Media Cache Files (What are they, How do I treat them?)

[bryanedmondson]

I vague about Adobe Premiere Pro's Media Cache Files: I do not clearly understand their function, nor how critical they are if I should alter or remove any. In terms of I/O I always considered cache to be a temporary buffer to speed up data access. I do not know if this is correct with Media Cache Files.

My basic problem is that I have limited space. I have most of my scratch disk directories on an 240 GB SSD RAID 0 Array [Lets just call the Array Drive J:\"] ( I think of this drive J: as some ridiculous, pretend speedway for anything in my computer that might go fast, or run on high octane fuel)

So, principally, out of ignorance, I put media cache directories on Drive J: for Premiere Pro, Premiere Elements, Bridge, After Effects and such. I also decided it might be good to send any captured audio or video sent to dirs on J as well.
Lastly I think, "Why not preview audio and video on J too?"

So as you may guess, in only 2 months I have filled half of the capacity of Drive J . Apparently Drive J is not the temporary buffer that flushes itself (unlike those awesome space-age, hands-free, laser detecting toilets).
And now I am wondering how large will this septic pool grow? I have seen rare options to "clean or purge the cache" on some adobe applications. But I still worry about this huge sewage pool that is accumulating. Will I have to move one day?

Honestly, I had good intentions when I got into this. But I did not use the least bit of foresight. Now guess what? surprise: I have traveled many miles. I carried all my burdens on my back to the community help forum. I am happy to show them to all. You may think of them as bad gifts,

I heard someone say muvipix is the last refuge of fools. A magical place full of smart, smiling people, who love nothing more than to drop everything they are doing--so as to cure lepers who did not decode the answer, "RTFM"
Well it isa lot to ask. Sorry guys. Any suggestions are much appreciated.

Respectfully Bryan Edmondson

[momoffduty]

I am sure one of the techie guys/gals on here can explain the best course of action and how stuff works, but this is how I have it set up. At first I had my scratch disks & media cache going to the SSD since this is supposedly faster but it filled up too quick. So now I have it on my second RAID drive 2T. The second drive is where I keep all my media.

AE CS6 saves your preview files now so I clean the Media Cache out just to keep things from building up. In this version and in past versions of AE generally do the File>Purge.

In this thread Bob explains the media cache:
viewtopic.php?f=88&t=11980&p=102154#p102154


The one thing about PrPro & AE there is only the Help files and not a manual, so hard to Read The Fine Manual.

[John 'twosheds' McDonald]

.......so hard to Read The Fine Manual.

(Feigned innocence) So that's what it means.

[Peru]

The PPro "clean" button only cleans the Media Cache Database, not the actual Media Cache files. You have to delete those manually. Those files are only used for preview, so when you are done with a project, just delete them. Don't worry about deleting the wrong Cache files, as PPro will recreate them if it needs to do so.

[Bob]

I [am] vague about Adobe Premiere Pro's Media Cache Files: I do not clearly understand their function, nor how critical they are if I should alter or remove any. In terms of I/O I always considered cache to be a temporary buffer to speed up data access. I do not know if this is correct with Media Cache Files.

The purpose of the Media Cache files is to speed up processing of video and audio so you can playback and edit more smoothly while working in the editor. It does this by performing certain types of conversions and calculations and storing them in the cache so they don't have to be done in real time. Examples: when you see the red line above a clip and press enter to render, that goes in the cache. When the audio sample rate doesn't match the project sample rate, it must be conformed to the project, that goes in the cache. Even the waveform for the audio that's displayed on the timeline is pre-calculated and stored in the cache.

The cache files are temporary in that they are generally only needed for the duration of the project. Sometimes, you may use the same source clips in multiple projects. To minimize disk space, rather than create multiple copies of the cache files, one per project, the software will keep track of cache files in the Media Cache Database and only create a new cache file when it doesn't exist elsewhere. When you are done with the project(s), you can delete the project and cache files. It doesn't hurt if you delete the cache files earlier, but they will be recreated when needed so you don't really gain anything by doing that. After you delete the cache files, you should use the clean button to update the Media Cache Database to remove outdated entries.

[bryanedmondson]

The PPro "clean" button only cleans the Media Cache Database, not the actual Media Cache files. You have to delete those manually. Those files are only used for preview, so when you are done with a project, just delete them. Don't worry about deleting the wrong Cache files, as PPro will recreate them if it needs to do so.

Thanks Peru! You made my day. I appreciate your consultation.

p.s. Your commercial is very well done.

[bryanedmondson]

I [am] vague about Adobe Premiere Pro's Media Cache Files: I do not clearly understand their function, nor how critical they are if I should alter or remove any. In terms of I/O I always considered cache to be a temporary buffer to speed up data access. I do not know if this is correct with Media Cache Files.

