Hi,

This is a question for which I haven't figured out the answer for a long time.

There is this page with very nice impulse response files from Pori, Finland. It sounds comparable with – or in some cases better than – Bricasti M7, but they don't provide ready-to-use true stereo IR samples. However they have b-format samples that are more sophisticated, either 5 channels or 4.
I have been looking for a way to convert it to 2 stereo channels and load it in a true stereo reverb plugin (like in HOFA IQ-Reverb).
There has been a pair of plugins called VVMicVST and VVTetraVST and I tried them but couldn't get good result of it, not to mention that it created a longer sample file. I'm clueless about how this vst has to be set up to convert it right.

So far I was able to use the original B-format files, splitting the 4 channels and create 2 stereo channels and even though it seems silly because I know that those 4 channels don't represent the 1L-1R-2L-2R sides, it actually sounds quite good (I recommend anyone to try for example the s1_r3_sf.wav from Sndfld.zip), a little bit unbalanced (off the center) but using some orchestral sample libraries it gave a nice, dense, natural concert hall feeling.
I tried using the stereo samples of two different mic positions (R3 and R2) as left stereo and right stereo but they are located in different distances and too far from each other as seen in the provided room map and didn't really sound that good at all.

The best would be the real extracted b-format to true stereo.
Anyone has any helpful idea?

Thanks

 

Good question! Have you tried importing them into a multitrack audio editor, eg Audacity, and exporting them as stereo .wavs?

 

I doubt that Audacity can import b-format properly.
I just did a quick search after your comment and found this article in pdf that says – besides of other interesting infos – Apple Impulse Response Utility can read b-format and it is found in Logic Pro.
There is another site that can be promising regarding to the matter.

I can't test these in the near future but if someone else is interested in the topic, could have a try.

 

Fog Convolver can load 4-channel .wav files natively.

You could also use the binaural pack within the Pori impulses? They should be regular stereo files. I used them before and they sound great for standard reverbation duties (no fancy 5.1 surround stuff or anything like that).

 

Last edited: Jan 14, 2021

I took a look and they're complex IR measurements, there's not a direct correlation to left-right stereo IR. Some are captured with multidirectional mics, some corresponding to 4 different positions in the audience or stage.
Good but complex stuff

 

The files are in wav but as @Xupito also mentioned these are IR measurments packed/saved in a 4-channel wav.
It's probably just a coincidence that when I tried them as if those were real wav IR samples (separating them to two stereo tracks) it sounded surprisingly good but in no moment I believed it was properly used.
Pori has normal stereo IR samples in that pack but in that time I wanted to use those IRs for true stereo in HOFA/Reverberate or whatever reverb plugin.

 

It is not only a matter of file format.
It is a matter of sound take.

I didn't found any software to revert the acoustic sound take effect.
Because there are NO algos behind it.
Clear answer : NO, you can't convert such a complex sound take/format into "regular" mono/stereo impulses.

What makes them good is in the sound take concept.
Some reading :
http://legacy.spa.aalto.fi/projects/poririrs/docs/readme.txt
https://postperspective.com/vr-audio-differences-format-b-format/
http://legacy.spa.aalto.fi/research/cat/sirr/papers/SIRRwhitepaper.pdf