Category Archives: Processing

Descriptions of unique audio processing techniques

Hybridized Beat Repeat

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In my last post I explained how I rein in random processing behaviors to get the results I’m after. A good processor for randomizing audio is Ableton Live’s Beat Repeat. Beat Repeat effortlessly duplicates the once tedious process of repeating small chunks of a sample to get stuttering effects, but also has parameters to randomize the repetitions in a variety of ways.

For the Rhodes solo in “Six Weeks” I wanted to scramble my performance in some way to match the “broken” drum programming. Beat Repeat was the ticket, but I couldn’t get a complete take that fit well with the rest of the piece. If you look at the image you can see that the solo is made up of fifteen separate regions of audio. These are all abstracted from specific renders of the performance through Beat Repeat. After rendering the audio several times I selected specific phrases and organized them in a way that enhanced the dynamics of the piece, creating a hybrid. Listen to the solo by itself and then to hear it in context play the full track at 2:54.

Six Weeks (solo) – Hybrid Beat Repeat Solo

Six Weeks (full track) – One Day to Save All Life

Herding Random Behaviors

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After playing Precambrian Resonance for a few people and explaining how the arpeggiator was creating a randomness to the output I was asked how that randomness made it sound different from previous playback. This was easy for me to imagine since I had heard it rendered several different ways, but difficult to explain. Therefore I have re-rendered the piece to illustrate how it changes.

This brings up an issue that I have encountered on several occasions. When audio processing creates some sort of randomness in a mix, how can you get exactly what you want? What if after you export the audio there’s some chunk of randomized audio that just doesn’t quite work?

My solution is to render the track that has the random processing on it several times. For Precambrian Resonance 0.2 I rendered the processing eleven times. After that I’ll listen and compare the renders, or if I hear one that I like during the rendering, I’ll just choose it. Ableton Live makes this easy with the “Freeze Track” option that essentially renders the track while allowing you continue making adjustments.

Sometimes it is not that easy. I have encountered situations where version after version of the randomized processing doesn’t quite fit. At this stage what I do is carefully listen to the audio for phrases that have something interesting going on. The next step is to sequence the selected phrases into a complete track, effectively herding the random behaviors into what I’m after. I suppose that this is similar to using genetic algorithms to hybridize the audio in a semi-manual way.

Precambrian Resonance 0.2

Bit Reduction

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This drum loop has been processed by reducing the bit depth and down-sampling the clip until very little of it is reminiscent of it’s original state. As you can see in the image, the waveform has been reduced to a wide pulse that sounds very distorted (you might want to start at low volume). The top of the image represents a short section of the original audio, while the bottom is the processed version.

The bit depth was reduced to two, which allows for four possible positions for the amplitude of the waveform. Two above zero and two below zero. There are no zero crossings that aren’t straight lines, therefore the output sounds very similar to audio that has been badly clipped, but in my ears this sort of distortion has more charm than just clipping the waveform. The only other processing involved is automated pitch shifting from down four octaves up to its original pitch by about seven seconds into the audio. Here is where it sounds closest to it original form. Its stays there until about nine seconds in and then shifts back down minus forty eight semi-tones until it ends after almost twenty seconds.

redux

Tearing Grains

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Using the simple granular synth packaged with Pluggo I created this nasty tearing sound. Towards the middle it sounds like it’s causing speaker damage, but don’t worry your speakers are safe. The original waveform was a sawtooth before the grain table algorithms manipulated it as you can see in the image.

Granular synthesis involves separating a waveform into grains that can be rearranged either randomly or with various formulas resulting in dense or scattered clouds of sound particles. For more information about granular synthesis, check out this entry on Wikipedia.

Tearing Grains

Three Story Buildings

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How much processing can a voice recording take? I guess it depends on how badly you want to fuck it up. When it’s a recording of Donald Rumsfeld justifying the war on Iraq, I want to fuck it up as much as possible. That said, the recording is pitched and time expanded, run through a noise gate followed by a compressor, automated erosion, stereo delay (feedback at 80%, left at 5ms, right at 12.5ms, mix at 50%), and finally a reverb that creeps in with automated mix and decay. Enjoy!

Rumsfeld