Digital Video Tape

D-1, D-2 & D-3: histories of digital video tape

Enormous D-1 cassette held in hand

Large D-1 cassette dimensions: 36.5 x 20.3 x 3.2cm

D-2 tape with rulers showing size

D-2 cassette dimensions: 25.4 x 14.9 x 3cm

D-3 tape with rulers showing size

D-3 cassette size M: 21.2 x 12.4 x 2.5 cm

The images in this article are of the first digital video tape formats, the D-1, D-2 and D-3. The tendency to continually downsize audiovisual technology is clearly apparent: the gargantuan shell of the D-1 gradually shrinks to the D-3, which resembles the size of a domestic VHS tape.

Early digital video tape development

Behind every tape (and every tape format) lie interesting stories, and the technological wizardry and international diplomacy that helped shape the roots of our digital audio visual world are worth looking into.

In 1976, when the green shoots of digital audio technology were emerging at industry level, the question of whether Video Tape Recorders (VTRs) could be digitised began to be explored in earnest by R & D departments based at SONY, Ampex and Bosch G.m.b.H. There was considerable scepticism among researchers about whether digital video tape technology could be developed at all because of the wide frequency required to transmit a digital image.

In 1977 however, as reported on the SONY websiteYoshitaka Hashimoto and team began to intensely research digital VTRs and 'in just a year and a half, a digital image was played back on a VTR.'

Several years of product development followed, shaped, in part, by competing regional preferences. As Jim Slater argues in Modern Television Systems (1991): 'much of the initial work towards digital standardisation was concerned with trying to find ways of coping with the three very different colour subcarrier frequencies used in NTSC, SECAM and PAL systems, and a lot of time and effort was spent on this' (114).

Establishing a standard sampling frequency did of course have real financial consequences, it could not be randomly plucked out the air: the higher the sampling frequency, the greater overall bit rate; the greater overall bit rate, the more need for storage space in digital equipment. In 1982, after several years of negotiations, a 13.5 MHz sampling frequency was agreed. European, North American, 'Japanese, the Russians, and various other broadcasting organisations supported the proposals, and the various parameters were adopted as a world standard, Recommendation 601 [a.k.a. 4:2:2 DTV] standard of the CCIR [Consultative Committee for International Radio, now International Telecommunication Union]' (Slater, 116).

The 4:4:2 DTV was an international standard that would form the basis of the (almost) exclusively digital media environment we live in today. It was 'developed in a remarkably short time, considering its pioneering scope, as the worldwide television community recognised the urgent need for a solid basis for the development of an all-digital television production system', write Stanley Baron and David Wood

Once agreed upon, product development could proceed. The first digital video tape, the D-1, was introduced on the market in 1986. It was an uncompressed component video which used enormous bandwidth for its time: 173 Mbit/sec (bit rate), with maximum recording time of 94 minutes.

large cream-coloured video machine with electroluminescent display panel

BTS DCR 500 D-1 video recorder at Greatbear studio

As Slater writes: 'unfortunately these machines are very complex, difficult to manufacture, and therefore very expensive […] they also suffer from the disadvantage that being component machines, requiring luminance and colour-difference signals at input and output, they are difficult to install in a standard studio which has been built to deal with composite PAL signals. Indeed, to make full use of the D-1 format the whole studio distribution system must be replaced, at considerable expense' (125).

Being forced to effectively re-wire whole studios, and the considerable risk involved in doing this because of continual technological change, strikes a chord with the challenges UK broadcast companies face as they finally become 'tapeless' in October 2014 as part of the Digital Production Partnership's AS-11 policy.

Sequels and product development

As the story so often goes, D-1 would soon be followed by D-2. Those that did make the transition to D-1 were probably kicking themselves, and you can only speculate the amount of back injuries sustained getting the machines in the studio (from experience we can tell you they are huge and very heavy!)

It was fairly inevitable a sequel would be developed because even as the D-1 provided uncompromising image quality, it was most certainly an unwieldy format, apparent from its gigantic size and component wiring. In response a composite digital video, the D-2, was developed by Ampex and introduced in 1988.

