How to know when your audio is really clipping?

[Color Philospher]

Hello, so I use rokit 6 monitors and Audio technica m40x headphones, and when I listen to my audio I don't hear any clipping. However,  despite hearing no clipping on either monitor system, the input says it's clipping. The recorder is a tascam DR-10L with my settings having auto level, limiter, and dual record  on for a separate -6db version. It says the input is clipping in audition but I think even without a limiter the output isn't clipping? I can't remember what the settings were on the daw audio track as this  was a question I had a while back but never asked. But the input has almost always said that there's clipping with every new recoding/ project I work on. If I lower the volume or use a limiter in my daw, and I can't hear any clipping whatsoever, is it safe to say there isn't any "perceived" clipping that any non-audio savvy person would be able to hear? 

I do hear clipping sometimes if the subject yells or laughs really loudly, and I mix in/replace the -6db version for those parts. But there aren't that many time I hear clipping. 

[IronFilm]

8 hours ago, Color Philospher said:

The recorder is a tascam DR-10L with my settings having auto level, limiter, and dual record  on for a separate -6db version.

Auto level *and* a safety track? Seems over the top. 
I'd stop using auto level.  Auto level is bad bad news as it will drive up the noise floor (both of the device and the ambiance) during the quieter spots.
Set a conservative gain value for what you think the scene will be, and use the safety track. 

Paste a screen shot of the audio waveforms, if you're not trusting your ears (and it seems so, otherwise you wouldn't be asking), then use your eyes.

[kye]

I used to write electronic music and my experience was that you can clip quite a bit before it becomes audible, but that doesn't mean that you should.

I second what @IronFilm says above of using a conservative gain value and using a safety track - that's how I try to record my audio.

You'll find that things will seem quiet, but that's why you use compressors and limiters in post, which gives you much greater control over how things end up in the final mix.

[Kisaha]

On 6/15/2018 at 6:35 AM, kye said:

I used to write electronic music and my experience was that you can clip quite a bit before it becomes audible, but that doesn't mean that you should.

I second what @IronFilm says above of using a conservative gain value and using a safety track - that's how I try to record my audio.

You'll find that things will seem quiet, but that's why you use compressors and limiters in post, which gives you much greater control over how things end up in the final mix.

There is no "clip quite a bit", in digital sound; it clips or not.

If you have good sound to start with, you do not usually need compressors/limiters in post. It is good to have good quality limiters for extreme sound gathering.

Auto levels are a no-go, dual levels should be sufficient. Limiters in cheap Tascams are very limited, you should set your gain right and conservative. It is not a disaster to add a few dBs later on, but clipping sound is (almost) unusable.

Last night I was doing camera for a live performance, the person(producer) setting the recorder set the gain in the sound test (I told him to be conservative, but he didn't listen/knew), when the band really started playing the sound started peaking. Result? Totally unusable sound. The producer just hopes that the band was recording the performance. 

[kye]

6 hours ago, Kisaha said:

There is no "clip quite a bit", in digital sound; it clips or not.

Yes and no.

Technically, when it clips it clips, so you're right about that.

However, if your audio looks like this:

and you up the gain by just a tiny bit then it will clip, but only at one point and on only one transient.  Will it be audible?  Very very very unlikely.

Let's understand what is happening when you clip a signal like this:

The unclipped signal on the left appears to be a Sin wave, and assuming that it is, it will be a single audio frequency.  The clipped signal on the right is approaching a Square wave, which has a base frequency but also has a series of odd harmonics - the difference in tone between an acoustic guitar and the kind of distortion that Metallica might use.

So, here's the "quite a bit" part..  If you push a Sine wave into clipping by a very small amount then what you end up with is a base frequency at full volume and a series of odd harmonics that are very quiet in comparison.  The harder you clip the signal the louder these odd harmonics will be.

This is why a "little bit" of clipping only gives you a "little bit" of distortion and "quite a bit" of clipping gives you "quite a bit" of audible distortion.

ie, there is a huge difference between these two:

I hope this helps to explain.  Audio is hugely complicated and it's easy to make simple statements but as with most things there's usually more to it.

[Kisaha]

1 hour ago, kye said:

Yes and no.

Technically, when it clips it clips, so you're right about that.

However, if your audio looks like this:

and you up the gain by just a tiny bit then it will clip, but only at one point and on only one transient.  Will it be audible?  Very very very unlikely.

Let's understand what is happening when you clip a signal like this:

The unclipped signal on the left appears to be a Sin wave, and assuming that it is, it will be a single audio frequency.  The clipped signal on the right is approaching a Square wave, which has a base frequency but also has a series of odd harmonics - the difference in tone between an acoustic guitar and the kind of distortion that Metallica might use.

So, here's the "quite a bit" part..  If you push a Sine wave into clipping by a very small amount then what you end up with is a base frequency at full volume and a series of odd harmonics that are very quiet in comparison.  The harder you clip the signal the louder these odd harmonics will be.

This is why a "little bit" of clipping only gives you a "little bit" of distortion and "quite a bit" of clipping gives you "quite a bit" of audible distortion.

ie, there is a huge difference between these two:

I hope this helps to explain.  Audio is hugely complicated and it's easy to make simple statements but as with most things there's usually more to it.

