Room correction with convolution per sample rate

[digimuse]

I was able to get similar results to yours by switching from ffmpeg 4.1 to 3.4.2 (even version 4.0.3 resulted in a severe volume reduction).

I created the FIR filter files using Acourate. Details of the procedure to generate the filters can be found at:Acourate Digital Room and Loudspeaker Correction Software Walkthrough.

When generating the correction filter, Acourate reports the "Correction filter gain ratio approx: -x.y". For example, in the link above, look at the figure below "Run macro 4" (which shows -8.9).

For me, Acourate reported an expected gain ratio of -3.78 dB.

I loaded all the correction filters in JRiver MC, and played a 1 kHz warble test tone from Editor's Choice: Stereophile's Sampler & Test CD.

In JRiver it is possible to turn the FIR convolution filters on/off with a check-box in the DSP Studio. I compared the SPL of the 1 kHz warble tone with/without the filter, and it was approximately 5 dB.

I brought this up with the developer of Acourate, Dr. Ulrich Brüggemann, who thought the difference was not material. It could have to do with level normalization in JRiver (e.g., Re: Native JRiver 64bit fp convolution engine for Room Correction (FIR filters)?).