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Thread: Need help with audio library and effects

  1. #1
    Junior Member
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    Jul 2021
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    Need help with audio library and effects

    I am making a project using teensy 4.0 and the audio shield that adds effects to audio from is2 input and output it right away to is2 out. I will be using only bitcrusher, chorus, and delay. I made a menu screen with LCD and I want to make it so that you can select one or more effects from that menu. But it always has to be in this order: bitcrusher --> chorus --> delay. Since I am very new to teensy and audio processing in general so I have no idea how. Can anyone give me some examples?

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Nov 2012
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    Quote Originally Posted by Taemin View Post
    Since I am very new to teensy and audio processing in general so I have no idea how.
    First check out the 31 page tutorial, if you haven't already.

    https://www.pjrc.com/store/audio_tutorial_kit.html

    If you have no idea how to use the audio library, this tutorial will walk you though all the basics. If you're pressed for time, just read the first few sections of part 2, so you understand how to use the design tool.

    Best to read the tutorial and actually do each part. But if you get stuck, there's a full 45 minute walkthrough where you can watch every part of the tutorial.


    Can anyone give me some examples?
    Well, from what you described, you'd probably do something like this in the design tool.

    Click image for larger version. 

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    This is pretty standard practice in audio (not just Teensy) to apply some effect and then have a 2-input mixer with the "wet" processed sound and "dry" original sound. Often a single knob changes the gain on both inputs (so they always have a combined gain of 1.0) so you can gradually vary how much of the effect is applied. Of course, if you want a simple on-off control, just set the 2 inputs to gain of 0 and 1.0, so the desired signal passes through and the one you don't want it cut off.

    As with all projects, the best path to success is incremental progress, where you get just part of the project working and then build upon each small success. So I would urge you to first just get the effects working, even if you just hard-code numbers for the mixer gains and have to upload again to change them. Then separately focus on getting the display working. Then build your user interface code. If you try to get everything working all at once, you might succeed, but even for experts it can be quite difficult to troubleshoot when you have so many unknown things to all diagnose and debug at once. Build your project up in pieces and test each one carefully before working on another.

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