IBC Printed Guide - September 2014 - 16
www.inbroadcast.com PRODUCT GUIDE | Sept 12 - 16, 2014
Shades Of Grey In Quality Assurance
Modern QA is about much, much, more than the simplicity of black and white and the
straightforward fallacy of a digital binary status being either on or off...
Simen K. Frostad
et's look at a couple of old
technologies to illustrate a point
When CD was first introduced,
it was heralded as - 'finally' - the
answer to the music lover's quest
for perfect reproduction.
indestructible and would deliver
with total accuracy the information
encoded on it. So that what left
the mastering studio would be
what the listener heard, without
the crackles and scratches that
plagued vinyl, and without the
degradation caused by a worn
stylus or a poorly biased tone arm.
Audiophile experts soon saw
through that argument. The
earliest CD recordings were
awful. Deutsche Grammophon's
pioneering Karajan releases made
the sumptuous textures of the
Berlin Philharmonic sound like
three mice starving in a tin bucket.
Far from CD delivering the dream
of perfect reproduction, these
recordings and others that earlyadopters snapped up were a grave
disappointment, and prompted
the realisation that the technology
was not a black-and-white binary
matter of 'either it works or it
doesn't'. Rather, there were infinite
shades of grey.
As the engineers gradually learnt
the tricks of mastering recordings
for the new medium, and as
A/D/A conversion became more
sophisticated and evolved to
produce sounds that were more
amenable to the human ear, the
The CD buying public (at least
the more thoughtful elements
of it) also learned not to take the
marketing literally and use their
disks as drinks coasters before
popping them into the player.
Sampling rates, error-correction
and other murky concepts began
to filter into the pages of the hi-fi
The QA message should indicate if "it's working but it's under stress, and you need to
take action before it stops working..."
magazines, and people started to
understand that damage to the CD
surface could in fact disrupt the
'infallible' flow of zeros and ones in
which the music was recorded.
This same on-off fallacy is a
persistent one whenever people
think about digital technology.
zero is off, and one is on. Either it
is, or it isn't: that's the beauty of
binary, and the genius of digital.
But as the growing pains of the
CD proved, it's never that simple,
however much we would like it
system can be - and should be -
much greater than this. In a sense,
the black-and-white nature of that
concept of QA leaves operators
vulnerable and under informed.
The pattern of response becomes:
if everything's working, we do
nothing; if there's a failure, we find
it and fix it.
The monitoring system only
prompts action when a failure has
already occurred, and therefore
when customers have probably
already experienced disruption to
And so, in digital media delivery,
it's easy for people to fall prey to
this way of thinking when it comes
to QA. Easy to accept the idea
that monitoring systems are there
to deliver the message that the
delivery chain is either working,
or it isn't working. And if it isn't
working, where the fault is, and if
possible what type of fault it is.
But the QA value of a monitoring
Shades of Grey
How much more useful would it
be for the QA message to include
those shades of grey which tell
us: it's working but it's under
stress, and you need to take
action before it stops working.
Something equivalent to the
audible degradation of a worn
stylus on a vinyl LP, or the wow
and flutter of a loose turntable
belt. We shouldn't need to wait for
the music to stop entirely before
realising something's wrong.
To deliver full value, a monitoring
system should be giving its users
a clearly graduated scale of health
messages about the media delivery
chain, showing where things are
going really well, where they are
within acceptable limits according
to the parameters defined by
the user, and where things are
stretched close to breaking point.
If part of the chain is still working
but only just, the green light is not
a useful message.
If, say, with a 10% increase
in load it's going to fail, the
monitoring system should be able
to deliver the message that extra
resources are needed, so that
operators can head-off potential
failure and prevent the subscriber
Green and red are not the
only colours, any more than
black and white are.
Health messages about the media delivery chain are vital.