Created attachment 178110 [details]
python script

When running a gnlcomposition with two video sources and a gnloperation containing a mixer to control the transition from one source to the other, at certain framerates and at the very end of the transition to the second source, the first source will flash a single frame over the second source.

The attached python script shows the problem. In this script, the framerate is set to 30000/1001. The first source runs from time 0 to 5 seconds. The second source runs from time 1 to 6 seconds. The mixer runs from time 1 to 5 and a controller sweeps the alpha of the second source to create a 4 second fade from the first source to the second source. If you watch closely, you will see that at the very end of the transition (at time 5 seconds), that the first source flashes what appears to be a single frame. You have to watch closely at time 5 seconds to see it. If you change the frame rate (for example to 30000/1000), then it does not happen.

The python script is completely self-contained and should run for you without any issues.

Is this a problem with time quantization in the scheduler in gnonlin? Or am I doing something wrong?