Understand Vicon system timecode functionality
- Gisela Roberts
- Ben Stanley
This topic describes the timecode functionality that is available when you connect external video sources to a Vicon Lock Studio.
Timecode is a time stamp that can be present in video or audio signals to provide timing information (i.e. time and frame number reference). Within a 24-hour period, each frame has its own unique timecode. You can configure the Vicon Lock unit to trigger from a connected video source containing embedded VITC (Vertical Interval Timecode) or a video source in conjunction with LTC (Longitudinal Timecode). You do this using the Vicon application software on the Vicon host PC.
The following table shows the international SD and HD video formats supported by Vicon optical camera systems.
| Format | Description | Variant supported |
|---|---|---|
| EBU (European Broadcasting Union): Based on cameras operating at a multiple of 25Hz. In Vicon documentation, the term EBU is used interchangeably with the following terms: | ||
| PAL (Phase Alternating Line) | The color standard used in Europe, except France. | PAL 50 2:1 (Interlaced) |
| SECAM (Sequential Couleur avec Mémoire) | The color standard used in France, the Middle East, and most of Eastern Europe. | SECAM 50 2:1 (Interlaced) |
| CCIR (Consultative Committee for International Radio) | The black and white standard. | 2:1 (interlaced) |
| SMPTE (Society of Motion Picture & Television Engineers): Based on cameras operating at a multiple of 29.97Hz. In Vicon documentation, the term SMPTE is used interchangeably with the following terms: | ||
| NTSC (National Television System Committee) | The color standard used in the United States. | NTSC 59.94 2:1 (Interlaced) |
| EIA (Electronic Industry Association) | The black and white standard. | 2:1 (interlaced) |
| HD (High Definition film): Based on cameras operating at a multiple of 24fps, 23.98fps, or 30fps. | ||
| 24fps | Cameras operating at a multiple of 24fps | 1920 x 1080 24 1:1 (Progressive) |
| 23.98fps | Cameras operating at a multiple of 23.98fps | 1920 x 1080 23.98 1:1 (Progressive) |
| 30fps | Cameras operating at a multiple of 30fps | 1920 x 1080 30 1:1 (Progressive) |
Vicon Lock Studio units do not use any color sub-carrier if present. For each of the EBU and SMPTE formats, Vicon Lock Studio units support the use of both LTC and VITC forms of timecode:
- LTC signal characteristics are compatible with standard audio channels so that they can be recorded onto audio tracks or to an audio track on video. Lock units are intended to be used with industry-standard balanced signals which are terminated in 600Ω (ohm). LTC frame rates supported are 30, 29.97, 25, 24 and 23.98 fps.
- VITC is encoded directly into spare lines in the vertical interval of the analog SD video signal.
For the analog HD formats, which inherently do not support VITC, LTC timecode must be used in conjunction with the synchronized genlock source.
The Vicon Lock unit can take the timecode from a LTC source connected to the LTC In socket, and timestamp the associated synchronized video signal connected to the Ref Loop Input. It can also take the timecode from a Ref Loop Input itself, if it has embedded VITC, which may be the case with SD analog video. You can select the timecode source in your Vicon application software.
Within a 24-hour period, each video frame has an associated timecode which is encoded in hours, minutes, and seconds, along with a sequential frame number.
Standard timecode format is:
hh:mm:ss:ff
where:
hh
|
= | hours | 00–23 |
mm
|
= | minutes | 00–59 |
ss
|
= | seconds | 00–59 |
ff
|
= | frames | 00–23 for HD (FILM) 00–24 for EBU (PAL/SECAM) 00–29 for SMPTE (NTSC) and HD (30) |
For NTSC, the separator character changes between a colon ( : ) for non-drop frames and a semicolon ( ; ) for drop frames.
The Vicon system reads the sequential timecode from the selected timecode source and subsequently timestamps the Vicon raw (X2D) data, along with any reference Vicon Vue video, with that of the external timecode. This can then be used to locate a precise reference point for editing your data.
Timecode triggering
From the Vicon application software on the Vicon host PC, you can configure Timecode triggering to automatically cause the Vicon Lock unit to start and/or stop data capture based on the timecode.
You can set the data capture start time to the required timecode and trigger the capture process to that particular timecode number. The Vicon Lock unit then starts the capture when the specified timecode is reached.
