98 lines
3.0 KiB
HTML
98 lines
3.0 KiB
HTML
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<p>
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Considering the numerical nature of MIDI events, it can be tempting to apply
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mathematical transformations to our MIDI regions by using mathematical
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operations. Ardour makes it very easy and powerful with the Transform tool.
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</p>
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<figure>
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<img src="/images/MIDI_transform.png" alt="MIDI transformation">
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<figcaption>MIDI transformation</figcaption>
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</figure>
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<p>
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Accessing the Transform tool is done by <kbd class="mouse">right</kbd> clicking
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the MIDI region <kbd class="menu">><em>name_of_the_region</em> > MIDI
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> Transform…</kbd>
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</p>
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<p>
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To act on a property, it must be selected in the <kbd
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class="menu">Set</kbd> field, then the target value must be changed using the two
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following fields. To add more operands the "+" sign should be clicked to
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create new lines. These can be removed using the "-" sign on the
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right of the newly created lines.
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</p>
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<p>
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In the picture above, the Transform tool has been used to add a bit of
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humanization, by slightly changing the velocity of each note of the region, by
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a random number between -19 and +19 from its original velocity. So
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three operations are applied:
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</p>
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<ul>
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<li>Set velocity to this note's velocity</li>
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<li>+ a random number from 1 to 20</li>
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<li>- a random number from 1 to 20</li>
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</ul>
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<p>
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Each note will trigger a calculation of its own, so its velocity will be
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increased by a random number between 1 and 20, then decreased by a random
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number between 1 and 20.
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</p>
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<p>
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The properties that can be computed are:
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</p>
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<ul>
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<li>note number (eg C2 is note number 24, C#2 is 25 and <a href="@@midi-notes-ref">so on</a>)</li>
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<li>velocity (the global intensity of the note, between 0 and 127)</li>
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<li>start time (in beats)</li>
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<li>length (in beats)</li>
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<li>channel</li>
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</ul>
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<p>
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and the calculation may be based on the following properties:
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</p>
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<ul>
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<li>this note's</li>
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<li>the previous note's</li>
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<li>this note's index (number of the note, i.e. the first one is 0, the second
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is 1, etc.)</li>
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<li>exactly (for a constant value, between 1 and 127)</li>
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<li>a random number from <em>lower</em> to <em>higher</em> (<em>lower</em> and
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<em>higher</em> beeing constant values between 1 and 127)</li>
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<li>equal steps from <em>lower</em> to <em>higher</em> (<em>lower</em> and
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<em>higher</em> beeing constant values between 1 and 127).</li>
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</ul>
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<p>
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The mathematical operators can be:
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</p>
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<ul>
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<li>+ (addition)</li>
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<li>- (subtraction)</li>
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<li>* (multiplication)</li>
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<li>/ (euclidian division)</li>
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<li>mod (remainder of the euclidian division).</li>
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</ul>
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<p class="note">
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All these operations can be very handy, as long as there is a mathematical way
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to achieve the targeted goal. Beware though of odd "border cases": division by
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zero (which does nothing), using the note's index and forgetting it starts at
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0 and not 1, etc.
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<p>
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<p>
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Very interesting results can nevertheless be created, like humanizing
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(randomizing the velocity, start time and duration of all the notes), creating
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arpeggios, automating tedious tasks, transposing, etc.
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</p>
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