In this 1988 promotional video, you can see the D-2 in action. Amazingly for our eyes and ears today the D-2 is presented as the ideal archival format. Amazing for its physical size (hardly inconspicuous on the storage shelf!) but also because it used composite video signal technology. Composite signals combine on one wire all the component parts which make up a video signal: chrominance (colour, or Red Green, Blue - RGB) and luminance (the brightness or black and white information, including grayscale).

While the composite video signal used lower bandwidth and was more compatible with existing analogue systems used in the broadcast industry of the time, its value as an archival format is questionable. A comparable process for the storage we use today would be to add compression to a file in order to save file space and create access copies. While this is useful in the short term it does risk compromising file authenticity and quality in the long term. The Ampex video is fun to watch however, and you get a real sense of how big the tapes were and the practical impact this would have had on the amount of time it took to produce TV programmes.

Enter the D-3

Following the D-2 is the D-3, which is the final video tape covered in this article (although there were of course the D5 and D9.)

The D-3 was introduced by Panasonic in 1991 in order to compete with Ampex's D-2. It has the same sampling rate as the D-2 with the main difference being the smaller shell size.

The D-3's biggest claim to fame was that it was the archival digital video tape of choice for the BBC, who migrated their analogue video tape collections to the format in the early 1990s. One can only speculate that the decision to take the archival plunge with the D-3 was a calculated risk: it appeared to be a stable-ish technology (it wasn't a first generation technology and the difference between D-2 and D-3 is negligible).

The extent of the D-3 archive is documented in a white paper published in 2008, D3 Preservation File Format, written by Philip de Nier and Phil Tudor: 'the BBC Archive has around 315,000 D-3 tapes in the archive, which hold around 362,000 programme items. The D-3 tape format has become obsolete and in 2007 the D-3 Preservation Project was started with the goal to transfer the material from the D-3 tapes onto file-based storage.'

Tom Heritage, reporting on the development of the D3 preservation project in 2013/2014, reveals that 'so far, around 100,000 D3 and 125,000 DigiBeta videotapes have been ingested representing about 15 Petabytes of content (single copy).'

It has then taken six years to migrate less than a third of the BBC's D-3 archive. Given that D-3 machines are now obsolete, it is more than questionable whether there are enough D-3 head hours left in existence to read all the information back clearly and to an archive standard. The archival headache is compounded by the fact that 'with a large proportion of the content held on LTO3 data tape [first introduced 2004, now on LTO-6], action will soon be required to migrate this to a new storage technology before these tapes become difficult to read.' With the much publicised collapse of the BBC's (DMI) digital media initiative in 2013, you'd have to very strong disposition to work in the BBC's audio visual archive department.

The roots of the audio visual digital world

The development of digital video tape, and the international standards which accompanied its evolution, is an interesting place to start understanding our current media environment. They are also a great place to begin examining the problems of digital archiving, particularly when file migration has become embedded within organisational data management policy, and data collections are growing exponentially.

While the D-1 may look like an alien-techno species from a distant land compared with the modest, immaterial file lists neatly stored on hard drives that we are accustomed to, they are related through the 4:2:2 sample rate which revolutionised high-end digital video production and continues to shape our mediated perceptions.

Preserving early digital video formats

More more information on transferring D-1, D-2, D3, D-5, D-5HD & D-9 / Digital S from tape to digital files, visit our digitising pages for:

D-1 (Sony) component and D-2 (Ampex) composite 19mm digital video cassettes

Composite digital D-3 and uncompressed component digital D-5 and D-5HD (Panasonic) video cassettes

D-9 / Digital S (JVC) video cassettes

Posted by debra in video tape, video technology, machines, equipment, 5 comments

End of year thank yous to our customers

What a year it has been in the life of Greatbear Analogue and Digital Media. As always the material customers have sent us to digitise has been fascinating and diverse, both in terms of the recordings themselves and the technical challenges presented in the transfer process. At the end of a busy year we want to take this opportunity to thank our customers for sending us their valuable tape collections, which over the course of 2013 has amounted to a whopping 900 hours of digitised material.

We feel very honoured to play a part in preserving personal and institutional archives that are often incredibly rare, unique and, more often than not, very entertaining. It is a fairly regular occurrence in the Great Bear Studio to have radio jingles from the 60s, oral histories of war veterans, recordings of family get-togethers and video documentation of avant-garde 1970s art experiments simultaneously migrating in a vibrant melee of digitisation.

