OneLoopDrumMachine - Revision history

Michael Murtaugh at 11:09, 21 May 2008

2008-05-21T11:09:52Z

← Older revision		Revision as of 13:09, 21 May 2008
Line 1:		Line 1:
	~~= One Loop Drum Machine =~~
	using [[PyGame]]		using [[PyGame]]

Line 18:		Line 17:

	So playing the sound with [[PyGame]]:		So playing the sound with [[PyGame]]:
	<~~pre~~>		<source lang="python">
	~~#!python~~
	import pygame		import pygame
	pygame.init()		pygame.init()
Line 29:		Line 27:
	while True:		while True:
	pass		pass
	</~~pre~~>		</source>

	Now with a clock to control the rhythm:		Now with a clock to control the rhythm:
	<~~pre~~>		<source lang="python">
	~~#!python~~
	import pygame		import pygame
	pygame.init()		pygame.init()
Line 48:		Line 45:
	cow.play() ## plays in background (like & )		cow.play() ## plays in background (like & )
	clock.tick(fps)		clock.tick(fps)
	</~~pre~~>		</source>

	Exercise:		Exercise:
Line 61:		Line 58:


	~~attachment~~:~~beatpattern_wb~~.png		[[Image:Beatpattern_wb.png]]

	<~~pre~~>		<source lang="python">
	~~#!python~~
	import pygame		import pygame
	pygame.init()		pygame.init()
Line 86:		Line 82:
	if beat==4: beat=0		if beat==4: beat=0
	clock.tick(fps)		clock.tick(fps)
	</~~pre~~>		</source>


	This is a buggy version of an attempt to make the rhythm loop more responsive to the keyboard:		This is a buggy version of an attempt to make the rhythm loop more responsive to the keyboard:
	<~~pre~~>		<source lang="python">
	~~#!python~~
	import sys, pygame		import sys, pygame
	from pygame.locals import *		from pygame.locals import *
Line 138:		Line 133:

	clock.tick(30)		clock.tick(30)
	</~~pre~~>		</source>

	The solution is to move the "drum machine" code (the two play commands) inside the if block (so ''only'' when the beat changes, are new sounds triggered).		The solution is to move the "drum machine" code (the two play commands) inside the if block (so ''only'' when the beat changes, are new sounds triggered).

	<~~pre~~>		<source lang="python">
	~~#!python~~
	import sys, pygame		import sys, pygame
	from pygame.locals import *		from pygame.locals import *
Line 191:		Line 185:

	clock.tick(30)		clock.tick(30)
	</~~pre~~>		</source>

Michael Murtaugh: /* One Loop Drum Machine */

2008-05-21T11:06:47Z

One Loop Drum Machine

← Older revision		Revision as of 13:06, 21 May 2008
Line 7:		Line 7:
	http://www.hydrogen-music.org/		http://www.hydrogen-music.org/

	[[Image:~~Hyndrogen~~.png\|Hydrogen]]		[[Image:Hydrogen.png\|Hydrogen]]

	In a simple single-loop program, there is no explicit timeline. So you have to simulate it using variables as state.		In a simple single-loop program, there is no explicit timeline. So you have to simulate it using variables as state.

Michael Murtaugh at 11:06, 21 May 2008

2008-05-21T11:06:30Z

New page

= One Loop Drum Machine =
using [[PyGame]]

Drum machines (and software simulating them), typically work with spreadsheet-like timeline views that allow you to trigger playback of different percussive sounds as a pattern in time.

Example drum machine software:
http://www.hydrogen-music.org/

[[Image:Hyndrogen.png|Hydrogen]]

In a simple single-loop program, there is no explicit timeline. So you have to simulate it using variables as state.

For instance, you might create a variable called beat to represent what portion (column) of the timeline / pattern you are currently in.

=== Programming a simple drum machine in [[PyGame]] ===

First, you need some sound samples. You could pull them from a program like Hydrogen (just make sure they're either OGG or raw wav format for [[PyGame]] to load. Or you can use ["sox"] to generate some retro 8bit sounds.

So playing the sound with [[PyGame]]:
<pre>
#!python
import pygame
pygame.init()
pygame.mixer.init()

sweep = pygame.mixer.Sound("sweep_up.wav")
sweep.play()

while True:
pass
</pre>

Now with a clock to control the rhythm:
<pre>
#!python
import pygame
pygame.init()
pygame.mixer.init()

sweep = pygame.mixer.Sound("sweep.wav")
cow = pygame.mixer.Sound("sweep_up_long.wav")
clock = pygame.time.Clock()

bpm = 180
fps = float(bpm) / 60

while True:
cow.play() ## plays in background (like & )
clock.tick(fps)
</pre>

Exercise:
How, with this single loop, might you implement a simple drum pattern such as:

{| border="1"
|bell|| ||x|| ||x||
|-
|beep||x||x||x||x||
|-
|}

attachment:beatpattern_wb.png

<pre>
#!python
import pygame
pygame.init()
pygame.mixer.init()

beep = pygame.mixer.Sound("08.wav")
noise = pygame.mixer.Sound("noise.wav")
clock = pygame.time.Clock()

bpm = 120
fps = float(bpm) / 60
beat = 0

while True:
print beat
beep.play()
# lbeat = beat % 4
if beat == 0 or beat==2:
noise.play()
beat += 1
if beat==4: beat=0
clock.tick(fps)
</pre>

This is a buggy version of an attempt to make the rhythm loop more responsive to the keyboard:
<pre>
#!python
import sys, pygame
from pygame.locals import *

pygame.init()
pygame.mixer.init()
beep = pygame.mixer.Sound("08.wav")
noise = pygame.mixer.Sound("noise.wav")
cowbell = pygame.mixer.Sound("hi.wav")
clock = pygame.time.Clock()
bpm = 120
fps = float(bpm) / 60
beat = 0

screen = pygame.display.set_mode((320, 240))

frame = 0
playCow = False

while True:
print frame, beat

# HANDLE EVENTS
for event in pygame.event.get():
if event.type == QUIT:
sys.exit()

if event.type == KEYDOWN and event.key == K_SPACE:
cowbell.play()

# print beat
beep.play()
# lbeat = beat % 4
if beat == 0 or beat==2:
noise.play()

if frame == 15:
# UPDATE BEAT
beat += 1
if beat==4: beat=0
frame = 0

# add frame counter
frame += 1

clock.tick(30)
</pre>

The solution is to move the "drum machine" code (the two play commands) inside the if block (so ''only'' when the beat changes, are new sounds triggered).

<pre>
#!python
import sys, pygame
from pygame.locals import *

pygame.init()
pygame.mixer.init()
beep = pygame.mixer.Sound("08.wav")
noise = pygame.mixer.Sound("noise.wav")
cowbell = pygame.mixer.Sound("hi.wav")
clock = pygame.time.Clock()
bpm = 120
fps = float(bpm) / 60
beat = 0

screen = pygame.display.set_mode((320, 240))

frame = 0
playCow = False

while True:
print frame, beat

# HANDLE EVENTS
for event in pygame.event.get():
if event.type == QUIT:
sys.exit()

if event.type == KEYDOWN and event.key == K_SPACE:
cowbell.play()

if frame == 15:
# UPDATE BEAT
beat += 1
if beat==4: beat=0
frame = 0

# print beat
beep.play()
# lbeat = beat % 4
if beat == 0 or beat==2:
noise.play()

# add frame counter
frame += 1

clock.tick(30)
</pre>