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[NickM]

I, perhaps naively thought, that the cache subdirectory in a specific library folder held the cache of tumbnails read from a watched folder.
I seem to remember someone saying the cache could be moved by a registry edit, but cannot find the old topic on this (help please!).
But, anyway, I think that the default location for this should be library specific and in the same directory as the library.

[NickM]

I stupidly didn't look in the user directory... So found thumbnails large, medium & small at:-
C:\Documents and Settings\user\Application Data\J River\Media Center 12\Thumbnails\{F5CAE9D0-770B-44CD-9FE6-EBB2261648B5}\Normal (v3)

Is it possible to change this location?

[Alex B]

It is in the Windows registry:

HKEY_CURRENT_USER\Software\JRiver\Media Center 12\Properties\Thumbnails - Base Path

You can change the value, but use only a local fast HD unless you are willing to sacrifice speed and possibly also stability.

I use this registry value: C:\MC12lib\tn\. The "tn" folder is subfolder of my main MC12 library folder.

[NickM]

Thanks Alex.  After changing the registry, MC still creates a sub-directory under what is specified in the registry ( in my case {F5CAE9D0-770B-44CD-9FE6-EBB2261648B5}\Normal (v3) ).
Presumeably that long number represents MC's identifier for my library name?  I wonder if it can be removed?

The original base path contained a variable [Application Data Path].  It would be ideal if there were a variable that refered to the library path instead.  Then there would be no need to have to re-edit the registry if the library location changed.

[NickM]

If you change the default location from [Application Data Path] to anything else, then the next time you close and restart MC12, the thumbnails get erased and rebuilt. A bug...
Resetting the registry back to [Application Data Path] seems to fix the problem.

[Alex B]

MC makes thumbnail folders for all libraries under the same path. The cryptic subdirectory name includes a library identifier. I don't think it can be changed.

Registry tweaking is not a standard procedure and doesn't invoke any code that could move the thumbnails. If MC finds up-to-date thumbnail folders and files from the specified path it does not reset them on startup. After changing the registry key you need to copy the subfolder(s) to the new thumbnail location before starting MC if you want to avoid thumbnail creation.

A library restore from a backup zip file clears old thumbnails. I copy the thumbnails and library files between four PCs so that I don't need to create new thumbnails each time I update a library. I use ".bat" batch files for this. glynor has published VBS scripts in the main MC forum for the same purpose.

[NickM]

Alex, I understand your explanation and the logic.  But, on my installation, if I make a change to the resistry for this parameter, then everytime MC is re-started, it wipes the 3 thumbnail files and re-creates them again from scratch.
I too use a batch file to copy the library files to each machine in the house. I was trying to include the thumbnails as well.

[raym]

On my installation, if I make a change to the resistry for this parameter, then everytime MC is re-started, it wipes the 3 thumbnail files and re-creates them again from scratch.

I experienced this when trying to specify a network drive for my thumbs.

[Alex B]

I have not tried a network path, but at least a mapped network drive should work, except that it would be too slow.

NickM, do you make a separate thumbnail folder for each PC? You cannot share it. I have noticed that if the thumbnail files are not fully synchronized with the database info MC clears the thumbnails on startup.

[NickM]

No, just one main PC where I customise the library and create the thumbnails.  Then the library & thumbnails get copied to each other PC in a batch file.

[park]

I had the same problem as you Nick, with MC11.1, but (fingers crossed) things are working for me fine in MC12 with my own custom file path. I dont have any ideas as to why it happens, just want to chip in and say i've seen this behaviour too.

[JimH]

It's probably not a good idea to move thumbnails or even back them up.  Just let MC rebuild them if necessary. 

If you're having problems with thumbnails, use MC Tools/Options/Tree and View/Thumbnails and do:

Erase
Build Missing

[NickM]

Probably right - yes.  Please let me go back to the original post...  A library should be a complete entity, together with its cache & thumbnails. ( And perhaps some other MC settings, but that's a topic for later. )

[Alex B]

It's probably not a good idea to move thumbnails or even back them up.  Just let MC rebuild them if necessary. 

