How to speed up render times

Posted by DM 
How to speed up render times
August 06, 2012 10:39AM
Need advice on the most effective way to speed up renders

What is the main cause of slow renders?
Working with 1080 XDCAM and HDV formats. However, the projects are up to 2 hours in length. Final render times are killing us. Medium amount of effects.

1-nor enough RAM.
2-Drive access speeds?
4-All of the above

My system is non-raid, internal drive and FireWire 800 based

Mac Pro dual quad core
6 gigs of RAM
4 internal drives. 1- system, 2-media, 1-pro tools
Re: How to speed up render times
August 06, 2012 07:06PM
FCP7 can only use 4GB of RAM, so it's not that. Internal drives can be slow, but the firewire should really be quick enough too. It's most likely the fact that you're working with HDV and XDCam, which are processor intensive in FCP7 - had you converted them to prores before ingest?

Re: How to speed up render times
August 06, 2012 08:30PM
Hi Jude,

Funny you should mention that about HDV.

I have a confession. I convert ProRes files to HDV for editing. Then I conform back to ProRes for final delivery.

Here's why:

Using an 8 Core (2 x 3 Ghz Quad Core Intel).
Final Cut 6.0.6 on System 10.6.7.
Internal 7200rpm drive - not the drive on which either the system or FCP reside.
I also rendered to a different drive than the one with the original footage.

HDV 115mb camera file for the first test and a conversion of that same file to ProRes 422 using MPEG Streamclip for the 2nd test.

I timed the renders of an FX Factory plug in called "Spotlight multiple" which gives a very serviceable impression of a 1980's disco and that always cheers me up.


Test with 115mb HDV file: Zero minutes and 52 seconds.

Test with 115mb ProRes 422 file: 5 minutes and 9 seconds.

That's a big ol' difference. It's 6 times faster to render that shot in Prores.

Prior to testing and between tests, I closed down the Mac for 3 minutes, then started up and trashed prefs. And - yes - I did use the correct codecs and settings for Project and Sequence files.

I am not in love with HDV and have no axe to grind.

So that's my dirty little secret to speeding up rendering time in FCP.

Best wishes,

Re: How to speed up render times
August 06, 2012 10:11PM
Well no.. on the conversion. U think that's a significant speed up? I guess so?
Re: How to speed up render times
August 06, 2012 11:37PM
Obviously different solutions will be more tolerable depending on how involved your show is and how much footage is involved. Your description makes it sound like you are using two different codecs in your timeline. Which is always a problem because one will of these codecs will need to be rendered anytime anything is done to it.

A: cut in the codec used more often, or maybe it might be better to just use the XDcam, as using mpeg will require re-encoding of any Mpeg file with even just a fade.

B: If your mostly cut, export a quicktime in XDCAM put it in the timeline, and add to it. That way every little trim wont require a new render.

C: Media manage just the mpeg footage. Then hide the old footage and re-point. It actually might be better to do this with compressor as you could leverage multiple processors. And Media manager can do some retarded things to names of files.
Re: How to speed up render times
August 07, 2012 03:59AM
HDV is approx. 25 Mbps, while ProRes 422 is approx. 145 Mbps, so a fairer comparison of rendering times would be HDV vs. ProRes Proxy (approx. 45 Mbps).

HDV is interframe compression while ProRes is intraframe. Speculation: when the effect to be rendered requires decoding and recoding all frames -- denoising is an example -- the interframe is disadvantageous. Speculation: when the effect to be rendered does not require decoding and recoding all frames -- color change is an example -- the interframe is advantageous.

Dennis Couzin
Berlin, Germany
Re: How to speed up render times
August 07, 2012 04:21PM
Well, sounds like Pro res LT is the solution. Will try it on the next round. Thx to all for the replys
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