Throughout the year we have been transported to a breathtaking array of places and situations via the ‘mysterious little reddish-brown ribbon.’ Spoken word has featured heavily, with highlights including Brian Pimm-Smith‘s recordings of his drive across the Sahara desert, Pilot Officer Edwin Aldridge ‘Finn’ Haddock’s memories of World-War Two, and poet Paul Roche reading his translation of Sophocles’ Antigone.

We have also received a large amount of rare or ‘lost’ audio recordings through which we have encountered unique moments in popular music history. These include live recordings from the Couriers Folk Club in Leicester, demo tapes from artists who achieved niche success like 80s John Peel favourites BOB, and large archives of prolific but unknown songwriters such as the late Jack Hollingshead, who was briefly signed to the Beatles’ Apple label in the 1960s. We always have a steady stream of tapes from Bristol Archive Records, who continue to acquire rare recordings from bands active in the UK’s reggae and post-punk scenes.  We have also migrated VHS footage of local band Meet Your Feet from the early 1990s.

Rack of three digital multi-track machines On our blog we have delved into the wonderful world of digital preservation and information management, discussing issues such as ‘parsimonious preservation‘ which is advocated by the National Archives, as well as processes such as migration, normalisation and emulation. Our research suggests that there is still no ‘one-size-fits-all’ strategy in place for digital information management, and we will continue to monitor the debates and emerging practices in this field in the coming year. Migrating analogue and digital tapes to digital files remains strongly recommended for access and preservation reasons, with some experts bookmarking 15 April 2023 as the date when obsolescence for many formats will come into full effect.

We have been developing the blog into a source of information and advice for our customers, particularly relating to issues such as copyright and compression/ digital format delivery. We hope you have found it useful!

While the world is facing a growing electronic waste crisis, Great Bear is doing its bit to buck the trend by recycling old domestic and professional tape machines. In 2013 we have acquired over 20 ‘new’ old analogue and digital video machines. This has included early ’70s video cassette domestic machines such as the N1502, up to the most recent obsolete formats such as Digital Betacam. We are always looking for old machines, both working and not working, so do get in touch if your spring clean involves ridding yourself of obsolete tape machines!

Our collection of test equipment is also growing as we acquire more wave form monitors, rare time-based correctors and vectorscopes. In audio preservation we’ve invested heavily in early digital audio machines such as multi-track DTRS and ADAT machines which are rapidly becoming obsolete.

We are very much looking forward to new challenges in 2014 as we help more people migrate their tape-based collections to digital formats. We are particularly keen to develop our work with larger archives and memory institutions, and can offer consultation on technical issues that arise from planning and delivering a large-scale digitisation project, so please do get in touch if you want to benefit from our knowledge and experience.

Once again a big thank you from us at Greatbear, and we hope to hear from you in the new year.

Posted by debra in audio tape, video tape, 0 comments

Transfer Digital Betacam (DigiBeta) to Quicktime or AVI now, one day they will be obsolete

Even relatively recent born-digital formats like Digital Betacam (or DigiBeta, as it’s often referred to) should be viewed as a potentially obsolete format. This Standard Definition (SD) format while very popular for many years is not the preferred delivery format now the industry has embraced High Definition (HD).

When serviced these machines are very reliable and would be worked hard in a production environment. Designed to be serviced with little expense spared these were some of Sony’s most expensive decks and even if second hand values of machines have dropped recently, new spares have not. As with most video formats though as they become less popular the spares availability will become a problem as parts inventory dry up. One day and it may not be that far away a popular format like DigiBeta will become a threatened, obsolete format.

Digibeta_close up right angle

Digital Betacam recorders  were introduced in 1993, superseding the Betacam and Betacam SP, while costing significantly less, and being dramatically smaller than (!), the D-1.

We are particularly pleased with this machine because there are relatively low hours on its original head drum (1000 hours). The average headlife for this format is up to three times that or more, depending on the environment it was used in.

If the machine was used in a heavy production environment, for example, it would be constantly drawing in air to cool the electronics and, potentially, large amounts of dust and debris with it. This is one of the factors affecting head life.

