Clipping

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steve
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Re: Clipping

Post by steve » Thu May 13, 2021 7:06 pm

Best to avoid clipping altogether if possible.

At best, ClipFix is just a guess at what the clipped peaks may have been like to make the damage less noticeable, but it's more of a sticking plaster than a cure. For sever clipping it's like putting a sticking plaster on a broken leg :shock:
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Jebbers
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Re: Clipping

Post by Jebbers » Tue May 18, 2021 6:41 pm

Thanks Koz, Doug and Steve. I remember first recording on a TEAC (?) reel to reel. I've also recosrded with a Tascam 4 track cassette. I always had the Vu meters just touching the red. I read this instruction in a book on recording. I had no isea that it was to overcome tape hiss. So, I can use much lower input levels? I was recording at 70 to 90 depending on the signal strength. I'm now trying some lower setting like 50 or 60. Is there a limit to that? Can I set my level to 1 or 2? Why or why not?

Steve - does cubic whatever have something to do with analytical geometry? I know that sound wave is three dimensional. It has to be represented on the two dimensional window of Audacity. A cube is 3D. I would spose that you need at least two cubes to represent a sound and a third to connect them together. What dimensions are being represented by a cube? I imagine the height for amplitude, and another dimension for the longitude of the wave cycle or pitch and another for duration? But there are also other elements to a sound such as timbre from the overtones, and attack and decay.

In other words, I don't know what you are talking about? :mrgreen:

https://en.wikipedia.org/wiki/Bicubic_interpolation

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Re: Clipping

Post by steve » Tue May 18, 2021 7:23 pm

Jebbers wrote:
Tue May 18, 2021 6:41 pm
I'm now trying some lower setting like 50 or 60. Is there a limit to that? Can I set my level to 1 or 2? Why or why not?
Your sound card probably captures audio as 16-bit numbers. That means there are 65536 discrete amplitude levels, which allows the digital audio to match the (continuously varying) analog sound very accurately. If you "only" use half of the available range, then there are still 32768 distinct levels, which is still enough for very high quality. However, if the recording level is extremely low, then there will not be enough discrete levels to be able to accurately represent the analog sound, and the sound quality will suffer.

This file is close to the best quality possible if you recorded at -70 dB with a 16-bit sound card:
70dB.wav
(845.11 KiB) Downloaded 2 times
Jebbers wrote:
Tue May 18, 2021 6:41 pm
does cubic whatever have something to do with analytical geometry?
Not really. It's just a way of smoothly filling in a gap between two points on a curve. ;)
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Re: Clipping

Post by DVDdoug » Tue May 18, 2021 7:28 pm

So, I can use much lower input levels?
Yes. -6dB (50%) is fine, and if your levels are unpredictable and you occasionally get clipping you can go lower. Your recorder works at 24-bits which give you enormous dynamic range and you could record at -20dB (10%) with no loss of sound quality!

That's assuming the levels are low because you've turned-down the recording level... If your levels are low because you're across the room from the mic (or something like that on the acoustic/analog side) that will affect quality.
I was recording at 70 to 90 depending on the signal strength. I'm now trying some lower setting like 50 or 60. Is there a limit to that? Can I set my level to 1 or 2? Why or why not?
You're "settings" aren't important, it's the actual level you're getting.
Steve - does cubic whatever have something to do with analytical geometry? I know that sound wave is three dimensional.
Steve will have to explain the algorithm but audio can be completely defined in 2-dimensions (time & amplitude).* digial audio is simply a series of samples (amplitude values or the "height" of the wave) with each sample representing one point in time. (i.e. 44,100 samples pre second). When you play the audio, the digital-to-analog converter "connects the dots" and re-creates a smooth analog "waveform" (a varying voltage). The digital values could represent the position of the loudspeaker as it vibrates to reproduce sound.



