I don’t want to ask a repeated question, so I’ll say upfront that I’ve searched in several places on this subject, but none of them gave me a precise answer to my question. So, I recorded a longplay with OBS at 1080p 60fps and CQP 16, and now I want to render it to upscale it to 1440p (because of the YouTube codec). The only thing I’m not sure about is what CRF I should use. By default, I use CRF 16, but I don’t know if I should stick with 16 or if I can use a lower CRF. My priority is maximum quality; I don’t care about rendering time (the MAXIMUM rendering time I’d like is about 8 hours, i.e., overnight with the PC on) or storage space. And for God’s sake, if you’re going to say “oH, tHeN pUt ThE CRF aT 1,” don’t even bother. One more thing is that the last recording was 3 hours and 20 minutes and ended up being 189 GB. And in total I still have 391 GB free.
What is the export codec? H.264, HEVC, AV1, etc.
The CRF will depend on the codec.
For recording I use the AMD HW H.265 (HEVC) codec, for rendering I use the libx264 codec, but I’m considering switching to libx265.
Below a certain CRF (typically ~16), visual quality plateaus and additional bits mainly increase file size rather than perceptible detail.
Now, here we have 2 problems, you’re up-scaling, and it’s for Youtube, I would say stick with CRF 16
Rule of thumb
- CRF 18 = Sweet spot for quality vs size
- CRF 16 = High-detail or grain-heavy content
- CRF < 16 = Diminishing returns, mostly size
Youtube…
Once the upload exceeds YouTube’s internal quality thresholds… (Youtube did not publish those, though) extra detail is quantized away during re-encoding, grain and dither may be smoothed.
Even when upscaling to 1440p, CRF still matters, but values below ~15 rarely improve YouTube playback quality beyond what the platform preserves.
IMHO > Going below CRF 14 is wasteful, and I would stick with CRF 16.