Cobalt Digital COMPASS 9067 Upconverter - Manual (Page 58)

3
9067 Function Submenu List and Descriptions
3-26 9067 PRODUCT MANUAL 9067-OM (V4.4)
(continued)
• Audio Hard Resync Threshold Control Sets threshold at which hard resync is applied if audio-video offset
exceeds threshold (see below). Hard resync provides fastest snyc-up
suitable for off-air manipulation. Conversely, a threshold setting high
enough to accommodate normal on-air offsets allows on-air resync that is
glitch-free.
(Range is 1.5 to 13.0 frames in 0.1 frame increments)
• Audio Offset Control Adds or reduces (offsets) audio delay from the matching video delay
(audio delay offset setting adds or removes delay in addition to any delay
included by other actions). This control is useful for correcting lip sync
problems when video and audio paths in the chain experience differing
overall delays.
(-575.0 msec to 575.0 msec range; null = 0.0 msec)
Note: Delay offset values of less than approximately 1 frame are
progressively applied by the card to provide a seamless, glitch-free
retiming. However, delay offset values exceeding 1-1/2 frames may
result in a slight audio discontinuity at the moment when the offset
is applied using this control if the Audio Hard Resync Threshold
control is not at a setting greater than the delay offset.
To prevent this condition during an on-air manipulation, it is
recommended that the Audio Hard Resync Threshold control be
set high enough such that expected delay offsets exceeding 1-1/2
frames are progressively applied.
Note: If using Audio Offset control to perform off-air corrections, it is
recommended to temporarily set the Audio Hard Resync
Threshold control to its minimum setting, thereby allowing the
offset to be assessed and corrected as fast as possible.
Table 3-2 9067 Function Submenu List — continued
Video:
40 msec
In this example, initial offset of 200 msec (appr. 6 frames) is
below 9 frame threshold and results in soft resync being
progressively applied.
t
Audio:
240 msec
With offset less than selected hard resync threshold, resync is progressively applied in many small
steps to provide a seamless, glitch-free retiming. After the successive steps, the audio is synchronized
with the video (in this example, 40 msec). (Progressive correction is applied at 1 msec/sec appr. rate.)
Video:
40 msec
t
Audio:
440 msec
With offset greater than selected hard resync
threshold, resync is immediately applied.
9 6
9
12
In this example, initial offset of 400 msec (appr. 12 frames) is
above 9 frame threshold and results in immediate hard resync.