Controlling Velocity in Vegas Pro
by Gary Rebholz
We've all seen the effective use of velocity changes (slowing down or speeding up the motion) in movies and videos. In fact, in some uses we absolutely take the technique for granted; what would TV sports announcers talk about if they couldn't analyze that last play in slow motion?
I'm guessing that most of you have at one time or another wanted to include slow or fast motion clips in your projects. In Vegas Pro software you can create velocity changes in a few different ways and you really have great control over the speed of the motion in your video. In this article I'll talk about creating velocity changes in Vegas Pro software and give you a few ideas on when to use one method over the others.
Let's start with event properties. The most straight-forward way to change the velocity of a clip on your timeline is to simply change the properties of the event that holds it. Specifically you'll change the Playback rate property. This method works well when you have the event already edited into the video you're creating and you don't want to change the position or length of that event. In other words, you want the clip to take the same amount of time in your project that it takes now, but you want it to play faster or slower.
Figure 1 shows two clips in my timeline. I'll assume you're following along with two similarly arranged clips on your timeline. Don't trim edit the events; just add the clips to the timeline and leave the events at their natural lengths. Notice that there are no indentations in the top edge of the first event. I'll get to the significance of that shortly. Now, let's speed up the motion of the clip.
Right-click the event and choose Properties from the pop-up menu. In the Properties dialog, you can use the Playback rate setting to change the clip's velocity from 0.25 (a quarter of full speed) to 4.0 (four times full speed). Set the Playback rate to 4.0 and click OK.
Figure 2 shows the same events after making this property change. Notice that the event has not changed length and it still occupies the same space in the timeline. However, also notice that now it has several indentations in its top edge to indicate looping points. Play your project to see the results of the velocity change you've made. Since the video clip now plays so fast, it's not long enough to fill the entire event without looping.
Also notice the saw-toothed line running through the background of the event. This line serves as a handy visual indication that the velocity has been changed for this event. Keep in mind that the indentations in the event do not by themselves indicate a velocity change. It's entirely possible to have a video clip playing at normal velocity but still not be long enough to fill the event you created for it. Therefore, you'll rely on the saw-toothed line and not the indentations to identify events that have had their velocities changed.
Right-click the same event again and choose Properties from the pop-up menu. Now, change the Playback rate property to 0.25 and click OK. As you see in Figure 3, the event no longer contains indentations (more proof that you can't identify a velocity-changed event using them). Notice that the saw-toothed line is now much more spread out. You can use the shape of the line to get a general sense of what type of velocity change has been applied to the event: Close saw teeth indicate fast motion and saw teeth that are spread out indicate slow motion. Play your project to see the results.
To summarize this first method, changing the Playback rate property enables you to change the velocity of your clip without changing the size or position of the event that holds it. Naturally, you'll typically make changes that don't necessarily approach the extremes that I used in this example and you'll often be working with events that don't show the entire clip so that if you speed the video up, you won't have to worry about it looping inside the event.
Just keep in mind that when you change the velocity with this method, you change the portion of video you'll see play when the project plays through that event. If you set your rate to fast motion, you'll see more of the video in the time of the event. On the other hand, if you set your rate to slow motion, you'll see less of the video during that time. You'll use this method when the time that the video occupies in the timeline is more important than how much of the video you actually see when you watch it.
Now, what if the time that the video event occupies in the timeline is less important than seeing a specific portion of the video? In other words, say you want to show exactly the same section of the video (that is, you don't want to change the in or out points of the video), but you still need a velocity change. We'll use another method of changing velocity which enables you to change both the Playback rate property and the length of the event simultaneously. With this method you'll change the playback rate and at the same time make the event exactly as long (or as short) as it needs to be in order to preserve the in and out points of the video inside the event.
Before I show you how to do this, use the technique you just learned to reset the Playback rate of the first video event back to its normal value of 1.0. Now, point to the right edge of the first event. You see your mouse icon change to the familiar box with double-pointing arrow that indicates you are in position to trim the edge of the event. While still pointing to the edge of the event, hold the Ctrl key. As you see in Figure 4, now the icon changes to have a saw-toothed line under it. You should recognize that saw toothed line; the line indicates that if you trim the event now, you'll simultaneously change the playback rate of the video inside the event.
Continue to hold the Ctrl key as you trim the right edge of the first event to the left. You can see that as you make the event smaller, the saw-toothed line inside the event grows more compact. This means that the video playback rate is speeding up in order to ensure that the same portion of the video fits into this shorter event as it did before you shortened the event.
After you make the event a bit smaller release the mouse button and play your project. Of course, now you have a hole in your project timeline and if you were doing real work, you'd want to close that hole. Right-click the event and choose Properties again. Here you can see the exact value of the Playback rate setting as a result of your edit. Close the Properties dialog box.
