Blackmagic Forum

I have a PC with resolve 12.5 - 32 meg ram - gtx nvidia 980 4gig system. I use lot's of xavc s codec and noticed the smart cache make scrubbing better but playback worse. I turn it off and playback is fine but scrubbing is terrible. I took a prores 422 clip and added a barn door transition - with smart cache the transition is slow - without it is normal --- seems playback in both cases should be excellent with smart cache on but it is not - and I did check.. the blue bar is there.

I've done some digging in google but haven't discovered anything -

Solved - switched "cache frames in" to DNxHR 444 - HQ .. works like a champ!

If anyone can explain why uncompressed 10bit doesn't do the job please do!

I'd guess that the uncompressed 10 bit is saturating your storage bandwidth when playing back at 1.0 speed. However, when you scrub the timeline, uncompressed needs very little processing unlike XAVC which needs some CPU power to decode.

Thanks - sounds logical - !

So, here's a question I've always had. What impact does the cache file type on the quality of the grade? For example, I you were to key a green screen shot from raw footage, then cached the clip in, let's say prores proxy, would the key look different while grading versus the quality of the key upon final output from the raw.
What happens when you grade from a 422 cache file, then render out 4444 from the raw files. Obviously, the quality of the grade would be less compared to what would be achievable from raw, but how does that transfer of information work when you switch off the cache files, but the corrections you made are applied to raw?
Or, if you are source caching for editing, should you delete your cache for grading (to pull a better key from the raw), then allow caching after grading for better playback.
My head hurts.

Narc - I'm sure (from the way you asked these questions) you already know the answers. Your intuition/common sense provides them for you, and they are right; just stick to them:)

When I started using Resolve not long ago, I had a similar dilemma: my footage usually doesn't need noise reduction, unless I need some stabilization - after zooming into the stabilized clip, noise becomes apparent. But I wasn't comportable about that the noise I see isn't actually in the source footage, but the cached files... I didn't even have to delete them, just switch them off temporarily to see the real noise pattern in the real footage - I would then tweak the NR parameters, and turn cache again but only for the NR nodes. I guess this is exactly how it should be done...

Another example: on Deliver page, you have the option to use cache or optimized media to speed up rendering. Again, common sense suffles to only use them if you final export format is not intended to be higher quality than your cache/optimized media; otherwise render the original footage!

Piotr

But the company's name is blackMAGICdesign. I can only assume from that, that the software is capable of conjuring up more quality than what you put into it.

I guess the my real question is, whether the link between the monitor and the original footage is utterly broken any time you apply caching. With caching enabled, is there any access to the information from the original footage? I almost never use cache files to render out, and I've never seen any noticeable difference between the rendered image and the image within the color page (which is almost always cached in some form). I guess I would have expected to see something break apart by now, when the cached correction nodes are applied to the original footage.
But, like you said, use your gut.

Just cache a short very high quality clip to the lowest-quality format available, and you will see which is displayed.

Piotr

I know this is an old thread but I am having the same problem - scrubbing is fine, playback is terrible.

Solved - switched "cache frames in" to DNxHR 444 - HQ .. works like a champ!

Where do I find the "cache frames in" in Resolve 16.2.7.010. Or is this not relevant any more?

I have set my 'Optimized Media and Render Cache' to 'DNxHR SQ' and ticked all the boxes under that.

Or any other suggestions on how to get playback faster?

Thanks!