Sound Devices 788T - Manual (Page 73)

Notes regarding Word Clock Input and Digital Input clock references
1. Loss of clock reference: When using external clock and the clock source is removed, the portion of
the fi le recorded after the loss of the clock source may not play back at the proper speed. For fi le integrity,
it is recommended that you set the 788T to the same sample frequency as the external clock source. Loss of
the clock signal in this case will likely cause a short glitch in the fi le as the internal generator takes over,
but the fi le may still be usable since it will play back 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
activate the hardware Sample Rate Converters on the 788T Digital Inputs and ensure that all inputs are
synchronized.
Time Code
The 788T holds accurate time code for up 4 hours between battery changes using its internal, Li-Ion
time code battery. After 4 hours without power, the 788T reverts to a slightly less-precise time-of-day
crystal to maintain the date/time of the unit. This time code battery is charged from internal or exter-
nal power whenever the 788T is powered up.
If the time-of-day clock is reset during the production day or if the time code mode is changed from
24 hour run to another mode and back, the time code value will change. You must re-jam all time
code devices to ensure proper synchronization.
File-based recorders place a single time code stamp in the BEXT and iXML chunks of an AES31
(Broadcast WAV) fi le. The 788T generates SMPTE time code from this number and extrapolates it
based on the time code frame rate for playback.
Files recorded on the 788T will always begin and end on a 0 frame. Pre- or post-roll (respectively)
will be applied automatically to accomplish this. Time code stamps will be adjusted accordingly. This
simplifi es synchronization in post-production.
Frame Rate
A single time code frame rate is selected in the Setup Menu option TIMECODE: FRAME RATE.
Sound Devices strongly recommends that the appropriate frame rate be confi rmed with Post Production
prior to the start of production.
The 788T supports all of the common production time code frame rates, including:
• 23.976 – This frame rate is most often used in productions shooting high defi nition video.
Counts 0.1% slower than real time.
Sync
hronization and T
imecode
6
788T/788T-SSD User Guide and Technical Information
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