4K Scrubbing

H

Hand Crank Media

Member
I'm shooting on a Panasonic G7 (4K footage, pretty much identical to the GH4), which will play back just fine in the Premiere. The problem starts when I scrub the footage, it is not smooth at all and is nearly worthless for editing. Lowering the playback resolution to 1/4 or 1/8 does nothing to help. For test purposes, I actually downloaded some 4K and 6K Red Scarlet footage and to my surprise they played and scrubbed without issues (I did have to lower resolution to 1/4). Is the main issue the h.264 codec used by the G7?



Here are my hardware specs:
CPU: Intel Core i7-5820K 3.3 GHz

RAM: 24GB DDR4

GPU: Geforce GTX 750Ti 2GB 128-Bit GDDR5

Motherboard: MSI X99A SLI Plus



I'm also using separate SSDs for my OS, Scratch, and Footage drives.



Is there any obvious weaknesses in my hardware setup?
 
I'm on a 2009 Mac Pro 8 core so we are somewhat talking apples to oranges a bit but ill share a few things that I've experienced when working with 4k.

- SSD dramatically helped with getting up to about 360MB/sec (samsung EVO 850). you already have a SSD setup so things are similar. with my regular HD's it wasn't as good as some of them are in the low to mid 100MB's. i can only imagine a RAID might be the game changer if i wanted to actually edit natively in 4k.

- I'm currently on a GTX Titan X (12GB) prior i had a GTX780 or earlier a GTX680. this didn't seem to play into the issue you are having but once you start putting "effects" on your video in "4k" then the more you have the better for real-time and smooth playback or scrubbing. it seems like in 4k adding any effects starts to quickly create stuttery and funky scrubbing.

- the "codec" i use helps a lot. if i transcode media to ProRez on my Mac then things are smoother than an mp4, H.264 or AVCHD for instance. in 4k its sooooo much easier to reach the "stuttery" computer performance issues so in my experience so far....i convert to ProRezLT or ProRezHQ. in the PC platform i don't know what the equivalent would be but I'm sure someone here will chime in.

i don't work much in 4k yet but i have played and tested a bit. it seems like if i plan to have 2-6 layers of video in 4k i just don't think it will work with what i have especially since i like to pile on Lumetri effects which sucks down a lot of my Titan X 12GB GPU.

I've read and seen the new Adobe CC promo (to be released early summer) that it will create "proxy" media upon ingest and let you freely switch back and forth between your original 4k, 6k or 8k media and back to your "proxy" at a flip of a switch all you want. it seem to me the obvious solution for me and i think many others will be to mostly edit in "proxy mode" which they say even light weight computers will handle easily. i don't know what kind of file=type their proxy format will be. like i said on my Mac its usually some for of ProRez which is all friendly to work with and ProRez Proxy being small in file/size so friendly to not take up space on HD's.

on a comparitive note..Davinci Resolve...
to edit in 4k they say at least a "4GB GPU" to get started and recommend more if you plan to get "node" heavy. reading on their forums it seems more like a 6GB GPU is preferred and many heavy users have multiple GPU's. in PP CC 2015 some processes use CPU where many of the optimized plugins use dominantly the GPU's. RAM i guess comes into it somewhere but never seems like much of a factor to me. I've got 32GB's which is probably an average amount i think.

my post is a bit scattered and i can't really answer specifically to your system but rather give a little input what I've experienced going from 1080-4k so far. i tend to read a lot here on dvxuser but there doesn't seem like there is a lot of frequent activity on many of the forums. you might want to check out the Adobe forums as well.

good luck!
david
 
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Codec is a big factor in how smooth the playback will be. H.264 is very compressed codec, great on space saving (and hard drive throughput) but requires additional power from the CPU. Two things I can recommend:

1. Transcoding your footage to a a less compressed codec. This will make more use of your SSD but take the burden off of your CPU/GPU.

2. Switch over to software playback engine and keep it at 1/4 resolution. With compressed codecs, this will often playback better than hardware/GPU playback at 1/4.
 
I have lower specs than that and my 4k H.264 footage scrubs fine in FCP X. A shot in the dark but do you have Perian installed?
 
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