Using Keyframes: Changing Effects Over Time

What's really exciting about these last few video effects?as well as most others in the Video Effects palette?is that you can change the characteristics of the effects throughout the duration of your video clip.

You accomplish that by using keyframes, which work something like the volume-control red rubberband handles. You place keyframes (little diamond icons) on a line in the expanded view of the video (or audio) clip and instruct Premiere as to what to do with the selected effect at those keyframes. Most video and audio effects will make changes gradually from one keyframe to the next.

Task: Try Out Keyframes on an Audio Clip

I want you to try this effect first on an audio clip:

  1. Drag an audio-only or linked audio/video clip to the timeline.

  2. Select the audio clip.

  3. Expand the audio track by clicking the triangle next to Audio 1.

  4. As you did in Hour 5, "Adding Transitions: From Dissolves to Zooms," note the four icons in the lower-left area. I've highlighted them in Figure 11.5. Select the keyframe gray/white diamond icon, which brings up the keyframe line in the expanded view beneath the audio clip.

    Figure 11.5. Expanding the audio track reveals four icons: Display Waveform, Keyframes, red volume rubberband, blue fade rubberband.

    graphics/11fig05.jpg

  5. Open the Effect Controls palette. It should have your audio clip's name at the top.

  6. Locate Echo in the Audio Effects/Reverb & Delay file folder and drag it to the Effect Controls palette (or to your clip on the timeline).

Applying an audio effect to your clip causes three things to happen on the timeline. I've highlighted them in Figure 11.6:

  • The name of the audio effect (Echo) pops up in the keyframe track.

  • The Keyframe Navigator appears. It's a little check box with two arrows on each side (although they sometimes don't pop up onscreen right away) to the right of the four icons.

  • Square boxes appear at each end of the keyframe track.

Figure 11.6. Adding an audio effect displays its name in the keyframe track, pops up the Keyframe Navigator, and places two keyframe boxes in the expanded audio track.

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The Keyframe Navigator (the check box with two triangles) lets you move easily from one keyframe to another. The two boxes mark the beginning and end of the effect. Now, here's the next set of steps to follow:

  1. In the Effect Controls palette, slide the Echo slider way to the right to make a really obvious echo.

  2. Grab the left keyframe box and drag it to the right.

  3. Grab the right keyframe box and drag it to the left. Your clip should look like Figure 11.7. What you've done is to tell Premiere to start the Echo audio effect somewhere in the clip (not at its very beginning) and end the effect somewhere before the clip finishes.

    Figure 11.7. Moving the keyframe start/end boxes sets new in/out locations for the Echo effect within the audio clip.

    graphics/11fig07.jpg

  4. Play the clip and note when the echo kicks in and when the audio returns to normal. Note that you can click the Keyframe Navigator triangles to jump the edit line from the start to the end of the effect.

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Consider how you could use this. Perhaps you want your narrator to suddenly have a booming, echoing voice. To create that, follow these steps:

  1. Move the edit line to that spot in the clip.

  2. Make two adjacent handles on the volume red rubberband (this lets you keep the volume at its original level right up to the booming/ echoing segment).

  3. Raise the volume of the entire second half of the clip by dragging up the rubberband to the right of the second handle using the Fade Adjustment tool (the up/down-arrow tool in the Audio section of the toolbox).

  4. Add the Echo audio effect to the audio track.

  5. Click the Keyframe icon next to the red rubberband icon to open the keyframe track.

  6. Drag the keyframe start box to that location?meaning the volume increase will coincide with the Echo effect.

Voila?booming audio.


Task: Use Keyframes to Change an Effect Over Time

The real power of keyframing is to change an effect over time, not simply to switch it on and off somewhere within a clip. Here are the steps for this task:

  1. Turn on keyframes by going to the Effect Controls palette and clicking that little empty gray check box next to the effect name, Echo. Take a look at the keyframe track. Those start and end boxes just changed to gray/white diamonds. Keyframing is on. I've highlighted the differences in Figure 11.8.

    Figure 11.8. After keyframes are turned on, the white boxes in the expanded timeline track change to gray/white diamonds.

    graphics/11fig08.jpg

  2. Note that the gray/white color scheme has a purpose. The white side of the diamond indicates where the effect begins or ends.

  3. Drag those diamonds closer to the start and end of the clip to give yourself a little more room.

  4. Select the "start" diamond by clicking the left triangle Keyframe Navigator icon in the expanded audio track. Note that if you drag the edit line ahead of the start diamond, the Echo effect "grays out" in the Effect Controls palette, indicating the Echo effect is nonfunctional at that location on the clip.

  5. Set a low Echo value on the slider in the Effect Controls palette.

  6. Move the edit line to the center of your clip. Change the Echo value slider to a much higher number. By changing the value at a new location on the keyframe line you automatically create a new keyframe.

    graphics/bookpencil_icon.gif

    Changing the Effect value places a white diamond on the keyframe line at that point. That's the new keyframe. You can grab it and slide it to change its location.

    Scrub the edit line back and forth along the audio clip and note how the Echo value on the slider gradually changes as Premiere interpolates the Echo value difference between the two points.


  7. Add one other Keyframe using a different method. Simply drag the edit Line to a new location within the audio clip and click the Keyframe Navigator check box between those two triangles. This adds another keyframe with an Echo value set automatically at whatever it would have been as the value changed gradually between two other keyframes.

  8. Use the slider in the Effect Controls palette to adjust that Echo value.

  9. Listen to your keyframed audio clip. The echo should become more pronounced as the clip plays and then gradually fade away at the end.

