Re: A number of simple questions (still a few unanswered)
Re: A number of simple questions (still a few unanswered)
- Subject: Re: A number of simple questions (still a few unanswered)
- From: Seth Willits <email@hidden>
- Date: Wed, 06 Feb 2013 16:04:43 -0800
On Wed, Feb 6, 2013 at 4:45 PM, James McCartney <email@hidden> wrote:
> On Dec 5, 2012, at 12:11 PM, Paul Davis <email@hidden> wrote:
>
>> On Wed, Dec 5, 2012 at 2:14 PM, Seth Willits <email@hidden> wrote:
>>
>> Still a few I'm unsure about. :)
>>
>>
>> - Why is AudioTimeStamp.mSampleTime a float if it's an integer number of samples?
>>
>> because apple don't want accurate timestamps beyond 12 (or even 6 hours).</sarcasm>
>
> Answering an old question, but this is wrong.
>
> mSampleTime is a Float64.
>
> Float64s have 52 bits of mantissa. With the implicit one bit, that gives 2^53 representable nonnegative integers.
>
> Let's say you are running at 192000 samples per second.
> 3600 seconds per hour
> 24 hours per day
> 365.25 days per year
>
> pow(2,53) / 192000 / 3600 / 24 / 365.25 = 1486.57 years before loss of sample accuracy.
Still curious why it's a Float64 in the first place. :)
--
Seth Willits
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