John Paines wrote:There have a few reports, including mine, that RX6 plugins are not reliable, at least on Windows. One or two may work, or at least work well enough that you won't notice any defects. More than, including more than one application of NR, will likely cause pre-echos, loss of sync, etc. These artifacts will be retained in any renders.
These are issues related to latency and delay compensation, and have been the case since Izotope released RX version 2 in 2007 with certain modules as plugins.
Try NR
Which settings are active within the Spectral DeNoise module?
The Adaptive mode in Spectral De-noise uses a significant amount of memory and computational power. For a more efficient form of adaptive noise reduction, try the Adaptive mode in Voice De-noise, which is designed to be highly efficient and zero-latency.
Voice De-noise has been specifically designed to provide high efficiency, zero latency adaptive noise removal when inserted on a track in your DAW or NLE. The Spectral De-noise plug-in is far more resource intensive and uses higher latency.
A: is the least CPU intensive process and is suitable for real-time operation.
B: is more CPU intensive and has more latency, but can still run in real-time on most machines.
C: is a very CPU intensive algorithm and can only run in real-time on faster multicore machines.
D: The speed of algorithm D is similar to algorithm C.
de-hum
Disabling Linear Phase Filters will reduce the latency used by De-hum when it is being used as a real-time plug-in.
DeClickLOW LATENCY: Works well on mouth clicks and other clicks that cannot be handled by other algorithms. This mode has very low latency and is suitable for real-time work in RX De-click plug-in.
It's easy enough to test. Try NR, de-crackle, de-hum, de-clip. That's usually enough to do it.
Izotope's Notes on Latency:iZotope plug-ins use complex DSP, which can create audible latency. During playback, this can result in a delay or offset to a single track's output, which can put a track out of sync with the rest of a mix.
[*] Make sure the "Enable delay compensation"* feature is enabled in the Options/Preferences window. This option is available in the General section under "Latency" or "Delay Compensation."
[*] Note that this feature reports the exact offset in samples to the host application. The host itself will need to compensate for the offset.
Make your host's delay compensation feature is enabled. This will usually be available in the preferences window or an options/settings menu.
[*] If your host application does not support Delay Compensation, you can still manually adjust your track to compensate for the offset. The current offset is available in the "Latency" or "Delay Compensation" section of the Options/Preferences panel.
I do not think that Resolve 14.x provides the required full latency compensation in its native implementation, and it certainly doesn’t provide any options within the application Preferences related to Delay Compensation, so manual compensation is required.
My suspicion is that the Fairlight Accelerator card is required for full latency compensation, as hinted at on the Resolve marketing pages:
Add Fairlight Audio Accelerator zero latency realtime performance!
For the absolute best performance, add a Fairlight Audio Accelerator to your system! You’ll get blazing performance with amazing sub‑millisecond latency, up to 1,000 tracks, and with full real time processing of EQ, expander/gate, compressor and limiter dynamics, and up to 6 real time VST plug‑ins per channel!