Eff is designed to be the most comprehensive loudness measurement and correction tool that is available. However a level of complexity in configuring is necessary for the product to cover all possibilities.
The first stage in configuring eFF is to decide what to measure. Each type of measurement can be individually enabled. The choices available within some sections also varies depending on the standard selected from the associated drop down.
Choose Measurements – Loudness
When you select to make Loudness measurements, a choice of possible measurements are displayed, and the choices depend on the loudness standard that is selected. The main variations are – select R128 as your measurement standard to have access to Short Term and Momentary loudness measurements, or select ATSC A85 to have access to (optional) Dolby dialog intelligence
From the drop down, you should choose the loudness standard required. When you click the dropdown, a list of currently supported standards is displayed.
BS1770 is the original standard that all modern loudness specifications are built upon, and has undergone a number of updates since its first release. The method of gating and measuring Loudness was last updated in BS1770-2, whilst the method of measuring True Peak was updated in BS1770-3, and this version was released in August 2012. eFF fully implements the base Loudness algorithm and base True Peak measurement algorithm from this standard. As of September 2014, the current release of BS1770 is version 3.
EBU R128 is the European Standard that was developed by the ‘PLoud’ group of people, chaired by Florian Camerer, Senior Sound Engineer at ORF, and it is through the efforts of this group that we have our current standard of targeting Program Loudness at -23 LUFS. The latest information suggests that a tolerance of +- 0.5 LU is allowable to cope with accuracies of differing measurement equipment, for recorded material, although +-1 LU is permitted in live broadcast. Program Loudness is always based on the full duration of the media.
The A85 standard was developed by the ATSC and is applicable to most broadcast in USA. It differs from R128 in that the target value for Program Loudness is -24, and the units are LKFS instead of LUFS. The tolerance is normally given as +-2. Unlike R128, the A85 specification also allows for the optional use of the Dolby Dialog Intelligence algorithm. Ideally you should not mix measurements taking with Dialog Intelligence, with measurements taken without Dialog Intelligence, as of course they will differ.
TR-B32 is the Loudness standard defined in Japan, and normally has a target of -24 LKFS.
Leq(A) is the only loudness standard not based on BS1770. As of September 2014, this is still used in some Nordic areas, although they are believed to be transitioning to loudness levelling based on BS1770.
OP-59 is the Loudness Standard defined in Australia and New Zealand and is based upon BS1770-3, with a target of -24 LKFS.
219/09/CSP is the Loudness Standard from Italy’s Agcom organisation, and has a target of -24 LUFS.
BS1771 defines how a Loudness Meter should work, and this standard includes the option to offset the target to a value of 0 LU. A reference offset is added to the actual loudness measurement such that a target of -23 LUFS would have an offset of +23 added, giving a target of 0. The standard defines that measurements will be expressed in LU, which prevents confusion when comparing with measurements taken without an offset, which, in BS1770, are measured in LKFS.
Program Loudness Choices
Once you have enabled Program Loudness measurement, there are a few choices to be aware of. The concept of ‘gated’ measurements were introduced in BS1770-2. Loudness standards now have an absolute gate at -70 LUFS. Audio below this level is excluded from the calculations, and this happens automatically. There is also a relative gate, and this is usually set to -10 – ie the gate is 10 LUFS below the main loudness level. In eFF, the default value in the UI for the relative gate will be -10, but you can change this, as some older specifications set the gate to -8.
Short Term Loudness Choices
Short Term Loudness is defined as part of Tech 3341, and metering modes. Short Term Loudness is not used as a target, but rather as a maximum not to exceed. The value for short term loudness might typically be 6 LU higher than that selected for Program Loudness. It is normally used as part of live mixing, rather than as a target for completed files. Tech 3341 defines the averaging duration as 3 seconds.
Momentary Loudness Choices
Momentary Loudness is defined as part of Tech 3341, and metering modes. Momentary Loudness is not used as a target, but rather as a maximum not to exceed. The value for momentary loudness might typically be 9 LU higher than that selected for Program Loudness. It is normally used as part of live mixing, rather than as a target for completed files. Tech 3341 defines the averaging duration as 0.4 seconds.
Choose Measurements – Loudness Range (LRA)
The Loudness Range (abbreviated to LRA) is defined by the EBU in Tech 3342. The value of LRA is based on the Loudness distribution in audio under test. The Loudness distribution is calculated using a similar algorithm to that for Program Loudness, but the LRA is the range between the 10th and 95th percentile of that distribution. For normal television broadcast, the largest acceptable LRA might be in the range of 15 to 18, depending on choice by the different broadcasters. On eFF, you can enable a Loudness Range warning, and enter a from value of 0 and a to value of 15, for eFF to always report the measured LRA, and to give a warning if the maximum value is exceeded.
Choose Measurements – PPM or VU
eFF is fully compliant with ‘older’ measurements, and supports a range of PPM or VU measurements. You can only enable one of the other. When you have selected PPM or VU, you can select a scale from the dropdown menu. The PPM scale supports both type I and type II ballistics. You need to enter you chosen threshold, but do note that some scales, such as BBC, use positive values, and other scales, such as dBFS, use negative numbers, and you will need to enter this correctly.
A tolerance parameter is available for both PPM and VU, and this uses the same units as the scale. So if you wished to allow PPM measurements up to 6.1, then you could perhaps specify a threshold of 6, and a tolerance of 0.2