* The "normal" waveform is time domain representation. It can also be represented as frequency over time (the frequency domain) and that's what you see in the spectrogram view. Some effects/processing is done in the frequency domain. But "basic" digital audio (analog-to-digital-converters, digital-to-analog converters, WAV files, etc., are all time-domain.

Jebbers
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Re: Clipping

Post by Jebbers » Tue May 18, 2021 7:33 pm

https://en.wikipedia.org/wiki/Time_domain

This wiki page refers to a "Fourier transform." Isn't this analytical geometry?

"In mathematics, a Fourier transform (FT) is a mathematical transform that decomposes functions depending on space or time into functions depending on spatial or temporal frequency, such as the expression of a musical chord in terms of the volumes and frequencies of its constituent notes. The term Fourier transform refers to both the frequency domain representation and the mathematical operation that associates the frequency domain representation to a function of space or time."

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Re: Clipping

Post by kozikowski » Tue May 18, 2021 7:41 pm

Then light clipping is OK but it must be corrected with ClipFix?
No clipping is OK. Clip Fix produces a mathematical algorithm, not the original sound. It reduces the gritty, annoying, crunchy sound without actually fixing the music or voice.

Unlike tape, the digital system has straight-line transfers. No gentle magnetic saturation and ultra-sonic bias. You get louder until the system runs out of numbers and whacks off your peaks with a sharp knife.

The general recommended voice recording level is peaks about -6dB or half-way on the blue waves.

The bouncing sound meter starts changing color right about there, going from green toward yellow. If you hit red, you've got clipping damage.

Image

Also remember the digital system isn't insanely noisy like tape. 16-bit sound range is 0dB (clipping) down to -96dB! You can slide sound quieter and louder anywhere in that range without damage. Don't run out on either end, and don't overload your analog system. Watch those red PEAK lights.


You can certainly produce a robust, dense sound for a show, but it's strongly recommended you produce a clean recording, save it for protection, and then get there with effects. We can go from a clean recording to anything else, once you produce distortion right at the top, you're stuck.

Koz

steve
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Re: Clipping

Post by steve » Tue May 18, 2021 7:46 pm

This is the simplest and clearest explanation of the Fourier Transform that I've seen on the Internet: https://www.youtube.com/watch?v=spUNpyF58BY
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Jebbers
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Re: Clipping

Post by Jebbers » Tue May 18, 2021 7:49 pm

Koz - That looks like something that I would boost. But I'm not sure I should. The listener has a volume control. Does it help them any if I boost this?

Jebbers
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Re: Clipping

Post by Jebbers » Tue May 18, 2021 7:52 pm

Steve - This video is beginning to explain some of the wave formations I am seeing in my files.

kozikowski
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Re: Clipping

Post by kozikowski » Tue May 18, 2021 9:19 pm

The listener has a volume control.
Yes, but. Pay attention to your production values and associated productions.

A podcast I like has started cranking out messy work and making mistakes I don't remember happening before. Be sure to Like and Subscribe and remember to hit that bell icon. and then snaps right back to normal volume just when you're leading forward to hear they they said. Yes, it's attention-getting, but if you grab too much attention, I'll lean forward and change the channel.

Two flying shows settled on different announce volumes. One settled down here and the other is a good hand-full of dB louder. I'm wearing out the Volume/Balance knob—and yes I do have one. I don't have to click on anything or fish the phone out of my pocket.


I know of three production sound standards. The audiobook one where they tell you how loud to get in actual electrical measurements, the LUFS one which is supposed to be an up and coming universal standard, and the cheat where you Effect > Amplify to -1dB, just short of clipping and ship it.

https://www.izotope.com/en/learn/master ... forms.html

Audacity Effect > Loudness Normalization supports both RMS (Audiobook) and LUFS.

Honorable mention goes out to The New York Times for their Mini Crossword Puzzle "success" fanfare. It's loud enough to crack plates and notify the neighbors. You learn to turn the volume down before you put that last letter in the box. I can't tell if they did that on purpose or not.

Koz

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