Video Sync; Digital Inputs - Sound Devices 788T-SSD User Manual And Technical Information

Video Sync

The 788T locks to any valid video sync source, including composite NTSC, PAL and Tri-level con-
nected via the Sync Input connector. If a valid video sync is detected, 'V' is displayed in the LCD. If a
valid video sync is not detected, the input activity LED rings will fl ash yellow and the Lock indica-
tor, 'V' will not appear.

Digital Inputs 1-2, 3-4, 5-6, 7-8

The 788T can be set to lock and derive its clock from any valid digital input pair even if the equiva-
lent numbered analog input pair has been selected for recording. For example, sync reference is
set to digital input 1-2 and inputs 1 and 2 are both set to MIC. If a valid digital input sync source is
detected, 'D' is displayed in the LCD. If a valid digital input is not detected, the Input Activity Ring
LED associated with the selected digital input sync source will fl ash yellow and the Lock indicator,
'D' will not appear.
If digital audio is connected to the 788T from more than one digital source, you must lock these
sources together to a common reference otherwise differences between the sources' clocks will ren-
der their signals unusable. There is no sample rate conversion on the digital inputs when sync source
is set to Digital Inputs, Word Clock, or Video Sync.
Notes regarding Word Clock Input and Digital Input clock references
1. Loss of clock reference: If this occurs, the portion of the fi le recorded after the loss of ext clock refer-
ence may not play back at the proper speed. For reliability, we recommend you set the 788T to the same
sample frequency as the external clock source. Loss of the clock signal in this case will most likely cause a
short glitch in the fi le, but the fi le may still be usable since it will playback at nominally the correct speed.
2. The 788T LCD main display screen shows the sample clock rate of the incoming word clock or digital
input reference when locked ('D' or 'W' indicators are ON).
3. If multiple Digital Inputs are used, it is best practice to set the sync source to Internal. This will enable
the hardware Sample Rate Converters on the 788T Digital Inputs and ensure that all inputs are synchro-
nized.
788T/788T-SSD User Guide and Technical Information
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