convert video tape

Copying U-matic tape: digitise via dub connector or composite video?

umatic dub to y/c converter detail

Digitising legacy and obsolete video formats in essence is simple but the technical details make the process more complex. Experience and knowledge are therefore needed to make the most appropriate choices for the medium.

The U-matic video format usually had two types of video output, composite and a y/c type connector that Sony named ‘Dub’. Originally designed as a higher quality method to make analogue ‘dubs’, or for connections in an edit suite, the Dub connector offers a higher performance signal path for the video signal.

It would make sense to use the higher quality dub output when digitising U-matic tapes but here lies the problem. Firstly the connector uses the larger 7 pin y/c type connector that can be quite hard to find connectors for.

Secondly and most significantly, the chrominance subcarrier frequency is not the standard PAL  4.43Mhz but down converted by U-matic recorders to 0.686Mhz for low band recordings and 0.984Mhz for high band recordings.

What this means in practice is that you’ll only get a monochrome image using the U-matic dub connector unless you can find a way to convert the chroma subcarrier frequency back to 4.43Mhz.

There are several solutions:

  1. Convert this Dub signal chroma frequency using one of a few older Timebase Correctors / Frame Synchronisers  from the U-matic era.
    These are now rare and often have other other faults that would degrade the signal.
  2. Take the Luma and Chroma signals at the correct frequency directly from certain test points on the circuit boards inside the machines.
    This can work well but is a slightly ‘messy’ solution and makes it hard to swap machines around, which is a necessity with older hardware.
  3. Convert the dub signal using a dedicated external dub – y/c converter circuit.
    This is our preferred solution that works well technically. It is flexible enough to swap around to different machines easily. It is also a relatively simple circuit that is easy to repair and doesn’t subject the video signal to  unnecessary extra processing.

Below are two stills taken from a Apple ProRes recording from a Low Band PAL U-matic tape.
The first image is via the Dub connecter but converted to PAL Y/C.
The second images is via the Composite video out.

kieran prendiville umatic screenshot dub connector

 

kieran prendiville umatic screenshot composite video connector

It’s clear from the images that there is more fine detail in the picture from the U-matic Dub version. The pattern / texture in the jacket and the texture and tone in the face is more detailed.  In contrast, the version digitised through the Composite video connector has less noise but due to the extra encoding and decoding there is less detail and more ‘blurring’.

While less noise may be preferable in some instances, having the option to choose between these two is always better. It’s this kind of attention detail and investment in equipment and knowledge that we are proud of and makes us a preferred supplier of digitising services for U-matic video tape.

Posted by greatbear in digitisation expertise, video tape, 7 comments

copy tape to cd, convert video to dvd, is it a good thing?

mountainous pile of old cassette tapes

Digital formats are great and the ease of access and distribution that an Audio CD and a Video DVD offers is fantastic at the moment with cheap players, recorders and personal computers. In the audio and video tape transfer business, getting your business website to rank well in the search engines for key phrases such as ‘copy tape to cd’ or ‘convert video to dvd’ should get you a steady stream of enquiries from people who, primarily, can’t access their tapes any more. The preservation of the valuable recording is usually perceived to be CD or the DVD.

My  concerns with the ‘…to CD’ and ‘…to DVD’ process are:

  • Optical Media that can be burnt using computers, CDr and DVDr, are not as reliable as commercially produced or ‘stamped’ discs and their quality and longevity can vary between different manufacturers.
  • The digital video stored on a DVD Video is a lossy compressed format that depending on the original footage and if pushed for too much running time can easily make the digital transfer look much worse than the original – not a good reason to transfer the tape!
  • The everyday nature of audio and video discs and some of the domestic technology we now have has conspired to make what is and can be a complex, time consuming and often problematic process too simple in the eyes of many people.

Since the early marketing of the compact disc in the ’80s by spreading jam on it to highlight its resilience compared to vinyl or tape, many of us have been taken in by this and have a skewed belief on the longevity of CD and DVD optical media. In fact optical media can degrade and become unreadable and unplayable in a very short space of time even with good storage practices. Tape based storage formats of course have their numerous problems but they can often be incredibly resilient over time even in under poor storage conditions. When tape does degrade it is rare event when it cannot be treated and made playable .

CDr and DVDr Longevity

Optical media that can be burnt form CD / DVD writers uses a dye that the laser alters to create pits that are read back as digital data. CD and DVDr discs use different dyes due to the different data storage needs. The dye can be affected by bright sunlight and compared to commercial or ‘stamped’ optical media it is not as reliable.

In an exhaustive Library of Congress report, http://www.loc.gov/preservation/resources/rt/NIST_LC_OpticalDiscLongevity.pdf  ‘good quality’ CDR media was expected to last ‘several decades’ and be more reliable than DVDr media:

It has been speculated that the archival quality of CD is superior to that of DVD. The basis for this lay with the physical differences in CD and DVD optical media and the maturity of the technology. In particular, the size of the bit markings in CD media not only reduces the relative effect of media or dye degradation, but also means that more stable, less sensitive dye may be used.

 

Out with old, in with the new

The march of technology can cost us money while making huge profits too. This of the CD reissues of old back catalogue albums, the pressure to replace vinyl collections with CDs, video tape collections with DVDs or CRT televisions with LCD or plasma screens. New technology is marketed as ‘better’ in many ways, yet it can be worse too.

Posted by greatbear in audio tape, 1 comment