I have a huge collection of video files that are in the range of CRF 16-20 taking up TB's of space. The only need I have for these originals is that I have to encode them from time to time but the CRF of these final encodes is very low (CRF 26-28).
I understand that a lossy to lossy conversion ALWAYS results in some quality loss but my question is what if the intermediate file is almost visually lossless compared to the final output.
So to sum up, what quality difference should I expect from the following routes?
CRF 18 (original) -----> CRF 28 (final) CRF 18 (original) -----> CRF 22 (long-term storage) -----> Lossy CRF 28 (final)