PRISM MPI2-25 and MPX2-25 Media Analysis Platform User Manual
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Additional offset displays are available for Quad Link SDI signals (See
Figure 128
.):
•
Link Offsets
: Time delays of Links B, C, and D relative to Link A.
These time delays are also shown graphically under the timing display
window.
•
Max Link Offset
: Maximum time delay between any two links.
Figure 128: Timing application display for Quad Link SDI signals
Timing offsets for IP
signals
Use cases for measuring
timing
Because ST2022-6 streams are complete SDI signals encapsulated in IP, the
timing measurement treats these IP signals as if they were SDI. So the timing
system detects the start of the IP frame, then extrapolates to the 0h point of the
encapsulated SDI. Then using PTP as the reference, the ideal alignment point for
that frame rate is calculated based on the PTP epoch. Finally the offset between
the ST2022-6 signal and the ideal alignment is displayed. The display shows both
absolute time and the time parsed into lines or horizontal delay as time and pixels.
For ST2110-20 streams, the Timing application displays the time of the first
packet of the frame. Since ST2110 does not include blanking, the first packet
is nominally coincident with the first active line in the SDI raster. This means
that it is normal for the ST2110 streams to be delayed by the lines in the vertical
blanking of a given format. This value varies up to 42 lines for some formats.
According to ST2110-21, both gapped and linear flows should have the start of
frame delayed by the equivalent of vertical blanking.
One use case for the Timing application is to measure the delay in a gateway and
network. If a properly timed SDI signal is applied to a gateway, then the timing
measurement on the resulting IP flow will display the combined latency in the
gateway and the network.
Each ST2110 stream also carries time stamps. The Stream Timing application
allows for the analysis of these time stamps.
