7 Feb
2012
7 Feb
'12
1:40 a.m.
Luppp's internals use a single(!) floating point, which mixes a bar number,
and a "percent" of that bar.
Found it quite nice to work with, to get the bar you just:
int bar = (int) floatBeatPercent;
while to get the percent you:
float percent = floatBeatPercent - ((int)floatBeatPercent);
In C you mention "bar" as int, and "beat" as float, I presume you want
to
use the decimal part of the float to show "progress" trough that beat?
Thinking about very slow BPM's.. that could become important.
-Harry
On Tue, Feb 7, 2012 at 12:28 AM, David Robillard <d(a)drobilla.net> wrote:
Hi all, seeking opinions:
I have to choose a way to represent beat-based tempo time in 64 bits.
Uses are many, but the main one is event time stamps for plugins.
Requirements:
* No odd data sizes (for performance / programmer ease)
* High precision (ideally close to sample accurate for most tempos)
* Fits in the same space as two uint32_t's
Questions:
* Is "bar" needed?
* Use floating point? Rounding errors an issue?
Options:
/* A (moderate range, ultra precise) */
struct {
uint16_t bar;
uint16_t beat;
uint32_t tick;
};
/* B (high range, moderate precision) */
struct {
uint32_t bar;
uint16_t beat;
uint16_t tick;
};
/* C (high range, good precision?) */
struct {
uint32_t bar
float beat;
};
/* D (high range/precision, but no bar) */
double beat;
I havn't run the math on precision yet, but I am leaning towards C. I
actually hadn't considered mixing int and float before writing this
email, but it seems the best trade-off, and working with float is
certainly more pleasant than fixed point.
Thoughts?
-dr
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