mcanthony/html5bytebeat

Bytebeats in HTML5

HTML5 Bytebeat

Bytebeat is the name of type of music made from math.

You provide a function who's only input is time t and from that write some code to generate a sound.

In this particular case t is an 8000hz timer that counts up. For example

sin(t) * 127 + 127

You can choose traditional bytebeat where the output of your function is expected to be 0 to 255 or you can choose floatbeat where the output is expected to be -1 to +1.

Functions are just plain JavaScript though sin, cos, tan, floor, ceil and int will automatically be converted to Math.sin, Math.cos, Math.tan, Math.floor, Math.ceil, and Math.floor respectively.

Click here to try your hand at Bytebeat.

Here are a few sample songs

• http://goo.gl/KABRP glitch machine
• http://goo.gl/MtkP38 octo
• http://goo.gl/0UO8Kx seargeant
• http://goo.gl/TcKUSp splatterpiller
• http://goo.gl/V5Mrl
• http://goo.gl/qrAkf
• http://goo.gl/w3ugG
• http://goo.gl/NRwRT
• http://goo.gl/ObMwR
• http://goo.gl/Arptn
• http://goo.gl/pD3lx kb 2011-10-04
• http://goo.gl/MuQWe ryg 2011-10-10
• http://goo.gl/rFNPL blueberry 2011-10-05
• http://goo.gl/lQyDd mu6k
• http://goo.gl/6Uz0d mix 2 channels
• http://goo.gl/6cC5gK quiddit
• http://goo.gl/RG8IEk rythymgrind
• http://goo.gl/QRjRf8 robot toothbrush
• http://goo.gl/Vk6WPK number machine
• http://goo.gl/4dOPIJ starlost
• http://goo.gl/VHm5c7 guitarhead

Instructions

Modes

There 2 modes

• bytebeat: Your expression is expected to generate byte values from 0 to 255
• floatbeat: Your expression is expected to generate float values from -1.0 to 1.0

Expression Types

• Infix: Standard expressions eg. "(t * 2) / 4"
• Postfix(rpn): Reverse Polish Notation eg "t 2 * 4 /"
• glitch: glitch format or glitch urls.

Infix is standard JavaScript so all Math functions are available. Most math functions you can drop the "Math." part. In other words

sin(t)

is the same as

Math.sin(t)

Postfix requires that each element have at least one space between it.

t2*    // BAD!
t 2 *  // Good!

If you're unfamiliar with postfix see below

Glitch is a format used by glitch machine for sharing. Examples

• 42_forever!a13880fa400he!a5kma6kn40g!aCk28!a12k1ld!2fladm!43n
• pipe_symphony!aEk5h5f!a11k2h!a9k3hdf!aDk4hg!ad4e!p5fm!a11k2h1rg!a5kdm

These can be prefixed with "glitch://". For example

• glitch://sadglitch!4.4.9.8.9.6.4.2!aoCk8hq!ad2d!aFk3h1fe!p5d3em!a63hm!a7kFFlp80slf

There's a bunch more here. I have a feeling there's a bug or 2 left for full glitch support

Postfix

Postfix in this case I guess can be described as [forth](http://en.wikipedia.org/wiki/Forth_(programming_language) like. It works with a stack. Each command either adds things to the stack or uses what's on the stack to do something. For example

123       // pushes 123 on the stack               stack = 123
456       // pushes 456 on the stack               stack = 123, 456
+         // pop the stop 2 things on the stack
          // adds them, puts the result on the
          // stack                                 stack = 569

Note the stack is only 256 elements deep. If you push 257 elements it wraps around. Similary if you use pick with a large value your pick will wrap around. The static is neither cleared nor reset on each iteration of your function. Some postfix based bytebeat songs take advantage of this were each iteration leaves things on the stack for the next iteration.

The postfix operators are

>, < ,=

These take the top two things from the stack, do the comparision, then push 0xFFFFFFFF if the result is true or 0x0 if the result is false. Is the TOP thing on the stack >, <, = the next thing on the stack.

drop

removes the top thing from the stack

dup

duplicates the top thing on the stack.

swap

swaps the top 2 things on the stack

pick

pops the top thing from the stack and duplicates that many items back. In other words if the stack is 1,2,3,4,5,6,7,3 then pick pops the top thing 3 and duplicates the 3rd thing back counting from 0, which is no 4. The stack is then 1,2,3,4,5,6,7,4.

Another way to look at it is dup is the same as 0 pick.

put

sets the n'th element from the top of the stack to the current top. In other words if the stack is 1,2,3,4,5,6,7,3,100 then put will pull the top 100 and then set the 3 element back. The stack will then be 1,2,3,4,100,6,7,3.

abs, sqrt, round, tan, log, exp, sin, cos, tan, floor, ceil, int min, max, pow

These operators all pop the top value from the stack, apply the operator, then push the result on the stack

/, +, -, *, %, >>, <<, |, &, ^, &&, ||:

These operators pop the top 2 values from the stack, apply the operator, then push the result. The order is as follows

b = pop
a = pop
push(a op b)

In other words 4 2 / is 4 divided by 2.

~

Pops the top of the static, applies the binary negate to it, pushes the result.

Extra

Comments can be both // or /* */ style

There are several extra inputs available

The mouse position is available as mouseX and mouseY

sin(t * mouseX * 0.001) + cos(t * mouseY * 0.003)

The size of the window is available width and height

The orientation of a device may be available as tiltX and tiltY.

(sin(t * 0.1 * tiltX) + cos(t * tiltY * 0.07)) * 0.5

Also note, using the comma operator you can write fairly arbitrary code.

http://goo.gl/IZVBS

For more info

Check out http://canonical.org/~kragen/bytebeat/ and be sure follow the many links.

Special thanks to:

• Paul Pridham for his Glitch Machine iOS Bytebeat program.
• Mr.Doob for his GLSL Sandbox where much of this code was cribbed.
• Nathan Rugg for his LZMA-JS library.
• Darius Bacon for his bytebeat program and for tips and examples to test it.