QuickTip: Fixing Noisy Sound Clips with Audition

Hi again,

One of the commonest problems on any film shoot is poorly recorded sound.  Often sound levels are too low meaning a lot of 'gain' has to be added to make the sound louder.  Alternatively, faulty equipment or a bad recording environment can ruin the sound.  Either way you can end up with very noisy audio which can be very distracting.

Luckily there have been major improvements in sound processing tech which mean (some of) these problems can be fixed.  For example, Adobe Audition has powerful noise reduction filters which can rescue badly recorded sound.  Here's how you do it:

First, import your noisy sound clip into Audition:

You'll see a standard 'waveform' sound display.  Its sometimes easier to see the noise damage by turning on the Spectral Frequency Display by pressing SHIFT D

The example sound file is a ticking clock.  The 'Ticks' are the tall spikes in the frequency display.  The noise shows up as grainy dots all over the background.  Before Audition can remove the noise, you have to tell it what the noise sounds like by selecting a section of the clip where there is only noise and no 'foreground' sounds.  Press T to turn on the Time Selection Tool then drag out a box on the sound between two sound peaks.

With just the noise selected, go to Effects > Noise Reduction / Restoration > Capture Noise Print or press SHIFT P and Audition will analyse the noise to identify specific frequencies.

Once you have a noise print, select a bigger portion of the clip, one including the recorded sound and go to Effects > Noise Reduction / Restoration > Noise Reduction (process) and a new window will open up.

Press the Play button in the bottom left of the new window to listen to the processed sound.  The filter will only affect the section you have highlighted.  By pressing Play a few times, you can listen to the whole sound to get a 'before' and 'after' of the noise reduction.  If the sound is really noisy, you can adjust the sliders to remove more or less noise but remember that overdoing it will start to make the sound 'tinny' and synthetic.  Once you are happy with the result press the Select Entire File button, then click Apply and the sound is fixed; just save it back out to your Final Cut Pro project folder and import it back into Final Cut and you're done!

P.S. Audition is only installed on the iMacs in DMW 4 (room G123b)

QuickTip: Sweetening Sound Effects

There are a few rules you have to follow when editing audio.

One of the most important is that you should always cut sound clips on a 'Zero Crossing'.  What's a zero crossing? -- well, digital sound is just a series of numbers, CD sound for example is stored as numbers ranging from -127 to +127.  The number Zero is the same as silence.  The further away from zero the number values get, the louder the sound.

In most programmes, audio waveforms are drawn with Zero along the middle of the track, with +127 at the top and -127 at the bottom (assuming you're using CD quality sound).  If you zoom right into the waveform, you'll see that the sound wave goes up and down passing through Zero over and over again.  In the screenshot from Final Cut Pro 7 below,  Zero happens to be along the dark purple line and a single frame of video is highlighted in black:

Each point where the waveform passes through Zero is a 'Zero Crossing' and this is where you should ideally cut the audio.

But there are a couple of problems.  Firstly, FCP 7 only lets you make cuts exactly on video frames.  Chances are there won't be a zero crossing exactly at the beginning or end of the frame.  The next problem is that wherever you have two sound clips together that don't both start and end at Zero, you'll get a nasty 'click' on the sound track where they join.  So how to fix this?

The easiest and most effective way is simply to add a subtle 'Fade-In' and 'Fade-Out' effect to every single Sound FX clip.  That way you can guarantee that every clip will start and end on Zero and there will be no chance of getting a glitch on the sound track.

You could use audio transitions from the Effects menu to add the Fade-In and Fade-Out but there is another way which is worth knowing about.  Make sure you have clip overlays turned on and put a Fade-In and Fade-Out on one clip like this.

Next select the clip and go to Edit > Copy

Now select all of the other sound effects clips by pressing A for the arrow tool and drawing a box around them in the timeline.  When they are all selected, go to Edit > Paste Attributes

The Paste Attributes window will open up.  We only want to copy and paste the 'Levels' keyframes we put on the first clip.  We also want to make sure that the keyframes are squashed or stretched to the length of the other clips otherwise they might drop off the end of the clip.  Make sure "Scale Attribute Times" is ticked and then tick "Levels" as the only attribute we want to paste:

Click OK and you should end up with Fade-In and Fade-Out on every Sound FX clip with no more worries about bad clicking on the audio track.

QuickTip: Normalising Sound Clips

In this quick tip I'll be reviewing the workshop session from last week about 'Audio Sweetening'.

A very common problem in post-production is editing together sound tracks with different volumes or 'levels'.  Sound recorded on different shoots or with different equipment may be louder or quieter than they should be.  You could adjust the levels on each clip until they match -- but there is a better way.

The Normalisation Gain tool will analyse the sound volume and automatically adjust the levels so that the volume is constant through-out your edit.  Here is how to use it:

In the timeline select all the clips you want to fix

You can see from the waveforms that the volume of the sound in each clip don't match.  Next go to Modify > Audio > Apply Normalization Gain

A small window will open which allows you to set the target volume in decibels (dB).  Your dialog track should usually be set to around -12dB.  Move the slider to -12bB and click OK.

