User Manual

Preparing to Capture Video
219
Capturing from Unstable Time-Base Sources
Your Avid system is optimized for use with modern, broadcast-quality VTRs that contain
time-base correctors (TBCs). If the input is stable, your system captures the video by using a
high-quality, very-low-jitter clock reference.
However, some sources do not include an internal TBC. In some cases, due either to the deck
performance or the deck performance in conjunction with a particular videotape, your system
does not lock to non-TBC sources. As a result, the image might be unstable or might have
reduced or missing color, or syncing might not be possible at all.
If you select SignalLock > Consumer in the Video Input tool, a wider bandwidth (more closely
tracking time-base) improves the range of syncing capability. In this mode, the video input levels
are set by automatic gain control. Not all of the Video Input tool’s adjustment sliders operate,
and the video might be slightly softened, but the syncing in most cases is more reliable and more
stable. The overall image quality is not as high as with normal operation.
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The Video Input tool is not available on all models. If your model does not have the Video Input
tool, your Avid editing application sets the default input options automatically.
If you continue to experience difficulty with a source that does not include an internal TBC, Avid
recommends that your process the video signal through an external TBC for maximum image
quality. For more information on time-base correctors, contact your Avid Reseller.
Green Line in VHS Video
Some VHS tape decks do not output the full 240 lines of video normally included in the VHS
format. As a result, after you capture from a device such as a VCR, a green line might appear at
the bottom of the monitors in your Avid editing application.
This line is at the bottom of the visible area of the picture, and is not seen in a standard consumer
monitor in most cases. If you use the video in a circumstance in which the line is visible, you can
remove it by cropping the bottom edge of the picture.
Saving Video Input Settings
You can save the settings for an individual tape each time you calibrate bars. Saved settings are
restored each time you select the same tape for recapturing clips. The settings that are saved and
restored are the Level adjustments made with the sliders and the selection status of the
SignalLock or 100% Bars options.