Audio glitches with f.lux running

  • After a few days of debugging my new audio setup, I've realised that f.lux is (possibly indirectly) causing intermittent glitches (pops and crackles) with my audio system. I'm running various VST plugins under Reaper and so far, it's only the EastWest ones using their Play engine that seem to suffer, which is weird. I've a ton of Native Instruments stuff that seems absolutely fine at any buffer sizes.

    PC spec:
    CPU: i7-5960X (not overclocked)
    RAM: 64GB 2133MHz RAM
    Disk: Intel SSD 750
    Motherboard: Asus Rampage V Extreme
    Audio: Focusrite Saffire Pro40 - connected using a VIA chipset Firewire PCI-E card.
    Graphics: NVIDIA GTX 960 (353.62 driver)
    OS: Windows 8.1 64-bit

    So it's not really a system that should be struggling with low ASIO buffer sizes, and certainly shouldn't need the 2048 sample buffer to achieve glitchless operation. I've run Latency Monitor ( including its in-depth test, but the results are all very good, typically under 200us latency and ISR/DPC execution time.

    Stopping f.lux seems to remove the problem completely, and I can now run with an ASIO buffer size of 32 samples (i.e. very low) without any glitches. With f.lux running, there are glitches every few seconds. When the f.lux sunset is running the glitches go mad and are constant until it finishes. Reaper's metering updates are erratic during this time. With f.lux's safe mode enabled, it's not quite so bad, but still very much there. The test at shows lots of problems during sunset and occasional problems at other times.

    I don't believe that f.lux is the real problem here. If I go into Windows resolution/monitor settings or do anything in the Nvidia control panel, including something trivial like switching tabs or pages, these glitches occur even without f.lux running. I'm certainly not complaining about f.lux at all (which is great by the way!), but I thought I'd post this in case someone else is having similar problems. It isn't like the workaround is difficult :)


  • Many thanks for pointing this out! Same happened to me dur
    ing band rehearsal w/ NI Kontakt, even with RME hardware...thought I am going crazy since nothing showed up in LatencyMon!

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