Posts Tagged ‘BBC’

D1, D2 & D3 – histories of digital video tape

Monday, July 14th, 2014

D1 tape

The images in this article are of the first digital video tape formats, the D1, D2 and D3. The tendency to continually downsize audiovisual technology is clearly apparent: the gargantuan shell of the D1 gradually shrinks to the D3, which resembles the size of a domestic VHS tape.

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 recognized 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 D1, 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. D-2 and D-3 Tapes

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 D1 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, D1 would soon be followed by D2. Those that did make the transition to D1 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 D2 – 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 D2 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 D3

Following the D2 is the D3, which is the final video tape covered in this article (although there were of course the D5 and D9.)

The D3 was introduced by Panasonic in 1991 in order to compete with Ampex’s D2. It has the same sampling rate as the D2 with the main difference being the smaller shell size.

The D3’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 D3 was a calculated risk: it appeared to be a stable-ish technology (it wasn’t a first generation technology and the difference between D2 and D3 is negligible).

The extent of the D3 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 D3 tapes in the archive, which hold around 362,000 programme items. The D3 tape format has become obsolete and in 2007 the D3 Preservation Project was started with the goal to transfer the material from the D3 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 D3 archive. Given that D3 machines are now obsolete, it is more than questionable whether there are enough D3 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 D1 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.

New additions in the Great Bear Studio – BBC-adapted Studer Open reel tape machine

Tuesday, June 24th, 2014

BBC Adapted Studer_FaderWe recently acquired a new Studer open reel tape machine to add to our extensive collection of playback equipment.

This Studer is, however, different from the rest, because it originally belonged to BBC Bristol. It therefore bears the hall marks of a machine specifically adapted for broadcast use.

The tell tale signs can be found in customised features, such as control faders and switches. These enabled sound levels to be controlled remotely or manually.

 The presence of peak programme meters (P.P.M.), buttons that made it easy to see recording speeds (7.5/ 15 inches per second), as well as switches between cues and channels, were also specific to broadcast use.

Adapted Studer_Sound Levels

Studer tape machines were favoured in professional contexts because of their ‘sturdy tape transport mechanism with integrated logic control, electronically controlled tape tension even during fast wind and braking phases, electronic sensing of tape motion and direction, electronic tape timing, electronic speed control, plug-in amplifier modules with separately plug-gable equalization and level pre-sets plus electronic equalization changeover.’

Because of Studer’s emphasis on engineering quality, machines could be adapted according to the specific needs of a recording or broadcast project.  

In our digitisation work at Great Bear, we have also adapted a Studer machine to clean damaged or shedding tapes prior to transfer. The flexibility of machine enables us to remove fixed guides so vulnerable tape can move safely through the transport. This preservation-based adaption is testimony to the considered design of Studer open reel tape machines, even though it diverges from its intended use.    

If you want to learn a bit more about the Equipment department at the BBC who would have been responsible for adapting machines, follow this link.

Adapted Studer_BBC Bristol

ADAPT, who are researching the history of television production also have an excellent links section of their website, including one to the BBC’s Research and Develop (R&D) archive which houses many key digitised publications relating to the adoption and use of magnetic tape in the broadcast industry.

‘Missing Believed Wiped’: The Search For Lost TV Treasures

Monday, March 10th, 2014

Contemporary culture is often presented as drowning in mindless nostalgia, with everything that has ever been recorded circulating in a deluge of digital information.

Whole subcultures have emerged in this memory boom, as digital technologies enable people to come together via a shared passion for saving obscurities presumed to be lost forever. One such organisation is Kaleidoscope, whose aim is to keep the memory of ‘vintage’ British television alive. Their activities capture an urgent desire bubbling underneath the surface of culture to save everything, even if the quality of that everything is questionable.

Of course, as the saying goes, one person’s rubbish is another person’s treasure. As with most cultural heritage practices, the question of value is at the centre of people’s motivations, even if that value is expressed through a love for Pan’s People, Upstairs, Downstairs, Dick Emery and the Black and White Minstrel Show.

We were recently contacted by a customer hunting for lost TV episodes. His request: to lay hands on any old tapes that may unwittingly be laden with lost jewels of TV history. His enquiry is not so strange since a 70s Top of the Pops programme, a large proportion of which were deleted from the official BBC archive, trailed the end of ½ EIAJ video tape we recently migrated. And how many other video tapes stored in attics, sheds or barns potentially contain similar material? Or, as stated on the Kaleidoscope website:

‘Who’d have ever imagined that a modest, sometimes mould-infested collection of VHS tapes in a cramped back bedroom in Pill would lead to the current Kaleidoscope archive, which hosts the collections of many industry bodies as well as such legendary figures as Bob Monkhouse or Frankie Howard?’

Selection and appraisal in the archive

Selection of video tapes

Mysterious tapes?

Living in an age of seemingly infinite information, it is easy to forget that any archival project involves keeping some things and throwing away others. Careful considerations about the value of an item needs to be made, both in relation to contemporary culture and the projected needs of subsequent generations.

