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3.12.2 CALIBRATION AND HEADROOM
In digital audio systems, levels exceeding ‘legal’ values are ‘clipped’ (uniformly assigned the
maximum value). This results in audible glitches that cannot be easily corrected later. For this
reason, it’s customary to configure normal operating level (also referred to as the ‘alignment level’,
and sometimes, ‘nominal level’) well below the clipping limit – sufficiently so that occasional
excessively loud sounds (say, loud laughter or applause) can be accommodated without risk.
The range between nominal level and the highest possible level is referred to as ‘headroom’. What
is considered a suitable headroom allowance varies is somewhat objective, and standards vary from
one locale to another, in different industry applications, and even in individual studios. TalkShow
follows well-established conventions, providing 20dB headroom above nominal level by default.
Hint: Confusion sometimes arises because different scales are in common use in various audio
realms, and even for different device types and software. For example, analog mixers commonly
show VU scales that top out at +20 dB VU, with a 0dB ‘Alignment level’ below. In contrast, digital
devices and editing software usually display levels in dBFS (Decibels Full Scale) with 0dBFS – the
absolute maximum signal level that can be recorded – at the top. TalkShow’s VU meters use this
scale.
Whatever system you are accustomed to, you can use the Volume controls provided in the Return to
Caller panel to avoid over-modulation.
SECTION 3.13 CONFIGURE GENLOCK
Configure Talkshow’s genlock feature as follows:
1. Open TalkShow‘s Setup panel by clicking the configuration (gear) gadget near the titlebar clock.
2. The default Reference Type in the Genlock settings group is SD (Bi-level), as this is currently the
most common reference signal type. However, if you supply an HD reference signal to the
Genlock input, you may want to change the setting to HD (Tri-level).
3. With the aid of Waveform and Vector Scopes, adjust TalkShow’s Horizontal and Vertical Position
and Phase settings in the Genlock section of the I/O Configuration panel.
FIGURE 15
Note: For a deeper discussion of genlocking, please see Appendix B.
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