If you play back the edit the sound levels should now match with no really loud or really quite dialog.  The waveforms in the timeline haven't changed though.  That's because the Normalize Gain tool doesn't alter the sound directly, instead it adds a Gain Filter to the sound.  This means the changes aren't permanent and each clip can be easily adjusted if you want.  Double click a clip to open it in the Viewer and click the Filters tab to see the Gain Filter settings:

Remember, negative dB values make the sound quieter, and every 3dB doubles the effect.

QuickTip: Audio Mixing in the Timeline

One more Final Cut quick tip today guys!

You probably know that you can fade audio tracks in or out by adding a "Fade" effect to your clips in the timeline.  But you can do the same thing much quicker by using Clip Overlays and Keyframes.

You can turn on Clip Overlays by pressing the Toggle Clip Overlays button underneath the timeline.  The keyboard shortcut for this is ALT and W.  When you turn this option on, Final Cut puts a pink line over the audio tracks.  The pink line is a volume control for the sound clip measured in Decibels (dB).  Pulling the line down with the mouse will make the whole clip quieter and pushing it up will make it louder.  Even better, you can also adjust the volume of parts of the clip by adding keyframes to split the line into sections.

To add keyframes to the volume, turn on Clip Overlays then select the Pen tool from the tool box by clicking on the icon at the bottom -- it looks just like the Pen tool icon in Photoshop.  The quickest way to activate the Pen tool is to press the P key.  Switch back to the normal mouse pointer by pressing A for Arrow.  If you hold down the Pen icon you'll see that there are actually three versions of the tool.  For now you'll only need the standard Pen but once you've mastered that, play around with the others to see what they do.

Once you have the Pen activated, just click on the pink Clip Overlay line to add keyframes.  If you want a fade in or fade out, you'll need at least two keyframes -- one to set the clip's normal playback volume and one to turn the volume down to silence.  When you're measuring volume in Decibels, silence isn't Zero like you might expect.  Instead silence is defined as minus Infinity Decibels.  Put two keyframes near the end or begining of the sound clip then press A to turn the Arrow tool back on so you can pull the line up or down.  Moving the line sections nearest to the ends of the clip down to -inf dB (minus Infinity) will create a Fade-In or Fade-Out Effect.  You should see that the line makes a smooth curve from the playback volume down to silence.  This gives the best sounding fade effect, but you can set this to go in a straight line if you want.

Fade-In and Fade-Out added to a clip by using Keyframes in the Timeline

QuickTip: Timeline Overlays

Hi again,

Here's a very quick tip for customizing the timeline in Final Cut.

You can show your video and audio clips visually in the timeline by using the Timeline Layout Menu.  Click on the small, right pointing arrow below the timeline to open the Layout Menu.  The top two options are off by default.  "Show Audio Waveforms" will draw the sound waves in the green audio tracks.  This gives a really quick visual guide to spot things like audio peaks.  "Show Video Filmstrip" will add still frames along the whole video track giving a quick way to spot where the action is.  It can sometimes make the edits hard to see though so you'll probably want to switch it off occasionally.

Turning on both options makes the timeline look like this:

QuickTip: Resize Final Cut's Timeline

Here's another quick tip for Final Cut that will make all your editing work easier.

While you're editing your movies, you'll spend most of your time working with Final Cut's Sequence Timeline.  By default, the timeline shows you the minimum you need to edit your clips and sound track, but there is a lot more information that can be shown.

The basic timeline looks like this:

Along the bottom of the timeline window are some really small buttons which control the display

Timeline Track Height

 This little panel controls the size of the video and audio tracks in the timeline.  Selecting the different sized boxes makes the tracks taller or smaller.  You can also press the SHIFT and T keys to cycle through the different track height settings.



Clicking the tallest box makes the timeline look like this:

You can zoom into the timeline to focus on a  few shots or zoom out to get an overview of the whole sequence.  There are few ways to zoom.  First, you can use the Zoom Slider control at the bottom of the timeline.  Moving the small grey pointer to the right zooms out, showing you more of the edit and moving to the left zooms in to focus on a shorter time period.

Zoom Slider

There are also keyboard shortcuts for the same thing.  Pressing the CMD key and = together zooms in while CMD and - will zoom out.  If you have a Mac laptop, you can zoom in and out by doing a two finger 'pinch' gesture on the trackpad just like on an iPad or iPhone.


Zooming in completely lets you see individual frames of video which is really useful if you have an 'orphan' frame left between clips caused by a messy edit.  Final Cut draws a dark grey highlight over the time code strip of the timeline representing one frame right next to the play head like this:

The final way you can zoom in and out of the timeline is to use the tags at each end of the window sliding bar at the bottom of the timeline.  Pulling the tags apart stretches the sliding bar showing more you more of your edit (zoom out).  Pushing them together does the opposite.

Window Slider: Use Left and Right Tab to Zoom In and Out

QuickTip: Using Sound FX

Final Cut Studio comes with an extensive library of sound fx which are installed on the Macs in the workshop.  They come as "Core Audio File" or '.caf' files.  The easiest way to find them is to use the magnifying glass tool in the top right corner of the menu bar and search for the .caf file extension:

Click on "Show All" to browse through all the available sound effects

Double click the effect you want to open it in Soundtrack Pro and select 'Save As' from the file menu to export it as an AIFF file:

Finally copy the new file to your EditShare project folder and import it into Final Cut and you're done!