New, Better, Free - Upgrade your DB4 and DB8
The 3.40 software upgrade for DB4 and DB8 includes a new Advanced Loudness Correction processor, the remarkable ALC6. And the radar loudness meter, LM6, now has the ability to display numbers in "LKFS" as well as in "LUFS".
ALC6 offers BS.1770 compliant Loudness Correction and True-peak limiting for mono, stereo and 5.1 programs. This low latency, 48 bit resolution processor introduces several industry-first features, just like DB4 and DB8 users have come to expect (see note 1).
Broadcasters around the world are going through a transition
towards loudness based production and program normalization. In
order to comply with legislation such as the CALM Act, as a quick
fix, it's tempting to insert "sausage processing" at the point of
transmission. However, sausage processing is completely against the
spirit and the purpose of new American, Brazilian, Chinese,
European and Japanese audio standards - and also against the
philosophy of TC.
With ALC6, it's no longer a choice between plague and cholera. Processing at a higher resolution than any other audio device or codec in the broadcast signalpath, DB4 or DB8 will never be your quality bottleneck.
ALC6's adaptive Stridency Reduction parameter brings overly loud content under tight control while leaving normal content untouched. Another setting allows the operator to indicate whether a program is already normalized, not normalized or sometimes normalized. If content is 5.1, ALC6 may automatically dissolve into bypass, or you may set a different Target level depending on the format. ALC6 is transparent in several senses of the word.
Measuring the loudness of a 5.1 program can give significantly
different results from measuring a stereo or a mono downmix of the
same program. Furthermore, these differences are systematic because
measuring loudness according to BS.1770 is insensitive to
inter-channel phase differences, while a downmix is not (see note
2). Tight tolerances on program loudness therefore presents a
dilemma when it comes to mono or stereo listeners, generally the
vast majority of a station's audience.
ALC6 introduces a new way of dealing with this issue: A 5.1 program may be adjusted based on what it measures in 5.1, or on what it measures using a specific set of downmix coefficients.
ALC6 also helps getting a higher audio quality and more headroom out of AC3 data reduction. The downmix part of the decoder is prone to overload, especially when AC3 DRC is set to Off. On the other hand, enabling DRC inserts a crude processor which nobody can get rid of again. Use the new "AC3 Codec" setting with ALC6's true-peak limiter to prevent downmix clipping while preserving headroom, thereby making it safe to switch off DRC and make AC3 more transparent.
For a happy ending, ALC6 even reads presets made with its predecessor, the industry-standard ALC5.1. The operator therefore hits the ground running after the upgrade, and may try all of its features one by one.
DB4 and DB8's integrated Radar Loudness Meter, LM6,
includes two new functions: The meter may now show loudness units
in "LKFS" rather than "LUFS", and a Short-term loudness warning
threshold may be set. Realtime loudness warnings are visible in the
remote application on a Mac, a PC or on the TC Icon hardware unit.
Warnings are also relayed via the processor's extensive SNMP alert
and logging system.
- DB4/8 were industry-first to offer true-peak limiting, BS.1770 based loudness adjustment, metering, auto-sensing up-conversion, logging and more.
- Bruce Jacobs, Chief Technologist at Twin Cities Public Television, covered challenges of loudness in relation to downmix at the 2012 HPA and NAB engineering conferences.
Icon software v.: 6.60
Frame software v.: 3.40
DSP software v.: 3.40
Ethernet software v.: 8.10