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Posted by on Dec 29, 2012 | 5 comments

Recording Impulse Responses

With growing computing power over the last decade, convolution plugins have become commonplace. Some of the most common ones include Audio Ease Altiverb, Logic’s Space Designer, Avid TL Space, Waves IR-1 and McDsp Revolver. They are usually packaged with large and useful libraries of impulse responses (more on what all this means below), but what makes them really powerful is the fact that it is quite easy to record and use your own impulse responses. This not only helps ‘personalise’ your mixes, but is extremely useful in post-production and in the design of new sounds.

Each of the above mentioned plugins need slightly different techniques for creating a custom library of impulse responses. This article is a description of the general concepts behind recording good impulse responses and should be easily adaptable to any convolution/de-convolution tool.

What is convolution?

Convolution is the process where a single sample of a sound is multiplied by every sample of another sound. It is different from the plain multiplication of two sounds where a single sample of the first sound is multiplied by the corresponding single sample of a second sound.

Curtis Roads (The Computer Music Tutorial) describes convolution as:

Convolution of two audio signals is equivalent to filtering the spectrum of one sound by the spectrum of another sound. Convolution of spectra means that each point in the discrete frequency spectrum of input a is convolved with every point in the spectrum b.

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Posted by on Dec 13, 2012 | 0 comments

Rewind…Audio Implementation Greats #3: Crackdown – Realtime Worlds

In the run-up to this month’s reverb theme, former contributor Damian Kastbauer suggested we re-run this article he put together discussing the game Crackdown for XBOX. The article may be two years old, but the content remains undeniably relevant. Never one to ignore good suggestions, here we are…

Crackdown

One area that has been gaining ground since the early days of EAX on the PC platform, and more recently it’s omnipresence in audio middleware toolsets, is Reverb. With the ability to enhance the sounds playing back in the game with reverberant information from the surrounding space, you can effectively communicate to the player a truer approximation of “being there” and help to further immerse them in the game world. While we often take Reverb for granted in our everyday life as something that helps us position ourselves in a space (the cavernous echo of an airport, the openness of a forest), it is something that is continually giving us feedback on our surroundings, and thus a critical part of the way we experience the world.

Continue Reading >>

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Posted by on Nov 1, 2011 | 1 comment

Altiverb Impulse Responses Available for Wwise

Audiokinetik has announced a new partnership with Audio Ease. Altiverb IR packages on Wwise.

Audiokinetic Inc. and Audio Ease B.V. announce a partnership where Audiokinetic will distribute award winning Altiverb Impulse Response packages for the Wwise convolution reverb plug-in. The first package will be available before the end of this year and will contain 49 impulse responses mostly oriented for the reproduction of outdoor environments. Reproducing outdoor environments is probably one of the most difficult tasks for sound designers today and this package arrives at the right moment for professionals seeking quality and realism in their games.

“At the design phase of our convolution reverb, we set a very challenging goal that we could have the best technology from the post-production world running in games, said Simon Ashby, VP Products at Audiokinetic. Given that our convolution reverb operates with high performance and that we proudly partner with Audio Ease, which is certainly the most respected player in this field, I think we can say that we have achieved our goal”.

“Convolution reverb approaches the real world so much better than synthetic reverb that it had no trouble taking over Hollywood film sound. I hope this set of movie post-pro Altiverb IR’s will help convolution reverb do the same in game sound, added Arjen van der Schoot, Co-owner of Audio Ease. We had been waiting for the right opportunity to start applying our IR’s in real time in games. When Audiokinetic came along, we did not hesitate. I believe we have chosen to partner with a company as devoted to impressive sounding audio as we are.”

Audiokinetik | Audio Ease

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Posted by on Jun 16, 2011 | 0 comments

IR Reverb Comparisons

I published an article on IR reverb and deconvolution comparisons on my blog. Quite a few people found it useful and Miguel thought it would a good idea to share it with the rest of the community who aren’t on Twitter. If you aren’t on Twitter, join now! The sound community is nothing short of fabulous.

After my previous post on recording and mangling IRs, I decided to find a way to use the sweep I recorded for Altiverb in other convolution reverb plugins. I also thought it would be a good opportunity to compare the sound of these plugins and listen to how differently they deconvolve sweeps. The list of plugins include:

This is not a comparison of their features but of how each one of them sound.

Deconvolution Comparison:

Preparation:

The Altiverb sweep generator produces a sweep with a start and end beep (which it uses for identification). Since most other deconvolution tools don’t recognize these beeps, I created two versions of the sweep – one with the beeps and one without and normalized them to -0.3dBFS. The recorded sweep at the venue also included broadband noise and AC hum, which Altiverb’s processor did a good job of neglecting. The other plugins weren’t as good and included the noise along with the impulse. To make the comparison easier I used some amount of noise reduction on both versions of the recorded sweep.

1. AudioEase Altiverb:

AudioEase’s IR Pre-Processor needs to be used to deconvolve a sweep that is usable in Altiverb. The process is very simple – select a folder with the recorded sweep (make sure they are stereo-split SDII files), an output folder (your Altiverb preset folder), an input description file (in this case, “Sweeps, not to be equalized”) and hit “Process”. Re-scan your IR directory in Altiverb and it should show up.

Here’s what the sweep recorded at the venue for Altiverb sounded like (with beeps, noise reduction and normalization). Make sure you aren’t monitoring too loud:

Continue reading and listening here.

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Posted by on Feb 10, 2010 | 5 comments

Audio Implementation Greats #3: Crackdown – Realtime Worlds

Crackdown

One area that has been gaining ground since the early days of EAX on the PC platform, and more recently it’s omnipresence in audio middleware toolsets, is Reverb. With the ability to enhance the sounds playing back in the game with reverberant information from the surrounding space, you can effectively communicate to the player a truer approximation of “being there” and help to further immerse them in the game world. While we often take Reverb for granted in our everyday life as something that helps us position ourselves in a space (the cavernous echo of an airport, the openness of a forest), it is something that is continually giving us feedback on our surroundings, and thus a critical part of the way we experience the world.

While It has become standard practice to enable Reverb within a single game level and apply a single preset algorithm to a subset of the sound mix. Many developers have taken this a step further and created Reverb regions that will call different Reverb presets based on the area the player is currently located. This allows the Reverb to change based on predetermined locations using predefined Reverb settings. Furthermore, these presets have been extended to area’s outside of the player region so that sounds coming from a different region can use the region and settings of the sounds origin in order to get their Reverberant information. Each of these scenarios is valid in an industry where you must carefully balance all of your resources, and where features must play to the strengths of your game design.

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