retaining clipping

[Xerlome]

Audacity 2.1.1
Windows 7

Sometimes when most of the graphic is in the mid-range, but there are numerous tiny peaks that reach or exceed the maximum level, I want to mostly trim those peaks off and then reduce the overall volume to -1 with the clips removed. Is there a way to lose those clips in a single action? They always return when I try to reduce to -1.

[Gale Andrews]

If you recorded this audio yourself into Audacity and you are in 32-bit float Default Sample Format then use Effect > Amplify... . If there is clipped audio above 0 dB you will observe the Amplification offered is a negative amount which will reduce the audio to 0 dB peak. In your case, set New Peak Amplitude of -1 dB. This works because in 32-bit float, peaks above 0 dB are stored, so deamplifying retains the peaks.

If the audio is a 16-bit file and already clipped, you can try Effect > Clip Fix.... Note that a 16-bit file will by default show as 32-bit float to left of the blue waves, because the file is opened in 32-bit resolution. But when you open Amplify you will see 0.0 as the default amplification. The peaks are already lost, and reducing amplification won't restore them.


Gale

[DVDdoug]

Sometimes when most of the graphic is in the mid-range, but there are numerous tiny peaks that reach or exceed the maximum level

Where did the recording/file come from? If you recorded it yourself, the best solution is to record at a lower level and prevent clipping. You can boost the volume in post-production to hit 0dB or -1dB, etc., and you can optionally use limiting/dynamic compression to reduce the peaks without clipping them while bringing-up the overall-average volume.

They always return when I try to reduce to -1.

Are you using the Amplify Effect Or the Normalize Effect to set the peaks to -1dB? That works perfectly for me every time!

You may need to tell us more about what you're doing so we can figure out why it's not working for you...




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MP3 ???

If you export to MP3 (or other lossy format) the wave shapes will change making some peaks higher and some peaks lower. It's not unusual to start with a -1dB peaks and end-up with an MP3 that hits 0dB, or even goes over 0dB.

If you want to keep your MP3s below 0dB, you may have to try normalizing to -2dB (or maybe lower) before MP3 compression. Every file compresses differently so it may take some trial-and-error.

But, since MP3s are not hard-limited to 0dB, they can go safely over 0dB without clipping. If you re-open the MP3 in Audacity, you'll see red for potential clipping even though the actual waveform is not clipped. I'd guess that most of my MP3s (mostly ripped from CD) "show red" in Audacity. ...If you export to a "regular" WAV file the wave file can be clipped, or play it full-volume into your soundcard/DAC, the analog waveform will be clipped, but as far as I know that slight clipping is not audible. That is, if you're hearing MP3 compression artifacts those artifacts won't go away if you reduce the level before converting to MP3. And, if the MP3 compression is transparent (sounds exactly like the original) at -1dB, it will be transparent at +1dB too.

[Xerlome]

To Gale's reply: If I am understanding you correctly, I have observed what you described. I've also observed that downloaded audio often behaves as in your description of self-recorded audio.

What I am speaking of now is voice audio I've recorded. I am trying to permanently clip the narrow spiky peaks which rise maybe 7 points above the main level of the audio, in one action rather than spending a long time reducing each peak, so that I can then raise the mid-range audio to -1 and save that way. Can this be done?

To DVDdoug's reply: I'll try the normalize effect. Not sure I quite grasp the last few lines of your reply.

I may want to clip either an existing file or a self recorded. I'm generally comfortable with a final level of -1.

Recording at a lower level lowers both the main level and the peaks, so it doesn't solve the problem.

[DVDdoug]

...the narrow spiky peaks which rise maybe 7 points above the main level of the audio, in one action rather than spending a long time reducing each peak, so that I can then raise the mid-range audio to -1 and save that way. Can this be done?

Try the Limiter Effect. Try the Hard Limit option. That should knock-down your peaks without clipping. You can use Make Up Gain within that effect, or use the Amplify Effect later to bring-up the overall volume.

I'm not sure what a "point" is, but a normal recording typically has a peak-to-average ratio of about 20dB (10:1). Most "natural" sounds have a greater ratio than that and most professional recordings have some compression & limiting to bring down that ratio (to bring up the average level/loudness). (Loudness War).

What I am speaking of now is voice audio I've recorded. I am trying to permanently clip...

Clipping is distorted flat-topped and flat-bottomed waves caused by exceeding the maximum level of your hardware/software, etc.

Recording at a lower level lowers both the main level and the peaks, so it doesn't solve the problem.

...Now that you know what clipping is, you can see that recording at the proper level does prevent clipping (at the recording stage).

[Xerlome]

.. I'm not sure what a "point" is

Clipping is distorted flat-topped and flat-bottomed waves caused by exceeding the maximum level of your hardware/software, etc.

Now that you know what clipping is, you can see that recording at the proper level does prevent clipping (at the recording stage).

"Point" is just a word I used to refer to 0 to -10 levels

Maybe I should have used the word "cut" instead of "clip". Cutting peaks down with draw works for me, but takes too long. I'll try the methods you suggest.

Adjusting recording volume doesn't work for me. It may be the mic, or something else, but I've been through that issue at length in the past here. I really just need to snip the spikes in one action, for self-recorded and downloaded talk. Then I can raise the whole volume where I want.