compress the orchestra

On Fri, 15 Nov 2019 13:12:39 +0000 (UTC), spope384@gmail.com (Steve
Pope) wrote:

>Steve Pope <spope384@gmail.com> wrote:
>
>>Eric Jacobsen <theman@ericjacobsen.org> wrote:
>
>>>If transmitting to different devices I don't know why that wouldn't
>>>just be handled at the terminal device.   Keeping the dgitized signal
>>>linear allows use at any device with a little bit of processing at the
>>>device to suit that device or installation.   Not sure why companding
>>>would be distributed in a digital transmission.
>
>>Certainly.  OP had compained about the "compressed" audio though...
>>worth disambiguating what was going on.
>
>Another aspect - companding at the endpoint may not be sufficient.
>
>"Radio ready" mixes are often not simply compressed, but tweaked to 
>the source material by engineers.
>
>https://www.sageaudio.com/blog/pre-mastering-tips/mixing-radio.php
>
>
>Steve

It does drive me a little bit bonkers when two tunes play
back-to-back, on SiriusXM or broadcast radio or whatever, and a
significant volume adjustment is required because of the differences
in mixing.  Kind of like how they used to predistort commercials to
make them seem louder.   So not everybody is doing this uniformly and
it's probably just annoying people.  ;)

Back in the day there were standards for the analog deviation on FM
signals and in the FM audio subcarrier for NTSC TV signals.   Maybe
there still is, as our local NPR FM station always requires adjusting
the volume up a lot more than most other broadcast stations, and
public broadcast has historically been notorious for sticking to
published regs...i.e., everybody else probably turns up their
deviation a bit.

When I was in grad school I took care of some of the engineering for a
local low-power TV station that swapped out an (illegal) modulator for
a more kosher one.  The equipment needed to set the audio deviation
per the technical regs wasn't available so I just took a little
portable TV with me to the transmitter shack and adjusted the
deviation until it sounded about like everybody else, i.e., I didn't
have to adjust the volume when I tuned between it and other stations.

So it's not that hard, and it just seems annoying when it gets
overdone.

/End grumpy rant.

Eric Jacobsen <theman@ericjacobsen.org> wrote:

>On Fri, 15 Nov 2019 13:12:39 +0000 (UTC), spope384@gmail.com (Steve

>Pope) wrote:
>
>>Another aspect - companding at the endpoint may not be sufficient.
>>
>>"Radio ready" mixes are often not simply compressed, but tweaked to 
>>the source material by engineers.
>>
>>https://www.sageaudio.com/blog/pre-mastering-tips/mixing-radio.php

>It does drive me a little bit bonkers when two tunes play
>back-to-back, on SiriusXM or broadcast radio or whatever, and a
>significant volume adjustment is required because of the differences
>in mixing.  Kind of like how they used to predistort commercials to
>make them seem louder.   So not everybody is doing this uniformly and
>it's probably just annoying people.  ;)

>Back in the day there were standards for the analog deviation on FM
>signals and in the FM audio subcarrier for NTSC TV signals.   Maybe
>there still is, as our local NPR FM station always requires adjusting
>the volume up a lot more than most other broadcast stations, and
>public broadcast has historically been notorious for sticking to
>published regs...i.e., everybody else probably turns up their
>deviation a bit.

>When I was in grad school I took care of some of the engineering for a
>local low-power TV station that swapped out an (illegal) modulator for
>a more kosher one.  The equipment needed to set the audio deviation
>per the technical regs wasn't available so I just took a little
>portable TV with me to the transmitter shack and adjusted the
>deviation until it sounded about like everybody else, i.e., I didn't
>have to adjust the volume when I tuned between it and other stations.

Yes, it does seem the rules re. FM deviation (i.e. you couldn't 
undermodulate) have been abandonded.  I still listen to a lot of FM
radio -- mostly college radio -- and they feel free to have very
quiet sections of audio.  Also, one no longer is required to have
at least a 3rd Class Radiotelephone Engineer on site when broadcasing.

But for vehicular listening you do want to compress the dynamic
range.  I hear casettes are making a comeback.  Back then, if making
cassettes to listen to in the car, I'd just turn on the limiter
and shove the input levels away up.  Primitive technology works.

Steve

On Tuesday, October 15, 2019 at 7:57:58 PM UTC-7, Steve Pope wrote:

(snip)

> I would hire a professional musician, rather than believing that
> DSP is some sort of holy grail for all tasks in the world.

> Hint: many in the real world are just not down with engineers
> believing they can replace musicians.   It's bad form at minimum...
> some would call us scabs.  Musicians who can do this are paid
> union scale.

Many musicians I have known are also interested in math or physics
or engineering, so I suspect that you wouldn't have such a hard
time finding someone interested in both.

Reminds me, though, of Shazam:

https://www.shazam.com/

Shazam will identify a musical recording given a small sample
of an often noisy version of the source. Not so obvious, it makes
an exact match to the original.  That is, it won't just identify
the musical piece but the exact CD that it came from. 

They do this by extracting some parts of the signal, certain
frequency ranges, fingerprint those, and then compare them with
saved fingerprints. That is, they have the ability to compress
a musical composition down to a fairly small number of bits,
and match up those bits.