On 03/02/2017 12:00, Mike Rivers wrote:
On Fri, 3 Feb 2017 04:14:57 +0000 (UTC), wrote:
I'm wondering who the hell is responsible for a particularly
annoying audio peak amplitude indicator metering function.
Specifically, after the peak hold time has expired, instead
of extinguishing, the peak indicator slowly drifts downward
one segment at a time.
On 2/3/2017 2:56 AM, Don Pearce wrote:
That's simple. The source is the analogue mechanical meter on which it
was based. The pointer doesn't vanish when the peak is finished, it
slowly drifts down, one graduation at a time.
There's a specific fallback time for a standard VU meter, and it's
pretty fast, not a slow crawl. While I've never seen a meter that works
like the one Billy described, my guess is to give you a better chance of
noticing that something overloaded.
There is also a standard for a (Quasi)PPM, initially set back in the
days when the BBC started using them in the 1930s. It's set at about 2.3
seconds to drop by 24db (Six scale divisions) when the signal disappears
entirely. The meter should integrate short peaks, depending on their
level taking up to 100ms to show a true peak level and under reading on
shorter ones. It works in the same way as the peak hold facility on my
DAW metering, but with a slower rise time.
PPM's were normally only used in broadcast settings, with most people
using VU meters for day to day recordings.
--
Tciao for Now!
John.