These decisions are not easy and carry great responsibility. After all, how is it possible to know what society will want to remember in 10, 20 or even 30 years from now, let alone 200? The need to remember is not static either, and may change radically over time. What is kept now also strongly shapes future societies because our identities, lives and knowledge are woven from the memory resources we have access to. Who then would be an archivist?

When faced with a such a conundrum the impulse to save everything is fairly seductive, but this is simply not possible. Perhaps things were easier in the analogue era when physical storage constraints conditioned the arrangement of the archive. Things had to be thrown away because the clutter was overwhelming. With the digital archive, always storing more seems possible because data appears to take up less space. Yet as we have written about before on the blog, just because you can’t touch or even see digital information, doesn’t mean it is not there. Energy consumption is costly in a different way, and still needs to be accounted for when appraising how resource intensive digital archives are.

For those who want their media memories to remain intact, whole and accessible, learning about the clinical nature of archival decisions may raise concern. The line does however need to be drawn somewhere. In an interview in 2004 posted on the Digital Curation Centre’s website, Richard Wright, who worked in the BBC’s Information and Archives section, explained the long term preservation strategy for the institution at the time.

‘For the BBC, national programmes that have entered the main archive and been fully catalogued have not, in general, been deleted. The deletions within the retention policy mainly apply to “contribution material” i.e. components (rushes) of a final programme, or untransmitted material. Hence, “long-term” for “national programmes that have entered the main archive and been fully catalogued” means in perpetuity. We have already kept some material for more than 75 years, including multiple format migrations.’

Value – whose responsibility?

For all those episodes, missing believed wiped, the treasure hunters who track them down tread a fine line between a personal obsession and offering an invaluable service to society. You decide.

What is inspiring about amateur preservationists is that they take the question of archival value into their own hands. In the 21st century, appraising and selecting the value of cultural artifacts is therefore no longer the exclusive domain of the archivist, even if expertise about how to manage, describe and preserve collections certainly is.

Does the popularity of such activities change the constitution of archives? Are they now more egalitarian spaces that different kinds of people contribute to? It certainly suggests that now, more than ever, archives always need to be thought of in plural terms, as do the different elaborations of value they represent.

Digitising Low Band U-Matic Video Tapes – The resurgence of Philip Jap, pop icon

Monday, February 24th, 2014

Front cover of 7" single 'Save Us', Philip Jap making an elegant dance pose

Philip Jap came from a time when mime, dance, slapped bass lines, mascara and techno-dystopic anthems were staple parts of a successful popular music career. Cut from the same new wave goth cloth as Gary Numan, Human League and John Foxx, sporting mesmeric dance moves like a male Kate Bush, Jap lit up the early 1980s with performances on the David Essex Showcase, an audience participation talent show similar to today’s Britain’s Got Talent or Pop Idol. Jap went on to sign for Carlin Music Publishing and A&M Records, release an eponymous solo album and have a top 40 hit with ‘Save Us,’ a dramatic plea for liberation from an increasingly intrusive ‘mechanical world.’

Jap retains a modest yet loyal fanbase (The Philip Jap Army), and his recordings will soon be made available through his twitter site. Although he did not have runaway commercial chart success, Jap went on to have a successful career as a composer and arranger for TV series and commercials and is the co-founder of AUDIOfield, a music production company.

The Great Bear studio has been graced with Jap’s music this week because we have been migrating a collection of low-band U-Matic videos that feature a number of TV appearances and promotional videos, including the 30 minute ‘special’ that was recorded for the BBC.  In similar fashion to our recent transfer of Manchester Oi! band State Victims, the tapes were found in an old suitcase in a barn!

Although the tapes were mostly in good condition, some of the tapes were recorded on early SONY brand and were suffering from low Radio Frequency (RF) levels. RF levels are the recorded levels that can be read off the tape itself. To get a good, clear picture it is essential that the RF levels are strong. According to the AV Artifact Atlas, RF deterioration can occur because of a ‘poorly made recording on broken or mis-calibrated machine/record heads, or the use of poor quality video tape stock.’ Low RF levels may also occur if ‘the source media itself has been exposed to a strong magnetic field (unshielded speakers, motors, high-voltage transformers, etc.)’.

Close up of radio frequency monitor on U-Matic machineWhen a tape is suffering from low RF levels there are not loads of things you can do to reverse the process. This is because the signal recorded on the tape has essentially faded over time, due to a bad initial recording, unsuitable storage conditions leading to de-magnetisation or sticky shed, or poor quality tape (such as AMPEX or SONY U-matic tapes, although not exclusively). It is possible however to modify the tracking, a calibration adjustment which ensures the spinning playback head is properly aligned with the helical scan signal written onto the video tape. Tracking changes the speed at which the tape moves past the tape heads, which although spinning during playback, remain stationary. It is not the answer of all low RF ills, however, because the signal on the tape itself has become weaker, even if the calibration adjustment helps the machine read the signal more effectively.

Thankfully the tapes play back well, which is pretty amazing given that the tapes are over 30 years old and were never meant to be archive copies in the first place. We have also had a pretty enjoyable time watching and listening to Philip Jap’s amazing music. It is definitely time for a revival!


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