[tempost]

I think you are suggesting a slightly simpler way of droping frames.

FPS reduction proccess:
1.Determining which frames can be droped.
2.Droping frames to reach Forced FPS.

Audio~Video Based FPS reduction/Frame Dropping:
1.Determining which frames can be droped.
2.Calculating how many frames are necessary to drop to reach
Audio~Video Synch.
3.Droping frames to reach calculation results.

While both ways drop frames, the Audio~Video way uses the computer
for reaching the best results + the Audio~Video way isn't limited to any
fixed amount of FPS (23/29) and thus reaches better results (a very slow
computer might need 20FPS while a medium computer might need 26FPS).

Never the less when developing the Audio~Video Frame Droping, the FPS
reduction will be a step for the ultimate goal of not involving the user in
such knowledge required tasks by leting the computer make the best
choice for him.