Maintaining Audio Quality in the Broadcast Facility 2011 - Orban

in the Broadcast/Netcast Facility 11
At this writing, there is still debate over the reliability and longevity of the tape.
Some testers have reported deterioration after as little as 10 passes, while others
have demonstrated almost 1000 passes without problems. Each demonstration of a
tape surviving hundreds of passes shows that it is physically possible for R-DAT to be
reliable and durable. Nevertheless, we now advise broadcasters not to trust the reliability
of DAT tape for long-term storage and never to use it for new recordings.
Always make a backup, particularly because DAT is now an obsolete format and
finding players in working order is more and more difficult. If your facility has DAT
tapes in storage, it would be wise to copy them to other medium as soon as practical.
Hard Disk Systems
Hard disk systems use sealed Winchester hard magnetic disks or optical disks (originally
developed for mass storage in data processing) to store digitized audio. This
technology has become increasingly popular as a delivery system for material to be
aired. There are many manufacturers offering systems combining proprietary software
with a bit of proprietary hardware and a great deal of off-the-shelf hardware.
If they are correctly administered and maintained, these systems are the best way to
ensure high, consistent source quality in the broadcast facility because once a source
is copied onto a hard drive, playout is consistent. There are no random cueing variations
and the medium does not suffer from the same casual wear and tear as CDs. Of
course, hard drives fail catastrophically from time to time, but RAID arrays can make
a system immune to almost any such fault.
It is beyond the scope of this document to discuss the mechanics of digital delivery
systems, which relate more to ergonomics and reliability than to audio quality.
However, two crucial issues are how the audio is input and output from the system,
and whether the audio data is stored in uncompressed (linear PCM) form or using
some sort of data compression.
Audio is usually input and output from these systems through sound cards. Please
see the discussion on page 24 regarding sound cards and line-up levels.
Flash RAM
As its price continues to fall, flash RAM has become ever more popular as an audio
storage medium. It is available, packaged with a controller, with many different interfaces,
USB2.0 being one of the most popular and universally compatible. Unlike
CD-RW and DVD-RW, flash RAM is capable of tens of thousands of writes and hundreds
of thousands of reads. It can be written to and read from in faster than real
time for any commonly used audio sample rate and bit depth.
Flash RAM is available in two main technologies, called NOR and NAND-types. Both
are usable for audio recording and have different trade-offs. While neither is capable
of true random access writes because old data must be block-erased, this is usually
not a limitation for audio recording.