Building a better box

I think it would be really fun to build my own drum sequencer.  I lack a lot of the skills to do so, but it looks like there are enough oem kits around where I should be able to hack something together.  If I'm ever going to get this done, I'll need to setup a timeline and phases, and then commit to it.  

Components

Obviously, the sequencer will be made up of the following pieces:

HW - Hardware (cpu, mobo, peripherals, interfaces, etc)
OS - Operating System
SW - Drivers, Sequencer

Phases

I see each component having two phases:

RAP - Rapid Prototyping

PRD - Production Implementation

Cycle

Each phase will have the following cycles:

OEM DSGN - COTS / OEM Selection

OEM ORDR - COTS / OEM Acquisition

OEM INTG - COTS / OEM Integration

DIY DSGN - DIY Designs

DIY BUILD  - DIY part acquisition / component build

DIY IMPL - DIY Design implementation

SYS INTG - Component Integration

 

Why the schedule formality?

Obviously, the benefits of a hobby project is jumping around and breaking schedule.  However, I know if I don't set targets,  I'll never get velocity.  I've done a lot of hobby projects before, and things work best when velocity is reached.  I've done more complicated ones, and they required 100% DIY pieces--they never got finished.  i've got to be realistic, and retrospective as time goes on.

Rapid Prototype Phase Goals

I've got to avoid the traps of past efforts--I need to leverage as much as existing, COTS/OEM/libs as possible.  The rapid prototype phase will focus most on the SW / controller integration piece.  MIdi performance will not be a focus.  At the same time, I do plan on exceeding existing jitter / latency timings--otherwise, what is the point?  So any sw development will need to go through an abstraction layer, so later on, we can tie calls to very high performance, tightly integrated custom libs.  Up front though, if I do that, I'll likely get nowhere fast.

Notional Schedule

	Phase	HW	OS	SW
OEM DSGN	RAP	Nov,  2009	Apr, 2010	Feb, 2010
OEM ORDR	RAP	Jan, 2010	Apr, 2010	Sep, 2010
OEM INTG	RAP	Feb, 2010	Apr, 2010	Nov, 2010
DIY DSGN	RAP	Feb, 2010	Jun, 2010	Apr, 2010
DIY BUILD	RAP	Feb, 2010	Jun, 2010	Feb, 2011
DIY IMPL	RAP	Feb, 2010	Jun, 2010	Jun, 2011
SYS INTG	RAP	Jul, 2010	Jul, 2010	Jul, 2011

2 years might seem like a long time, but really it isn't that long at all, sadly.

Converting BPM to Measures Per Minute

How often have you sat down to record something, and wondered--how many measures will I need at this bpm?  And, what happens to my 7 minute song if I increase/decrease the tempo?

@ 4/4, the following table spells it all out.  This is actually part of a Mac Numbers document which is a little more interactive.  Since I can't upload documents to blogger (BOOO) I figured I'd just walk folks through the basic math.

