Nevion FSR-HD - Manual (Page 11)

FRS-HD Rev. G
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Figure 7: Another example of delayed outgoing video
To reiterate: The phase delay can be both positive and negative and sets the difference
between the phase of the sync input and the video output. The video delay sets the delay
between video output and video input. However, the actual delay might be longer as it
also needs to phase up to the sync input. The actual delay may be up to 1 frame longer
than the minimum video delay.
The user may specify a video delay between 2 lines (min) and 7 frames
(max).
The two parameters allow a user to delay the incoming video, and reference it to the
sync input. By this mechanism, the user can precompensate processing delay in other
equipment. The video delay setting simply determines a lower limit to a 1 frame wide
window into a long delay line. The phase delay may be seen as a specification of the
delay between the sync input, and a signal "isync". The output video is always
synchronized to isync. A few more examples:
Example 1: The SDI input signal is isosynchronous to a sync signal, but 12 lines, 0
samples delayed. The video delay is set to 1 frame, 0 lines and 0 samples. The phase
delay is set to 65 samples. The actual delay between the input video and the output video
will be 2 frames - 12 lines + 65 samples.
Example 2: The SDI input signal is asynchronous to the sync signal (the frame frequency
is slightly different). The video delay is set to 1 frame, 13 lines and 0 samples. The phase
delay is set to -1 line. The actual delay will gradually change between 1 frame and 13
lines to 2 frames and 13 lines. The output will appear 1 line (in the output video format)
ahead of the sync signal.
Example 3: The SDI input signal is isosynchronous to the sync signal, but 12 lines ahead
of the sync signal. The video delay is set to 1 frame, 0 lines and 0 samples. The phase
delay is set to -2 lines. The actual delay between the input video and the output video
will be 1 frame + 10 lines.
The frames and lines are measured in units of the output SDI video standard. If the output
SDI standard is 1080i25, a delay of one line is equal to 35.5us. If the output SDI standard
is 720p50, a delay of one line is equal to 26.6us. If the output SDI standard is 625i25, a
delay of one line is equal to 64us.