I am a professional sound man of 19 years with a degree in sound engineering and acoustics, among other degrees, and honestly I am not sure what are you are trying to say with the above, and why we have to confuse people with irrelevant theories. 

"A little bit of clipping" could end my career in less time than the time you needed to write your above response.

[IronFilm]

What he is saying is that there is a little bit more nuance to it than the black and white of "clipping vs no clipping". 
A teeny bit of clipping like in the first image is extremely likely to be "ok", while the clipping in the last image with the blue audio waveform is completely destroyed audio. 
They're both "clipping", but the nature of each is completely different to each other. 
Thus why the phrase "a little bit of clipping" can kinda make sense in the context, I understood what he meant. 

[kye]

Thanks @IronFilm 

@Kisaha Are you perhaps talking about delivering audio with parts at -0dB vs capture of audio with clipping?  

My point was that if you clip a very small part of the signal (ie, just the extreme peaks) and you do it on capture (and then process it to be ok in post before delivery) that you're probably ok.

Otherwise we'd have huge problems with signal-to-noise while capturing the entire dynamic range of uncompressed audio sources (assuming we didn't have a limiter before the capture device).

I'm simply trying to be practical.  We tend to recommend that the thing we're recording (a voice perhaps) doesn't go above, say, -12dB, and that we have a safety track at perhaps 20dB less than that again, which would give us 32dB headroom over the peaks in our target audio.  If we were recording on-set sound of a narrative in a kitchen, perhaps, and someone puts the saucepan on the stove down a bit harder than they intended then we'd be screwed if our mantra was "no clipping under any circumstances ever".  Even more if we're recording in public where transients can be significant.  
In reality, we accept that the transient clipped, it only did it for a few ms, the associated distortion (THD and IMD in this case) probably wasn't audible, and we just fix that moment in post and move on with our lives.  We don't go to the lengths of recording in 24-bit and having a -60dB safety track to ensure that no transient never ever clips

I guess in summary, the OP was talking about clipping and audibility, and my point was that you can have clipping without it being audible, and that's probably ok.

In terms of your audio credentials, good stuff.  One day we can talk about high quality audio reproduction

[IronFilm]

47 minutes ago, kye said:

If we were recording on-set sound of a narrative in a kitchen, perhaps, and someone puts the saucepan on the stove down a bit harder than they intended then we'd be screwed if our mantra was "no clipping under any circumstances ever".  Even more if we're recording in public where transients can be significant.  

Meh, depending on the situation, I might perhaps not be too worried about the saucepan as it is not part of the dialogue. 

[Kisaha]

Analogue peaking is different than digital clipping. Big time. The way we approach sound in fully analogue studios and digital ones is way different, and that is why I mentioned my sound credentials, because I have worked in both environments. I lived between the two eras, so all my education (sound/moving and still image) started with analogue equipment.

If you have "a little bit of clipping", let's say once every half a second, in a 5 minutes piece you have 600 unwanted (wrong/mistakes/bad job) elements in your sound gathering. Now, every one of these times, add another "little bit of" +3 stops of light in your image, or clip the greens of your perfectly exposured image. Do you see where I am going with that?

Any way, for the zillionth time here and everywhere, a hobbyist judges things differently, and -normally- more lightly; I would expect someone that wants to improve to try the best way possible, because when you start the discounts in your job/hobby, then that can go really low. True story.

 When I shoot 3 pointers, 3 out of 10 are amazing for me, if you are a professional basketball player, a percentage less than 35-37% is a bad percentage (at least for everyone under 7 foot). But when I shoot, I am trying to be Curry, not Tristan Thomson.

The OP should just try to avoid clipping, and as already mentioned, it is much easier to add a few db, than try to fix clipping sound in post (which the huge majority is unfixable anyway).

Dual level recording is a very clever method to achieve that, and my opinion is to be conservative even in your highest setting.

[Mmmbeats]

I've messed up an audio recording on a job I did recently.  I'd like to get some opinion on whether it is recoverable or not.  Would this thread be an okay place to post it up?

Actually - scrap that - I've just heard we're doing a re-shoot.  Not nice to have that fall on my head, but to be fair, the client is being really good about it all.  It's a long-term client who I always deliver good work to, so I think they just appreciate it as a rare mistake.  It helped that I just put my hand up straight away and said I'd messed up actually ?.

[IronFilm]

If you can, share a thirty second clip of the old audio anyway?

[Mmmbeats]

13 hours ago, IronFilm said:

If you can, share a thirty second clip of the old audio anyway?

Here's the clip.  Was recorded on Rodelink radio mic straight into the GH4 (I have a pre-amp which I foolishly didn't use on this occasion).  I believe that gain was set to -20db on the transmitter, and -12db on the camera mic level.  The limiter in the camera was set to 'on'.

audiosample.wav

[Mmmbeats]

Just bumping this a little in case anybody does want to have a listen to my errant file.  My photography is way further advanced than my sound recording - something that I must address.  So if anybody has any insights into what particularly might have gone wrong here, I'd be eager to hear them.

Particularly paging @IronFilm

[IronFilm]

That is a very short clip, but what in particular are you finding the most obnoxious about it?