Are High Speed Transfers a Good Thing?
- Steve Puffenberger
- Movie Film, Home Video, Audio
Why you may not want to have your legacy materials transferred at high speed.
Our primary national competitor in the legacy digital transfer business has been advertising "High Speed" digital transfers, meaning you'll get your transfers back in two weeks or so. They say they use high speed equipment to do that. We can too, but for the most part we prefer to transfer things in "real time," as in playing the tape and digitizing it as it was meant to be played. There are several technical reasons why:
The main concern with all recording is the bandwidth of the analog signal that we're trying to transfer. Audio gear is, logically, tuned to the frequency range of human hearing. Young ears can discern sounds between 20Hz (cycles per second), which are very low rumbles, to 20,000Hz, the highest high. As we get older we generally lose the ability to hear the highest frequencies, so most usable audio content is between 50Hz and 12KHz. Still, most consumer and pro audio equipment is tuned to the 20-20KHz audio spectrum. Slow speed tapes, such as cassettes can rarely achieve the really high frequencies.
To do high speed transfer, this involves (at least) doubling the tape speed. When that happens, guess what happens to the frequency spectrum? It doubles, so any frequencies at 20KHz become 40KHZ. But the analog-digital converters, and the tape heads and electronics also tuned to the 20-20K frequency range, don't reproduce anything above 20K. So, when we digitally slow the high speed recording down, we're lucky to have 10KHz as the top end. Therefore if you have a lot of high frequency content, it may be lost.
Nonetheless, if you have a tape recorded at slow speed, like an old 1 7/8 ips voice recording, there's no very high frequency content there. We can transfer those sorts of recordings at high speed with no loss of signal, because high frequencies aren't there in the first place.
(We've even been known to do a "slow speed" transfer. A customer brought in a warped record, which acted like a ski jump for the stylus. By slowing the record down, we were able to track the groove, and then speed it back up to normal digitally.)
The same frequency doubling effect happens if you speed up videotapes as well, and because all home videotape formats use spinning heads on a drum to provide adequate tape-to-head speeds for the super-high frequencies needed for analog video, it's virtually impossible to speed up a videotape and slow it down digitally.* To facilitate rapid videotape transfer, we use multiple video digitizing workstations, so we can run 3 or even 4 tapes at the same time. That triples or quadruples the througput, but each tape is done in realtime - the best way.
Mini-disc DVD camcorders are another story. Usually we can simply copy the data from the disc and transcode it to a release format, which is a high speed process with no signal loss because the source is digital, not analog. However, sometimes the mini-discs cannot be read by a comptuer. When that happens we have to play them on a DVD player and transfer them just like we would a videotape, in real time.
Bottom line, if the transfer house you are considering brags that they transfer your recordings at "high speed," be wary. You'll probably take a quality hit. At Advent Digitizing we don't cut corners. We make sure the quality of your original source material is reflected in your transfer, not only by doing real time transfers but also by mastering to high-bitrate professional quality files before compressing them to reasonably-sized "consumer" release files for your devices.
The quality of your old recordings can be amazing! Let us know what you have to transfer. Quotes are free.
Tell Us What You Have to Transfer
*Weren't VHS movies made at high speed?
Answer: Yes. The movie manufacturers had huge complicated machinery. The master tape was made on a special mastering tape deck that created a "mirror image" of the magnetic pattern on special metal tape. This master was brought into contact with the release tape at very high speed. At the point of contact it was zapped with a laser which imprinted the magnetic image onto large reels of release tape. From there the automated machinery cut and spooled the release tape into the shells, labeled and packaged them. The manufacturers could turn out hundreds of tapes per minute, but the setup fees were immense. Spread over thousands of copies, however, the per tape costs were only a couple of dollars. All those machines are retired now, and unless you wanted a thousand copies of your tape, it would be prohibitively expensive.