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Defining ppm and giving example of how it is relevent
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John Poole 2021-09-13 09:20:56 -07:00 committed by Scott Lamb
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@ -13,6 +13,14 @@ successfully, a following *open* may assign the same id to a new recording.
The open id disambiguates this and should be used whenever referring to a The open id disambiguates this and should be used whenever referring to a
recording that may be unflushed. recording that may be unflushed.
*ppm:* Part Per Million. Crystal Clock accuracy is defined in terms of ppm or
parts per million and it gives a convenient way of comparing accuracies
of different crystal specifications. "A typical crystal has an error of
100ppm (ish) this translates as 100/1e6 or (1e-4)...So the total error on a day
is 86400 x 1e-4= 8.64 seconds per day. In a month you would loose
30x8.64 = 259 seconds or 4.32 minutes per month."
Source: https://www.best-microcontroller-projects.com/ppm.html
*recording:* the video from a (typically 1-minute) portion of an RTSP session. *recording:* the video from a (typically 1-minute) portion of an RTSP session.
RTSP sessions are divided into recordings as a detail of the RTSP sessions are divided into recordings as a detail of the
storage schema. See [schema.md](schema.md) for details. This concept is exposed storage schema. See [schema.md](schema.md) for details. This concept is exposed