[[email protected]]

Hi, I'm setting up my DAW, I've got the output of a mixer going into
my computer. All mics are recorded through the mixer.

When viewing the waveforms in Audacity (or anything else), the very
"bottoms" of the waveforms looked "chopped" like they are peak
limited, but the very "tops" look normal (ragged).

Link to picture of waveform:
http://www.postimage.org/image.php?v=aV2idr9S

Then I tried really putting a loud sound into the mic. It's my voice
droning and changing pitch quite loudly in the microphone. The
waveform is so strange and not symmetrical. It undulates with the
raising and lower of the pitch of my voice:

Link to picture of waveform:
http://www.postimage.org/image.php?v=gx1nuWE9

Does anyone know what is going on?

My first reaction was DC offset, but I use Audacity's "Remove DC
offset" function and the waveform doesn't change.

[Eeyore]

" wrote:

Then I tried really putting a loud sound into the mic. It's my voice
droning and changing pitch quite loudly in the microphone. The
waveform is so strange and not symmetrical. It undulates with the
raising and lower of the pitch of my voice:

Sound ISN'T symmetrical.

Graham

[Eeyore]

Eeyore wrote:

" wrote:

Then I tried really putting a loud sound into the mic. It's my voice
droning and changing pitch quite loudly in the microphone. The
waveform is so strange and not symmetrical. It undulates with the
raising and lower of the pitch of my voice:

Sound ISN'T symmetrical.

p.s. use a lower recording level.

Graham

[[email protected]]

On Apr 18, 12:49*pm, Eeyore
wrote:
Eeyore wrote:
" wrote:

Then I tried really putting a loud sound into the mic. *It's my voice
droning and changing pitch quite loudly in the microphone. *The
waveform is so strange and not symmetrical. *It undulates with the
raising and lower of the pitch of my voice:

Sound ISN'T symmetrical.

p.s. use a lower recording level.

Graham

Okay, thanks. I suspected it might be a newbie problem (my fault) and
that wierd, undulating waveforms like this were normal. I had never
just never seen a waveform before that was so......snakelike.

[Paul Stamler[_2_]]

wrote in message
...
When viewing the waveforms in Audacity (or anything else), the very
"bottoms" of the waveforms looked "chopped" like they are peak
limited, but the very "tops" look normal (ragged).

Link to picture of waveform:
http://www.postimage.org/image.php?v=aV2idr9S

Then I tried really putting a loud sound into the mic. It's my voice
droning and changing pitch quite loudly in the microphone. The
waveform is so strange and not symmetrical. It undulates with the
raising and lower of the pitch of my voice:

Link to picture of waveform:
http://www.postimage.org/image.php?v=gx1nuWE9

Does anyone know what is going on?

Your second waveform is normal -- sounds, particularly vocal sounds, are
often asymmetrical.

Your first waveform, however, has problems. You're right in that the
negative excursions are clipped at about -0.7, whereas the positive
excursions clip at +1.0. Something in the system, possibly in the mixer, is
clipping asymmetrically, which means it's probably broken.

I'll add, though, that it would be more useful to show a waveform which
doesn't clip the positive excursions either. If you record so that the
positive excursions hit +0.9 maximum, do the negative excursions still clip
at -0.7?

Peace,
Paul

[[email protected]]

Thank you both for your patience with me - a newbie.

As for the top waveform with the clipping - I think it might have just
been the fault of the person who recorded it - with a Minidisc
recorder and cheap condenser mics. I am sure it didn't peak when I
transferred it (analog) to PC.

Now....there is something fundamental I'm not understanding about the
way the waveforms are represented by the software. Please forgive me
- as I have been using fairly ancient computers up until this year.
An Amiga running an old version of Samplitude and a PC running an old
version of Diamond Cut Audio. These older applications always
displayed the waveforms as laterally symmetrical. Therefore, I was a
little shocked by the way Audacity was displaying a non-symmetrical
waveform on my new "modern" PC.

Non symmetrical looking waveform in Audacity on my "new" PC:
url=http://www.postimage.org/image.php?v=aV2idr9S

And it looks the same in the DAW application "Reaper" on my "new" PC:
url=http://www.postimage.org/image.php?v=aV2iDhY9

So, I loaded this same audio file (the undulating one) into both of
these older pieces of software. Lo and behold - the waveform looks
symmetrical - the way I am "used" to seeing it!

