On 30/05/2012 12:01 PM, scott wrote:
>>> Try playing the same song (or your tick recording) on several different
>>> devices at the same time, you'll find they likely drift apart noticeably
>>> after only a minute or two.
>>
>> And here I was thinking that even cheap quartz oscillators are quite
>> accurate...
>
> Even cheap quartz oscillators are too expensive to just throw at a
> device like a tablet. The audio clock is likely derived from elsewhere
> with whatever divide-down ratio was cheapest to implement (the frequency
> will likely not even be designed to be spot on 44100 if the numbers
> don't work out nicely).

A deviation in playback speed of +0.6% or -0.6% corresponds to a pitch 
deviation of about 10 cents. That's audible. I'd be surprised if they 
allow it to be quite that large.

(I would have expected the DAC to run at whatever speed is convenient, 
and then resample the signal in software... But what do I know?)

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