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To delete a keyframe, simply select it by using the cursor (wait for it to turn to a gray hand) or by jumping to it using the triangles next to the Keyframe Navigator check box. Then click (uncheck) that check box. Alternatively, you also can delete a keyframe by dragging it off the ends of the keyframe line. This works only if that keyframe is the first or last in a sequence. If it's between two other keyframes, you can drag it only as far as a neighboring keyframe.


Using Keyframes on Video Effects

The process is almost the same for video effects, with two minor exceptions.

Remove all clips from the timeline and expand the Video 1 and Video 2 tracks. Note the differences highlighted in Figure 11.9.

Figure 11.9. Video 2 has only two options and Video 1 has none.

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Video 2 has two option icons in the lower-left corner: keyframing and the ubiquitous red rubberband. In this case the red rubberband does not change the audio volume; instead, it alters video transparency. You can create a translucent clip and layer it over whatever is in the track(s) below it. I'll cover transparency in detail in Hour 14, "Compositing Part 1: Layering Images and Clips," and Hour 15, "Compositing Part 2: Alpha Channels and Mattes."

Video 1 has no options. That's because there is only one thing you can do to a video clip on track 1?add video effects to it. You cannot change the transparency of a clip on Track 1 because you can't superimpose it over a clip beneath it?it's in the lowest track. Therefore, there's no need for a red "video transparency" rubberband.

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In all video and audio tracks are two check boxes in the upper-left corner (I've highlighted them in Figure 11.10): the eye (video) and the speaker (audio) icons indicate those tracks will be visible/heard when you play back the timeline. Clicking them removes the icons and turns off those tracks. You might do that if you want to listen to a specific audio passage on a track or see how a video clip looks without another clip superimposed over it.

Figure 11.10. Click the eye or speaker icon to exclude or include a track in the program. Click a track's lock icon to prevent any changes. Note the highlighted locked-track cursor.

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The other current unchecked box locks/unlocks the track. Locking a track ensures you can make no changes to it, including adding or deleting clips.

To see how this works, lock a track and move your cursor over it. It changes into an ominous black arrow with a padlock on it. I highlighted this in Figure 11.10.


Task: Try Out Video Keyframing

To see how video keyframing works, follow these steps:

  1. Drag a video-only or linked video/audio clip to the Video 1 track on the timeline.

  2. Drag the Crystallize video effect (from the Stylize file folder) to the Effect Controls palette. As Figure 11.11 illustrates, the same three things that happen when adding an audio effect happen with a video effect: The name of the effect appears in the expanded video track, the Keyframe Navigator box appears, and two white squares appear at the ends of the clip in the expanded view.

    Figure 11.11. Adding a video effect displays its name in the keyframe track, displays the Keyframe Navigator with its two triangles, and puts two keyframe boxes in the expanded video track.

    graphics/11fig11.jpg

  3. In the Crystallize Settings window, select the smallest cell size (3) and click OK.

  4. To see the Crystallize effect in action, Alt/Option-scrub through the clip or do a real-time preview by pressing Shift+Enter.

  5. Click the Keyframe check box next to the clip name in the Effect Controls palette. This turns on keyframes and causes those two boxes in the expanded Video 1 track to change to diamonds (at the moment, because they're at the ends of the clip, they look only like triangles).

  6. Move the edit line to some point toward the middle of the clip and increase the Cell Size value to something such as 40. This creates a new keyframe.

  7. Preview/render your clip to see how this works.

Your video clip transitions from a lovely postimpressionist painting to a screen full of animated solid-color polygons and then back to that lovely painting again.

Sometimes, even with keyframes, the video effect's changes can be abrupt. Try using keyframes with the Replicate Video effect.

You know the drill:

  1. Remove the Crystallize effect from your clip.

  2. Drag Replicate (from the Stylize file folder) to the Effect Controls palette.

  3. Turn on keyframing.

  4. Select the lowest Count value (2).

  5. Move the edit line to the center of the clip and change the Count value to its highest value (16). That creates a keyframe.

Render/preview or Alt/Option-scrub to view your handiwork. No gradual changes here. The image jumps with each change in box number.

For now this concludes this hour's coverage of keyframing. In Hour 12, "Using Higher-Level Video Effects," I'll cover a whole slew of exciting Premiere video effects that benefit from keyframing. Before moving on, here are the Premiere video effects that do not allow keyframing:

Anti-Alias? This effect is found in the Blur file folder. Just as anti-aliasing in transitions blurs sharply defined diagonal lines, this effect softens the edges between highly contrasting colors.

Black & White? Found in the Image Control file folder, this effect converts color clips into grayscale.

Facet? Found in the Pixelate file folder, this effect creates the oil-painting look.

Field Interpolate? Found in the Video file folder. This is a technical fix, not a creative tool. It re-creates missing scan lines dropped during capture.

Gaussian Sharpen? Found in the Sharpen file folder, this effect is supposed to dramatically sharpen a clip, but it looks more like the Crystallize effect.

Ghosting? Found in the Blur file folder, this very nifty effect creates a "comet tail" on any moving object (including camera moves). It's great for showing the flight of a thrown/hit/kicked ball. A steady camera is a must.

Horizontal Flip? Found in the Transform file folder, this effect reverses a clip left to right but still plays the clip forward. Use it if you "broke the plane" while shooting a cutaway.

Resize? Found in the Transform file folder, this effect takes lower-resolution clips and fits them into your output frame size. I found it gives unpredictable results.

Sharpen Edges? Found in the Sharpen file folder, this effect looks just as odd as Gaussian Sharpen. Apparently it's only effective for very soft focus clips.

Vertical Flip? Found in the Transform file folder, this effect flips clips upside down.

Vertical Hold? Found in the Transform file folder, this effect makes your clip look like the vertical hold is out of whack.



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