Paul Davis wrote: >>you absolutely need ppq for the tick system to properly map >>different measures (5/4 time, 6/8 time etc) as per previous >>post. > >well, if ppqn is variable, then sure. but cubase and all other vst >apps have defined it to be 1, which makes it irrelevant. their "pulse" >or "parts" (there seems to be disagreement over what the first "p" in >"ppqn" stands for) is not the same as the "tick" are discussing, >however.
it is ticks for all i know, spell it tpq if you happen to like that better. have you ever parsed a MIDI file? the same value is called 'division' in the file specs. >so yes, ticks-per-beat is still necessary, but its a constant (1920 in >ardour). there's no point in limiting this to be a fixed value. >>you're better off specifying tempo as quarter beats/minute >>uniformly for the above reasons. > >what reasons? after 2 rounds of fairly intense discussion on >ardour-dev, we could find no reason to favor quarters over any other >value. it makes no difference unless all the music you ever want to >handle uses quarters as the beat note value. since this is >demonstrably false, there is nothing particular interesting about >using quarters. you're right, it doesn't matter what reference length you choose. quarters simply happen to work well, and there's no need to break with convention here. >>add seconds-per-beat for plugins that are not limited to >>audio purposes. > >but thats just a straightforward transform of samples-per-beat given >samples-per-second, so there is no reason to specify both. either one >seems equally good to me. it must be assumed the hosts knows seconds-per-beat better than the plugin. thus, forcing another calculation back from frame units is illogical. >>>the METER event needs to include >>> >>> beats-per-measure (floating point value) [ 3, 5, 7, 9.5 etc ] >>> beat-note-value (floating point value) [quarter,1/16th, etc] >> >>i wouldn't make either a float, it is by far too uncommon >>to be justified and makes some arithmetic cumbersome. > >what arithmetic is cumbersome? beats-per-measure has to floating to >accomodate most non-western music, and if thats a float, you may as >well make beat-note-value the same, to avoid constant casting back and >forth. one of the basic properties of rhythmn is that human beings are able to count it, otherwise they cannot sync (groove) to it. no musical tradition i know of violates this principle; rhythmn is integral by its very nature. i'd be happy to hear a good example proving this wrong. but take note that i don't accept 1/2, 1/3 and relatives as qualifying because they can better be (and usually are) expressed using integer numbers. about arithmetic: float operations, as you know, introduce round-off error. integers can be used in accumulators with much less inconvenience. tim