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Adobe Premiere Pro - Advanced Training

Clearing cache & scratch disk for faster editing in Premiere Pro

Daniel Walter Scott

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Everyone, we are going to learn what Media Cache is, and what a Scratch Disk is, and how we can bend them to our will, and make our editing process faster. 

So first up, what are the differences between the two, because they get lumped together all the time, because they do a very similar job. Media Cache is a bunch of files that Premiere Pro create in the background, without you knowing or asking, to help it run nice and fast. For example, when I bring in, say this mp3 here for my music, Premiere Pro goes, I hate mp3s, they don't run very fast when they're editing, and it could try and do it with the native mp3, but it would be slow and jumpy, and we'd blame Premiere Pro, but it's a super compressed file. 

So what it does in the background, is it makes another file, in this case, a cfa or something, that it loads and uses for us, we don't know that, that process is happening, but that file gets created in the background, for us to have our editing flow be nice and smooth, thank you, Premiere Pro. So that happens with a bunch of different files, it creates lots of little mini files in the background, just to help us work. 

Scratch Disks are very similar, they're all kind of like supporting files, that are in the background, but they're a bit more, like purposeful. It's the ones that we make, we made them earlier, see these ones here, remember, that's our project file, and we looked at the video previews here. Remember, we made these for render in and out, and there's a bunch of files that get created in here to help us. You can see, my Timeline is green. So Scratch Disks are more like, the files that I create for my little previews to help run fast, and Media Cache is the one that Premiere Pro don't ask, and just do to make the flow go nicely. So that's the difference between, Media Cache and Scratch Disks, very similar.

Why do we need to know about them? Mainly because they can get big and bloated, and especially if you're on a slower machine, it can really slow things down. So why are they slowing me down? Just because they can get really big. Here's my Media Cache files here, don't go and try and find this file, it's buried deep in the machine, and it's very hard to find. I've dug it out here just to show you, you don't need to find it, but you can see here, I've been working on one project for like a day with you, and are already at 200 Megabytes. I've reformatted this machine, and cleared it all out just for this tutorial, and before I did that it was up to 4 Gigabytes. Now that's fine on this machine because I've got lots of space, but it can get really big, and if you are on a machine that has-- it's either older, slower, or it's full already, Media Cache clearing can be super useful, to kind of speed things up. Let's look at Media Cache first. 

All right, to find and manipulate our Media Cache, go to, on a Mac go to 'Premiere Pro', go to 'Preferences', and go to Media Cache. If you're on a PC go to 'Edit', and down the bottom here will be 'Preferences', and go to the same one called 'Media Cache'. So the quick and easy one is, just go and say delete all that media cache, clear it out, don't need it anymore, and if you've got a project open, you can only delete the unused cache, because it's got a Timeline open, and it's got stuff that it's using. It's only going to delete the stuff that hasn't-- it's not being used now, that'll happen if you say import an mp3, play it, don't like it, take it off again, it'll have generated it, it'll be sitting in that folder but not used. 

So it's a way of clearing out unused ones, and have the project close down everything, and go back to preferences to delete everything at once. That's my advice, because what happens is, if you delete everything, don't worry, as soon as a project opens back up, it will generate them all again, where I wouldn't do this is if I'm working on a really big documentary or a film, where actually there's quite a lot of Media Cache made, so to open it and to have deleted them all, it's going to take ages to generate. 

You'll notice it down here, there's like a little bar that appears, little blue one, have you seen it, when it starts generating things in the background, you never notice it that much. So that's the time that I wouldn't maybe generate-- delete all of them, so just close down your project, that will become available. 

So you've cleared out your cache. What else can you do? This one here is super useful, what to do, I don't know why it's not deleting them automatically. This seems like a really good idea. Let's click 'OK', it's going to automatically delete cache files older than 90 days, that seems good, but even 30 days, 60 days, it's up to your workflow, like hey, if you haven't touched it for that long, it's not a big drama to regenerate those media cache files, or you might decide that you do it this way here, delete it when the oldest cache files-- delete the oldest files when your cache exceeds this much Gigabytes, that feels like a lot of Gigabytes of my hard drive gone. 

I don't set it to that, I turn it down to like, I don't know, 10 Gigabytes. Have a look at your hard drive, how much free do you have, you might decide that you're happy to give Premiere Pro 10 Megabytes, sorry, 10 Gigabytes, and everything after that it will delete the oldest ones first. This is the one that I more likely use, and 90 days is fine for me, maybe even shorter. We'll talk about the database location in a second, we'll separate it in a separate video, because it relies on you having an extra SSD or hard drive, but I'll do that in the next video. Let's look at what we can do with our Scratch Disk. 

All right, let's clear out our Scratch Disks as well, to give us a bit of a performance boost, and it's only going to give you a performance boost if your machine is lacking hard drive space. So in this case it's in a slightly different place, we go to 'Sequence', and we go to this one, we've done it before. Delete our render files, we'll get rid of everything, remember, Delete Render Files In and Out will mean only delete the files in between here, my in point and my out point. I'm using the I and O shortcuts there, to set my in point and out point, but if you just want to clear everything out, just use that one. 

 All right, let's jump to the next video, where we talk a little bit more about Scratch Disks and Media Cache, and external hard drives. All right, see you in a sec. where we talk a little bit more about Scratch Disks and Media Cache, and external hard drives. All right, see you in a sec.