[Avid-L2] Europe here calling: p50 -> p25 - i25

Hi Avid-L2!

I'm looking into a complex frame rate thing and I am hoping for some input in that brain-cell circulation – please let me elaborate:

TV-Show, European, so we are looking at 25fps and multiples.

OBvan-recordings (2 Shows) @ UHDp50, one of the final outputs has to be 1080i25 (frameblending p50->i25 will do the trick).

However, I guess: we have to make sure all edits are done on the first "field", the even frame in the 50 raster (:00, :02, : 04, …)

Right?

Editing set up UHD (XAVC-300@500MBits, 9 Cams+PGM (clean) transferred via Avid>Transcode -> DNxHR LB 1080p50.

Create MultiClips, adjust drift ISO/PGM = PGM Video/Audio by 1f (in 50 raster) late to ISOs (Switcher on OBVan).

Re-edit Audio-AAF (incoming @ 25 and rounding errors) @ 50fps.

Hand-over that preliminary edit to the editor and tell "Edit timebase has to be 25fps in the p50 project!".

—

Afaik Avid has nor "real" 50 raster TC in the TC display, instead the software goes "." or ":", where the latter is equal to a 25fps fullframe (=upper field if you go down 1080i25. One do not want an edit on ".", the odd framenumber in 50 raster or, for that matter, the lower field in 1080i25 (which is "Upper Field first").

So: if we adjust the MultiClip for the drift on OBVan-Switcher's PGM to ISOs in 50-raster we adjust 1f. Which would be the second half of an interlaced frame. Everything is in sync now: we can switch PGM vs ISOs on their respective occurrence and are indent.

However, editing this kind of a MultiClip into a timeline and then switch each ISO to the Ref-PGM of the OBVan gives us edits (at least: sometimes) which are in the timeline at "." instead of ":" - so switching the project to 25 Editing Timebase will overstep the initial edit by one frame early or one frame late (in respective to the 50 Editing Timebase).

You still follow?

Since, as far as I know, there is no way to select a range of clips an "slip the clips whilst keeping the edits in place" or "move the edits without moving the clip's content with it…

We are doomed!?

-> all edits in the timeline ought to be at a ":"TC place

-> all source material has to be edited at their respective ":" TC

Where is the knot in my brain on this one?

Thanks in advance!

Jochen "Jo" Hermann

filter Media Postproduction

Salzburg, Austria