generate/draw timecode from image number

[uzer_name]

It is often need to burn timecode and other data to proxy/dailies (mainly h264 mov), converted from DPX/EXR/whatever sequence, numbered by timecode->framenumber.

But timecode currently could be added manually only via "timecode="xx:xx:xx:xx"
It could be good when will exists some option like "timecode="sf", so timecode could be generated from image sequence startnumber. It could help alot if batch converting alot of sequences with adding TC/framenum overlays.

Or/Also from embedded TC in DPX.
Also could be good if it will be added formatting string for "frame_num" variable (like %05d or so).
Also could be good to have absolute framenumber variable from image sequence, and sequence/image name variable.