I'm using the Wallpaper slide show feature where I point displayfusion to my photographs on my local hard drive. I have thousands of photos I've taken over the years and periodically I point DF to a new directory. It seems to me that its showing the same subset of pictures from the directory without ever showing some others.

I'm curious how the images are selected. Presumably you recursively traverse the directory hierarchy looking for all of the supported image types and you make a list that you then randomly select the image to display. Can you explain how the process works?

Is there a maximum number of images that can be candidates for display?

Many thanks,
Rob.

The DF selection process works fine if you have up to a couple thousand images or so. From my informal observations I think it starts breaking down in the 4000 to 5000 image range. The reason for this is when DF selects a new image to show (assuming a random image selection, not the "in order" option), it has to look up that filename in the wallpaper history database. This is an SQL file that has to be searched every time.

If the filename is not found, it is added to the history and then displayed as your wallpaper. If it *is* in the history, then DF "randomly" selects another image, searches the history DB, and the cycle repeats until it finds a file not in the history DB.

The random file selection, and the SQL database look-ups, all take time. DF limits this process to just a few seconds, which is okay for a few thousand images, but not when you get 50,000 or 500,000. For these larger image libraries, no one at DF has been able to explain to me what DF and SQL are really doing, and the number of users with these big image libraries is too small for DF to invest the time to investigate and fix it.

Also, a point Keith glides past (unless something has changed) is that DF enumerates the directory/directories every wallpaper change. This has the advantage of making sure new images are eligible to display immediately, but sucks up lots of CPU cycles with all that is involved.

All this said, in the Advanced Settings, make sure "Ignore Sub-Folders" is NOT set (a recent DF update somehow caused this to be enabled on one of my computers). Also, set "Days to Expire History Images" to 9999. When DF does eventually cycle through all the images in your library, it will just delete the entire history and start over. Note that DF maintains separate histories for each monitor and/or monitor split.

@Keith,

I was referring to a previous discussion with Jon on large image libraries.

https://www.displayfusion.com/Discussions/View/wallpaperhistoryv4db-corruptionbad-data/?ID=47ad4ed7-3fb6-49f8-9d25-0be3aa8f778a



and later in the same discussion:



More specifically, the underlying technical question is what does SQL do when it runs out of time, does it just grab the last filename it was looking up, or something else. (One thing I have noticed is that images just added to the library seem to bubble to the top of the selection list. Just a consistent observation.)

Frankly, I don't expect DF to fix this problem because the current method works with probably 90 percent plus of your user base. And it would probably be quicker to just write a new file selection module optimized for large libraries that could be optionally used (e.g., without the directory enumeration every wallpaper change, pre-building image-to-show lists, etc.) than it would be to troubleshoot and rewrite the existing code.

Thanks for the clarification on how this works guys. Its one of my favorite features in DF.

Oops. I initially posted this on the wrong account. This is my account with the license.