[nly]

It doesn't matter either way. If you wish to account for leap seconds then the device that creates the timestamp needs access to that very same database.

The advantage of ignoring leap-seconds on the recorder is you can map any sufficiently precise monotonic clock to UNIX time with a simple linear equation. Personally I think it makes a lot more sense to keep the complexity contained to the decoder, rather than the encoder where bugs could mean you end up not recording an accurate timestamp to begin with.