P: Video Cache is out of control

The Dynamic Link Media Server doesn't know about the LR Video Cache limit, and any videos that show up on a Import grid as you're clicking down to the ultimate folder for import will get cached via the DLMS and will stay in the cache even if you clear it within LR.

Here is a specific scenario I just tried:

I am using LR 2015.3.
My LR Video Cache Limit is 1.0GB.
I have manually deleted the contents of Video\Media Cache and Video\Media Cache Files but left those two folders under Video.
My external USB3-attached drive with photos is drive-letter P:.
The root of my P: drive has some videos I've downloaded over the years none of which I'll ever want to do anything with in LR.

I started an Import using File / Import Photos and Video
Clicked on the Photo drive top level P: to open it, not the expand arrow but just left-clicked on the P: drive entry in the LR Import panel source list.
The Import grid immediately populated with various photos and videos from the root folder.
I quickly clicked down further in to the folder tree until I got to the folder of a few recent photos I wanted to import. I clicked Import on those and they imported ok.

However within a minute or so the Media Cache Files had 2.4GB of .pek and .cfa files that matched the videos in the root folder of my P: drive that I'd momentarily clicked on trying to navigate down to my ultimate destination.

In my opinion what is wrong is LR should not be caching any video files in the import grid UNTIL you click Import and you've actually committed to importing them. It is this precaching prior to import even if the folder is touched only momentarily that is wrong, and obviously this precaching doesn't respect the LR Video Cache limit since I ended up with 2.4GB of files when my limit is 1GB.

The team has found and fixed some bugs that prevented Lightroom from correctly enforcing the video cache limit. Based on your feedback, I've asked the team to conduct some review in this area. Thanks.

Scroll up to my comment a few weeks ago that says what folders to delete manually in Windows Explorer to remove all the erroneously cached videos.

Simon Chen, the issue for me, at least, is not that a few videos are cached as they are imported, the issue is that the entire hard-drive of videos, media that will never be accessed with LR, is cached seemingly on a whim, due to LR handing off caching duties prior to import to the DynamicLinkMediaServer process which does NOT respect the caching limits set in LR because it's a separate program outside of LR.

Yes caching videos used by LR is useful, but your statement suggests you don't even understand what occurs when LR is importing, that the DLMS is told to cache everything on the hard-drive using up many 10s of gigs of data even though the videos in LR are only a few 100 MB and there are none in the current import at all.

Clicking on the hard-drive to navigate down to a folder to import from is enough to get LR to hand caching off to the DLMS which then scans the entire hard-drive and eats up gigs of space and slows down hard-drive access to the import drive while this scan is occurring.

Please help! I have the same problem. And my C drive is now fully occupied with 170 GB of video cache files thanks to Lightroom.

That is what a cache is supposed to do, however consider the following facts...

first of all , lightroom is STRICTLY a photo editing program, it cannot make even the simplest change to a video, therefore all that is needed of lightroom is to display the thumbnail of a video, so it can be cataloged with it's fellow photographs, playing it within lightroom could be completely optional since lightroom can't edit video... if you want to play it, just right click on it and open it with a real player, which one could easily do now by just selecting show in explorere and then launching the video from there.

Videos have NEVER needed to be cached, they load and play plenty fast enough.. I've been watching videos on computers since windows 3.11 and even then, the load time was not so bad that the video ever needed caching... you can only play one video at a time, why would you want to play any more than that anyway? as long as the thumbnail images load fast so if you have 1000 photos and 100 videos all in a folder that folder doesn't take a long time to load the thumbnails thus delaying the photos, that is all that was EVER needed, if one clicks a video to watch it, the normal load time of an un-cached video is just fine... heck even watching you tube videos on line buffer and play plenty fast enough and nobody hogged up any of our hard drive space for those. maybe some VERY few people play a LOT of videos in lightroom very often.. fine... but give the rest of us who just want a place holder to show the videos in sequence with their photos an option to shut this stupidity off... and video caching OFF should be the default, especially considering modern computers, you can't even run lightroom on a computer slow enough to require video caching anymore!

