3 title: Metering in Ardour
8 An engineer reading and using audio level meters compares to a musician
9 reading or writing sheet-music. Just like there are virtuoso musicians
10 who can't read a single note, there are great sound-engineers who just
11 go by their ears and produce great mixes and masters without ever looking
15 Yet, if you want to work in or with the broadcast industry, it is
16 usually unavoidable to use meters.
19 Audio level meters are very powerful tools that are useful in every
20 part of the entire production chain:
23 <li>When tracking, meters are used to ensure that the input
24 signal does not <dfn>overload</dfn> and maintains reasonable
25 <dfn>headroom</dfn>.</li>
26 <li>Meters offer a <dfn>quick visual indication</dfn> of a
27 activity when working with a large number of tracks.</li>
28 <li>During mixing, meters provide an rough estimate of the
29 <dfn>loudness</dfn> of each track.</li>
30 <li>At the mastering stage, meters are used to check
31 compliance with upstream <dfn>level</dfn> and <dfn>loudness
32 standards</dfn> and to optimize the <dfn>loudness range</dfn>
33 for a given medium.</li>
38 A general treatise on metering is beyond the scope of this
39 manual. It is a complex subject with a history...
40 For background information and further reading we recommend:
43 <li><a href="http://www.digido.com/how-to-make-better-recordings-part-2.html">How To Make Better Recordings in the 21st Century - An Integrated Approach to Metering, Monitoring, and Leveling Practices</a> by Bob Katz. Has a good historic overview of meters and motivates the K-meter</li>
44 <li><a href="https://en.wikipedia.org/wiki/Peak_programme_meter#Table_of_characteristics">Wikipedia: Peak programme meter</a> - overview of meter types.</li>
45 <li>"Audio Metering: Measurements, Standards and Practice: Measurements, Standards and Practics", by Eddy Brixen. ISBN: 0240814673</li>
46 <li>"Art of Digital Audio", by John Watkinson. ISBN: 0240515870</li>
50 There are different metering standards, most of which are available in Ardour. In short:
54 <dt>Digital peak-meter</dt>
55 <dd>A <dfn>Digital Peak Meter</dfn> displays the absolute maximum signal
56 of the raw audio PCM signal (for a given time). It is commonly used when
57 tracking to make sure the recorded audio never clips. To that end, DPMs
58 are always calibrated to 0 <abbr title="DeciBel Full
59 Scale">dBFS</abbr>, or the maximum level that can be represented digitally
60 in a given system. This value has no musical reason whatsoever and depends
61 only on the properties of the signal chain or target medium. There are
62 conventions for <dfn>fall-off-time</dfn> and <dfn>peak-hold</dfn>, but no
65 Various conventions for DPM fall-off times and dBFS line-up level can be
66 chosen in <kbd class="menu">Edit > Preferences > GUI</kbd>.
71 <dd>An <dfn><abbr title="Root Mean Square">RMS</abbr>-type meter</dfn>
72 is an averaging meter that looks at the energy in the signal. It
73 provides a general indication of loudness as perceived by humans. Ardour
74 features three RMS meters, all of which offer additonal peak indication.
76 <li><dfn>K20</dfn>: A meter according to the K-system introduced by Bob
77 Katz, scale aligned to -20 dBFS, rise/fall times and color schema
78 according to spec.</li>
79 <li><dfn>K14</dfn>: Same as K20 with scale aligned to -14 dBFS.</li>
80 <li><dfn>K12</dfn>: Same as K20 with scale aligned to -12 dBFS (since 3.5.143).</li>
81 <li><dfn>Peak + RMS</dfn>: standard RMS, customizable via
82 <kbd class="menu">Edit > Preferences > GUI > Metering</kbd></li>
87 <dd><dfn><abbr title="International Electrontechnical Commission">IEC</abbr>-type
88 <abbr title="Peak Programme Meters">PPM</abbr>s</dfn> are a mix between DPMs and
89 RMS meters, created mainly for the purpose of
90 interoperability. Many national and institutional varieties exist (<abbr
91 title="European Broadcasting Union">EBU</abbr>, <abbr title="British Broadcasting
92 Corporation">BBC</abbr>, <abbr title="Deutsche Industrie-Norm">DIN</abbr>).
94 These loudness and metering standards provide a common point of
95 reference which is used by broadcasters in particular so that the
96 interchange of material is uniform across their sphere of influence,
97 regardless of the equipment used to play it back.
