Topic: Creating balance with an AGC - Automatic Gain Control
An email thread talking about how to create balance in our AGC software so that the audio changes aren't obvious to the listener and help maintain the integrity of the dynamic range within a program.
One of our international representatives reported this: Our customer (name deleted) informed us:
When a huge sound happened, such as a lasting explosion for example, 9670 is
not able to compress this huge sound immediately. It needs at least 1 second
to down the sound to a pre-specified level. Listener will clearly feel the
sound fell down during this 1 second. Under this situation, transition time
is set to 1 second; analysis time is set to 1 second also.
In order to make this explosion to be compressed to a pre-specified level
more quickly, then set both transition and analysis time to minimum 0.5
second, then the sound will become fluctuating, suddenly goes high or low,
very rapidly. This rapid up and down makes person who is watching TV feel
uncomfortable.
Is it normal? Or should we change any parameters to let person who is
watching TV feel better.
(name deleted) is a head-end system and owns dozens channels. Maybe you
can tell us how they set the parameter on 9670.
My reply: The idea behind our AGC is not to compress the dynamic range of a (or
within a) program. An explosion should be loud, footsteps should be quiet.
The artistic director knows how they want the overall sound of the program
to be.
We help adjust very high or very low prolonged noises, or sound between
programs, or when you break for commercial, or...? The point is not to
never have a high or low noise, but to make sure that your customers
watching television aren't reaching for their remotes every 5 minutes to
adjust the volume when you go to commercial or when they change channels.
I agree that you don't want to set the transition and analysis time so
tightly, as it will sound like the audio is pumping.
One broadcaster who has been testing our Avenue 9670 AGC - Automatic Gain
Control Software - suggests the following settings for his station, a balance between
controlling wild levels and not making the AGC obvious:
Max Level 0 dB
Min Level -15 dB
Analysis Time 15 sec
Max Atten -10 dB
Max Gain 10 dB
Transition Time 3 sec
This may or may not be right for your client, but it is a good place to start.
Their reply: Thanks for your support and this real example of 9670.
I will try later and reply you.