Parameter tweaks to fix "System timer accuracy = BAD" ?

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iceman
Posts: 6
Joined: Sun Jun 26, 2016 5:59 pm
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Ran into this on one of the computers I've tried running QLC on with Open DMX. The sync is horrid on this computer. My show falls out of sync with the audio almost immediately.

I noticed it's possible to change certain parameters for QLC (DMX USB Enttec Open frequency and perhaps Master Timer frequency) but how do I know what I should be changing them to? I presume the goal would be to tweak these to sync the speeds to that of the computer that is running it, but what system specs or benchmark info should I be looking at to determine optimal frequencies? I'd rather not play with this through simple trial-and-error.

Also, is 'GOOD' the best result for "System timer accuracy" when looking at info for a DMX I/O device or is there an 'EXCELLENT' or 'PERFECT?'
plugz
Posts: 637
Joined: Sun Apr 12, 2015 6:30 pm
Real Name: David

Hello,

- What OS ?
- What are the specs of your computer ?
- Are you using a genuine Enttec Open DMX USB ?
iceman
Posts: 6
Joined: Sun Jun 26, 2016 5:59 pm
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OS is 32-bit Windows XP Pro (yeah I know, I just figured xmas light timing is something I could use this old girl for without having to buy another high-end modern PC).
ASUS M2N-MX motherboard (USB ports are v2.0)
AMD Athlon 64 X2 dual core 4200+ (2.21Ghz)
3GB RAM

Yes, it's a real ENTTEC, specifically the assembled widget.
janosvitok
Posts: 1265
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Location: Bratislava, Slovakia
Real Name: Jano Svitok
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The timer check is limited only to Enttec Open DMX USB output. It shows either GOOD or BAD values.
The check is quite simple: it starts timer, sleeps for 1 ms and checks whether timer shows max 3 ms elapsed.
If the result is BAD it means either sleep was too long, timer to coarse (sometimes the timer can't measure up to ms resolution),
or the CPU is to busy to return control to QLC+/open dmx output thread.

When the check returns BAD, different code is used that does not rely on sleep() function, it actively waits.

Regardless of what code is used, BAD timer only affects DMX output, so the frames may not be sent to output at precise times,
maybe some of them may be dropped, but the overall timing should be OK. It may show a global problem with timers though.

So to fix audio/lights drift, you may try these (I don't use audio, so I don't have any first hand experiences):
- if you use audio in mp3 format it may help to convert it to wav
- if you have antivirus, disable the realtime protection
- select maximum performance power settings
- in the computer properties, select "optimize for background services" (maybe even disable virtual memory)
- disable anything (software/devices) you don't really need
- you may open task manager, enable show kernel times and watch CPU usage (both total and kernel - the red part).
if total CPU usage is high (>80%?), find problematic program and disable it (ask here if QLC+ is problematic)
if the kernel times are high (let's say >20% ?), it means lots of time is spent in drivers. I can't help you how to find the offending driver,
try to google it if this is the case.
See also http://www.windowsnetworking.com/j_helmig/wxpperfm.htm for more detailed statistics.

Generally, look up any audio optimization guides on the internet.

Finally, you may have luck reinstalling the computer to linux which has better kernel, memory manager and filesystem, and does not need antivirus :)
igorrobertifoc
Posts: 45
Joined: Fri Apr 14, 2017 6:17 pm
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Hello,
I have the same problem but it's quite strange the reply.
I don't understand why with the 3d software all is working very well and when I use the USB it flicker..
If there is a Windows problem sleep syncro will be affect both way, no?

Thank you
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