tl;dr Converting MJPEG to HEVC took 75 hours, what gives?
I am in the process of archiving some 4K footage that was shot on a Canon 5D Mark IV (Motion JPEG) to HEVC. The goal is to reduce these massive MJPEG files to a manageable size for cold storage. I just finished encoding a roughly 45 min interview that was originally 75GB down to 4.3GB. Really good compression, but it literally took 75 hours for this export to complete.
Does anyone know if this is just because of the inefficiency of the MJPEG? Or should this encode take less than 3 days?
First and foremost, please tell us about your computer hardware, as the answer may lie there.
Also, are any effects at all being applied to source, or is this a straight transcode of material?
I've never encoded to HEVC before, and am not on my high-performance editing machine right now, but did just attempt on a Core i5 office computer as a test. An 8-second AVCHD clip took about 17 seconds to encode, so about twice real time. Then figure at least 4x slower for 4K since image it is 4x larger than HD, so I guess that makes 8x longer than real time to encode. That still doesn't explain the 75 hours, unless the computer is severely under-powered or there are maybe some effects filters involved.
Also - I see posts like this all the time -"my render took 3 days". A word of advice, if you see that happening - ABORT and seek help sooner rather than later, could be an easy solution to reduce render time. That is typically not normal for any kind of render and I can't imaging having my machine tied up that long.