Re: Float64 to unsigned bug shows in mSampleTime
Re: Float64 to unsigned bug shows in mSampleTime
- Subject: Re: Float64 to unsigned bug shows in mSampleTime
- From: Doug Wyatt <email@hidden>
- Date: Sun, 25 Aug 2002 13:12:15 -0700
On Saturday, Aug 24, 2002, at 00:40 US/Pacific, email@hidden
wrote:
A related question - is there any reason for me to leave the
mSampleTime field as a Float64? I mean, is the fractional part of the
mSampleTime field of any value to me as a user of Apple APIs which
supply
me with AudioTimeStamps or would I be just as well off to replace it
with
SInt64s by wrapping around any occurrences of AudioTimeStamps?
Personally I'd first consider using UInt32's, which are cheaper than
64-bit ints:
- on my first IOProc callback, remember the first mSampleTime I see as
a Float64, call it "zeroTime"
- on subsequent callbacks, subtract zeroTime from mSampleTime, and
store it in a UInt32.
Time will only go forward :-)
Note: if you need to run for more than 27 hours at 44.1, or shorter
periods at higher sample rates, then you do need more than 32 bits.
secondsPerHour = 3600.;
(pow(2,32) / 44100. / secondsPerHour) = 27.05
Doug
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