After you've viewed your results, hold the Ctrl key again and trim the right edge of the first event back to the right. Keep going so that it overlaps the second event (which, of course, automatically creates a crossfade). As you trim the event edge to the right, you not only change the length of the event, but (since you're holding the Ctrl key) you also slow down the playback rate. Once you go past the natural length of the event you begin to create slow motion and again the saw-toothed line indicates that. After you've created the crossfade, play your project again and watch the slow motion sequence you've created. Check your event properties again to see your exact playback rate value.
As you've seen, the Playback rate setting enables you to set the velocity of the video to as low as 25% (0.25) of normal speed. But what if you want to go even slower? What if you want to create a freeze frame? What the heck; what if you want to go backward? You can't do any of these things with the Playback rate setting, but you can do all of them with various other tools.
Let's talk about creating a freeze frame for a moment. As you saw earlier when you sped the video playback rate up without changing the length of the event, if the video finishes before the event ends, the video loops and plays until the event does end.
Set the length of the first video event back to normal (just snap it to the beginning of the second event). Change the playback rate to 4.0. Once again, you see the indentations that indicate the video will loop. To create a freeze frame (using the last frame of the video) instead of looping the video, right-click the event and choose Switches | Loop to turn the looping switch off.
Figure 5 shows that now the event has only one indentation in it. This indicates that the video ends before the event does and that the last frame of video freezes to fill the remaining event time. Play your project to see the results.
OK; turn the Loop event switch back on and set the Playback rate property back to 1.0. Now, let's talk about changing the video to play backwards. To set the first video into reverse motion, right-click the first event and choose Reverse from the pop-up menu. That was easy enough! Play your project and when you're done viewing the results, right-click and choose Reverse again to set the video back to normal playback.
While those last two techniques are great shortcuts, they're not always what you need. For instance, what if you want a freeze frame on something other than the last frame in the video? Or, what if you want to put the video into reverse motion, but not normal-speed reverse? Maybe you want slow reverse motion. And we still haven't solved the problem of creating video that goes faster than a freeze frame, but slower than 25% speed. And, as long as we're conjuring up velocity wishes, what if you want the video in an event to play at different velocities at different times? Further, what if you want it to gradually speed up or slow down? All of these things can be accomplished with the most powerful velocity tool of all, the Event Velocity envelope.
With the Event Velocity envelope you have full control over the playback rate of your video and you can create great effects with it.
Right-click the first event and choose Insert/Remove Envelope | Velocity from the pop-up menu. A green line appears through the middle of the event. If you're familiar with other envelope lines (like Volume or Composite Level), you'll be familiar with the tools related to the velocity envelope too. If you don't have experience with envelope tools in Vegas Pro software, don't sweat it; they're easy to learn.
Notice that the envelope line has a point at the beginning. Drag that point all the way to the top of the event. As you do, a ToolTip indicates the new velocity of the event. You also see that indentations begin to appear the faster you make the video. With the Event Velocity envelope, you can speed the video up 300%. (If you also change the event's playback rate to 4.0, meaning 400%, you can set the actual playback rate to 1,200% which is the playback rate of four times faster sped up by the 300% increase in speed caused by the event velocity envelope.)
You can add as many points to the envelope line as you want. Right-click the envelope line at about a quarter of the way through the event and choose Add Point from the pop-up menu. Add another point just to the right of that one. As you add points, you break the line up into individually adjustable segments. Drag the point you just added (the third point on the line) down. As you do, the velocity rate slows. Set the velocity at this point to 0%. If you have trouble hitting 0% exactly, right-click the point, choose Set to from the pop-up menu, type 0 into the text field and press the Enter key. Now the point sits at exactly 0%.
Add another point a bit further down the line, but leave it set to 0%. Finally, add one more point yet farther down the line and drag it down to around -50%. Figure 6 shows my project with the Event Velocity envelope in place. Notice that I've added one more point at the end of the event and set it to 0% so that the event ends up playing at normal speed.
Now, play your project and watch the video as it reacts to the settings of the velocity envelope. Keep in mind that, like changing the Playback rate property in the event Properties dialog box, changing the velocity of the video with the event velocity envelope does not change the length of the event. Therefore, you're going to see more or less of the video depending upon how you set your velocity envelope.
So, there you have several powerful tools for controlling the velocity of your video. And the next time the mood strikes you to put that car chase scene into slow motion or you want to create that Keystone Cops fast-motion effect for the next corporate board-meeting summary video you're asked to deliver, you know how to use the tools that'll help you get the job done easily. Now, whether good taste dictates that you should go for that Keystone Cops effect…well, I naturally have my opinions, but I leave the final decisions in your capable hands!
Gary Rebholz, is the training manager for Sony Creative Software. Gary produces the popular Seminar Series training packages for Vegas Pro, ACID Pro, and Sound Forge software. He is also co-author of the book Digital Video and Audio Production. Gary has conducted countless hands-on classes in the Sony Creative Software training center, as well as at tradeshows such as the National Association of Broadcasters show.