I wanted to further evidence and qualify the “improper convolution file resampling” bug I have identified, by measuring the impulse response through Roon DSP in various configurations.
What I did:
- create a “Dirac” file, sampling rate 96kHz, duration 2 secondes
- record Roon outcome for various NULL convolution files : 1) 96KHz 2) 44KHz sampling 3) 384KHz
- Compare outcome with initial “Dirac” file
Looking at the recordings it is obvious there is an issue with 44k and 384k NULL IR.
The 96k NULL IR turns the 96K DIrac into a Dirac as expected (minus dithering effect but this is normal and very low level anyway).
WIth REW, one can see that the improper resampling of 44K and 384K NULL IR at 96kHZ is creating a big mess to the phase in the mid/highs:
Here is the Audacity file with the 3 recordings.
Also I checked that the bug is not related to the filter’s file format, so I tried various ones, all at 384k:
- IEEE 64bit
- DBL 64bits
- LPCM 32bit
- IEEE 32bit
- LPCM 24bit
All failed to bring a clean recording of my 96k reference track “Cecile”. So it seems that the resampling bug occurs whatever the convolution file format is.
On a side note: i don’t know if it’s the expected behaviour, I experienced the following with DBL files:
- cannot be imported as a single file “unsupported file format” (whereas .wav can)
- if I i put the file in a .ZIP container : it was imported, but nothing would play
- it works well in a .ZIP container and a simple .cfg file