Fix clipped audio with De-clip - RX Tutorial

- [Instructor] A problem you occasionally, and hopefully, only occasionally, run into is clipped audio. This is what happened when the input level to your microphone or preamp is set too high, resulting in something that sounds like this. - [Recording] This is an example of distorted or clipped audio. - [Instructor] So you can clearly hear the distortion or clipping that's occurring in that recording. Now of course, if you have the ability to do so, you should always try to re-record the clipped audio because clipped audio essentially means you're missing data about that audio. I'm going to zoom out a bit here using the Amplitude scale slider. Currently, I have the Frequency zoom slider selected, so I'm going to click the wave form, and then I can zoom out a little bit here. That way we can see the wave form in its entirety. Notice the clipped areas are all literally clipped. They have these flat tops instead of the rounder edges. This is what gives you that distorted sound. The information that should be there is missing. Again, ideally, you would be able to re-record your audio with the proper input levels and get a nice, clean recording. If that simply isn't an option, you can try to repair the clipped audio, but your results will really vary. If it's only slightly clipped, you might produce some usable audio, but if it's extremely clipped, there's pretty much nothing you can do because the information to reconstruct the missing audio is simply not going to be there. This is kind of a purposely extreme example I'm using here so we can see what RX 6 might be able to do. If the clipping in your own files is less extreme, you'll most likely have better results. We're going to use RX 6's De-clip module. Now, in order to give it some room to work and redraw the tops of these clipped wave forms, we need to provide some head room. The first thing I'll do is select the entire clip, Command A or Control A, and I'm going to open up the Gain module. All I'm going to do here is simply reduce the overall amplitude by, let's say, 10 dB, and I'll process that. You can still see how the wave forms are clipped here. With everything still selected, let's open up the De-clip module. We have several controls here. The threshold controls show us a histogram of the audio. It displays how many samples are present at a given signal level over a window in time. The longer the lines across the chart in the histogram are, the more energy is present at that amplitude. If I zoom out here, you can kind of see the whole picture. Notice there's a lot of build up towards the top and bottom of the wave form. This is usually a tell-tale sign that the audio is clipped and distorted. We already know we have clipped audio anyway, but this just shows us where the build up of energy is occurring, and if it's towards the top, that usually tells us we have clipped audio. I suggest setting the Quality menu here to High. It might take a little longer to process, but it will get you the best results. Now, when you apply this module, you may find that they processed audio may sound louder than the original. If that's the case, you can use the Makeup Gain slider to reduce the amount of gain applied to the audio so that it more closely matches the original. But, I have the entire audio clip selected here instead of just a part of it so I don't have to worry about a section of the audio being louder than the rest. Therefore, I'm going to leave this Makeup Gain slider exactly where it is. We also have a Post Limiter option, which prevents the audio from re-clipping once it's been de-clipped. The wave forms get extended in the process of de-clipping, sometimes to the point of clipping again, so it's a good idea to leave the Post Limiter on to be safe. Alright, so the idea here is to use the threshold handles and set them just below the points where we can see the clipping occurring. I can see those two lines at the top and the bottom there. I'm going to try to drag the slider so the threshold lines are just inside those points. Notice the two of them move together. Now, if your clipping is asymmetrical, you can click this Unlink button to move them independently. There's also a Suggest button here, and that has the module try to determine the threshold points for you automatically. Let's click Compare and take a listen. Here's the original audio. - [Recording] This is an example of distorted or clipped audio. - [Instructor] And here's with the de-clipped settings. - [Recording] This is an example of distorted or clipped audio. - [Instructor] That sounds a little bit better, but I'm still hearing a fair amount of the clipping. Let's try manually moving the threshold points in a little bit more. I'll try unlinking those, maybe right about there. I'll hit Compare again. That adds all these settings to the Preview window. Again, here's the original. - [Recording] This is an example of distorted or clipped audio. - [Instructor] And here we are with the settings applied. - [Recording] This is an example of distorted or clipped audio. - [Instructor] And that sounds a lot better to me than the original. In fact, if you look at the wave form here, when I click the settings that I just chose, notice those wave form peaks no longer have those flat tops. The De-clip module has tried to reconstruct that missing information. - [Recording] This is an example of distorted or clipped audio. - [Instructor] That sounds much better to me than the result we got with the suggested setting, but again, your results may vary and you may get great results with the suggested settings. I'm pretty happy here, so I'm going to click Process, and now those wave forms are looking much better and more importantly, the audio sounds a lot better too. Again, it's not ideal, and your situation may vary, but if you're stuck with clipped audio with no option to re-record, take some time and run the audio through the De-clip module.