[Ricardo Guerreiro] “But changing the speed this way, with Frame Blending unchecked, will probably not re-incorporate the lost frames (assuming a 50% speed change) which was what I wanted, or will it? “
I just tried it and you’re right, FCP won’t restore the excised frames. Pity.
However, it took me less than 10 seconds to open the clip (ProRes 720p60) in Cinema Tools, click “Conform,” choose 29.97, close Cinema Tools, reimport the clip into FCP and voila – it played at half speed in a 29.97fps timeline perfectly with no dropped frames. It’s trivial, really.
It is not at all difficult to use Cinema Tools. In your particular case I suppose it is because you shot HDV, which is a long-GOP format not supported by Cinema Tools. I’m not bashing you for using a consumer format – XDCAM ad AVCIntra users are in the same boat. In your case it would benefit you to capture your footage as ProRes instead of HDV. It will be less processor intensive to edit, and it will be trivial to reconform in Cinema Tools should the need arise.
I assume that FCP handles 60p footage in a 29.97 timeline the way it does because 99% of the time, users just wants everything to play back in a way that looks consistent. Slow motion fluidity (when not done by using VFR overcranking in-camera) is not a primary consideration. In defining format behavior, Apple will most likely attempt to support the most common scenario first.
I would encourage you to submit your feedback to the Apple development team for consideration.