Sony DSR-130 ($19,000).


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