Any source in the Timeline can be moved or resized easily. In addition to dragging sources between tracks, they can also be moved to a new location on the same track. The duration of a source can be changed by several methods.
To move a source to a different location on the same track, simply select it with the mouse and drag it to the desired location. Press the Shift key while dragging with the mouse for smooth movement. You may also select the source and move it by tapping the Right or Left arrow keys. (Each tap moves the source by ½ second.) Keep the Shift key pressed if you want the movement to be slower. (Each shift-tap moves the source by 1/10 second.)
Multiple sources can be moved together in the same track or in different tracks relative to one another. For instance, you can move two videos, say clip 1 and clip 2, present in the video 1 and video 2 tracks respectively. The two videos can be moved in their respective tracks while maintaining their relative positions with respect to one another. Select the desired tracks by clicking on them while holding the Ctrl key. Now move the sources together using the arrow keys on the keyboard. This is very useful when the alignment of two videos or the video and audio streams of the same media file is to be maintained while moving them.
Note that neither dragging nor using the keyboard will move a source unless there's an open area on the timeline to move it into.
To resize a source, use the mouse to grab the triangle at the top right hand corner of the clip and drag. This will change the duration of the clip. Whenever you resize a clip, the speed at which the video or audio is played, changes.
For example if an audio clip is 10 seconds long and contains 20 beats of the drum, 2 beats will be audible every second. If you change the duration of this clip to 5 seconds by dragging it, you will hear 4 beats in a second. Technically this is called as a pitch shift.
If the duration of a video file is reduced, it will play faster than normal and if the duration is increased, it will appear to play in jagged slow motion. Thus, resizing sources drastically is not a good idea. However it is an easy way of changing the speed of the media that is being played in that clip.
You may select multiple sources and resize them together. This helps when video and audio belonging to the same file needs to be resized.
When you have more than one source on a track, then resizing one of the sources will not affect the position of the other sources. Their original position with respect to the Timeline remains the same. To view the time duration for which the source will be active, simply move the mouse pointer over the source.
You can also resize a source by selecting the Resize Sources button on the Timeline. See the figure given below.
You can then change the Selected Clip End time of the source, which lets you set the duration in exact numbers.
If you have resized the source and do not like the effect, you may restore it back to its original size (duration). Just select the media clip and choose Edit > Restore Size.