Chroma-keying Using Adobe Premiere Pro

Premiere Pro GlyphThis tutorial covers how to use Adobe Premiere Pro to merge your BS4TV data video with your track video. The technique, in a nutshell, involves importing both video tracks, putting them in the timeline, setting the blue screen options for the data track, then sync'ing the data with the action in your video.

Creating your track video using Adobe Premiere Pro CS4 is pretty straight-forward and is very similar to the procedure you would use for earlier versions of Premiere Pro. Here's the step-by-step on how to do it.

Contents

  1. Create a New Project
  2. Import the Videos
  3. Apply the Blue Screen Effect
  4. Sync the Blue Screen and Video Tracks
  5. Preview the Video
  6. Trim the Ends


1. Create A New Project

Start up Adobe Premiere Pro 2 and open new project. When a new project is created you will also be prompted to create a sequence. The sequence options should match that of your video.

New Premiere Project

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2. Import the Videos

Import the BS4TV data video and your track video clips, then place the blue screen video in the Video 2 track of the timeline and the track video in the Video 1 track. The screen shot below shows what everything should look like. Note that the blue screen track is showing in the preview panel (top-right). Click it to see it full size so you can examine the timeline and preview more closely.

Import the videos

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3. Apply the Blue Screen Effect

To apply the blue screen effect locate the Blue Screen Key, which can be found in the Effects Panel under Video Effects, Keying. Drag this effect to the blue screen track, then examine its settings in the Effects Control Panel. The screen shot below shows that the blue in the BS4TV track is now transparent. Adjust the threshold and cutoff to obtain the results you are looking for. In this example the threshold was set to 50% to allow the video to show through the navy-colored regions of the title and gauge bars. Click the image to view it full sized.

Adjust the blue screen settings

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4. Sync the Blue Screen and Video Tracks

Sync the blue screen and track videos. To do this you simply move the tracks along the timeline, relative to each other, until the sounds and action in the video track match the numbers in the blue screen track. Start with a signature event like your initial acceleration as you are pulling out of the pits. As the car starts moving and the engine sounds rise, the longitudinal G's and RPM numbers should increase. Adjust the timeline to get these events to be reasonably close to each other. Then, to improve this synchronization, look further down in the timeline to where you shift. In this case the car's sound will be your key. Fine tune the synchronization by matching the change in engine sound with the change in RPM. That should do it, but you may want to move even further down the timeline, even to the end, to make sure everything still matches up.

The screen shot below shows how I did this for the demo video. I previewed the video and located the first shift coming out of the pits by the sound. I then expanded the audio track so I could see the audio amplitudes and could see the first dip after the initial, gradual and steady rise. (I didn't try sync'ing to all the throttle play done before the car really got moving.) I then zoomed in on this region of the timeline so I could see things better, then moved through the timeline looking for a sharp drop in RPM. I found a 1000 RPM drop, then moved the video track to match these up. (Click the image to see it full size.) All this only took a couple of minutes.

Sync the tracks

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5. Preview the Video

Preview the whole video to check the results. Pay attention to your shifts and other notable events that should show up in the GTech Pro's data and make sure everything matches up. If at the start of the video everything looked great, but 5 or 10 minutes later, not so, then most likely the videos are not playing at the same rate. The speed for each clip can be adjusted as needed to fix this.

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6. Trim the Ends

Finally, trim the ends of the video. For instance, if you started recording data before you started recording video, then trim off the extra parts of the blue screen track. The same goes for the end of the video, unless for some reason you'd like to continue the data replay in your video, say, while the credits run. The screen shot below shows how the blue screen track starts before the video track does. I trimmed this off and moved everything to the beginning (time=0), then checked the other end of the video and trimmed that, too.

Sync the tracks

That's it. Your data and video have been merged. Now you can create a second sequence where you can edit the video. Copy the merged video sequence to the new sequence and trim out the boring parts and splice the clips back together again, add titles, graphics, music, then export it.

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