Popping in Mix Paste

Report · Apr 07, 2023

I'm editing an audiobook narration on a Windows machine, audio is 44.1/16.

I have a :30 sample of "room tone" on my clipboard.

When I go to "mix paste"/auto heal a pause with a breath or booth noise, and "mix paste", I'm getting a "pop" in the filled segment (usually at the beginning of the segment). Screenshots of an example of the "pop" as well as my mix-paste settings. Thank you!

Report · Apr 07, 2023

That looks like a zero crossing error - there's a step jump in the samples. You might be able to get rid of it by setting the snapping to 'snap to zero crossings', but there are two better things you can do; firstly make sure that your room tone file starts and ends with the signal at minus infinity (this is what a zero crossing is) and secondly, create more room tone in Multitrack view, where you can create it much more effectively by using two tracks and overlapping them - or using a single track and crossfades. Mix-paste can't do that!

Report · Apr 09, 2023

Hi Steve & thank you for the reply.

Pardon my ignorance, but "start and end with the signal at minus infinity" - does that mean to bascially inject "silence" at the front and back of the room tone? I like the multi-track suggestion and will look at that as well.

Thanks again!

Report · Apr 10, 2023

No it doesn't have to be silence. If you look at the waveform, you'll notice that positive excursions are generally followed by negative ones (where it dips below the centreline). The zero crossing point is where it crosses from positive to negative. If what you are trying to loop starts and ends with a value that is different, then at the looping point there will be an abrupt jump, and that's what produces your artifact. Normally it's easiest to arrange the start and end point of your loop to be at a zero-crossing point, but they don't absolutely have to be - it just has to be a smooth transition. You do have to be a bit careful though, as the rate of change of the waveform at the looping point can also make a difference to what you get in the way of an artifact, and it's not unusual to have to spend some time getting good looping points with nothing dodgy happening.

But as I said, this is generally much easier to achieve in Multitrack view, using crossfades.

Report · Apr 10, 2023

Thanks for the further detail. Is there a tutorial on the multirack view/using crossfades process, just so I know I'm doing it correct & efficiently?

Report · Apr 10, 2023

I'm sure that there are tutorials on using crossfades in general, but because I've never done one on using Multitrack for generating room tone, I suspect that there aren't any specifically about that. But you don't really need a tutorial - mostly what you need to use are your ears!

The single-track method is simple. You place your file at the start of a new track, and rather than set it so that it can loop, you just place a few instances of it next to each other on the track, and slide the second one back a little over the first one, and then the third one a little over the second one, and just keep going. Just listen as you do it, and you'll soon find out how much to overlap. As long as crossfades are enabled, Audition will do that bit for you.

What you might find is that when you listen to your room tone track, you can hear it repeating. If this happens, then copy all the clips from the first track onto a second track, and move them all along about half the length of an individual section, so that they overlap each other. You'll find the repeats far less noticeable then. If it's just one thing that stands out, then simply remove it! Mix the whole thing down to a new file, and when you need it you can insert it. If you do your entire edit in Multitrack (which is a very good idea) then inserting room tone from your file is easy!

The poshest way of dealing with room tone situations that I'm aware of is in iZotope's RX10, which has an Ambience Match module, but that's going to cost you money...

(Okay, I suppose that's a tutorial... 😉)

Report · Apr 10, 2023

I'll give that a try, but it sounds extremely labor intensive for audiobook work, where there are literally hundreds or thousands of instances where I'd need to fill in the gaps. I'll play around with it.

I do have iZotope RX8 - it looks like it has Ambience Match; I'll try that too.