Part of the service kit installed on the DigiBeta is designed to counter such damage because it allows you to replace the filters around the head drum area should they become clogged.

dvw-a510-digital-betacam-loading-gear

The big problem, as with so many of these machines, is acquiring relevant parts to ensure they can be serviced when they break down. Spare parts for DigiBeta machines can be expensive, costing several thousand pounds for a replacement head drum.

This machine has needed some work recently to keep it running smoothly. The loading gear had split which meant it couldn’t load tapes and gave reel motor errors. These were fixed easily by replacing the broken parts. After these repairs were completed the picture was still however displaying errors. This was because the bearing on the pinch roller was worn resulting in too much movement in the tape path. With the problem diagnosed a new pinch roller was installed and our new machine is working beautifully!

So send us your DigiBeta tapes!

Posted by debra in video tape, video technology, machines, equipment, 0 comments

D-1 digital video transfer – new additions and economies of size

A recent addition to the Greatear digitising studio is a BTS D-1 digital video cassette recorder.

As revolutionary as it was at the time, early digital audio and video tape recording is more threatened with obsolescence than earlier analogue formats.

bts-dcr-300-d1-digital-video-recorder

Introduced in 1986, D-1 was the very first, real-time, digital broadcast-quality tape format. It stored uncompressed digitized component video, had uncompromising picture quality and used enormous bandwidth for its time. The maximum record time on a D-1 tape is 94 minutes.

Enormous is certainly the word for the D-1 tape! Compared with the so-called ‘invisible’ nature of today’s digital data and the miniDV introduced in 1998, this tape from 1992 is in comedy proportions.

d1-minidv-tape-comparison-2

D-1 was notoriously expensive and the equipment required large infrastructure changes in facilities which upgraded to this digital recording format.

Early D-1 operations were plagued with difficulties, though the format quickly stabilized and is still renowned for its superb standard definition image quality, sometimes referred to as a ‘no compromise’ format.

D-1 kept the data recorded as uncompressed 8bit 4:2:2, unlike today where compression is required for digital data to save space and time for practical delivery to the home, but sacrificing the picture and sound quality in the process.

D1 was supplanted by subsequent D models that recorded component (D-5) and composite (D-2 and D-3) signals.

Read more about digitising D-1 (Sony) component and D-2 (Ampex) composite 19mm digital video cassettes and D-3 composite and D-5 uncompressed component (Panasonic) digital video cassettes on our project pages.

Posted by debra in video tape, video technology, machines, equipment, 1 comment

Digital Betacam tapes

As well as analogue tape, at Greatbear we also migrate digital tape to digital files. Digital media has become synonymous with the everyday consumption of information in the 21st century. Yet it may come as a surprise for people to encounter digital tape when we are so comfortable with the seemingly formless circulation of digital information on computers, at the cinema, on televisions, smartphones, tablets and other forms of mobile media. It is important to remember that digital information has a long history, and it doesn’t need to be binary or electronic – abacuses, Morse code and Braille are all examples of digital systems.

Digital Betacam tapes were launched in 1993 and superseded both Betacam and Betacam SP. Betacam remains the main acquisition and delivery format for broadcasting because there is very little compression on the tape. It is a very reliable format because it has a tried and tested mature transport mechanism.

Sony Digital Betacam video tape

While Digital Betacam is a current broadcast format, technology will inevitably move on – there is often a 10 year lifespan for broadcast media, as the parent company (SONY in this case) will cease to support the playing machines through selling spare parts.

We were sent some Digital Betacam tapes by Uli Meyer Animation Studios who are based in London. Uli Meyer make 3 and 2 D commercials, long and short films and TV commercials. 5-10 years ago the company would have had Digital Betacam machines, but as technology develops it becomes harder to justify keeping machines that can take up a lot of physical space.

Sony J-3 digital betacam SDI playback machine

Workflow in broadcasting is also becoming increasingly ‘tape less’, making digital tape formats surplus to requirements. Another issue facing the Digital Betacam is that it records information in Standard Definition format. With broadcasters using High Definition only, the need to transfer digital information in line with contemporary technological requirements is imperative for large parts of industry.

Posted by greatbear in video tape, 1 comment