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[RD James]

I had to restore a backup today due to moving some drives around and forgetting to disable auto-import first, which requires that all thumbnails are rebuilt.
Normally, this would not be a problem, but for some reason I am getting severe stuttering every few seconds. This affects the entire system - it's completely unresponsive to input.
The DPC latency results are off the charts, and I've seen results of over 50 milliseconds (1ms, or 1000µs, is considered to be enough to cause problems for audio/video playback).
 
This is on my 8-core/16-thread Ryzen system so it's not like the CPU can't handle the workload, or something that's been caused by the recent Meltdown/Spectre patches. All files are stored on local drives too.
I'm sure that I had seen someone complaining about this recently, but I did find a post about this issue all the way back in MC19, so it doesn't appear to be new: https://yabb.jriver.com/interact/index.php/topic,89918.msg617917.html
 
I've set up exclusions and even disabled Windows Defender temporarily, so it's not antivirus that is causing this.
And this is from a cold boot, so there's nothing else running in the background. I'm at a loss as to what could be causing it.
I currently have 50,000 audio thumbnails being rebuilt, and aside from not being able to use Media Center while that is happening since it's a modal dialog, everything is running smoothly. That leaves about the same number of video files which need thumbnails generated.
I can't even browse MC and set it up to create thumbnails overnight, as it starts automatically generating thumbnails for videos as I change to a new view.

[RD James]

Well there's not much that I can do while it's generating thumbnails for those audio files, and it appears to be mostly single-threaded, so it's going to take a while.
But I notice that nearly all of the CPU usage associated with Media Center is kernel-mode (red) rather than user-mode (green). Is that to be expected?

[RD James]

I think I've found a related bug with thumbnail generation.
I disabled thumbnail creation for videos so that I could continue using the computer while it was working.
Now that it has finished creating thumbnails for all non-video files, I re-enabled the "create thumbnails for videos" option.
Media Center thinks that all files in the library have thumbnails, and no longer attempts to generate them for any video files which are already imported.
 
Is there any way to identify which files do not have thumbnails and force Media Center to build them?
So far it looks like my only options are to either erase all thumbnails and start again, or use the "rebuild thumbnail" option which is modal and locks you out of using Media Center while it runs.
 
 
I still have no idea what is causing this extreme stuttering when Media Center is building thumbnails for video files.
I did notice that if I log into another user on the computer, it is not affected at all. Only the user account which is running Media Center is affected by the stuttering.

[RD James]

Spent a good amount of time trying to diagnose this today, and I haven't been able to figure out what is causing it.
Tried creating a new user and library on this machine, to no effect.
Tested a batch of videos on an older PC, and a clean install of Windows on a spare drive in this PC, and both were mostly free of issues.
There were still occasional DPC Latency spikes, but not for every video, and only to ~500µs which is acceptable if not ideal (should not interfere with normal system operations).
Having to completely wipe the OS and start over is far from an ideal situation though, so I'd really like to get to the bottom of this.
 
I've still not figured out a way to identify which videos have thumbnails and which do not, other than manually going through them all.
If nothing else, that bug which is causing Media Center to think the files have thumbnails when they do not, should probably be addressed.

[~OHM~]

I just had a little glitch on my everyday playing machine and needed to restore a back up....dummy me didn't think to save the thumbnail folder so I let it rebuild 300 thosand or so and I played music through most of it and never herd a glitch or a burp on my old del i5 with 16gb memory...now try and analyze over 5 at a time and playback will hick up...

[RD James]

I just had a little glitch on my everyday playing machine and needed to restore a back up....dummy me didn't think to save the thumbnail folder so I let it rebuild 300 thosand or so and I played music through most of it and never herd a glitch or a burp on my old del i5 with 16gb memory...now try and analyze over 5 at a time and playback will hick up...

Audio analysis is a separate issue, and 5 at a time is likely saturating whatever I/O connection is being used, or too much for your CPU to handle. Since it's an 'old i5', it won't have more than four CPU cores.
Stick to as many tracks as you have cores (or fewer), and set Memory Playback to "Load full file (not decoded) into memory".