My situation:
- Transcoding 1080p bluray videos to HEVC. Audio untouched;
- My rig is old (pre-2012) and to speed up the process I'm using
--preset ultrafast
; - From x265 documentation, I understand that video quality is independent of the preset used. And the slower the preset, the better the compression ratio it seems;
- I'm using FFmpeg.
My Reasoning:
- I want to start converting to HEVC now because the codec is good enough for me and the space saving is phenomenal;
- I've seen people reporting a 35GB video compressed to 1GB or so with
crf=18
and--preset veryslow
. It sounds ludicrous but an experiment of my own shows about 40% additional space saving between presetsultrafast
andveryslow
.
The Question:
When I get a new rig with a more capable CPU (Skylake or later, I hear), is it possible for me, to "re-compress" my HEVC videos using eg. --preset veryslow
, without quality loss due to encoding a second time?