LONDON—Experience demonstrates that when
mixing 5.1 audio practice makes perfect,
and in London the third time was the charm.
The experience gained by NBC’s crew mixing
Beijing and Vancouver in 5.1—coupled
with increasing work in 5.1 between Olympics—
was a big factor in helping produce
“the best sound we’ve had yet,” said Bob
Dixon, director, Sound Design for IBC, venues
and communications.
 |
|
NBC Olympics Audio Room |
“This is a very pleasant show to listen to,”
he said. “I don’t care what venue you tune
in on; by and large it’s really comfortable
and it’s fun. I think we’ve come a long way.”
Dixon was quick to credit host broadcaster
OBS as a partner in developing mic
plans and more. “They’ve been very handy
to work with, and this year we’ve gotten
all of our stems and mic splits from them
as MADI signals, which made the work so
much easier for them, and for us.”
SIMPLER MODEL
The big audio news from London was
a change in the way NBC handled audio
tracks. In recent Games where 5.1 audio
was a factor, the network moved 16 tracks
of audio around. In London a simpler
8-track model eliminated the Stereo workflows
that were used in the past, and used
either 6 channels for full Surround or a subset
of just the first 3 channels. This 3 channel
mode contains just the original Front
L&R from the surround signal (used as Stereo
EFX) and the mono announce channel
on track 3.
This “split track” signal is far easier to
upmix to Surround and sounds better than
upmixing from a full 2 channel stereo mix,
according to the NBC Olympics IBC tech
manual and the network’s experience in
London and at pre-Games test
events.
Central to the new workflow
were Linear Acoustic upmixers
with special software
for automatic detection of
3-channel or 6-channel content.
The boxes would seamlessly
change between upmix
or bypass mode to make a consistent
6-channel output.
“We discovered by accident
how much better an upmix
sounds when you don’t include
the announcer in that
mix,” said Dixon. “The sound
image we got out of mixing all these sound
effects was stable; didn’t collapse to mono.
It stayed full and open.”
Dixon said that if editors—who have a
variety of audio comfort levels and are often
working in rooms not ideal for 5.1—
were uncomfortable working in 5.1, they
could work in 3.0. In these situations, the
editor would have access to a Miranda iSolo,
which, when an HD/SDI signal is put into it,
allows the user to do a downmix. It will put
the center in the center automatically, and
left goes to the left, the right goes to right,
and the center goes to both.
“It comes out of there as a stereo mix,” he
said. “We give them two speakers [the editors]
and they will edit just as they always
have in stereo. The thing is that they’re cutting
across three channels, instead of two.
So the announcer’s always separate.
“There are still some editors that want
to work in 3.0, and that’s fine,” said Dixon.
“And now that we have Tim’s box [Linear
Acoustic President Tim Carroll, on-site in
London], we don’t even have to worry
about, ‘is this coming to us as a 3.0 or a 5.1?’
because it doesn’t matter—the box will
pass it through if it’s 5.1 or will upmix in
stereo effects only and pass the announcers
if it’s 3.0.”
Dixon was very happy with the sound
of the London Games, and on a personal
note said that he was retiring after London.
His Olympic career started in Los Angeles in
1984, and includes 12 Games in all.