The purpose of the Media Cache files is to speed up processing of video and audio so you can playback and edit more smoothly while working in the editor. It does this by performing certain types of conversions and calculations and storing them in the cache so they don't have to be done in real time. Examples: when you see the red line above a clip and press enter to render, that goes in the cache. When the audio sample rate doesn't match the project sample rate, it must be conformed to the project, that goes in the cache. Even the waveform for the audio that's displayed on the timeline is pre-calculated and stored in the cache.

The cache files are temporary in that they are generally only needed for the duration of the project. Sometimes, you may use the same source clips in multiple projects. To minimize disk space, rather than create multiple copies of the cache files, one per project, the software will keep track of cache files in the Media Cache Database and only create a new cache file when it doesn't exist elsewhere. When you are done with the project(s), you can delete the project and cache files. It doesn't hurt if you delete the cache files earlier, but they will be recreated when needed so you don't really gain anything by doing that. After you delete the cache files, you should use the clean button to update the Media Cache Database to remove outdated entries.

*********
RE BOB.

See file treed dir structure of other media file dirs on drive J: at http://noodletoes.com/?attachment_id=2197

Thanks Bob, that clears up a lot of doubt. If I may ask one more question, I am confused about other[ project preferences/ scratch disk ]optional directories that I placed on this drive J: with the aforementioned Media Cache Files.

Specifically I refer to the .jpg at the link above. In the file tree one can see the "Captured Audio” “Audio Previews,” “Video Previews,” and “Video Capture” Dirs. All files in these DIRs seem optional (pek, cfa, imi, index..). My concern in the Dir “Video Capture” as it contains valid premiere pro CS6 project files and project asset files. In this "Captured Video," Dir, these files did not come from any sort of video tape captures. I do not understand what these files are. The sub-directories ...."Trimmed_PremiereProProjectName..." Appear very similar to the Archived Projects Dir in Premiere Elements. I like to keep archived projects in the case that I need to go back in the future and edit one specific part of a long exported video project media file. (To change a logo in the video, for example)

My question is, can I delete these project and asset files in the Trimmed__XXXXX subsirs and still access my original project files within Premiere Pro. IE. Are these Trimmed_XXXX subdirectories linked to the main project or are they an archive of some sort? In either case is there any reason to keep them.

I am sorry that this is a jumbled, disorganized question. I hope I am clear enough to be coherent. Thanks so much
T

[Bob]

My concern in the Dir “Video Capture” as it contains valid premiere pro CS6 project files and project asset files. In this "Captured Video," Dir, these files did not come from any sort of video tape captures. I do not understand what these files are. The sub-directories ...."Trimmed_PremiereProProjectName..." Appear very similar to the Archived Projects Dir in Premiere Elements.

Those appear to be a trimmed archive. Why they are there, in the captured video directory, I don't know -- archives aren't created automatically and that's definitely not the default location. They appear similar to archived projects in Premiere Elements because Premiere Elements shares some architecture with Premiere Pro.

My question is, can I delete these project and asset files in the Trimmed__XXXXX subsirs and still access my original project files within Premiere Pro. IE. Are these Trimmed_XXXX subdirectories linked to the main project or are they an archive of some sort? In either case is there any reason to keep them.

Yes, they appear to be archives. No, they should not be linked to the main project. Yes, you can delete them -- but, first be sure that you aren't opening that project file and working on it thinking that it is the main project file. When you do create an archive, put it someplace else, preferably on a different drive.

[bryanedmondson]

My concern in the Dir “Video Capture” as it contains valid premiere pro CS6 project files and project asset files. In this "Captured Video," Dir, these files did not come from any sort of video tape captures. I do not understand what these files are. The sub-directories ...."Trimmed_PremiereProProjectName..." Appear very similar to the Archived Projects Dir in Premiere Elements.

Those appear to be a trimmed archive. Why they are there, in the captured video directory, I don't know -- archives aren't created automatically and that's definitely not the default location. They appear similar to archived projects in Premiere Elements because Premiere Elements shares some architecture with Premiere Pro.

My question is, can I delete these project and asset files in the Trimmed__XXXXX subsirs and still access my original project files within Premiere Pro. IE. Are these Trimmed_XXXX subdirectories linked to the main project or are they an archive of some sort? In either case is there any reason to keep them.

Yes, they appear to be archives. No, they should not be linked to the main project. Yes, you can delete them -- but, first be sure that you aren't opening that project file and working on it thinking that it is the main project file. When you do create an archive, put it someplace else, preferably on a different drive.

Bob, thanks so much as always. It is good to have your expertise and consultation. Have a good day.