Audio Playback and Pitch Tracking

Abstract

In this chapter, we will look at some of the ways that you can play back and record sound files. As you know, Max lets you design the way you control the variables in your patch. We will apply these design concepts to the ways we control the playback of recorded sound. We will also look at some ways to track the pitch of analog audio and convert it into MIDI numbers. By the end of this chapter, you will have written a program that allows you to play back sound files using a computer keyboard as a control interface as well as a program that tracks the pitch you’re singing from a microphone and automatically harmonizes in real time. We will create a simple patch that plays back some prerecorded files I have prepared. Please locate the8 “.aif ” audio files located in the Chapter 13 Examples folder. 1. Copy these 8 audio files to a new folder somewhere on your computer 2. In Max, create a new patch 3. Click File>Save As and save the patch as playing_sounds.maxpat in the same folder where you put these 8 audio files. There should be 9 files total in the folder (8 audio and 1 Max patch) 4. Close the patch playing_sounds.maxpat 5. Re-open playing_sounds.maxpat (the audio files will now be in the search path of the Max patch) We can play back the prerecorded audio files we just copied using an object called sfplay~. The sfplay~ object takes an argument to specify how many channels of audio you would like the object to handle. For instance, if you are loading a stereo (two channel) file, you can specify the argument 2. Loading a sound file is easy: simply send the sfplay~ object the message open. Playing back the sound is just as easy: send it a 1 or a 0 from a toggle. Let’s build a patch that plays back these files.