BPM to Measure Length

bpm	seconds per measure	Measures per minute
120	2.0	30.00
50	4.8	12.50
51	4.7	12.75
52	4.6	13.00
53	4.5	13.25
54	4.4	13.50
55	4.4	13.75
56	4.3	14.00
57	4.2	14.25
58	4.1	14.50
59	4.1	14.75
60	4.0	15.00
61	3.9	15.25
62	3.9	15.50
63	3.8	15.75
64	3.8	16.00
65	3.7	16.25
66	3.6	16.50
67	3.6	16.75
68	3.5	17.00
69	3.5	17.25
70	3.4	17.50
71	3.4	17.75
72	3.3	18.00
73	3.3	18.25
74	3.2	18.50
75	3.2	18.75
76	3.2	19.00
77	3.1	19.25
78	3.1	19.50
79	3.0	19.75
80	3.0	20.00
81	3.0	20.25
82	2.9	20.50
83	2.9	20.75
84	2.9	21.00
85	2.8	21.25
86	2.8	21.50
87	2.8	21.75
88	2.7	22.00
89	2.7	22.25
90	2.7	22.50
91	2.6	22.75
92	2.6	23.00
93	2.6	23.25
94	2.6	23.50
95	2.5	23.75
96	2.5	24.00
97	2.5	24.25
98	2.4	24.50
99	2.4	24.75
100	2.4	25.00
101	2.4	25.25
102	2.4	25.50
103	2.3	25.75
104	2.3	26.00
105	2.3	26.25
106	2.3	26.50
107	2.2	26.75
108	2.2	27.00
109	2.2	27.25
110	2.2	27.50
111	2.2	27.75
112	2.1	28.00
113	2.1	28.25
114	2.1	28.50
115	2.1	28.75
116	2.1	29.00
117	2.1	29.25
118	2.0	29.50
119	2.0	29.75
120	2.0	30.00
121	2.0	30.25
122	2.0	30.50
123	2.0	30.75
124	1.9	31.00
125	1.9	31.25
126	1.9	31.50
127	1.9	31.75
128	1.9	32.00
129	1.9	32.25
130	1.8	32.50
131	1.8	32.75
132	1.8	33.00
133	1.8	33.25
134	1.8	33.50
135	1.8	33.75
136	1.8	34.00
137	1.8	34.25
138	1.7	34.50
139	1.7	34.75
140	1.7	35.00
141	1.7	35.25
142	1.7	35.50
143	1.7	35.75
144	1.7	36.00
145	1.7	36.25
146	1.6	36.50
147	1.6	36.75
148	1.6	37.00
149	1.6	37.25
150	1.6	37.50
151	1.6	37.75
152	1.6	38.00
153	1.6	38.25
154	1.6	38.50
155	1.5	38.75
156	1.5	39.00
157	1.5	39.25
158	1.5	39.50
159	1.5	39.75
160	1.5	40.00
161	1.5	40.25
162	1.5	40.50
163	1.5	40.75
164	1.5	41.00
165	1.5	41.25
166	1.4	41.50
167	1.4	41.75
168	1.4	42.00
169	1.4	42.25
170	1.4	42.50
171	1.4	42.75
172	1.4	43.00
173	1.4	43.25
174	1.4	43.50
175	1.4	43.75
176	1.4	44.00
177	1.4	44.25
178	1.3	44.50
179	1.3	44.75
180	1.3	45.00
181	1.3	45.25
182	1.3	45.50
183	1.3	45.75
184	1.3	46.00
185	1.3	46.25
186	1.3	46.50

Exercise for the Reader

In my Numbers document (which is GREAT btw, for stuff like this simply beats the pants off Microsoft/Open Office), I have the following tables...the math is very basic, and the following equations should convert quite easily to almost any format.

BPM 

This is a very basic table that converts BPM to Seconds per Measure and Measure Per Minute...

• BPM (120, an input cell)
• Notes per beat (4, an input cell)
• Measure (4, an input cell)
• Seconds per Measure = Measure / bpm * 60
• Measure per Minute = 60 / Seconds Per Measure

Song Length -  Input

This is a table we can use to define the basic structure of our song (intro-verse-chorus-verse-outro, for example)

• BPM = BPM::BPM
• Intro (min)  = 1 for 1 minute intros
• Verse (min) = 2 for 2 minute verses
• Verse Count = 2 for 2 verses
• Chorus (min) = 1 for 1 minute chorus
• Chorus Count = 1 for 1 chorus
• Outro (min) = 1 for 1 minute outro

Song Length - Output
This table calculates how many measures we'll need to meet our song obligations.

• Measures Per Minute = BPM::Measures per Minute
• Intro (measures) = Measures Per Minute / Intro (min)
• Verse (measures) = Measures Per Minute / Verse (min)
• Chorus (measures) = Measures Per Minute / Chorus (min)
• Outro (measures) = Measures Per Minute / Outro (min)
• Song Length (Measures) = Intro (measures) + Verse Count * Verse (measures) + Chorus Count * Chorus(measures) + Outro (measures) 
• Song Length (Time) = Time(0,intro (min) + verse (min) * verse count + chorus (min) * chorus count + outro (min),0)

Measure Input
Now...what happens if we have a song of X measures, and we want to change the tempo? What will that do to our song length, for example, if we have Y minutes to fill?  This table contains our basic song structure, assuming all verses/choruses are the same.  It should be trivial to change per song if you need to (eg Verse 1, Verse 2, Chorus 1, fill, etc...add whatever parts you need!)

• BPM = BPM
• Intro (measures) = 30
• Verse (measures) = 60
• Chorus (measures) = 30
• outro (measures) = 30

Measures Output

Converts measures above into minutes.

• Seconds Per Measure = BPM::Seconds Per Measure
• Intro (minutes) = Time(0,0,Intro (measures) * Seconds Per Measure)
• Verse (minutes) = Time(0,0,Verse (measures) * Seconds Per Measure)
• Chorus (minutes) = Time(0,0,Chorus (measures) * Seconds Per Measure)
• Outro (minutes) =  Time(0,0,Outro(measures) * Seconds Per Measure)

Settings this up, note--very easy.  It took a lot longer to type up this blog entry then create the document, as automatic formula copy/paste is a beautiful thing. 

Thats it for a few weeks....