Audacity Forum

stevethefiddle wrote:

whomper wrote:always try to record -18 to -24 dB lower than your expected max.

The "ideal" amount of headroom depends on several factors. You only ever need >0dB headroom - the important thing is that clipping distortion is avoided.

do that and you will clip a lot unless you record a flat line signal
headroom ensures the peaks don't hit 0dbFS
that is why it is called headroom

The more headroom that is given, the less dynamic range is available.
Allowing for lsb inaccuracy and overhead from filters, 16 bit provides < 90dB dynamic range. If you intend to allow 24dB headroom, but estimate the level a few dB on the conservative side, you could easily be restricting the dynamic range to less than 60dB, which is lower than can be achieved with a good cassette recorder.

so record with 24 or 32 bits and amplify later before converting to 16

... the "ideal" amount of headroom to allow will depend on your confidence in how accurately you can estimate what the maximum peak level will be. In this sense "headroom" is essentially allowing room for error.

you need headroom that will be enough for the signals to come that you have not seen and do not know how much louder they will be.
there are recommended standards and most are in the -18 to -24 range for headroom.

all recordings have way too much dynamic range anyway. 30db is about the most you can use in normal environments. if you have an anechoic chamber and use headphones you might want more. most of us prefer our music so the highs dont wake the baby and the lows are not lost under the traffic noise outside. and that might be too much range for use in a car stereo.

The singer spends most of his time in severe peak distortion and that's usually fatal. Clip-Fix and most tools like that are good for occasional tick here and there, not when the performance is a quarter distortion.

You might try the clip fix, though. One of the oddities of the tool is that it sometimes works better when you apply it multiple times.

Koz

<<<and that might be too much range for use in a car stereo.>>>

And that's precisely the reason Chris developed his famous compressor. To listen to opera in the car without turning the performance into garbage.

Listening room aside, it's still necessary to capture live performances in the volume they're being produced. I generally use -15dB as a design center and that's only because I can reach over and smack the voice talent or singer if they go over. In uncontrolled conditions, I can understand wanting more.

In the case of a rock band, you might also want a microphone with the thermo-chemical or nuclear detonation option.

Television "normal" level is -20 in the US and -18 in Europe.

Koz

Trebor wrote:Yep that’s overload distortion.

Not a lot that can be done. I’ve butchered the spectrum, (have a look at the before and after frequency analyses to see what frequencies I’ve amputated),
and applied “Floorfish” (free) expander at different frequencies …

Woodhand's distorted opera singer, Before-After.mp3

I slso tried "centre pan isolation" using Kn0ck0ut, it has less overload distortion but sounds computery, (digital artifacts), basically swapping one type of distortion for another ...

Woodhand's distorted opera singer, Before-After Kn0ck0ut (et al).mp3

Hi Trebor,

It is very impressive that you took the time to do this for me ... thanks. I'm learning a lot in this thread. I almost like the Floorfish result, but it changes the character enough I'd be tempted to apply it to the entire vocal parts in order to get consistent timbre. I assume you meant to see Plot Spectrum in Aud ... yes, you clobbered a lot above 7k. The "fish" tools look interesting. Did it take you a while to learn how to do them? Are you an "audio engineer"?

Again, thank you for the education.

kozikowski wrote:...

Listening room aside, it's still necessary to capture live performances in the volume they're being produced. I generally use -15dB as a design center and that's only because I can reach over and smack the voice talent or singer if they go over. In uncontrolled conditions, I can understand wanting more.

In the case of a rock band, you might also want a microphone with the thermo-chemical or nuclear detonation option.

Television "normal" level is -20 in the US and -18 in Europe.

Koz

i have no control over the performers.

i fail to see why i have to record them at their SPL.
I can and will use normalise/amplify and compress to set the final level and loudness on the cd. as long as there is no noise on the low end you can record them waaaay below their level and increase the headroom even more to remove all risk of clipping.

being cautious , i leave plenty of headroom as the lesser evil.
-24dBFS seems to work for me with most sound sources as long as I can get some preliminary testing to see their typical level.
and I compress the last several db in RT as further insurance.
typically record 24 bits , process - normalise eq etc. - depending on the music, i may also compress -- , dithertrunc to 16, and burn cds.

for rock bands i just back up a few hundred yards.
(we were 80 feet from phish with hearos and earmuffs and the sound was still too loud! )

The floorfish results are about the best you're likely to get.
I've had a go using a different method, and restricting the effects to those included in Audacity.

The method here was to generate a bit of pink noise, and deliberately clip it severely. This could be done by amplifying it with the "allow clipping" box selected, then amplifying it negatively to drop the level down again - I actually used the Nyquist prompt to do the clipping, but its the same effect.

I then used that noise to create a noise profile in the Noise Remover effect, then used Noise Remover on the track.

Finally I used a bit of Eq (Equalizer effect) to drop down frequencies in the 4 kHz range.

The result is certainly no better than Trebor's "floorfish" example, but still a reasonable salvage job. What flavour of bad sound do you want

As you said at the very beginning woodhands, "this type of distortion is tought to deal with".

stevethefiddle wrote:The floorfish results are about the best you're likely to get.
I've had a go using a different method, and restricting the effects to those included in Audacity.

The method here was to generate a bit of pink noise, and deliberately clip it severely. This could be done by amplifying it with the "allow clipping" box selected, then amplifying it negatively to drop the level down again - I actually used the Nyquist prompt to do the clipping, but its the same effect.

I then used that noise to create a noise profile in the Noise Remover effect, then used Noise Remover on the track.

Hmmmm .... why use pink noise for the noise sample? It seems so different than the type of sound heard from overmodulating as here.

I tried Noise Remover on a particularly staticky section, but no result.

I imagine one would want a simple signal (pure 440Hz tone?), amplify it so it distorts, then extract that pure tone signal - leaving the noise alone. Can that be done in A?

S

woodhands wrote:why use pink noise for the noise sample?

It started as pink noise, but then was severely truncated (clipped) so that it had a waveform like this:
It's a valid point that you raise - I picked truncated pink noise because it has visual similarity to the "noise" that we're trying to remove. Experimenting with other noise profile could produce better results, but I doubt that the improvement would be enough to justify the time.

To get any noticeable effect on your recording requires that the amplitude of the noise profile is very large - I used a noise sample with roughly the amplitude shown in the above screenshot.

how can it flattop before 1.0? bug in the linear display ??
dB view would be more useful IMHO - magnify the top part to really see what is happening wrt clipping.

whomper wrote:how can it flattop before 1.0? bug in the linear display ??
dB view would be more useful IMHO - magnify the top part to really see what is happening wrt clipping.

I agree db view would be a nice _option_.

The clipping occurred before in Audac - I lowered the amplitude so it wouldn't be so loud; and to create headroom for this recreation work.

Thanks to all for an informative discussion!

WH