Wohler's Pandora

TV loudness is an issue that has been simmering with the viewing public for a while. But, it's taken on new urgency with the passage of the Commercial Advertisement Loudness Mitigation (CALM) Act in the United States and other similar regulation in various stages of enactment throughout the world. In the past few months, loudness monitoring and control has moved much higher on broadcasters' to-do lists, and many are identifying requirements and evaluating systems designed to address the issue. The net effect is that producers and broadcasters need to replace VU with LU (relative Loudness Units, ITU-LKFS or EBU-LUFS absolute units) for average program level measurement, and replace PPM with TP (True Peak) for peak headroom insurance.

A solution is Pandora — a compact, affordable and easy-to-read loudness analyzer that can be employed at any point in the broadcast chain requiring simple, accurate loudness monitoring. The loudness analyzer provides a clear, accurate reading of loudness measurements for any SDI video signal with audio, to help broadcasters and producers alike ensure that content meets EBU R128, ITU BS.1770, and ITU BS.1771 standards.

Striking a balance

Broadcasters are concerned about monitoring the final output and being able to log and report on the data in order to demonstrate compliance, or defend against loudness complaints. Producers, on the other hand, need loudness monitoring tools that can integrate with their existing editing, mixing and mastering processes in order to deliver a compliant program to the broadcasters. While most monitoring and control solutions are targeted to either one side or the other, Pandora offers tools that address requirements for both groups. For instance, the system can be set to continuous mode, which enables broadcasters to monitor output, and manual start-stop mode for production and post-production editing. In addition, the unit's form factor can be adapted for either environment — as a desktop mount for production live mixing and post-production editing, or as a rack-mount solution for broadcast compliance monitoring.

Easy configuration and use

Many broadcasters, as well as production and post houses, are entering new territory as they attempt to adopt loudness monitoring. That being the case, they need tools that will reduce the complexity of complying with multiple standards. The loudness analyzer boils standards-based monitoring down to selecting between ITU vs. EBU reference/limit sets, without requiring operators to have much knowledge about the inner workings of the standards. Operators can set their own reference parameters, including over/under limits, as well as integration time and metering modes. A unique feature of the unit is its integration with the Apple iPod touch, which provides a vivid display and an easy-to-use touch-screen interface. (A separate iPod touch purchase is required.) Since the Pandora software is available free from the iTunes App Store, operators can always access the most current version required to maintain compliance with evolving industry standards and practice.

Measurements at a glance

Accepting and analyzing AES or PCM de-embedded from SDI as stereo, 5.1 or multichannel audio, the analyzer gives the user an accurate reading of loudness, and true peak measurements for up to eight channels, over a user-defined period of time ranging from five seconds to 60 minutes. A large, numerical display shows LKFS/LUFS/LU readings, and a warning light indicates when this value exceeds acceptable thresholds. The unit's multichannel level meter display in the left pane shows absolute loudness values as multicolored bars, with red true peak floating segments in real time. The right pane always shows integrated loudness for the entire program set relative to the reference level setting. (See Figure 1.) Live production audio mixing can be adjusted on the fly by referencing the real-time multichannel display plus the program LU meter looking backwards over the appropriate integration time period.

Additionally, the loudness analyzer allows users to set a range of loudness parameters, including reference level and integration time, as well as configure the system for 2.0 (stereo), 5.1 or 7.1, (surround) or free-form 8 × 1 (AES or SDI) operation. A single-menu matrix sets up meter arrangements and channel assignments with loudness contributions.

Much of a program's peak, loudness and dynamic range profile can be intuitively derived from a loudness histogram. A finger swipe to the side shifts to the unit's histogram view to give a graphical representation of program loudness at any given point over the preceding time period set, with the red line showing true peak levels. (See left pane in Figure 2.)

Broadcasters will like the ability to view the histogram over the 24-hour maximum period, while producers can set views to program length from seconds to hours as needed.

Comprehensive logging

Although the CALM Act is now law, the FCC has yet to define its complaint pursuit criteria, which means broadcasters must take an “overkill” approach to logging in order to cover all potential scenarios. Via the iPod touch's 8GB or more of data storage, users can perform compliance logging over years of time. (See Figure 3.) This deep log memory enables standalone use where a network connection is not available, and preserves original data in case a downloaded file is lost or suspect. The system provides the ability to email log data over a wireless connection, eliminating the need for the system to be hard-wired to a receiving computer and network.


With loudness standards continuing to evolve, so will the sophistication of tools for monitoring and logging loudness levels in both production and broadcasting environments. Pandora offers an attractive and conveniently sized system for addressing the demands of global loudness standards, giving operators the precise information they need to confirm loudness levels and maintain new standards compliance.

Martin Winsemius is sustaining engineering manager for Wohler Technologies.