Why do certain Lumetri creative luts take forever to export?

[Jer T]

For instance the Sl clean straight LDR is giving me an export time of close to 9 hours. I am doing color test exports for a 6 minute film and the others took under half hour each, yet this one for some odd reason...

[R Neil Haugen]

Huh. Just tested that one and it worked the same as the others on my old laptop. That's ... bizarre.

How about some information on your hardware & media?

Neil

[Jer T]

i5 2500k, 16gb ram, cache is on an SSD along with the OS and Program on a seperate one, files are various codecs, AVC, Jpeg and MP4 from a DJI, C-100 and a 1DX Mk 2.

Tried this with another custom LUT I downloaded and it gave super long render times as well. Doesn't make sense why certain ones take so long.

[R Neil Haugen]

Each LUT does different things ... some are more extensive than others, and it's not always easily visible which one actually does more fine-tuning. One LUT that makes a huge visible change may be a simple luminance curve adjustment, basically only an S-curve. Another far more subtle appearing LUT may make tons of targeted changes, and require much more processing.

Another thing ... if this was on say media from the drone or the 1Dx, which both may very well be very long-GOP media, and compared against a clip from say the C-100, you could have a huge hit on processing from the codec involved. Long-GOP media takes many times the processing power that intraframe media (such as ProRes, Cineform, DNxHD/R) requires.

Neil