AVFoundation variable to constant frame rate question

Some video composition instructions are “tweened”, meaning that they produce different output at different times, even if the source frame did not change. So it’s important that those be rendered at all the multiples of the frameDuration. The video composition processor interrogates video composition instructions to see if each containsTweening to figure out whether this is necessary. If not, and if the frame duration of the composition is lower (= higher frame rate) than the source tracks, it may skip rendering, which you could think of as dropping frames — frames that would be duplicates anyhow.

The video composition processor interrogates video composition instructions to see if each containsTweening to figure out whether this is necessary. If not, and if the frame duration of the composition is lower (= higher frame rate) than the source tracks, it may skip rendering, which you could think of as dropping frames — frames that would be duplicates anyhow.

So in other words, if I understand you correctly, AVFoundation guarantees constant frame rate conversion for variable frame rate videos -- both in playback and rendering. Correct?