HITHER GATE MUSIC

Starting Point (varied inputs)

In general, varied and rhythmic sounds work well. If the sound is too steady state, the result may not change enough during the course of playback to remain interesting. Also, if a sound is already very rough to start with, the distortion processing may go over the top.

Step 1: Copy

Make a copy of the input soundfile, giving it a single letter name.

It is presumed that the input is mono and begins and ends smoothly, i.e., without a click or being suddenly cut off. Of the various inputs tried, a frog and a tom (drum) worked best. The vibrations of the frog's voice were nicely extended, and the tom's resonance led to some very finely etched and changing burbles.

Dialogue box:

Default parameters

New name is 'b.mp3'

Command:

rem function mode infile outfile
copysfx tomcdt.wav b.mp3

Step 2: Distort

Distort with wavecycle repetition

This form of distortion, developed by Trevor Wishart, uses the changing lengths of soundfile which lie between zero crossings. There are two parameters: repetitions – the number of wavecycles in a group, and groups – the number of times to repeat each group.

Dialogue box:

Wavecycle distortion

Command:

rem function mode infile outfile repetitions groups
distort repeat b bdr 5 -c2

PLAY bdr.mp3 (distorted soundfile)
New name: 'a distort-repeat'

Step 3: Ring Modulate

Pass the distorted sound through a ring modulator.

This process adds and subtracts a specified number of frequencies to the source, thus tending to split it into high and low components. A somewhat 'hollow' sound can often result.

The number of frequencies specified here is 1000.

Dialogue box:

Ring modulate

Command:

rem function mode infile outfile freq_in_Hz
modify radical 5 bdr bdrrm 1000

PLAY bdrrm.mp3 (ring-modulated soundfile)
New name: 'a distort-repeat ring-modulate'

Step 4: Loop

Loop segments (not the whole soundfile)

Now we divide up the soundfile into segments and either overlap or separate them. In this case we overlap them because the length of the step is shorter than the length of the segment. The processing begins at time zero in the infile.

Segment_length and step are given in milliseconds. 1000ms = 1 sec. In this case, therefore, each loop is ½ sec. long and the next segment begins after 1/10^th of a second, an overlap of 4/5^ths. Note that this is not an overlap in that the two sound together. Rather, it means that the start point of the next segment occurs 0.1 sec after the previous one. Thus 4/5^ths of the sound material is the same. The segments are placed end-to-end, thus resulting in a longer soundfile.

Dialogue box:

Loop defined segment lengths

Command:

rem function mode infile outfile start-time segment_length step
extend loop 1 bdrrm bdrrmloop 0.0 500 100

PLAY bdrrmloop.mp3 (looped soundfile)
New name: 'a distort-repeat ring-modulate loop'

Step 5: Scramble

Segment the looped soundfile and mix up the order of the segments.

To make it more unpredictable, we use segments of different lengths. We do this by specifying both a minimum and a maximum size. The program selects a segment length at random from somewhere within this range. The output duration parameter means that we can specify just how long we want the output soundfile to be. You can also specify the length of splice between the segments, a longer splice length giving a somewhat smoother result. The default value is 15ms, and here we are making it a little longer.

Without the Scramble process, the looped segments, being all of the same length, create a regular, motoric effect. Some of this is retained because maxseglen is a little more than twice the size of the loops. But the changing lengths and scrambled segment order reduces the motoric effect, making it more varied and unpredictable.

Dialogue box:

Scramble the segments

Command:

rem function mode infile outfile minseglen maxseglen output_duration splice
extend scramble 1 bdrrmloop bdrrmloopscr 0.06 1.1 32 -w25

PLAY bdrrmloopscr.mp3 (scrambled soundfile)
New name: 'a distort-repeat ring-modulate loop scramble'

Step 6: Analyse

An analysis is needed to prepare for the function to follow.

We convert the soundfile data to analysisfile data, because the Trace operation deals with analysis channels.

Dialogue box:

Default parameters

Command:

rem function mode infile outfile
pvoc anal 1 bdrrmloopscr bdrrmloopscr.ana

Step 7: Trace

Retain only a specified number of the loudest analysis channels.

The analysis channels contain the (changing) frequency + amplitude data of the sound, organised in a vertical series of frequency 'bins' – each bin covers a set frequency range. A given bin or channel may or may not have any partial data, and even if it does, the loudness will differ. Ecah bin only lasts for a very short time, so as the sound progresses, the content of each bin changes.

The Trace process retains the loudest bins and discards the rest. If you specify many bins, e.g., 300, the output will probably sound almost the same as the input. But if you specify only a few, e.g., 10 or less, only a 'trace' of the original sound remains. This is where the sound changes to light burbles. The churning aspect came from the loop operation.

Dialogue box:

Enter number of channels to retain

Command:

rem function mode infile outfile loudest_channels_to_retain
hilite trace 1 bdrrmloopscr.ana bdrrmloopscrtr.ana 10

It is possible to play this analysis file within Soundshaper. Simply hit the Spacebar or click the Transport PLAY button, either of which will call pvplay.exe as necessary. [text updated]

Step 8: Re-synthesise

Finally, we reconstitute the soundfile.

Synthesis converts analysis data back to soundfile data, ready for audition as a .wav file.