Diamond Cut Audio on my "old" PC:
url=http://www.postimage.org/image.php?v=Pq2jK5jA

Samplitude on my ancient (but beloved) Amiga:
url=http://www.postimage.org/image.php?v=gx1nZHK9

So....obviously there is something I am not understanding about the
way that Audacity & Reaper display waveform data vs. the way the older
software displays it (which I am used to).

This is the crux of the problem for me (lack of understanding the
difference).

Can anyone clue me in on why the displays are different?

[[email protected]]

Crap...sorry, some of those image links in the last message were wrong
(the first one).

Here they are again:

Non symmetrical looking waveform in Audacity on my "new" PC:
http://www.postimage.org/image.php?v=gx1nuWE9

And it looks the same in the DAW application "Reaper" on my "new" PC:
http://www.postimage.org/image.php?v=aV2iDhY9

So, I loaded this same audio file (the undulating one) into both of
these older pieces of software. Lo and behold - the waveform looks
symmetrical - the way I am "used" to seeing it!

Diamond Cut Audio on my "old" PC:
http://www.postimage.org/image.php?v=Pq2jK5jA

Samplitude on my ancient (but beloved) Amiga:
http://www.postimage.org/image.php?v=gx1nZHK9

[[email protected]]

When viewing the waveforms in Audacity (or anything else), the very
"bottoms" of the waveforms looked "chopped"

This has come up here a couple of times.
The explanation I most believe is that there is a bad connection that is
acting like a rectifier.

[Scott Dorsey]

wrote:
Then I tried really putting a loud sound into the mic. It's my voice
droning and changing pitch quite loudly in the microphone. The
waveform is so strange and not symmetrical. It undulates with the
raising and lower of the pitch of my voice:

Link to picture of waveform:
http://www.postimage.org/image.php?v=gx1nuWE9

Does anyone know what is going on?

It's your voice. It's like that, because of the way your vocal cords
work. There's a really great paper on the subject in a book called
_Physiological Acoustics_ in the Benchmark Papers in Acoustics series.

Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

My first reaction was DC offset, but I use Audacity's "Remove DC
offset" function and the waveform doesn't change.

Yup, because it's not DC offset, it's just asymmetry. If you think the
voice is bad, you should see the huge spiky waveform from a trumpet!
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Apr 18, 1:59*pm, "
wrote:
Crap...sorry, some of those image links in the last message were wrong
(the first one).

Here they are again:

Non symmetrical looking waveform in Audacity on my "new" PC:http://www.postimage.org/image.php?v=gx1nuWE9

And it looks the same in the DAW application "Reaper" on my "new" PC:http://www.postimage.org/image.php?v=aV2iDhY9

So, I loaded this same audio file (the undulating one) into both of
these older pieces of software. *Lo and behold - the waveform looks
symmetrical - the way I am "used" to seeing it!

Diamond Cut Audio on my "old" PC:http://www.postimage.org/image.php?v=Pq2jK5jA

Samplitude on my ancient (but beloved) Amiga:http://www.postimage.org/image.php?v=gx1nZHK9

What you describe is very strange. The same file look completely
different between your new and old computers. Does it sound different
on the two machines which might suggest some kind of format problem?
You might want to make the actual audio file available.

[Scott Dorsey]

wrote:

What you describe is very strange. The same file look completely
different between your new and old computers. Does it sound different
on the two machines which might suggest some kind of format problem?
You might want to make the actual audio file available.

The thing is, neither software package actually displays real waveforms,
they display envelopes. And they probably display envelopes differently.
That's the thing about averaging.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

wrote in message


Non symmetrical looking waveform in Audacity on my "new"
PC: url=http://www.postimage.org/image.php?v=aV2idr9S

The actual time scale used in this picture shows a far shorter segment of
audio than all the rest:

And it looks the same in the DAW application "Reaper" on
my "new" PC:
url=http://www.postimage.org/image.php?v=aV2iDhY9

So, I loaded this same audio file (the undulating one)
into both of these older pieces of software. Lo and
behold - the waveform looks symmetrical - the way I am
"used" to seeing it!

Diamond Cut Audio on my "old" PC:
url=http://www.postimage.org/image.php?v=Pq2jK5jA

Samplitude on my ancient (but beloved) Amiga:
url=http://www.postimage.org/image.php?v=gx1nZHK9

So....obviously there is something I am not understanding
about the way that Audacity & Reaper display waveform
data vs. the way the older software displays it (which I
am used to).

