Based on the Target Frame Rate set in the Isadora Preferences, the is a fixed amount of time per frame in which Isadora must complete that rendering process. The LOAD indicator tells you how much of that time is being used to execute all active actors in all active scenes.
When the LOAD indicator is between 0 and 100%, then Isadora should be able to render video at the requested Target Frame Rate. When the LOAD goes over 100%, then Isadora will start dropping frames because your hardware cannot keep up with the demands you are making on it.
There can be many reasons for this happening: playing too many movies at once, executing a large number of video effects on high resolution video, recording the stage to disk, extremely complex GLSL shaders and more.
If you encounter this situation, you should try reducing one of the above factors if possible, e.g., playing less movies at the same time, etc.
If you can't remove actors from the scene, then try reducing the resolution of the videos you are playing in the movie player or processing with effects.
HOW IS THE LOAD CALCULATED?
Let's say you're running at 25fps; that means there are 40 milliseconds between each frame.
(You can calculate the number of milliseconds available per frame by dividing 1.0 by the frame rate and multiplying by 1000. For our example, 1.0 ÷ 25.0 * 1000.0 = 40.0 milliseconds).
- If it takes 4mS to execute all of the actors, the LOAD indicator would show 10% because 4mS is 10% of 40mS.
- If it takes 30mS to execute all of the actors, the LOAD indicator would show 75% because 30mS is 75% of 40mS.
- If it takes 44mS to execute all of the actors, the LOAD indicator would show 110% because 44mS is 110% of 40mS.