What happened so far?
Over the end of the last semester and the summer, implementation became the main topic for the process. I managed to find decent placeholder models for the EQ, pitch shifting and reverb unit in the Max default resource examples: (in the ‚pitch and time‘/‘effects‘ folder, access by right click > object > open.amxd). With these, I did some testing using exports from the original Paulstretch software to make sure the results could work in the context of what I am trying to create.
Although initially I was headed towards just slightly modifying the phase vocoder that is available for Max, I realised that for my understanding of the algorithm and Max itself it might be better to start and troubleshoot from scratch, to get a result that I could fully explain and modify as needed. To do so, I used my Python analysis and the available Github repository to break down the most important steps of the algorithm (to recap in overview terms: Fourier Transform > Windowing Function > Spectral Processing > Inverse Fourier Transform > Interpolation and Smoothing) in terms of understanding, but also mathematically so I would be able to send the signal through the correct processing chain in Max for the output I am looking for. This also required me to go back into my mathematical education a little bit in order to properly understand what I was working with.
Ultimately I aimed for 4 manually changeable parameters for now: Window size (to control spectral resolution), Overlap (to control overlap between windows), Stretch factor (the most important one) and a Smoothing parameter which is supposed to help create a smoother output with some to few artefacts.
For Future Reference
Another new consideration that came up during this process was that it might be useful to have a tuner of some sort integrated tob e able to tune the edited audio as needed for the current project. However, this is not a priority right now.
Ongoing
I am currently also trying to plan first listening experiences, to be able to test my prototype in the future. My supervisor suggested I look into webmushra to set up listening test scenarios, and another idea was to set up a sonified „Find the Mistake“ station at the exhibition so people could playfully get results for me to evaluate, in a less controlled context of course.
Results and Reflection
The stage of the project I am in right now is not the most rewarding in that I don’t get any immediate results at the moment, as I am setting up and testing the patch based off my notes and the process I noted down fort he audio signal, but I know it is essential to create a sounding prototype and am hopeful that it will pay off. Either way, I have learned a lot about digital signal processing during my research for this phase of the project, which is always useful.
Objectives for Next Time
- Get sound through the new signal chain
- Come up with test scenarios and mockups
- If I get that far: Try to get reloadable presets set up
