IR formats....

[Lindon]

OK so I have a convolution reverb in the fx rack (actually a whole bunch of them but that's another story)....

The audio designer can hear distinct distortions showing up from the engine, these have reduced when we went from 24-bit IRs to 16-bit IRs, so it got me thinking perhaps we are creating these IRs all wrong...

Whats everyones rule-of-thumb when making /using IRs ?

We are "just" making/using 16-bit wav files ....is there anything else We should be doing?

[ustk]

@Lindon I haven’t used IRs in Hise seriously yet (essentially because I need to check the stereo/mono/quadri thing) But for reverberations, 16bit seems too low. This is exactly where using 24bits makes sense so why reducing the dynamic range in the first place?
The distortion probably comes from a conversion that has been done without dithering… Be sure to check the True Peak value too.

[d.healey]

I use 24bit 48Khz

[Lindon]

@ustk - hmm, seems logical - but experience is - he made them as 24-bit wav files - we loaded them and they distort MORE than the 16-bit ones...

what do you mean by this?

The distortion probably comes from a conversion that has been done without dithering

What conversion?

[d.healey]

@Lindon Distortion with IRs is often due to a gain increase created by the IR. Can you send me some of the 24bit ones that cause issues for you?

[Lindon]

@d-healey - sure I will get him to send some of them over...thanks

[ustk]

@Lindon @d-healey's right, often the distortion doesn't come directly from the IR itself but for the convolution resulting in an over 0dB signal. Although a simple gain after the convolution will tell the truth about this.

Sorry I just misunderstood this:

these have reduced when we went from 24-bit IRs to 16-bit IRs

You said the distortions reduced from 24 to 16bits, but I heard the files have been reduced. My bad :)

When does the distortion happen? In the early reflections/transient only? On the whole file? The late tail only?

[Lindon]

@ustk said in IR formats....:

@Lindon @d-healey's right, often the distortion doesn't come directly from the IR itself but for the convolution resulting in an over 0dB signal. Although a simple gain after the convolution will tell the truth about this.

Sorry I just misunderstood this:

these have reduced when we went from 24-bit IRs to 16-bit IRs

You said the distortions reduced from 24 to 16bits, but I heard the files have been reduced. My bad :)

When does the distortion happen? In the early reflections/transient only? On the whole file? The late tail only?

Well quoting the audio developer:

"The easy way to try it.. is run a sine wave. (Play low end like you would a sine bass) and you can hear all the harmonic distortion. - sounds like a waveshaper has been added into the IR engine...

Then for some reason, in Hise it adds a 19K spike of 12DB gain.. - although good luck hearing this"

[ustk]

@Lindon Hmm... Interesting...
Does it happen with IRs from another online bank for instance?

[Lindon]

@ustk said in IR formats....:

@Lindon Hmm... Interesting...
Does it happen with IRs from another online bank for instance?

Not sure - but the very same IRs when used in other convolution reverbs sound fine.....

[d.healey]

@Lindon I'm not hearing any distortion when I use those IRs and a sine-wave gen. I did have to turn the wet down a bit with some of them to prevent clipping.

Do you have a couple of audio examples of what you're hearing in HISE (with distortion) and what you're hearing with another convo that doesn't have distortion? This way I'll have a better idea of what I should be listening for. It would be good if both demos are created with a sine gen so we can compare more easily.

[Lindon]

@d-healey said in IR formats....:

@Lindon I'm not hearing any distortion when I use those IRs and a sine-wave gen. I did have to turn the wet down a bit with some of them to prevent clipping.
Do you have a couple of audio examples of what you're hearing in HISE (with distortion) and what you're hearing with another convo that doesn't have distortion? This way I'll have a better idea of what I should be listening for. It would be good if both demos are created with a sine gen so we can compare more easily.

• I will ask him.