If you're having problems with thumbnails, use MC Tools/Options/Tree and View/Thumbnails and do:

Erase
Build Missing

For me copying the thumbnail folder is absolutely necessary. My MC12 thumbnails are currently 264 MB (The MC11 thumbnails take even more space). Creating them from the scratch takes almost two hours from a local HD. Creating them over LAN would take even longer. I maintain the library mostly on one of the PCs that has the files available locally and copy the same main library to the other PCs. I have configured the network so that all PCs can use the same directory paths for accessing the media files.

I need to update the database almost daily on the other PCs. As said earlier, a library restore needs to reset the thumbnails since they would otherwise be out of synch. The only working solution is to copy the library files and the thumbnails to identical locations to each PC (Naturally all MC instances must be closed during that.) If this is done correctly it is safe.

On the fly thumbnail creation is not an alternative for me. It would slow down everything, especially on the PCs that access the media files through the LAN.

The thumbnail path string in the Windows registry is just a standard folder path. The path can be any legal path that points to a local HD, but it is good to keep it short. (Mine is C:\MC12lib\tn\.) After it has been changed MC uses the new path exactly the same way as it used the default path. Also the default path varies from an installation to another because it contains the user name.

[Alex B]

NickM,

I cannot reproduce the problem. Copying the thumbnail and library folders from one PC to another works fine for me.

Could you explain exactly how you do it? Perhaps we could find out what is different in our procedures.


Edit

I too would welcome a library backup that would include the thumbnails, but only as an option that can be used when needed. My library backup file is currently about 8.5 MB. With the thumbnails it would be a lot bigger.

[NickM]

Primary PC (laptop) is where I work.  I copy the library and thumbnail folders to a network directory.
A secondary PC reads the the library from there and uses the thumbnails (from there) ALL OK.

The process of achieving above involved copying i) the library folder and ii) the thumbnail folder to the server.

So, I thought I would simplify the process and make the thumbnail folder a sub-directory of the library folder and just copy one folder ( the library folder ) to the server.

The problem that I encountered was that any change from the default location in the registry for the thumbnail folder causes the laptop to not regonise the (moved) thumbnail files and to recreate the thumbnails everytime MC is started.

[Alex B]

The problem that I encountered was that any change from the default location in the registry for the thumbnail folder causes the laptop to not regonise the (moved) thumbnail files and to recreate the thumbnails everytime MC is started.

So the copy process and other PCs are actually not incolved in this problem. It is enough to change the folder path in the registry and recreate the thumbnails on the laptop (as a standalone PC). Next time you start MC it starts creating them again. Correct?

[NickM]

So the copy process and other PCs are actually not incolved in this problem.

Correct

Just changing the thumbnail path in the registry creates the problem (everytime MC starts it erases and rebuilds the 3 files).

[Alex B]

That does not happen to me with MC11.1 (on four different PCs) or MC12 (on two PCs).

What is your selected thumbnail exit behavior option (Options > Tree & View > Thumbnails > Thumbnail exit behavior)? What is your thumbnail path? Do you do anything with the library database files when MC is closed before restarting it?

[NickM]

The Thumbnail Exit Behaviour is set to Erase Orphans ( such a cruel thing... )

The steps that I take to create the problem are as follows:-
i) Create library and make sure thumbnails are all re-built
ii) Close MC
iii) Move the folder Normal(v3) to a new location
iv) Edit registry to that location
v) Restart MC
At which point, the three previously created files in the new thumbnails directory get deleted and re-built.

[raym]

NickM, I don't know if this is what your experiencing but I discovered yesterday that if you set your Thumbnail folder (with the base folder name "Thumbnails") to reside under the root of your MC library directory, the thumbnail .jmd files will get deleted every time MC starts. EG>

C:\MCLib\Cache
C:\MCLib\Logs
C:\MCLib\Thumbnails
C:\MCLib\<.jmd files>
....
....
...
C:\MCLib\<.jmd files>


The workaround for me was to give the base thumbnail folder the name "Thumbs" instead of "Thumbnails" Eg>

C:\MCLib\Cache
C:\MCLib\Logs
C:\MCLib\Thumbs
C:\MCLib\<.jmd files>
....
....
...
C:\MCLib\<.jmd files>


Alternatively, make your thumbnail path point somewhere other than under the library base path.

