Can you measure the actual wavelength depending on if pair production occurs or not?

We know that pair production only occurs when the photon when the photon wavelength is 1.21 picometers or higher (or higher than the sum of the rest frame energies of the electron positron pair). Furthermore, we also know that the relative velocity with which you are moving to an emitter affects the frequency of the photon that you observe. However, if I observe both that the wavelength is higher and that pair production has occurred, does that mean I can deduce that the actual wavelength of the photon was lower?

Apologies if the question doesn't make sense.