Can anyone clue me in on why the displays are different?

Different software produces different pictures, particularly when the time
scale is such that you're showing the entirely of a long clip on the screen.

Zoom in, and you should eventually find something that looks more like the
first image you posted.

[Anahata]

On Sat, 18 Apr 2009 23:36:28 -0400, Scott Dorsey wrote:

The thing is, neither software package actually displays real waveforms,
they display envelopes.

I don't know about the others, but Audacity with switch to waveform
display when you zoom in close enough.

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827

[Keith W. Blackwell]

Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.


Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

Can you elaborate?

Thanks,
--
Keith W. Blackwell
(my employer has nothing to do with this posting)

[[email protected]]

On Apr 20, 3:06*pm, "Keith W. Blackwell"
wrote:
Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

Can you elaborate?

Thanks,
--
Keith W. Blackwell
(my employer has nothing to do with this posting)

Keith,

I think the concept as applied to radio station processing is that the
phase manipulation reduces the peak value relative to the average,
which allows you to turn up the gain which does increase the volume
without exceeding the allowed peak.

The phase manipulation itself does not increase the volume, but it
allows the volume to be incresed without exceeding a peak limit.

Mark

[[email protected]]

On Apr 20, 3:37*pm, wrote:
On Apr 20, 3:06*pm, "Keith W. Blackwell"





wrote:
Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

Can you elaborate?

Thanks,
--
Keith W. Blackwell
(my employer has nothing to do with this posting)

Keith,

I think the concept as applied to radio station processing is that the
phase manipulation reduces the peak value relative to the average,
which allows you to turn up the gain which does increase the volume
without exceeding the allowed peak.

The phase manipulation itself does not increase the volume, but it
allows the volume to be incresed without exceeding a peak limit.

Mark- Hide quoted text -

- Show quoted text -

Oh and there is another concept that applies only to AM radio
stations, they are allowed 100% negative modulation but something like
125% positive modulation, so the processor will invert the polarity
(sometimes incorrectly called the phase) of the audio so that whatever
natural assymetry there is will be in the + modulation direction.
Almost all audio has some assymetry, at least before it's been
processed to H*** and back.

Mark

[Scott Dorsey]

Keith W. Blackwell wrote:
Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

The actual volume DOES stay the same, but then you can adjust the DC
offset to make your waveform fit into a fixed range of values with a
higher peak value.

Can you elaborate?

The Foti and Orban paper "What Happens to my Recording when it's Played
On the Radio" has a little info, but the manuals for the old Orban Optimods
are probably best to check out for how the process works.

As far as I know, the first device to do this was the Garron Stereo Phase
Enhancer, a device for which I have been looking for real documentation for
many years.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ty Ford]

On Mon, 20 Apr 2009 15:37:40 -0400, wrote
(in article
):

On Apr 20, 3:06*pm, "Keith W. Blackwell"
wrote:
Scott Dorsey wrote:
Most commercial recordings don't look like that, because they have
been compressed and phase-rotated to make them louder.

Scott, this is the first time I've ever heard of
the concept of phase-rotating to increase loudness.
It seems to me that if you use a filter that merely
performs frequency-dependent phase-shifting but
without changing amplitude, you may make the
waveform have greater (or lesser) maxima, but the
actual volume should stay the same.

Can you elaborate?

Thanks,
--
Keith W. Blackwell
(my employer has nothing to do with this posting)

Keith,

I think the concept as applied to radio station processing is that the
phase manipulation reduces the peak value relative to the average,
which allows you to turn up the gain which does increase the volume
without exceeding the allowed peak.

Not a peak to RMS thing.

It's to even out commonplace asymetrical modulation of the waveform. With
positive and negative peaks closer to the same value, you can raise the
modulation more without having the previously higher peak (positive or
negative) clip or be illegal as per the FCC.

Regards,

Ty Ford


--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA

[Keith W. Blackwell]

Thanks, Mark, Ty, and Scott. It all makes perfect sense.

--
Keith W. Blackwell
(my employer has nothing to do with this posting)

[Goran Tomas]

On Mon, 27 Apr 2009 18:36:44 +0000 (UTC), "Keith W. Blackwell"
wrote:
Thanks, Mark, Ty, and Scott. It all makes perfect sense.

For more sense, read this:

http://www.tonnesoftware.com/appnote...s/allpass.html


Regards,
Goran Tomas