I don't know when this started but it never used to be the case until recently. MC11.1 is also now behaving the same way.

[Alex B]

As I already said, C:\MC12lib\tn\ works for me. The main library is in C:\MC12lib\.
I have some smaller libraries elsewhere and the folder location works with them too.

Though, I have not recently tried copying the thumbnails from the default folder. I have built them in the custom location that is defined in the registry.

The Thumbnail Exit Behaviour is set to Erase Orphans ( such a cruel thing... )

The steps that I take to create the problem are as follows:-
i) Create library and make sure thumbnails are all re-built
ii) Close MC
iii) Move the folder Normal(v3) to a new location
iv) Edit registry to that location
v) Restart MC
At which point, the three previously created files in the new thumbnails directory get deleted and re-built.

iii) Why do you say "Normal(v3)"?  Do you mean that you didn't include the library specific base folder(s) that look(s) like this: {DD39E844-3DE1-46E0-9095-B2E2719C6361} ?

So what happens on next restart after you have built the thumbnails in the custom location?

[NickM]

MC deletes the 3 files and re-builds them.

[Matt]

We'll take a look.

Let me reiterate that we don't make this easy because it's critical that thumbnails be on a fast drive.  The performance of thumbnails are highly disk access time dependent.

AlexB's solution is quite elegant.  We've toyed with creating a system to automatically allow sharing of the same library (only one read+write at a time), but pumping through the network for thumbnails isn't great.  Alex's solution fixes this although it makes synching changes back to the master library a little more complicated.

[raym]

MC deletes the 3 files and re-builds them.

Did you see my post above? I too can reproduce what you see...

[NickM]

Raym, sorry, missed your post.  I'll try still in the library but under a different name as you suggest.

Matt, these are still on a local fast HDD; just copied using a batch file to other PC's.

[park]

Raym I think you have it. I used to have the thumbnails path set to the same root folder as my library back in mc11.1 and had the problem. then since moving to mc12 the problem disapeared. It must be because i unconciously specified a special new folder that is different to my mc12 library path.

So now at least we know how to make the hack work. I'd say that with all this activity though (the number of people who use this hack) it deserves to be an option somewhere. Maybe an option which forces the user to keep the thumbnail directory on a local disk (assuming a usb drive still counts as local), just to make sure it's always on a fast disk.

[NickM]

Raym & Alex, many thanks.  Just changing the folder name from Thumbnails to tn works fine now.
My batch file now just copies one directory to the other PC's and my library schemes and thumbnails remain intact and don't get re-built.  Phew..
And yes, I think that the library location and thumbnail location should be user-definable in the library options.

[kwake]

Hi,

I would like to move the location of my Thumbnail directory in MC12 build 533 and found this post on the subject.

It says to edit the registry value: HKEY_CURRENT_USER\Software\JRiver\Media Center 12\Properties\Thumbnails - Base Path

I just checked and there is no Thumbnails entry under Properties in the registry.

Is there a new way to do this now?

The reason I want to move it is because I make an image of my C: drive and don't want to include the Thumbnails as it's over one gig in size. I just want to move it to my D: drive.

Thanks,
Kwake

[Matt]

That is the correct registry path.  Double-check that you're looking for the value "Thumbnails - Base Path".

However, we do not recommend changing this value.  You could slow Media Center down if you're not careful.  Proceed at your own risk.

[hit_ny]

This thread has got me thinking that the thumbnails folder could ideally be placed on another HD (internal of course).

That way MC's library access & thumbnail generation are on two physically different drives.

Won't get any faster than that 

Trick remains to place the thumbnail folders at the very edge of the other drive..ie the first folder if you look at it from a defragger view. That way its at the fastest point on the HD.

....hmm, how to do that without mirroring the drive ?

[rjm]

That way MC's library access & thumbnail generation are on two physically different drives.

I've always assumed that most of the library is in memory and therefore moving the thumbnail cache to a different drive would not improve performance.

Would love Matt to weigh in here with the facts...

[hit_ny]

Bump!