Page 1 of 1

Win7 TranscodedWallpaper.jpg and heavy disk use

Posted: Sun Dec 30, 2012 11:41 am
by SophiaNOTLoren
Hi there!

I've been regularly using WSSPro for quite some time now, and I've noticed something interesting...

On Windows XP, when WSSP creates

Code: Select all

C:\Documents and Settings\{username}\Application Data\WallpaperSSPro\Wallpaper.bmp
it can be directly applied as the wallpaper -- and in fact, WinXP converts any file type manually set as a wallpaper to a bitmap file anyway, even when Active Desktop is enabled.

But in Windows 7, wallpapers seem to be converted to JPG in order to display, under

Code: Select all

so unless I'm missing something, when WSSP creates the BMP file, windows converts it back into a JPG which is causing a CPU and disk usage spike when changing between wallpapers with the program.

What possibility is there of testing to see what version of Windows the application is running under, and writing a BMP to disk for XP and a JPG for newer operating systems? I haven't had the chance to see how things work in Windows 8 yet, but I'd guess that it's probably using JPG as well, so Windows XP would be the special case...

Thanks for reading, and I look forward to a reply!

Re: Win7 TranscodedWallpaper.jpg and heavy disk use

Posted: Sun Dec 30, 2012 11:08 pm
by gpb
the creation of the jpg file inside the Themes folder is not documented, in the same way Microsoft doesn't document which file formats are supported by SetWallpaper API, jpg may work or may not work, windows is a very complex environment, there are lots of combinations of hardware and software used by customers and it is not possible to rely a software on an undocumented feature.
Anyway it seems that jpeg is created only when smooth transitions are used, this is a special case because the transition is performed by a specific windows component (wallpaper slideshow). It's normal that there is some cpu and disk activity when a new wallpaper is set, Wallpaper Slideshow has to load one or more jpeg files, resize them, build another bitmap for the full desktop and save it as bmp. The additional conversion to jpeg on a modern computer can't take more than 1 or 2 seconds and I think can't be avoided when using smooth transitions.

Re: Win7 TranscodedWallpaper.jpg and heavy disk use

Posted: Tue Jan 15, 2013 6:16 am
by SophiaNOTLoren
Thanks for the reply! I hadn't thought to test it without "smooth transitions" enabled -- disabling that option makes a big difference.

The additional conversion doesn't take even a full second (at least on this system -- Win7 x64, AMD A10-5800K CPU and 8GB RAM) but it does do a fair bit of disk thrashing when smooth transitions are enabled. Turning that off is a fair tradeoff, and WSSP is performing much better now!