VirtualDub: inserted frames exactly every hour on Windows 7

[^rooker]

[PROBLEM]
On a newly set up Windows 7 machine (yikes. This OS really, really sucks...), I wanted to capture analogue video using VirtualDub. VirtualDub is an excellent tool for video capturing, and I've been using it for years for that purpose. However, on that new computer with Windows 7, it puked precisely every hour and left me with 2 seconds inserted frames.

I've used perfmon to find out what happens, but the only thing I could see was, that the "system" task caused a CPU load spike and an I/O block, that caused the RAID10 drive to misbehave - and VirtualDub required 2 seconds to recover from that burst.

I've spent hours on that, disabled all obviously unnecessary services, checked scheduled tasks for 1-hour reoccurring entries - but nothing helped, until I've read some forum entries about the new and shiny "Windows Multimedia Class Scheduling Service", causing similar problems on other systems. I couldn't deactivate it though, because that also disabled audio on the system.

[SOLUTION]
Since I couldn't deactivate the culprit that probably caused this misbehavior, I had to give VirtualDub the ability to hold it's breath a bit longer during these hourly spikes.

So I changed Capture > Disk I/O settings from:

Code: Select all

Chunk size: 512 K
Chunks in buffer: 2

to a more contemporary amount of buffer size:

Code: Select all

Chunk size: 512 K
Chunks in buffer: 128

Voila! Now the system can run havok in the background, VirtualDub dives through and even manages to keep up realtime encoding (!!) of FFv1 lossless codec.