MUSI11066 Audio Programming Assignment 2: Drone challenge
Audio Programming Assignment 2: Drone challenge
• The mark for this assignment will be worth 30% of your final course mark.
Assignment overview
This assignment is designed to let you experiment creatively with some of the basic audio DSP elements we have covered so far. You will submit a single Juce project that uses the Audio Plug-In template to render audio, although the focus will be on the standalone application build target. The application should generate drone music. For us, that means that we can create sounds with a relatively static set of synthesis elements and we don’t necessarily have to worry about constructions such as notes or rhythms (things that would often be determined outside of a plugin in the MIDI data). Make sure you think about how the sound will evolve over time, and draw the ear in to the detail. Note that the software should not be controlled by the user (no sliders, dials, buttons, etc): once the program is running, it develops by itself.
The assignment will be marked in relation to creative sonic/musical exploration of the programming (45%), well implemented code (35%, including considerations of efficiency, structure, absence of redundant code, etc), readability (10%) and comments and documentation (10%).
Elements to submit
• Your software. To keep submission files small, please just include the Source folder and Projucer project file, and any other files necessary to build and run the software (e.g. if you have any of your own files being used that are not in these directories). You do not need to submit the Build folder or the JuceLibraryCode folder. Make sure that your own header files are included in the Source folder. • A 2-4 minute audio recording of your project (see below on how to do this if you’re not sure). This can be a WAV or MP3 file. • A short 400 word report that outlines your approach to the drone piece, including a simplified flow chart or block diagram representing the structure of your audio elements (e.g. identifying oscillators/filters/modulators, etc and showing how they relate to each other). Note that the report stay focused on the sonic elements rather than the specifics of the coding, as these elements should already be addressed in your code comments. This report should be a pdf.
Coding objectives
Create a piece of software with the Juce Audio Plug-in Template that generates an engaging drone piece. As part of this, your code should incorporate the following:
- At least two classes that you have created (not including the Oscillator examples that we have looked at so far). These might be classes that extend the oscillators, or classes that include several oscillators together into a larger class, or something else of your own devising. The classes should be defined in a separate header file with a relevant name (or multiple header files as appropriate).
- At least one std::vector<> that includes multiple instances of a particular class (your own or perhaps a Juce class).
- At least one instance of the juce::IIRFilter class, or potentially another filter of your own
devising.
These are the essential elements, but you will likely need a range of other elements too to create a rich
drone.
It is very important that you document comment your code judiciously. Comments can help you to
obtain marks for the assessment elements even if the code is not fully working for certain aspects. You
should include brief comments that explain:
• the role of any variables that you define,
• the function of particular classes,
• the role of particular functions, noting both the type of data that is accepted as an argument (if
relevant), and the kind of data returned (again, if relevant).
• for classes and functions, use /* .../ to create a documentation block, e.g.
/* * * Convert MIDI pitches to frequencies in Hz * * @param note midi note (60 = middle C , 69 = 440 Hz ) * @return frequency in Hz */ float midiToFrequency ( float note ) { // ... }
Tips for engaging drones
Some potentially interesting aspects to consider for creating drone pieces: • Modulation can be very interesting for creating richer timbres and evolving those timbres over time (see LFOs below). You have already tried out phase modulation, but you could also explore frequency modulation, amplitude modulation, or experiment with other parameters to see what works well. • Low frequency oscillators (LFOs) can be very useful for making parameters change slowly over time (e.g. volumes, frequencies, timbral parameters such as modulation frequencies, modulation indexes, filter cutoff and resonance parameters, or any other aspect that might be sonically engaging to vary). These are easy to create as we already have oscillator classes that we can set the frequencies for and apply however we like. Note that you can also use LFOs to vary the rate and intensity of the effect of LFOs (e.g. like depth or modulation index as with the phase modulation example), and have other LFOs modulate those LFOs and so on, creating much less predictable patterns than simple ramps or sine sweeps. You could also think about how you might generate different shapes, e.g. the square of a sine function has a different shape from a regular sine function that may be useful. If you want things to happen discontinuously rather than continuously (e.g. regular jumps instead of a smooth link), you could think about doing something like scaling the output of a phasor ramp so that it goes from 0-9, and then forcing this into an integer range. You could then potentially use this as an index to an array (e.g. of oscillator frequencies for regular pitch changes).
