Clipping in Phone Call

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mac_audio
Posts: 122
Joined: Sun Aug 19, 2018 1:28 am
Operating System: macOS 10.15 Catalina or later

Clipping in Phone Call

Post by mac_audio » Mon Sep 03, 2018 1:58 am

When I record a VoIP call on my Mac, the IVR system is getting clipped as shown below...

Image


I am using Zoiper, Loopback and macOS Sierra.

I adjusted the Audio MIDI Setup so that Channel 2 in my virtual Loopback device was turned down and left lots of "headroom" for the IVR syste, yet when the lady started talking, it looks like things are sawed off.

This cannot be traditional clipping as even with the gain turned down it is like it reaches a glass ceiling and then gets smooshed?!

The audio sounds okay, which makes me wonder if it is coming this way from the tele # I am calling?

What is happening here?

Thanks,


Mac Audio
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Trebor
Posts: 9847
Joined: Sat Dec 27, 2008 5:22 pm
Operating System: Windows 8 or 8.1

Re: Clipping in Phone Call

Post by Trebor » Mon Sep 03, 2018 5:10 am

mac_audio wrote: ↑
Mon Sep 03, 2018 1:58 am
 This cannot be traditional clipping as even with the gain turned down it is like it reaches a glass ceiling and then gets smooshed?!

The audio sounds okay, which makes me wonder if it is coming this way from the tele # I am calling?

What is happening here?
If it sounds OK then it's a (soft) limiter effect, rather than clipping, (Audacity has one).
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mac_audio
Posts: 122
Joined: Sun Aug 19, 2018 1:28 am
Operating System: macOS 10.15 Catalina or later

Re: Clipping in Phone Call

Post by mac_audio » Tue Sep 04, 2018 1:51 am

Trebor wrote: ↑
Mon Sep 03, 2018 5:10 am
 If it sounds OK then it's a (soft) limiter effect, rather than clipping, (Audacity has one).
So is the phone company or my VoIP company doing this to the phone call before it gets to me (and Audacity)?
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kozikowski
Forum Staff
Posts: 68902
Joined: Thu Aug 02, 2007 5:57 pm
Operating System: macOS 10.13 High Sierra

Re: Clipping in Phone Call

Post by kozikowski » Tue Sep 04, 2018 3:11 am

Somebody's law says if more than three organizations are involved, you'll never figure out who was to blame.

But you can do some investigation.

As above, if it was careful but stiff processing to maintain volume in the transmission, the tops of the waves will look more or less like the originals, but the tips will be the same level. You'll have to take my word that all those waves looked exactly like that before, just taller.


Screen Shot 2018-09-03 at 19.58.40.png
Screen Shot 2018-09-03 at 19.58.40.png (23.59 KiB) Viewed 259 times

But if it's End-Of-The-World overload damage, the tops of the waves will look like somebody took a knife to them. That sounds harsh and crisp if it's bad enough.


Screen Shot 2018-09-03 at 19.59.26.png
Screen Shot 2018-09-03 at 19.59.26.png (16.73 KiB) Viewed 259 times

The first one was likely intentional. That process appears in AudioBook Mastering. The second was sound or data damage somewhere. You can magnify/zoom the waves and see what you have.

https://manual.audacityteam.org/man/tools_toolbar.html

Koz
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