Years ago I played around with some EBU/SMPTE time code reader electronics, but was foiled by the price of accurate timing test equipment, to make a digital slate.

In the last couple of years  a Rubidium Frequency Reference, the FE5680,  became available cheaply  on ebay.  I can now measure time to well within 0.1 part per million, that’s about 8 milliseconds  a day, or about 1/4 video frame.