[time-nuts] frequency (absolute) accuracy in sound recording/playback

[Magnus Danielson]

On 05/08/2012 04:25 AM, J. Forster wrote:
> The SMPTE Time Code was on one line in first 20 odd of the Verticle
> Blanking Interval (VBI), along with the Color Bars, Multiburst, Closed
> Captrion data and some other things.
>
> It was not accurate to microseconds. It had a format of HH:MM:SS:FR
>
> (Hours, Minutes, Seconds, Frame) ...  the frame was a number of 1 to 30

SMPTE 12M Time code doesn't have to be very accurate in the labeling, as 
you for VITC has line-numbers and for LTC has the modulation. All 
allowing for locking up analogue video and audio tape recorders.

For modern times, approaches using GPS based time to form a form of 
absolute phase has been attempted, using the SMPTE 404M definition of a 
SMPTE Epoch (definition of all phases aligned). The SMPTE 404M had a bug 
in it when it was initially pre-published, it failed to detail which 
time-zone that midnight 1 Jan 1958 was on, but they corrected it after 
my comment on it.

Cheers,
Magnus