Last Modified: December 3, 2014
Previzion automatically searches for timecode in the following order:
- Timecode embedded in the HDSDI ANC metadata (VITC, VANC, HANC)
- LTC timecode embedded in the incoming audio data
If neither of these options is found, Previzion will generate reference timecode internally. The UI above is displayed in the Takes panel.
Analog LTC Input — Direct
As of build 5924, LTC timecode can be read directly into the RJ45 jack of the Merlin I/O breakout box using a BNC to RJ45 adapter.
In Previzion, set the LTC Source drop down to RJ45. Since timecode is acquired along with the video frame, the LTC light will only go green if the HDSDI input #1 is enabled and video is coming into the system.
Analog LTC Input — Embedder
Before build 5924, to read the analog LTC timecode format into the Previzion digital audio inputs, a converter must be used such as the AJA HD10AMA or the AJA ADA4.
Settings for the ADA4:
- LTC is routed into Input B
- Output A of the ADA4 is routed into the AES Audio 1 port of the Previzion breakout box.
- All DIP switches on the ADA 4 are set to OFF.
Settings for the HD10AMA:
- LTC is routed into Input B
Settings for RJ-45 LTC converter
Previzion now accepts LTC over RJ45 as of build version 5924
This box or panel allows a LTC signal sent over BNC to be converted to RJ45 and plug directly into the Merlin breakout. This elements the need for an audio embedder or allows for some audio emenders to be used to pass Audio through Previzion with with proper delay, while the RJ45 adapter handles getting LTC into the system.
Plug the BNC with LTC coming out of it into the BNC jack, and a RJ45 (ethernet) between the Merlin breakout and the JR45 adapter box.
The BNC-RJ45 adapter comes in panel mount to be installed inside of an Evertz 1u frame, or a compact 1u high box for systems without Evertz frames.
Supported Timecode Formats
Previzion supports both DF (drop frame) and NDF (non-drop frame) when the incoming timecode is being sent over as ANC data.
When LTC timecode is injected via an audio pair (Audio Embedder method) or RJ45 panel adapter, timecode will automatically be converted to NDF.
Under the Takes panel, set the LTC Source to the correct setting:
- AES1 Pair if using the AJA ADA4 plugged into the AES Audio 1 port
- Embedded Pair 0 if using the AJA HD10AMA to embed timecode directly into Channel 0 of the HDSDI video
When the timecode light flickers between ‘Generate’ and ‘LTC’, it usually means that the timecode is coming in at a different frequency than the video frames. (Timecode is set to 23.98 instead of video 29.97, or vice versa.)
Recommended LTC Sources
In cases where a direct line to the LTC source is too lengthy, an external LTC sync box can be used. This connects to the original signal and ‘jam syncs’ to the timecode. The box can then be disconnected, and its internal crystal timer keeps timecode sync for several hours.
- Denecke SB-3
- Denecke SB-T (includes genlock output, not usually necessary)
- Ambient Lockit Box ACL 203
In addition, for debugging purposes, there are IOs apps capable of generating (but not jamming) LTC. The crystal inside LTC sync boxes are much more accurate and reliable than IOs devices, but having an iPhone App with LTC can be handy sometimes. We recommend JumpStart LTC (available from the iTunes App Store).
To input production LTC coming from a BNC cable, for instance, you will need a couple of adapters. One to go from the iPhone/iPad headphone jack you will need: mini jack (male) to RCA (female) and another to go from RCA (male) to BNC (female).