The navigation features of the Viewer and Compositor behave very similarly. Each has a timebar and slider below the video output. The timebar and slider are critical for navigation.
The timebar represents the entire time covered by the program. When you define labels and in/out points it defines those, too. Finally the timebar defines a region known as the preview region.
The preview region is the region of the timeline which the slider affects. The slider only covers the time covered by the preview region. By using a preview region inside the entire program and using the slider inside the preview region you can quickly and precisely seek in the compositor and viewer.
When you replace the current project with a file the preview region automatically resizes to cover the entire file. When you append data or change the size of the current project, the preview region stays the same size and shrinks. Therefore, you need to resize the preview region.
Load a file and then slide around it using the compositor slider. The insertion point in the main window follows the compositor. Move the pointer over the compositor’s timebar until it turns into a left resize pointer. The click and drag right. The preview region should have changed and the slider resized proportionally.
Go to the right of the timebar until a right resize pointer appears. Drag left so the preview region shrinks.
Go to the center of the preview region in the timebar and drag it around to convince yourself if can be moved.
Note: When you append data or change the size of the current project, the preview region stays the same size and shrinks. Therefore, you need to resize the preview region.
Preview region in compositor
If you go to the slider and slide it around with the preview region shrunk, you will see the slider only affects the preview region. The timebar and slider in the viewer window work exactly the same.
Labels and in/out points are fully supported in the viewer and compositor. The only difference between the viewer and compositor is the compositor reflects the state of the program while the viewer reflects the state of a clip but not the program.
When you hit the label button in the compositor, the label appears both in the compositor timebar and the program timebar.
When you select a label or in/out point in the compositor, the insertion point in the program window jumps to that position. To scroll your video and thus move the insertion point into the visible part of the timeline, use the manual go to button of the compositor.
Labels and in/out points in the viewer.
In the viewer and compositor, labels and in/out points are displayed in the timebar. Instead of displaying just a region of the program, the timebar displays the entire program here.
Like the program window, the compositor has a zoom capability. First, the pull-down menu on the bottom of the compositor window has a number of zoom options. When set to Auto the video is zoomed to match the compositor window size as closely as possible. When set to any other percentage, the video is zoomed a power of 2 and scrollbars can be used to scroll around the output. When the video is zoomed bigger than the window size, not only do scrollbars scan around it but middle mouse button dragging in the video output scans around it. This is exactly when The Gimp does.
Furthermore, the zoom toggle causes the Compositor window to enter zoom mode. In zoom mode, clicking in the video output zooms in while ctrl-clicking in the video output zooms out. If you have a wheel mouse, rotating the wheel zooms in or out too.
Zooming in or out with the zoom tool does not change the rendered output, mind you. It is merely for scrutinizing video or fitting it in the desktop.
Playing video on the compositor when zoomed to any size other that 100%, the original size, requires Cinelerra to do extra processing steps. This could affect performance on slower systems.