WEBVTT

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hi

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i'm zachary canfer and this is waving

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and repetitive repetitive repetitive

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music over quarantine i've been bored

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and i found this android app that has a

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bunch of mini games

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one of which lets you compose music

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and it works but i

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want a little bit more functionality

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than it offers it's not very flexible

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so i thought what if i made this

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what and what programs could i make this

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in that are really flexible are really

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customizable

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emacs so i looked into it and

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emacs can play sounds right if you hit

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control g a couple times you'll hear

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like an error tone

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and it turns out that that is actually

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playing a wave file

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but what's a wave file

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well it turns out that wave is a musical

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file format

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or really an annoying file format

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so data in it can be an unsigned integer

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or a science integer it's not consistent

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and it's little ending by default which

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is not the way i like to think about it

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now you can set a wav file to be big

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endian but if you do that

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emacs can't play it so little ending it

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is

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there's also duplicate data fields

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here are some fields that are fine but

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then there's a fourth field that's

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calculated based on multiplying two of

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the other ones together

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and then there's another data field

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that's you multiply those three ones

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together so it's just repetitive and

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unnecessary but you have to do it or

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it's not a valid wave file

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also the last part of the file is

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described as data

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or as one website i found said

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the actual sound data now

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i don't know about you but when i see

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that i think

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what is a data it turns out

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that sound is just a wave and

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the data is just a bunch of measurements

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of the height of that wave forming each

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sample

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so this wave starts at 8 goes 9 11 13

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14 15 and then back down and if you just

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take those measurements those numbers

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put them in a file that's all your data

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is

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all right let's go to a demo of my

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program

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so this is what z music looks like the

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blue highlighted row is a single beat

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there's 16 of them in this z music file

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and each dash in the row

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is a single note increasing starting

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really low all the way on the left and

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going up

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as we go to the right so if we started

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playing

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we won't hear anything but we'll see the

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highlighted beat is the currently

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playing one

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and we see that it loops so we can stop

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it

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and now we can click to add some notes

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even more than one note at the same time

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works

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and we can even add notes while it's

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[Applause]

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playing

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[Applause]

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okay here are some other features that i

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didn't have time to demo

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so you can save the music to a file and

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this is interesting because normally

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if there's no note in a beat we just

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don't play that beat

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but if you're writing to a file you have

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to put something in

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so when it's playing it knows to not

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make a sound there

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we can also use different scales we're

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using the minor pentatonic

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in the demo but you can use the major

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scale the minor scale

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or anything else and there's also

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keyboard support but it sounds really

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bad

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and i'll explain why later

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here are some things i learned while

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writing z music

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emacs has buttons which are great as

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long

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as you don't put two of them right next

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to each other so if you do that

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mousing over one of them highlights both

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of them

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now that's because a button is really

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just a series of characters with a text

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property to highlight them

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so the fix is you put another character

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between the two buttons

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then mousing over one of them only

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highlights the one you want

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but even this doesn't work really great

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for z music

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because the music has a lot of very

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small buttons in a row

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so it's really easy to accidentally put

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your cursor over the space

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and click on that instead of the button

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so i looked into unicode and i found

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this character called

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a zero width space so we should be able

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to put that between buttons and not be

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able to accidentally click on it

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unfortunately a zeroth space isn't

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actually zero width

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if we put a hundred of them between two

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other characters you can see there's

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space there

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and i think what's happening is the

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space is zero width

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but then emax put uses one pixel between

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each pair of characters

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for the cursor so it's almost zero width

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some ways to play sound that don't quite

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work play sound plays music

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but it blocks you can't do things like

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set other notes or even pause the music

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and if you throw it into async.el it's

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silent and i don't know why

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so the solution i went with is taking

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that wav file

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ran into the file system and then

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shelling out to a native executable to

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play the sound

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and that works fine as long as you only

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do it once

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because if you do it a couple times at

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the same time like if you have a chord

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and you want to play three notes

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simultaneously

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you get this weird interference and

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that's actually why the keyboard from

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before didn't work

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also side effects have this unexpected

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impact

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uh when you saw the demo it was running

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pretty smoothly

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but if i just add one message statement

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every beat for

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debugging purposes i was getting lag and

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jitter

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here's the one thing i learned about

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music theory music theory

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is not easy to program

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i was looking around to see what

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concepts we can use to code the scales

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to code the

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notes the first thing that i saw is

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scale degrees

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and this when i looked into it you don't

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want to program in scale degrees

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so you see we have the first second

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third fourth fifth sixth seventh but

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then it wraps around that octave up

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is also a first and that's because both

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of those notes are c

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uh so that didn't work and also you

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couldn't really easily

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specify a flat or sharp you could say

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a sharp third uh or

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you know a flat seventh or whatever but

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then you kind of have these two pieces

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of data that indicate the note and i

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didn't i didn't love that

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so i looked a little looked again and i

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found intervals

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and then i thought about it and you

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don't really want to program in

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intervals either

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it fixes some of the problems with scale

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degrees you see

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all the way on the right you have an

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octave so you wrap to 8 and you

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go 9 10 and that works but you solve the

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same problem you see you have a major

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third but below we also have a minor

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third so you saw that problem of having

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two pieces of information

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uh so i thought about it music's really

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frequencies like an a is 440 hertz

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so at a low level that's what we're

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going to do we're just going to use

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frequencies

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and then at the one level above that uh

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that's a little bit easier for humans to

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think about

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we're going to use semitones up from the

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root which is kind of like scale degrees

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but instead of just counting each note

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as one more we're going to say how many

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semitones up it is

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so if there's a sharp between two notes

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that's going to be two steps up instead

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of just one

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and then we translate those two

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frequencies so your a is 440 hertz

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another note might be

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613.5

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or whatever and we that's we use the low

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level to play

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some future work i have i want to add

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some drums

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i want to make that keyboard actually

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work uh

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and uh computers and synthesizers are

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the only place you hear a pure sine wave

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like the one we have here

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so i want to add overtones or other

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octaves above it uh just to make it

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sound a little bit more realistic

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i've put notes references in the source

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code up at zck dot me slash emacs conf

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2020 i'm one of the organizers of emacs

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nyc

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check that out and if you take a look

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or have any thoughts i'd love to hear

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them and

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thanks so much for coming to my talk