a cache only becomes useful if the file is opened often, if it's rarely opened, it is just a waste of space, and on an SSD, space is precious. furthermore, if you have an SSD, you really have no need to cache anything ever.... give us the option to just shut off the cache.. you so-called programmers aren't even executing a cache function properly.. just cache everything on import weather it is EVER looked at once one not.. I think caching of any particular file should only happen at a bare minimum the second time within 1 day that a particular file is accessed... if if is not accessed more often than that, it is considered a rarely used file and caching is not needed. once it is cached, if the file is not accessed in over a week, it should be removed from cache, because it's obviously not needed often anymore. My video cache should be empty, because I have not even opened a folder with a video in it in years, but it's NOT. if sometime 6 months from now I go to play it again, I can wait 1.4 seconds for it to load and play.. no big deal... even if I had to wait 20 seconds for it to play, it would not be that big of a deal.. but no video takes that long to play, not even with the extra slow windows 8 metro app which is 15 times slower than windows media player... even so.. if and only if I start watching that video 6 months from now fairly often should that one video be cached, because now it is being accessed enough to justify the resources it takes to cache it.. and that brings me to a concept that EVERY computer scientist should be familiar with, especial as it pertains to caching.... EVERY action performed by a computer uses resources, The TRUE purpose of a Cache is to Save resources long term. If the resources used to create and store the cache are such that over the course of time, resources end up being saved because the cache saved the repeated loading and processing of some files, then the cache is valid, However, if the resources used to create and store the cache are GREATER than the total usefulness of the cache will ever save, then this is bad programming and wasteful. On modern computers it's very doubtful that caching any video is saving more resources than it is wasting.

and one more thing... MOST of the videos that end up belonging in lightroom are very short anyway.. they are cellphone quick vids of kids blowing out birthday candles or a bunch of short go pro shots of someone running down a ramp on a bmx bike... they aren't 2 hour movies.. they are so small they never needed to be cached.... and if they WERE 2 hour movies, they would STILL be best viewed outside lightroom, so again, caching is not needed, just show in explorere and then you can play it in a real media player.

The lightroom video cache is still just broken... scouring your hard drive for all video building a cache that contains full versions of every movie and tv show on your hard drive if you accidentally touch it during an import, these cache files are many times larger than the original file.. it completely ignores the limits and just keeps going until the drive is full... and it continues working on this RIDICULOUS procedure even after you exit lightroom.

The solution to this is so simple, LET US SET VIDEO CACHE TO OFF.... PLEASE! just cache the video thumbnail of it, which you can just get from with windows cache, you don't even need to bother to keep your own cache, since it's just a place holder, and videos are non-editable.. any crappy low res thumbnail will do just fine

The video cache stores some preprocessed files for the videos so that one would get smoother playback experience for those videos later.  

i'm on Mac,. I renamed DynamicLinkMediaServer file so it doesn't run anymore, but of course that means no more video viewing in LR but at least no more caching.
What is video cache setting inside LR for?

It is ok to delete the cache manually, yes. In fact that is the only way to clear it.

This problem has been around for quite a while, including in LR 5 and still in LR 6.

The cache is in two folders under:

C:\Users\--yourusername--\AppData\Local\Adobe\Lightroom\Caches\Video

The main problem is LR hands off video indexing to the DynamicLinkMediaServer executable for each folder you click on when navigating down to the folder you want to import from rather than merely the folder you're importing from, so if you click on the top-level folder of a drive to click down into the photos folder structure, the DLMS will index all videos on the entire drive and those indexed videos are usually similar size to the video files, themselves.

hi there, I havent upgraded to lightroom 6 yet, Im still using LR 5.7 and Im having the same issue. my cashe limit is set to 3 Gb and it has over 30 Gb currently. LR is installed on a 128 Gb SSD along with windows 8.1. while all other software is installed on my HDD.

is manual deletion of the cashe ok to do or is it not recommended?