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The waveform


show more The waveform provides you with in-depth training on Audio + Music. Taught by Dave Schroeder as part of the Digital Audio Principles show less
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The waveform

The waveform is how we represent a digital audio file visually. You'll see a lot of waveforms when you start working with digital audio. It's basically what we work with the most in terms of editing, changing things around. It shows a couple of cool things. It shows amplitude along a Y axis, and Time along the X axis. The other thing to take note of is the center line or the zero crossing, where the amplitude is above and below. I'll show you a few examples of why. But all waveforms are usually displayed with a center line running through the center of them as a point of reference to use for making edits.

We can look at, as things move away from the center line, the greater the amplitude in both directions, but time is always moving forward. Time is marching on, but amplitude is above and below the center line or point of reference. When you work with digital audio, you'll be working with lots of waveforms. So let's go into Pro Tools real quick, and just take a look and zoom around in a few different waveforms just talk about a few of the different characteristics you might find. So here we are, and we have a couple of different waveforms. We have a Mono track here that's a voiceover, and then a Stereo track, which is a piece of music.

So these two waveforms are the left and right channels of a Stereo track. We also have a waveform that you can see is really smashed up here. It's got really some great amplitude. That's actually distorted. When you see those flat lines, that means that we have a piece of digital audio that's gone beyond digital zero in terms of amplitude, and it's smashed. We'll take a little bit closer look of that in a minute. We also have a waveform that we can tell is a very quiet waveform, because it doesn't have a lot of amplitude in relation. So I just wanted to show you a quick visual of the difference between when you look at something, the relative amplitude on the Y axis, you can pretty quickly identify if something is going to be loud or quiet.

So let's zoom in and just take a look at a few different things, and just see what these look like up close. I'll make them a little bit taller. Let's get a little bit closer even still. So here is looking at a waveform zoomed in very close. You can see here is our center line running down the middle. Here is what we call the zero crossing, or the point where the waveform crosses the center line.

We'll show you later in the editing chapter why being aware of this is important, but in a nutshell it's going to help you make quiet edits. Let's go to the beginning. You can just see that waveforms just have a lot of different shapes. When you see these higher quicker peaks, you know that might be a quicker sound, when you see a longer thing like this that could be a longer word. If this is a voice-over track, that might be someone saying, wait now, wait now.

Let's zoom in on the really loud one, and the really quiet one, take a look at it--it might look like it's just zoomed way in, but you'll see that it was actually really flat. If I change that visual look, and scale it up here by making the zoom different, we can see that it's still really flat there, and that we still have a lot of flattening out. That is distortion. That's a bad thing. We don't really want to see that. For making recordings, we're getting a lot of that square flattened off look, we're recording things way too loud.

Now hopefully things like peak indicators and the fact that it sounds pretty terrible and hard to listen to will give you that indication. But who knows maybe sometimes someone will send you a file to work with, you'll get it, and it will look like that. If you bring it in, and you noticed it's the flat-top style, you're going to want to try and get that file again or get a different recording of that information, because it's pretty hard to work with things that are flattened out that much. Now if on the other hand if you get an audio file that's too quiet, you can always go ahead and turn it up.

It's not ideal to work with audio files that are very quiet. We really want to take advantage of the full dynamic range, and work with as loud the sounds as we can without getting to distortion, but we'll talk about that in another movie as well. So that's a quick tour of waveforms, and what they look like. I just wanted to give you a quick tour, and a little birds eye view, you'll be seeing tons of these throughout this title. If you're starting to work with digital audio, you'll be dreaming about them. You'll see so many of them. What's so great about the waveform is that they give us such quick visual information about the sound we're working with. So that allows us to do things pretty quick.

The old days of rewind and fast-forward, and let's listen back, they still exist but not quite the way they used to. You can be pretty efficient and pretty fast in terms of looking at a waveform, and going right into the area you want. For instance, if I know I want to take out some gaps or some silence, I know that this is a quiet passage, I can go in there and start to work out right away, as soon as I open the file. So waveforms are really helpful in terms of the way you work with sound. In the next movie, we'll take a look at the different audio file formats that you'll encounter when you work with digital audio.

The waveform
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The waveform provides you with in-depth training on Audio + Music. Taught by Dave Schroeder as part of the Digital Audio Principles

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Audio + Music
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