hpr-knowledge-base/hpr_transcripts/hpr0991.txt

Episode: 991
Title: HPR0991: Making a Music Sampler with Midi and Pygame
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr0991/hpr0991.mp3
Transcribed: 2025-10-17 17:03:18

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Hello, this is BeGraderClock and welcome to Hacker Public Radio.
Today we're going to be talking about PiGame, the MIDI modules that are contained in PiGame,
and how you can use those to make a very cool, inexpensive sampler out of a netbook.
I first learned about PiGame at the South East Linux Fest.
I was watching a presentation by Ryan Ikelis-Cordan about how easy it is to make games in Linux
using Python and how hard it is to do it, you know, in Windows, where you would have to
type in a ton of code in Windows just to get the little screen to update correctly, and
in Linux it was just like two lines.
I never really been that much of a gamer, just had a curiosity.
I was looking through the PiGame website, and I looked on the documentation link and
low and behold, there was some stuff on there about MIDI.
MIDI stands for Musical Instrument Digital Interface.
MIDI is very, very nerdy, and it's usually associated with keyboards and lots and lots
of cables, but some musicians use MIDI and live performances and makes the little less
nerdy.
Bands like Pick Face and KMFDM can mix electronic instruments and samples with live instruments
on stage, and it comes across as very powerful, not like karaoke, like you're singing along
to a tape.
Everything seems very live, and cohesive, and full of energy, and I've always been really
interested in that stuff and try to use electronics in live performances as I play drums, and
I was always put off by how expensive equipment is for electronic music.
If you want to buy a sampler, which is the little box that plays snippets of audio,
like if you want to play a silly little quote from a Clint Eastwood movie, or something
like that, something tough like that.
You'd have to pay hundreds of dollars for that, and the gear isn't very versatile.
It only holds so much information, you can only play the samples in certain ways, and
it's always been a problem.
But seeing the MIDI modules in the pie game program, I started thinking like, hey, maybe
I can just build a sampler.
If I can figure out how to use MIDI, I'm going to hook it up to maybe an old netbook.
Maybe I can build my own sampler for cheap.
So I kept looking around the pie game site, found their mailing list, hopped on it, asked
a couple dumb questions, got a bunch of very nice replies, and made it happen.
And if I can make it happen with my terrible programming skills, definitely you can make
it happen.
Before you start, you want to make sure you have pie game version 1.9.1, or better installed
on your system.
Older versions of pie game did not have the features to use MIDI.
Pie game is also a cross-platform.
It runs on macOS and Linux and Windows.
But for what we want to use it for, an old netbook, Linux was the obvious choice.
But if you're in the pain and you want to use Windows or something else, go for it.
So to build this sampler out of pie game in MIDI, I needed to learn how to use Python.
To learn Python, I just did a couple YouTube tutorials to print out hello world to the
screen, learn how to do an if statement and a for loop, which is pretty easy in Python.
If you've had any kind of a programming class, even if there's something like a web programming
class, I'm sure you can do this.
So I wrote a couple little Python test scripts, and I tried to incorporate some of the information
that was on the pie game documentation website, which didn't go as planned.
So I put a question on the pie game mailing list, and a guy named Leonard Lindstrom wrote
back and said, hey, just take a look at the midei.py file under the pie game examples folder.
And basically all that I wanted to do was already spelled out in that file.
All I needed to do was kind of copy and paste some things and move it around.
And it worked like a charm.
If you open up a terminal and go to the folder where the midei-py file is and type in python
midei.py space dash dash input and hit enter, it will list all the MIDI devices plugged
up to the computer at that point.
If you follow those same steps, and then after the dash dash input, put the number of the
device in the list that showed previously, the Python script will read all the events
coming out of the midei device.
Right now I have my keyboard hooked up to my computer.
I'm running that midei.py script, and if I press the middle C key, the white key on the
keyboard, it prints a string of information to the terminal.
One of the items in the comma delimited string is data 1, and it returns 60.
And now if I press the black key just above the original key I pressed, it returns the
same information, but it says 61 now.
So you can basically use the information that's being printed out to the screen inside
the midei.py file and just kind of go in there and put some if statements that say if
you see note 60, play a bass drum sample, and if you see 61, play a cleanyswood sample.
And if you see 63, play this piano sample four times, since you're programming your own
sample, you can do really neat stuff like using the random function in Python to say if
I press this key, randomly play a middle C or a high C. So by just playing normal drums
with a trigger hooked up to that middle C, it'll play a range of notes without you doing
anything special.
It's all just programmed in the little PyGames script.
You can do if statements based on the information that's returned.
You can say if I press this key, play a bass drum sound, and if I press this other key,
play a snare sound, but first stop playing the bass drum sound.
So you get this short cropped bass drum sound that's cut off by another sound, which
can sound really neat, have one drum that rings out forever in another drum that quickly
cuts the other one off.
You can put together some pretty interesting stuff.
Okay, this includes my little podcast about PyGame and MIDI.
I'm going to add some Python examples in the show notes for using if statements to play
sounds to get more information about PyGame and MIDI and PyGame.
Check out the PyGame.org website and hop on the mailing list.
Once again, that was p-y-g-a-m-e-dot-o-r-g.
Thanks for listening.
This has been BeGrader Clock.
Peace out.
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