[linux-audio-dev] PTAF link and comments

Paul Davis paul at linuxaudiosystems.com
Mon Feb 3 22:52:00 UTC 2003


>> * TransportJump: sample pos, beat, bar. (Why not just ticks?)
>
>But musically speaking, what is tick, and to what is it
>relative ? If you want to locate a position in a piece,
>you need two informations: the absolute date and the
>musical date, if relevant. Bar has a strong rhythmic value
>and refering to it is important. Beat is the musical
>position within the bar, measured ... in beats. Tick trick
>is not needed since the beat value is fractional (~infinite
>accuracy).

not quite. ticks exist to represent integer subdivisions of a
beat. this is why the preferred ticks-per-beat values are numbers with
large numbers of factors. for example, 1920 is a very good choice. if
you use floats, then anyone wanting to subdivide a beat by, say, 12,
will find that positional accuracy drifts. why? because 1/12 is
irrational and cannot be accurately represented by a floating point
value. if, by contrast, you express this 160 ticks, there is no loss
of accuracy over any duration at all.

why subdivide the beat? i presume this question doesn't need answering!

--p

ps. laurent - welcome to LAD! thanks for stopping by.



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