Subject: Re: [linux-audio-dev] XAP: a polemic
From: Tim Hockin (thockin_AT_hockin.org)
Date: Wed Dec 18 2002 - 04:08:38 EET
> Just one issue: Is float32 sufficient for tempo? (We'd need to switch
> to 64 byte events, or use double events to handle 64 bits +
> ramping...)
>
>
> Position could just be double, and no ramping, right? (No problem
> fitting that in a 32 byte event.) Provided that adding a float to a
> double should extend the float to double first, you'd actually have
> to *make* this go wrong explicitly, to break anything.
>
>
> > 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]
>
> Would two floats (32 bit) do?
Just to play devils advocate:
METER: uint32_t
meter & 0xffc00000 = beats-per-measure whole (0-1024)
meter & 0x003ff000 = beats-per-measure decimal (1/1000 increments)
meter & 0x00000fff = beat-note denominator (0-4096)
Obviously any of those field widths can be adjusted. I just wanted to point
out that we CAN transport that data in a single 32 bit field. Especially
since the 'float' values we're talking about tend towards simple fractions.
Now is someone going to tell me they have PI beats per measure?
I need to go eat. I'll read the remaining 30 emails when I get home :)
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