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Audio Loudness Meter 5.1

Audio Loudness and True Peak Meter
VST, AU, AAX plugin and standalone application, BS1770 and EBU R128 compliant

ALM5.1 Audio Loudness Meter Plugin

In the past, the standard for controlling the level of broadcasted audio materials consists counting samples. Today, the attention switches to the listener himself, more precisely to the listener’s audio perception and how he perceives the audio material.

In order to sustain this revolution in the audio world, a number of international broadcast standards have been developed (BS-1770, EBU R128, ATSC A/85) based on research and perception tests. We all know how annoying is to adjust the volume every time you change the program or during commercial breaks. But now, we have a solid foundation that helps us solve the problem of loudness variations, so you don’t have to reach for the remote control.

ALM 5.1 is designed as a key component in your mixing workflow. Based on the new ITU, EBU and ATSC loudness standards, the plugin offers you full Loudness and True Peak Metering for Mono, Stereo and 5.1 channel formats featuring measurements for Momentary, Short Term and Integrated Loudness, with Loudness Range and Max True Peak Level.

Wheter your want to target the loudness (-23 LUFS,according to EBU specification, or -24 LUFS, according to ATSC specification) or you want to use the relative gate of -10 LU, ALM 5.1 is all you need to control the loudness of your audio material. Both LU and LUFS scales are available, also, you can set the start and the stop of your measurements or you can simply let the plugin do it by following the host transport.

If you prefer a higher resolution for the target zone you can use the +9 LU scale and if you prefer a higher dynamic range you can use the + 18 LU scale. With both value and bar indicator for Loudness Range availabel, you can decide if your audio needs more dynamic compression or not.

The graphic interface is very flexible, you can use either the wide or the narrow view. In both cases, you don’t have to worry about the Peaks because there ALM 5.1 features peak holders and led indicators to let you know anytime an overload occurs. Two scales with different reference levels (-18 dBTP and -20 dBTP) are available for the True Peak Meter. Also, ALM 5.1 takes into account all the inter-samples that can be missed in quantization. The plug-in features a timecode counter of the measurements and you can reset all the results anytime you want.

There is an optional upgrade for the ALM 5.1 (the standalone version), that allows you to have more control over your loudness by recording all the values measured in XML files.

Plugin Features

  • Audio Loudness and True Peak Metering VST, AU and AAX plugins
  • Channel Formats: mono, stereo and 5.1
  • Full compliance with Loudness standards : BS-1770 (rev.3), EBU R128 and ATSC A/85 specifications
  • Complete loudness measurements using universal descriptors: Integrated Loudness (Program Loudness), Momentary Loudness, Short Time Loudness, Loudness Range
  • Real-time metering for Momentary Loudness, Short Term Loudness and Loudness Range;
  • True Peak Level Metering with peak hold
  • Max True Peak Level (calculated using inter-sample peaks that can be missed in quantization)
  • Correct measurements for all the usual sample rates: 44.1 kHz, 48 kHz and their multiples
  • Low CPU usage due to plugin optimization
  • Logging files in XML format (optional upgrade for the standalone version)

Minimum System Requirements

Dual Core CPU (Intel or AMD) with SSE2 support
Dual Core CPU (Intel or AMD)  with SSE2 support
Windows 7

Available Formats

VST 2.4 universal binary (32/64bits)
AU universal binary (32/64bits)
VST 2.4 universal binary (32/64bits)

Loudness Descriptors

  • Integrated Loudness (Program Loudness) – describes the long-term integrated loudness of an audio material from ‘start’ to ‘stop’
  • Momentary Loudness – calculated with a time window of 400 ms
  • Short Term Loudness – calculated with a time window of 3 s
  • Loudness Range – loudness dynamic range from ‘start’ to ‘stop’ that helps you decide if dynamic compression is necessary
  • Max True Peak Level – indicates the maximum value of the signal waveform in the continuous time domain (this value is calculated using inter-sample peaks that can be missed in quantization)

Loudness Metering

ALM 5.1 not only calculates the values of most important descriptors specified by the standards (Integrated Loudness -Program Loudness, Momentary Loudness, Short Time Loudness, Loudness Range), but offers you the possibility of choosing the scale for Momentary Loudness according to your needs. There are two options that can be accessed in the Settings window:
  • The standards: EBU with a reference level at -23 LUFS and ATSC with a reference level at -24 LUFS
  • The scales: +9 LU for a good resolution in the reference level zone and +18 LU for a bigger dynamic range

For the start, the measurements for Integrated Loudness and Loudness Range are done considering the gate at -10 LU. In this case, the name of the standard (EBU/ATSC) is green. If you opt for no gating, the name of the standards will be red.

ALM5.1 Audio Loudness Meter Plugin True Peak
You can also use the relative scales, with the reference level of 0 LU. In this case the scale is the same for both EBU and ATSC standards.

    ALM 5.1 offers you the flexibility to change the frame size:
    • When you first open it, the plugin has the Wide view with both Loudness Meter and True Peak Meter
    • Pressing the toggle button you can access the Narrow view with only the Loudness Meter. Note that there is a Peak Led indicator to announce you if a peak occurs.

True Peak

ALM 5.1 offers you real time True Peak Metering with peak hold for mono, stereo and 5.1 channels. Beside this, the plugin gives you the possibility to configure your measurements by accessing the Settings window.

You can choose the True Peak reference level -18dBTP or -20dBTP, the Peak Holding Time and the Overload Hold.

Note that for the case when you use the narrow view of the plugin, you still can see the peaks indicated by the Peak led. Also, the peaks are on until you reset the measurements or press on them.

ALM5.1 Audio Loudness Meter Plugin Statistics


ALM 5.1 offers the real time values of the main descriptors of your program.


  • EBU or ATSC specifications
  • Loudness Scales : +9 LU and +18 LU
  • Loudness Units : LUFS or LU
  • Integrated Loudness gating off : the gate at -10 LU is not used and the Integrated Loudness and Loudness Range values are calculated for the entire audio material
  • Follow transport : the measurements are done only when the audio material is in ‘play’ mode
  • True Peak ref. level : -18 dBTP and -20 dBTP
  • True Peak max. level : from -5 dBTP to -1 dBTP. Sets the maximum value of the signal waveform calculated using inter-sample peaks that can be missed in quantization. Above that value Peak Led indicators are red (the level is the same for all the channels)
  • Peak hold : from 0 s to 10 s. Represents the period of time the Peak holders are on
  • Overload hold : from 0 s to 10 s. Represents the period of time the Peak Led indicators are on

Standalone Version

The ALM 5.1 bundle also contains a standalone version with complex I/O Audio Settings and routing capabilities. In this way you can take advantage of the same features even if your system doesn’t support VST, AU or AAX plugins.