Timeline: Cookin' with Keyframes (page 2)

Keyframes become crucial with audio manipulation. Let's say we have a song we are using as a sound bed under an interview. When the interviewee is speaking, we want to lower the gain of the music, and when the speaker is silent while b-roll is playing, we raise the gain of the music. For example, in the beginning of a video, we see a montage of images, without voiceover, so we have the music at a relatively loud -6dB of gain. Two seconds before the speaker utters her first words, we set a keyframe. We then forward the playhead two seconds to position the playhead a couple of frames before the speaker begins talking and set a second keyframe. Now we advance the playhead to a couple of frames after the speaker completes her monologue and place keyframe number three. We advance the playhead an additional two seconds and place our fourth keyframe. The line representing the level of the monologue or the woman speaking is a straight line with four keyframes on it. Now we take our selection "arrow" tool, click-n-hold keyframe number two, pull it down twelve decibels to -20dB and release it. We move the selection tool over to the third keyframe and do the same. We have now dropped the level of the music while the interviewee is talking and raised it again when she is finished. This is "rubber banding." Imagine you had two pushpins stuck in a board, and you put a rubber band around them both, connecting them. Bring a third pin in between them, pull the rubber band down about an inch and push your pin in. Remember the map and the red yarn?

Keyframes pinpoint a group of variables not only with editing programs, but also with compositing programs such as After Effects and animation programs such as Flash. You will also see them used with compression, defining variables in a single frame to reference future frames, but this is an explanation for a more advanced article. So get into your editing "kitchen," find the "cupboard" where your program stores your keyframable goodies - your video, graphics, filters and audio - and start cooking.

Contributing editor Morgan Paar is a nomadic producer, shooter and editor, making documentaries worldwide.

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