Results tagged “basics” from Final Cut Studio, Avid, Adobe, and Video Streaming

During Editing

You've laid down your sequence, you've got your clips sounding consistent relative to each other - now you should check for peaks.  In Final Cut, this is as simple as picking Mark Menu -> Audio Peaks -> Mark.  Markers will appear above the sequence anywhere there's a peak.  Now, you could just pot down the gain on those clips, but if you do that you'll lose the consistency between your clips' audio levels.  So instead, you can hack out the individual peaks themselves.

You can do it by hand, or you can do it with a single step in Soundtrack Pro.  Read on ...

During Shooting

The first step comes while you're producing your footage in the first place: if you happen to be a one-man show and you're doing your own taping, be absolutely sure to check your audio levels on your camera as you're shooting.  Most cameras can be set up to show some kind of audio meters on their display; as a last resort, though, almost all will let your plug in headphones and listen for gross distortion.

Ever seen your audio meters go into the red?  Marked those unsightly peaks in your audio?  Heard the raging distortion that happens when somebody shouts into a mic?

Just as a computer thinks of video as a set of images, it thinks as audio as a whole lot of "snapshots" of this sound wave - tens of thousands of snapshots every second.  Each of those tiny little snapshots reflects the energy of the sound wave at that point.  Now, the human ear is capable of hearing frequencies that repeat up to about 20,000 times per second (20,000 Hertz).  Because of some fancy math, we have a rule of thumb: if the computer taps in to the sound wave twice as many times as the highest frequency we want to represent, it will describe the sound fully for us.  That's where the most common full-quality sample rates - 44,100Hz and 48,000Hz - come from.

I'm going to shift gears into discussing ways we can enhance the audio on our videos.  In order to do this, we should take a whirlwind tour of how computers think about audio.

Application: Fonts and Vector Images
Antialiasing also has something to do with why fonts and vector images always look good, even if they're really big or really small.  Actually, fonts are vector images, so that's a bit of a strange thing to say - but at any rate, vector images are simply a set of mathematical equations that describe the curves that make up a shape.  So, like the real world, the computer can "look at" these images with infinite precision.  Therefore, it knows enough about the shapes to behave like our eyes do, and approximate the way we would see the fonts and such if they didn't have to be on a quilt of pixels.

Application: Photoshop
One place where this knowledge might help you think is in Photoshop, especially if you're designing for compositing software or DVD production.  Say you're doing a glass bug for your video: did you notice the anti-alias checkbox when you used the Magic Wand tool?  That checkbox means that the computer will actually select fractions of pixels on the edge of the selection it shows - "blurring" the selection boundary in the same way that it did to the red channel in the example reproduced below.

We know antialiasing best as "smoothing" the jagged edges that any digital editor will eventually happen across.  Why do we need to antialias, and where do aliasing artifacts come from in the first place?  The answer is a little mathy, but we'll bring it down to size.

Whether you're using titles, creating supers, or doing any other sort of compositing, you're trying to tell the computer to show some parts of an image but to hide other parts.  

I've been surprised by the number of folks who were never really taught how that process works from the computer's point of view.  After the jump, an easy little primer that may help you understand --