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Jim Krause | Classes | P354/J560 Program Graphics & Animation

Lab 8


  • Reminder: Look at Midterm Projects tomorrow/Thursday
  • Working with Audio & Video
  • AE Quiz next Tuesday! It will be similar to the Photoshop quiz. (Will not cover 3D)

If you need some audio/video clips for today's exercise you can download these (AV folder) and these (AV2 folder).

Audio ------------------------------------

After Effects is not suited for editing sound, but offers some useful tools for animation.

Importing - Be sure to copy your audio into your local media folder *before* you import it. After Effects sometimes does not work well with compressed audio files (eg. MP3s). If you run into playback errors, try using uncompressed PCM (digital audio) formats (WAV or AIF).

Playing back audio - AE can output through any hardware you have attached to your computer. If you can't hear anything, go to AE's preferences and check your Audio Hardware.

After Effects doesn't always play your audio when you hit the spacebar or do a RAM preview. You can force an audio preview by pressing the period key on the extended, numeric keypad. This sacrifices video playback in order to perform an audio preview.

Layer Markers are useful for marking audio events (boings, bass hits, drumbeats, etc.). Even when the layer is collapsed, the markers are still visible.

Audio waveforms can be seen by twirling down the audio layer.

Try This:

Import some audio into your project and into your timeline. Then you can twirl down the audio layer's arrow button to expand the view until you can see levels. Note you can set keyframes and adjust the volume. If you view the audio monitor you can also set levels and keyframes there as well.

  • Try previewing the audio. (period key on the numeric keypad)
  • Tap the asterisk key while it's playing to set layer markers.

Audio Spectrum and Audio Waveform are two cool effects you can use with sound. Note: Audio Spectrum and Audio Waveform effects must be applied to a layer other than the audio. Solid layers work well for this.

If you want to use Audio Spectrum or Audio Waveform:

  • First, import an audio layer in your comp.
  • Then create a new solid layer.
  • Apply the audio effect to the solid layer. (Effects -> Render -> Audio Spectrum / Audio Waveform.)
  • In the Effect controls, make sure that the "Audio Layer" pull-down selector is pointing to the audio layer.
  • Experiment with the controls (Max height, thickness, color etc).

In-class Audio Spectrum and Audio Waveform Exercise

  • Start with a 1920x1080 comp, 15 seconds long, called "audio"
  • Import some audio
  • Create 2 solids (one for each effect)
  • Adjust the parameters (height, fill, color, etc.) to create a pleasing and dynamic effect
  • Add some text to Identify/label the effect (or use text of your own choice.) Please treat/format your text with some care/thought.
  • Turn in an H.264, ProRes422, or MP4 movie (with audio) to the appropriate Canvas assignment.

Working with and outputting video

While After Effects is not video editing software, you can still do basic trimming and a number of interesting video effects. (Yes, if you really wanted to, you could edit video, but it's not well suited for this.) However, manipulating video and compositing video with animations and other elements is one of the things that After Effects is best known for. It's also a good tool for making looping motion menus for DVDs.

Importing video - Be sure to copy your audio into your media folder before you import it. (Don't import video from temporary places like Downloads or Desktop.)

Trimming - Clips can be trimmed in the Timeline or in the Layer Window. Import a video clip into the Timeline. Slide the layer to the right a little so it doesn't start at 0. Double click the clip in the Timeline to open the layer window. The display shows 3 sets of counter numbers: in point, out point and duration.

Position the Layer window so you can see the Timeline. Note the in and out points in the Timeline. Move the time indicator somewhere near the beginning of the clip and press the in-point button. The duration value in the Layer window updates accordingly and the clip slides forward in the Timeline.

Now try dragging the triangular handle in the Timeline. This is another way you can move in and out points.

Pressing the left bracket [ button re-positions the layer to begin at wherever the time indicator is. With video clips, it will reposition the layer's in point to the current time indicator.

Slip Edits - Once you have a video clip (or any other layer that changes over time) in your Timeline, you may want to slide the video around without messing up your in and out points relative to the Timeline. In other words you want to do a slip edit.

Position the video clip so you can see the in and out points. Select the Pan Behind tool from the Tools palette and position the pointer over the video clips. It changes into a left-right arrow. You're now in Slip mode. Try dragging the pointer to the left and right with your video clip layer selected. It slides the clip around while retaining the in and out points relative to the Timeline.

Time Stretching

Time Stretching is easy in After Effects. As with most effects, there are a number of ways you can access it.

  • With the layer highlighted in the Timeline, select: Layer -> Time Stretch to open the Time Stretch window.
  • Control click or right-click on the headings in the TImeline and turn on Stretch (If it's not already on). Stretch values will appear in the Timeline. Click on one to open the Time Stretch window.

In the Time Stretch window you can either enter a value other than 100% or make a new duration.

Note that you can also select a different item to hold in place other than the Layer in point, (which is the default as it's what we usually expect when we enable slow motion or fast motion).

Note: Time stretching is NOT a good way to change the duration of still images.

Time re-mapping

Time remapping is a bit more interesting than simple time stretching. You can use it to vary time and the rate in which motion changes occur.

To use it first import a comp or a video clip. (something with movement)

The, highlight the layer and select Layer -> Enable Time Remapping.

Expand the layer's arrows to show the time remapping controls. You'll see two keyframes. One at the start of the clip, the other at the end.

What the numbers mean:

The number next to Time remap shows what frame is being displayed.

Value Time: The max is the length of the movie file. The value line is a visual cue as to what parts are playing and if they are playing forward or backward

Velocity time: The middle number is the important one. It shows how fast the movie is playing and if it’s going forward or backward (uses a minus sign for backward) The numbers at the top & bottom simply show the maximum time change used.

Try adding a couple keyframes in the middle. Then you can slide the time values up and down, or the keyframes left and right.

Frame blending - Each frame of a 15 FPS animation or movie will be duplicated in a 30 FPS comp. Some movements might not appear as smooth since frames will be repeated. Frame blending interpolates between the different frames. While it is a good thing to use- it takes longer to render. Click the box under the movie frame icon to turn it on.

Gradient Wipes - You can duplicate many popular wipe transitions with the transition tools. To use these you'll need to set two keyframes, one at the beginning of the transition and one at the end.

Interpret Footage - When importing interlaced video, After Effects usually guesses the field order correctly, but occasionally gets it wrong. If your video is stuttering or showing interlacing lines, try checking the field order. This is specified in the interpret footage window. To get to the interpret footage window, right click on the footage in the project window and choose main-> interpret footage.

In this area you can set parameters such as how the alpha channel is straight or premultiplied, the number of loops, etc. If you need to, you can go back and change them later. It's important to select the right field order (upper or lower) or your video clips will stutter. Whether you should use upper or lower field first is determined by the particular hardware of the video editing system. One thing to remember is that most HD video is upper field first. DV and most legacy firewire-captured video is lower field first.

Adobe's guide to field rendering for interlaced formats.

Once useful parameter in this area is the loop __ times function. If you want a movie to loop, simply bump the number from 1 up to something higher.

In-class "Time" Exercise:

  • Find two short video clips to work with.
  • Make a comp that matches their pixel dimensions and frame rate, about 20 seconds long. (You can name it "time.")
  • Make sure both video clips are in your comp
  • Apply an obvious time-remap to one clip and time stretch to another.
  • Insert a wipe of some type between the 2 layers
  • Using on-screen text, identify/label the time effects and wipe you used.
  • Render out a an MP4, H.264, or ProRes422 movie and upload it to the Canvas assignment called "time".



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