• Beat frequencies, the rhythmic pulsing caused by two tones that are close in frequency, are an
interesting way to add movement and texture to a drone piece. If two frequencies differ by N Hz,
you will hear a rhythmic pulsing at N Hz. This technique is also used to create thicker synthesis
sounds, by having two or more oscillators per note, with one slightly detuned from the other.
• Resonant filters can be very useful for highlighting particular frequencies in an input sound,
particularly where the cutoff frequency for the filter is moving in interesting patterns. The Juce
IIRFilter class is very helpful in this respect, alongside the IIRCoefficients class and the member
functions like juce::IIRCoefficients::makeLowPass(sampleRate, cutoff, resonance).
• Creating lots of a particular class that all behave slightly differently can be an interesting way to
dense undulating sounds. The std::vector<> can be very useful for this. If, for example, you
want to create many instances of a MyOsc class, you can create a single std::vector
Marking criteria
The assignment will be marked in relation to creative sonic/musical exploration (45%), well implemented code (35%, including considerations of efficiency, absence of redundant code, etc), readability (10%) and comments and documentation (10%). The criteria for marking this assessment is based on:
- Is the final audio result aesthetically engaging?
- Does it evolve in a way that could hold a listeners interest over a longer period of time?
- Does the code compile and do what it is supposed to (as articulated in your short report)?
- Is the code well documented and explained with comments?
- Is the code neatly laid out? Have a look at this Juce style for tips on clear writing, and adhering to Juce coding standards https://juce.com/discover/stories/coding-standards
- Is the code efficient, or are there superfluous elements? Try to adhere to the common coding mantra: Don’t Repeat Yourself (see the above link for more information).
- Have you explored ideas beyond the basic examples presented in lectures and tutorials?
Recording an excerpt from your software To create a stereo audio file example of your software, you can use a DAW. These instructions are for generating an audio file with Reaper:
- Make sure you have build your project as a VST or AU component.
- Open Reaper, start a new project, and go to Item −→ Insert Virtual Instrument on New Track.
- From the menu, look for your plugin and click OK (it may be under the New section, or otherwise check the AU/VST3 sections)
- You should now hear your program playing. Select an amount of time to record for by dragging a selection at the top of the timeline as shown in the image below. You will want to select between 2-4 minutes for this submission as you prefer.
Figure 1: Create a selection in the timeline to determine how long the recording will be
- Go to File −→ Render...
- Make sure you select Source: Master mix, and Bounds: Time selection as shown here. Use the Browse button to choose where to save the file, and give it an appropriate name with your exam number.
Figure 2: Example Render settings
Submission details
You should submit your code, report (pdf) and audio file (wav or mp3) as a single .zip file. The zip filename should include your exam number (e.g. B**), so your final file will be called something like: B123456 AudioProgramming Assignment 2.zip.
Selected Drone Listening ˆ Re-Sonante • Eliane Radigue - L’Ile https://www.youtube.com/watch?v=pfz_kIU3KTE • Eliane Radigue - Triptych https://www.youtube.com/watch?v=OgN3_KXv5O8 • Roland Kayn - Rhenit https://www.youtube.com/watch?v=fyMYpNeRO6Y • Eleh - Living Space https://elehreleases.bandcamp.com/album/living-space • Caterina Barbieri - Bestie Infinite https://imprec.bandcamp.com/album/caterina-barbieri-eleh-split • Giacinto Scelsci - Quattro pezzi su una nota sola https://www.youtube.com/watch?v=MfTjz6emd7c