Dialogue box:

Re-synthesise

Command:

rem function inanalysisfile outsoundfile
pvoc synth bdrrmloopscrtr.ana bdrrmloopscrtr.wav

PLAY bdrrmloopscrtr.mp3 (trace of soundfile)
New name: 'a distort-repeat ring-modulate loop scramble trace'

Complete Sequence: Batch File churbles.bat

Use churbdel.bat to remove the outputs

rem day2.bat - 'CHURBLES' batch file for second set of functions
rem Description: usually results in lightly churning burbles
rem Last updated: 24 March 2003

rem Sources (with results after processing):
rem   aklcdp.wav  (1.38 sec) - good rhythms & sonic changes
rem   bashdt.wav  (1.5 sec) - not good, too similar all through
rem   frogcdt.wav (1.8 sec) - excellent because spreads attack
rem   hoggdt.wav  (3.7 sec) - churning then lighter burbles
rem   tomcdt.wav  (1.3 sec) - remarkably good: goes very thin
	(it's the ring modulation that makes the biggest change)
rem   touccdt.wav (3.0 sec) - distortion very prominent
rem   whdtm.wav   (2.4 sec) - light randomised churning

echo on

rem Step 1. Copy to simple name
copysfx tomcdt.wav b.wav

rem Step 2. Distort Repeat x cyles in y groups
distort repeat b bdr 5 -c2

rem Step 3. Ring Modulate
modify radical 5 bdr bdrrm 1000

rem Step 4. Loop with longish overlapping segments
extend loop 1 bdrrm bdrrmloop 0.0 500 100

rem Step 5. Scramble the file of loops
extend scramble 1 bdrrmloop bdrrmloopscr 0.06 1.1 32 -w25

rem Step 6. Analyse
pvoc anal 1 bdrrmloopscr bdrrmloopscr.ana

rem Step 7. Trace to reduce to n loudest partials
hilite trace 1  bdrrmloopscr.ana  bdrrmloopscrtr.ana 10

rem Step 8. Synthesise final result
pvoc synth  bdrrmloopscrtr.ana  bdrrmloopscrtr

echo off

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SCREENSHOT UPDATES

(by Robert Fraser, March 2016)

The Soundshaper screenshots used in this tutorial are out of date in two respects:

• Output files are no longer named on Parameter Pages: instead, the output is saved to a temporary file and appears on the Main Page patchgrid in a new cell named after the process.
  If you want to save the output permanently, highlight the cell (if necessary) and click File/Save or CTRL+S to obtain a standard SAVE dialog:
  
  
  
  
  There is normally no need to do this until the end of the sequence.


• FFT conversion (PVOC Analysis / Resynthesis) now uses current settings and the FFT page is only used to set these, not to perform a conversion, as shown. As the tutorial examples use default values, there is nothing to set!
  Furthermore, Soundshaper does these conversions in the background, so you do not even have to select ANALYSE or SYNTH – just select the next process.

To run the CHURBLES chain of CDP processes in Soundshaper:

[After each step, you can play the result in the transport panel.]

• STEP 1 (COPYSFX): Open the tutorial folder. Drag and drop the source tomcdt.wav onto Soundshaper's Main Page.
  Program runs COPYSFX and outputs to cell A_0.


• STEP 2 (DISTORT): Select Soundfiles/Distort/Repeat.
  Parameter page: set parameters as in tutorial (Repeat=5, Cycles=2).
  Click OK to run; output appears in cell A_1 ("CycRepeat").


• STEP 3 (RING-MOD): Select Soundfiles/Pitch/RingMod.
  Parameter page: set parameters as in tutorial (ModFreq=1000).
  Click OK to run; output appears in cell A_2 ("RingMod").


• STEP 4 (LOOP): Select Soundfiles/Reverb-Echo/Loop.
  Parameter page: set parameters as in tutorial (Start=0,Loop-length=500, Step=100).
  Click OK to run; output appears in cell A_3 ("Loop").


• STEP 5 (SCRAMBLE): Select Soundfiles/Extend/Scramble.
  Parameter page: set parameters as in tutorial (Minseg=0.06, Maxseg=1.1, Duration=32, Splice=25).
  Click OK to run; output appears in cell A_4 ("Scramble").


• STEP 6 (PVOC ANALYSE): You can skip this step!
  The settings used are the defaults, so there is nothing to set.
  Soundshaper will run PVOC automatically before performing the next step.


• STEP 7 (TRACE): Select Spectral/Filter/Trace.
  Parameter page: set parameters as in tutorial (Trace=10 channels).
  Click OK to run; output appears in cell A_5 ("Trace").


• STEP 8 (RE-SYNTHESISE): Hit F9 or click Spectral/PVOC/Synth. Output appears in cell A_6 ("Pvoc Synth"):
  
  
  
  
  
• SAVE FILE (OPTIONAL): Save the result to a permanent file. Hit CTRL+S or File / Save(As) to obtain a standard SAVE dialog.
  Enter a file name, e.g. churbles.wav (or bdrrmloopscrtr.wav if you prefer).


• SAVE PATCH (OPTIONAL): Uncheck "Include Sources", unless you want to save the copied source (~A_0.wav) with the patch.
  Click the patch SAVE button (central panel). Select a save name (e.g. churbles.ssp); click OK. Optionally enter a description; click OK.
  


• RUN PATCH (OPTIONAL): To run the patch with a different source (assuming the patchgrid has not been cleared), click on cell A_0, select a source (e.g. by drag+drop) and click the central RUN button, with the "Whole Patch" checkbox checked.


• RELOAD PATCH (OPTIONAL): If the patch is not on the grid, click the central LOAD button. Select the .ssp file (e.g. churbles.ssp). If you have not saved the source (~A_0.wav), the patch will still run with it, provided it still exists in the same location. Otherwise, you will be prompted to select a source. To run the patch with a different source, see RUN PATCH above.