A question about memory and exporting

A thought occurred to me about the way I export finished videos.

Most of my work until recently, however long the end result, was made up of short pieces of video and/or animation using extensive filters and ending up between 5-15 minutes in length. Recently I’ve been working in a different style involving single large video files with chroma-key. When I export a ten minute video it may be cut down from about 20 minutes of the original source file which is around 4GB and chroma-keyed throughout against a static background. That ten minute file can take 90 minutes or more to export, whereas the same length video taken from shorter pieces with multiple effects may take 15-20 minutes.
I have 16GB of RAM on board and use 64bit OS & SC versions.

My question is - when I export the completed video - is the source video file(s) held in memory or is it being read from the HD as it is encoded? I ask because I keep all my primary files on one HD so I am writing onto the same disk the source file is held on. Consequently it might make my export times better if I output to a different drive to the one I’m reading from. If it’s exporting from RAM to the HD it shouldn’t make a difference, I would have thought.

Absolutely not in the case of audio, video, and image sequences. Only the file handle and some structures used for reading and decoding are held in memory. Still images are held in memory.

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Thanks for answering :slight_smile:

@shotcut beat me to an answer but I will say I’ve seen measurable changes moving from a single SSD workflow to a dual drive workflow with the project/imported files on one drive and the export moving to a second.

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That’s exactly why I asked. I’ll give this a go in a couple of days when I’m working on the next one.

I know this isn’t the most complete test(I’ll rerun it with a few more drives and such later) but This is just some quick exports on my current system. I have two primary work drives an older pcie OWC unit and an array of 1tb SATA drives in raid 0, writing from pcie to the dual sata saved me about 8 seconds on average to the dual sata but that’s only on a 2 minute export, a longer test should show a bigger gap as would systems that are even more storage bound(the dual sata raid isn’t exactly slow on it’s own i’ll throw a mechanical drive in at some point) These tests were done on a dual socket xeon desktop and are not cpu bound at this point.

Desktop refrence

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