Apple Final Cut Pro X Forum
Rendering files
Rendering files
by Joe Lukus on Aug 14, 2017 at 10:05:08 pm

Ok when you render a clip it creates a apple prores file correct? or does it just create its own type of readable "system file"

Basically what I am wanting to know is once you render a file were is it? if it is a prores file then I could just use that instead of having to "export" a whole other prores file!?
Or is this not how it works?

Thanks!


Re: Rendering files
by Jeff Kirkland on Aug 14, 2017 at 11:04:34 pm

FCPX renders in the flavour of ProRes you specify in the settings but it's in it's own format - lots of little chunks that aren't useable by anything else and may only represent a small section of the timeline - which makes sense because otherwise if you made a change that affected just a small portion of a clip, FCPX would have to re-render the entirety of the clip rather than just the section that changed.

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Jeff Kirkland | Video Producer & Cinematographer
Hobart, Tasmania | Twitter: @jeffkirkland


Re: Rendering files
by Joe Lukus on Aug 14, 2017 at 11:36:55 pm

Perfect thank you very much! That was what I was wondering! IF it created a useable file (prores file) from a selected rendered clip I choose to render off my timeline or it uses its own type of files like you mentioned.

I did find out just a bit ago that if you export a prores file it seemed to render in secs! So I am guessing it used all those little bits of rendered files to use if you export?!


Re: Rendering files
by Simon Billington on Aug 15, 2017 at 10:37:34 am

In a way there seems to be some redundancy to how FCPX renders versus what it exports, especially if its in the same format. I'm not sure as into what's going on as I'm not on the development team, but my guess is it's one of three things...

1. Since ProRes is a form of compression, even if it's lossless, it may involve quite bit of decoding and re-encoding just to update a specific change. It may have a negative impact on the performance. So FCPX just renders the file fully instead

2. Final Curt was designed to work largely with proxies and different media formats in a relatively transparent way. Because it is possible to work with footage in format and render out in another, it may not have been a thought for the developers to allow a "through" method when editors are outputting the same method they are editing in... I certainly wish the did though!!

3. It may actually be possible to achieve more effecting rendering when outputting in the same format as you edit, but the devs either never thought of implementing it, or maybe its just not high enough on their list of priorities.

It's always worthwhile leaving them some feedback if you wish for this type of feature. They do read them. I actually got a response from a dev a few weeks back concerning a hideous bug i uncovered with Logic. The fact that anyone responds, is a rarity though, especially if you are just requesting a feature.


Re: Rendering files
by Joe Marler on Aug 15, 2017 at 11:44:53 am

[Simon Billington] "there seems to be some redundancy to how FCPX renders versus what it exports, especially if its in the same format....Since ProRes is a form of compression, even if it's lossless, it may involve quite bit of decoding and re-encoding just to update a specific change. It may have a negative impact on the performance. So FCPX just renders the file fully instead.... It may actually be possible to achieve more effecting rendering when outputting in the same format as you edit, but the devs either never thought of implementing it, or maybe its just not high enough on their list of priorities."

In general FCPX does "smart rendering", IOW if the timeline (or portions thereof) are already rendered, it does not blindly re-render that when exporting. This is regardless of whether the timeline is H264, ProRes or H264 which was transcoded to optimized media, and regardless of whether export codec is H264 or ProRes.

This can be easily seen by applying a simple color correction effect which causes the timeline to go non-rendered, then exporting it immediately, then after pre-rendering it (CTRL-R). Whether using optimized media or H264 and whether exporting to ProRes or H264, it exports faster if the timeline is pre-rendered.

This doesn't mean that pre-rendering should be the standard practice or that background rendering is required. In general FCPX exports so fast that these usually aren't needed. However if the timeline or portions of it are pre-rendered, then FCPX will use that during export and not blindly re-render it.

There may be more complex effects cases where this isn't done but in general FCPX uses smart rendering.


Re: Rendering files
by Walter Soyka on Aug 15, 2017 at 6:55:37 pm

[Joe Marler] "There may be more complex effects cases where this isn't done but in general FCPX uses smart rendering."

Here's a little more on FCPX and smart rendering:
https://forums.creativecow.net/thread/344/24302#24364

I believe that FCPX copies raw frame data (versus re-encoding pre-rendered media on output) wherever possible.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


Re: Rendering files
by Simon Billington on Aug 15, 2017 at 11:19:37 pm

Oh yeah. of course it rerenders only sections in the timeline and is quite efficient at it. I was referring to rendering on output.

However, I do maintain the original point... if your project is, say set at ProRes 422, by the time you've done with it you already have a rendered version somewhere in cache. In theory to output at 422 there is almost nothing for FCPX to do, in theory, so output should only take a few seconds, no matter the length.

Contrary to my earlier point on closer inspection, I actually realise this is pretty much what it does do. I'm not entirely sure it has always done this though. I seem to recall different behaviour in the past. The fact that it does do "through" style rendering is enough. That's the most intelligent thing to do in this situation.




Re: Rendering files
by Doug Metz on Aug 17, 2017 at 2:54:11 am

[Simon Billington] "...if your project is, say set at ProRes 422, by the time you've done with it you already have a rendered version somewhere in cache."

Not necessarily. You can disable background rendering, and many do (myself included). Even with multiple formats / frame rates, I don't need or want to render everything during edit. There are cases where I'll render a small section if I'm retiming with Optical Flow or if I've just got too many layers stacked up to play smoothly. For me, those instances are infrequent. More often with compressed 4K footage than anything.

Doug Metz

Anode


Re: Rendering files
by Simon Billington on Aug 17, 2017 at 8:32:21 am

I think you're missing my point here. I was speaking of a hypothetical situation, that can exist from time to time, but more often than not, it doesn't for various reasons like you described.

The example was IF youre whole timeline existed in cache as ProRes 422 and you did output as 422, in theory it should just export straight out in a few seconds.

I live in the real world too, and I know it's an unlikely situation, but it can happen.


Re: Rendering files
by Doug Metz on Aug 17, 2017 at 1:23:37 pm

[Simon Billington] "I think you're missing my point here. I was speaking of a hypothetical situation, that can exist from time to time, but more often than not, it doesn't for various reasons like you described.

The example was IF youre whole timeline existed in cache as ProRes 422 and you did output as 422, in theory it should just export straight out in a few seconds.

I live in the real world too, and I know it's an unlikely situation, but it can happen."


My apologies, Simon.
I didn't miss your point - just wanted to fill in the gaps for those who may not know. Lots of good info here.

Doug Metz

Anode


Re: Rendering files
by Simon Billington on Sep 7, 2017 at 12:38:53 am

All good. Miscommunication is always bound to happen from time to time.





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