[opendtv] Re: DTV Audio
- From: "Hunold, Ken" <KRH@xxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 25 Aug 2008 12:15:32 -0400
In 1975 I was modifying several GE350 cameras in a Network game show
studio to meet the blanking specs (H- and V-blanking) after an affiliate
was cited for excessive V-blanking (actually a line of purple video
caused by the detail module.) Shortly after that, a whole boatload of
LDK-5 cameras needed to be modified (with fixed-resistor changes) to
have their H-blanking fixed. The next time I saw a GE350 camera was in
an OB unit at a baseball game. The engineers that ran the truck didn't
even know you could set head blanking. When asked why I was timing the
camera the way I was, my partner said "That's the only way you can do
it."
But back to DTV audio, it is amazing how audio levels are ignored in
stations, both large and small. As the setup engineers retired or were
laid off, audio levels were ignored and left for the audio "processing"
at the transmitter. What was originally designed only to keep the
transmitter from exceeding 100% modulation now was doing all of the
audio level matching.
While DTV audio doesn't require an external dynamics processor (and
indeed that function is already there, but implemented differently in
the audio encoding equipment the the station already owns) some stations
resort to installing new processors because they don't think it can be
handled any other way. This sometimes keeps DTV audio from sounding any
better than its analog predecessor.
Often, the Networks strive to keep things under control, but digital
audio delivery systems occasionally let some really wide excursions in
audio levels come through. It's at the local station where the "rubber
meets the road" and things need to be set right. The Network can do a
lot to make this job easier for the local station. You haven't really
lived until you've dealt with someone who has received a call from a
Hollywood producer screaming that you've "ruined [their] show."
Re-introducing a little QC into the process and a little more than a
cursory glance at the instruction book when installing a piece of gear
into a DTV station can pay big dividends in audio quality and
flexibility in the home. It's a little more complicated than just
increasing the air pressure in a tire, but there are processes and tools
to get the job done.
Regards,
Ken Hunold
________________________________
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of John Willkie
Sent: Friday, August 08, 2008 9:07 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: DTV Audio
H blanking fines went away about 1975, due in no small part to the use
of U-matic tape machines directly to air, and the high cost of tbcs.
John Willkie
________________________________
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
En nombre de Cliff Benham
Enviado el: Friday, August 08, 2008 6:01 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: DTV Audio
dan.grimes@xxxxxxxx wrote:
I wish all stations were that responsive. I've talked directly with the
chief engineers at certain affiliates to discuss problems with certain
programs and audio channels (like the SAP). But the feedback I get is
"it sounds good in our master control."
Once I was told by the operator, "The picture looks fine on our lobby
TV..."
It used to be that having wide H blanking, or video starting later than
line 21 would bring the FCC in with a hefty $2500 or maybe it was a
$10,000 fine. Now, no one at the FCC can even turn on a waveform monitor
much less read pulse widths on one.
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