100 For home recording, there is no real need for this level of
101 interoperability, and these meters are only strictly required when
102 working in or with the broadcast industry. However, IEC-type meters have
103 certain characteristics (rise-time, ballistics) that make them useful
104 outside the context of broadcast.
107 Their specification is very exact, and consquently, there are no
108 customizable parameters.
113 <dd><dfn><abbr title="Volume Unit">VU</abbr> meters</dfn> are the dinosaurs (1939)
114 amongst the meters. They react very slowly, averaging out peaks.
115 Their specification is very strict (300ms rise-time, 1 - 1.5% overshoot,
116 flat frequency response). Ardour's VU meter adheres to that spec, but for
117 visual consistency it is displayed as a bar-graph rather than needle-style
122 <h2>Ardour Specifics</h2>
124 <img class="right" src="/ardour/manual/html/screenshots/mixer-meter-context-menu.png" alt="mixer strip meter context menu" />
126 Meters are available in various places in ardour:
129 <li>The mixer window features fixed height meters for each <dfn>channel strip</dfn>.</li>
130 <li>There are small (narrow) meters on each <dfn>track-header</dfn> in the editor window.</li>
131 <li>There are variable height meters in the <dfn>meterbridge window</dfn>.</li>
132 <li>Optionally, a fixed-size <dfn>master meter</dfn> can be displayed in the main toolbar.</li>
133 <li>Various other locations (<dfn>file import</dfn>, <dfn>sends</dfn>) have level-meters.</li>
136 They all share the same configuration and color-theme which is available in
137 preferences and the theme-manager. Settings for the Peak and RMS+Peak meters
138 as well as VU meter standards are found in
139 <kbd class="menu">Edit > Preferences > GUI > Metering</kbd>.
142 The type of meter and the <dfn>metering point</dfn> (the place in the signal chain
143 where the meter taps the signal) are configurable in the context menu of each meter.
144 Depending on the <kbd class="menu">Edit > Preferences > GUI > Mixer
145 Strip</kbd> settings, the metering point is also accessible via a button in
148 <img class="right" src="/ardour/manual/html/screenshots/meter-preferences.png" alt="" />
150 Regardless of meter type and standard the meter display will highlight red if
151 the signal on the given channel exceeds the configured peak threshold.
154 <kbd class="mouse">Left</kbd> on the peak-indicator button resets the
155 <dfn>peak-hold indicator</dfn> of a single channel.<br />
156 <kbd class="mod1 mouse">Left</kbd> resets a whole <dfn>group</dfn>, and<br/>
157 <kbd class="mod13 mouse">Left</kbd> resets all meters.
160 <h2>Overview of meter types</h2>
163 The figure on the left shows all available meter-types in Ardour 3.4 when fed with a
164 -18 dBFS 1 kHz sine wave.
167 <img class="right" style="max-width:45%;height:400px;" src="/ardour/manual/html/screenshots/needle-meters-18.png"
168 alt="Needle-style meters as external LV2 plugins" />
169 <img style="max-width:45%; height:400px" src="/ardour/manual/html/screenshots/meter-types-18.png"
170 alt="Bar-graph meters in Ardour" />
173 Due to layout concerns and consistent look&feel all meters available in
174 Ardour itself are bar-graph type meters. Corresponding needle-style meters
175 — which take up more visual screen space — are available as
176 LV2 plugins (see image on the right):
177 <a href="https://github.com/x42/meters.lv2/">meters.lv2</a>.