[BC] Balancing processing from analog to digital

[Dana Puopolo]

Agreed, Frank.
How much processing IS too much?
With FM, you do need processing for two technical reasons:
FCC peak modulation compliance and 75us pre-emphais (which makes the former
even harder to do). The third reason that audio processing is used is for the
subjective: "sound signature". This includes subsets of loudness, brightness,
uniformity, etc., etc.

BUT...the main reason that peak limiting and or clipping is used is to deal
with the first two.

These two are NON-EXISTANT with HD radio!!

That beng the case, why even bother woth limting and clipping?
They, more then anything else are the most destructive to audio. 
It seems to me that siing them is simply redundant.

That said, the third reason (sound signature) is just as valid for HD as
analog. This by itself justifies processing for digital. I have no problem
with broadband and/or multi band AGC/compression. It's just the limiting and
clipping that I have issues with.

Listen to the '60's channel on satellite. The reverb there enhances the
programming. This is part of that sound signature.


Finally (and on a different subject), what I can't understand is why no one
replied to the second part of my Sangean post (The one about the $230.00
pocket Internet radio). With Earthlink lighting up mesh networks that
seamlessly cover 100% of Milpitas, CA and  New Orleans, LA this week, THIS is
what broadcasters need to be afraid of. 

Combine this with the 15 dollar Internet radio chipset mentioned here
yesterday, perhaps they should be very afraid...

Very afraid. 

 



 ------ Original Message ------
Received: Thu, 21 Dec 2006 01:09:50 PM EST
From: "padrino" <padrino at telos-systems.com>
To: broadcast at radiolists.net
Subject: [BC] Balancing processing from analog to digital

Dana,

I'm sensing that this thread is moving to the "processing vs no
processing" debate. Guess the question becomes, how much processing is too
much? Conventional FM will alwasys be too much, so to speak, due to
preemphasis. I'll bet that most folks do not realize that when they think
they're doing small amounts of processing on FM, they're still into "it"
more than they'd image, all because of the 17dB boost at 15kHz (75?s) here
in the USA, and 13dB (50?s) elsewhere. So, if you want to talk about
transients and punch, FM-Stereo basically offers an illusion to it. :)

What you desire, might play better on an HD-2 channel, at a higher
bitrate, like 48kbps, where that audio stream is not simulcasting the main
signal.

Sadly, while the discussion references the sound of CD audio, I'm sure
you've had a look at the dynamic range of those during the last 5+ years.
The processing done in mastering is almost on par with FM-Stereo.

An idea to ponder here, would be to employ META data with HD Radio. Then,
the consumer can choose the type of listening environment they desire.

-Frank Foti

Broadcasters' Mailing List <broadcast at radiolists.net> writes:
 >Yes, cutting peak limiting back from perhaps 6-10 db to five will make
 >things
 >have more 'punch'. BUT...eliminating it all together will make it even
 >punchier! Not to mention that conceptual coding algorithyms work best with
 >uncompressed audio as their source.
 >
 >
 >Now, I understand how look ahead limiting works - and it's a good
 >invention
 >and innovation...BUT just like any good thing, it can be overused. 5 db
 >of any
 >limiting in a medium with a wide dymanic range like HD is about 4 db too
 >much!
 >
 >
 >The bottom line is this: I have heard all the HD stations in three major
 >markets at length (NYC, Philadelphia and Boston). With a few standout
 >exceptions, most HD audio sounds unimpressive. Why? BECAUSE of the
 >processing!!  There's no "WOW!" factor!
 >
 >
 >AND...In the case of the standout stations, EVERY ONE is a few db softer
 >then
 >their analog main channels. Secondaries too. I'm talking about audio that
 >sounds noticeably BETTER then the main analog channel. Who cares if I
 >have to
 >turn the radio up a bit? I'd do it anyway, because the music DRAWS ME IN
 >when
 >it sounds really good, instead of pushing me away, as crushed, clipped
 >analog
 >FM does.
 >
 >
 >If we are going to claim 'CD like audio' for HD FM radio, we'd better
 >deliver
 >- and the crushed, limited MESS I hear on most stations just doesn't cut
 >it!
 >

_______________________________________________

The BROADCAST [BC] list is sponsored by SystemsStore On-Line Sales
Cable-Connectors-Blocks-Racks-Wire Management-Test Gear-Tools and More! 
www.SystemsStore.com       Tel: 407-656-3719    Sales at SystemsStore.com