[Wylug-discuss] Linux-specific buying advice - system purely for video editing/encoding/rendering

[Dave Fisher]

Thanks Paul,

I really appreciate your advice on this.

On 18 June 2010 20:46, Paul Brook <paul at codesourcery.com> wrote:
> I'd expect a video editing machine to have significantly different
> requirements from an encoding machine. Video editing software generally don't
> do edits on the fly. Instead they save a list of editing actions, then perform
> the edit/encode actions as a batch process.

I take your main points, here, but human editors do have to look at
the pictures in order to create clips, and set in and out points in
the edit list/s.

I've used several film industry offline editors  ... and they all
depend on being able to scroll visually and quickly through scenes.

> Your editing machine is likely to want fast disks, and lots of memory so that
> you can cache large amounts of the source file as you're moving around. Lots
> of CPU cores aren't likely to help a lot here. Given your description of the
> source material I wouldn't expect the graphics card to make a whole lot of
> difference. Even the most basic graphics card should be more than sufficient
> for video playback.

I've got several "most basic" graphic cards, and they are all
incapable of scrolling *quickly* back and forth to edit points.

I'm currently wasting vast amounts of time, just getting to exactly
the right frames that I need to cut at. None of my current systems can
play large high bitrate HD without judder.

>> 1. How much, if any, benefit can gained by adding cores or individual CPUs?
>
> I'd expect your best strategy to be having one encode job per core.  Splitting
> a single encode over multiple cores tends not to scale so well. Sounds like
> you have lots of separate videos, so this shouldn't be too much hassle. With
> this proviso, I'd expect performance to scale with number of cores.

That's what I've found on a simple 2-core machine. It's good to have
my observations confirmed.

> Machines with more than one CPU socket incur a significant price premium.
> If you want more through put than you can get from a single CPU then you're
> probably best going with a cluster of single-socket multicore machines. Gig-e
> is fairly ubiquitous nowadays, and should be more than sufficient for video
> transcoding.

Useful suggestion. I'm all Gig'd up already.

I've seen a few reviews that suggest that although the new AMD 6-core
CPU performance doesn't look great against the quad-core Intels, they
are competitively priced.

Given the aim of reducing the need for personal interaction, it might
be nicer to have 6 encoding queues running more slowly than 4 queues
going faster.

> Avoid Atom based machines if you care about CPU performance.
Oh yes.