manual/include/loudness-analyzer.html
2021-06-05 17:07:54 +02:00

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<p>
The Loudness Analyzer &amp; Normalizer is a tool that is useful at the
end of the mixing process to make the final audio file comply with
different specs regarding loudness.
</p>
<p>
It is enabled by checking
<kbd class="option">Enable master-bus output gain control</kbd> in the
<a href="@@preferences#preferences-mixer">Preferences</a>.
The <a href="@@master-bus-strip">Master Bus strip</a> then shows a <kbd class="menu">LAN</kbd>
button to start the analysis, and a volume slider that is the global gain
that can be set either manually or by the loudness normalizer.
</p>
<p>
The LAN can also be started from the <kbd class="menu">Session &gt; Loudness
assistant&hellip;</kbd> menu. If the option above is not enabled, Ardour
will link to the relevant page of the Preferences.
</p>
<p>Either method show the following window:</p>
<figure>
<img src="/images/pre_loudness.png" alt="The Loudness Analyzer realtime selector">
<figcaption>
The Loudness Analyzer realtime selector
</figcaption>
</figure>
<p>
This window allows to start the loudness analysis. A choice is offered
between freewheeling (i.e. Ardour renders the session as fast as possible
to measure the loudness), by default, or Realtime, for cases where freewheeling would
not accurately render the session, e.g. if a hardware or JACK effect
is used in the session, by clicking on the <kbd class="menu">Realtime</kbd>
toggle button.
</p>
<p>
After the analysis is over, the Loudness Analyzer and Normalizer is shown:
</p>
<figure>
<img src="/images/loudness_analyzer.png" alt="The Loudness Analyzer and Normalizer">
<figcaption>
The Loudness Analyzer and Normalizer
</figcaption>
</figure>
<h2>The Loudness Graph</h2>
<p>
At the top of the window, a loudness graph visually represents the
analysis. The x-axis represents the time, and the y-axis represents
the perceived loudness in <abbr title="Loudness Units referenced to
Full Scale">LUFS</abbr>:
</p>
<ul>
<li><span style="color:green;">Integrated loudness</span> averaging the loudness on the whole session</li>
<li><span style="color:red;">Short loudness</span> using a sliding time window of 3 seconds</li>
<li><span style="color:blue;">Momentary loudness</span> using a sliding time window of 400 ms.</li>
</ul>
<h2>Normalization Parameters</h2>
<p>
As loudness is a perceived sonic energy, and depends on the level, frequency,
duration and nature of the sound, this window allows to base the calculation
of the loudness normalization on different parameters :
</p>
<ul>
<li><dfn>Peak :</dfn> is the highest signal level value</li>
<li><dfn>True Peak :</dfn> is the highest signal level value where the
signal has been oversampled to figure out more in-between values
between the samples (interpolation)</li>
<li><dfn>Integrated Loudness :</dfn> is the loudness computed from the
whole session or range</li>
<li><dfn>Max Short Loudness :</dfn> is the maximum loudness computed
on short time ranges (3 seconds)</li>
<li><dfn>Max Momentary Loudness :</dfn> is the maximum momentary loudness</li>
</ul>
<p>
Any combination of these parameters can be taken into account when determining
the gain normalization, by checking its momentary button, and setting a
<em>Target</em> value.
</p>
<p>
Ardour shows both the <em>Measured</em> value of the parameters, and the
<em>Delta</em> value, i.e. the difference between the <em>Target</em>
and <em>Measured</em> values, hence the gain correction.
</p>
<p>
The maximum <em>Delta</em> value is the Gain correction to apply to fit
all the Target values.
</p>
<p>
Ardour shows, under the parameters, a summary of the calculation :
</p>
<ul>
<li><dfn>Gain to normalize:</dfn> is the max <em>Delta</em> value</li>
<li><dfn>Previous output gain:</dfn> is the current Master track gain</li>
<li><dfn>Total Gain:</dfn> is the difference between these two values,
hence the correction to apply</li>
</ul>
<h2>Presets</h2>
<p>
A selection of presets is offered to simplify the normalization. These
presets apply the relevant parameters and their target values. Below
is a table of these presets:
</p>
<table>
<thead>
<tr><th>Parameter name: </th><th>dbFS </th><th>dBTP </th><th>LUFS </th><th>short</th><th>mom. </th><th>FS</th><th>TP </th><th>int</th><th>sht </th><th>mom</th><th>maxIntg</th><th>notes</th></tr>
</thead>
<tbody>
<tr><th>EBU R128 </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-23</td><td> 0</td><td> 0</td><td>-22.5</td><td> -23.5</td></tr>
<tr><th>EBU R128 S1 </th><td>false</td><td> true</td><td> true</td><td> true</td><td>false</td><td> 0</td><td>-1.0</td><td>-23</td><td>-18</td><td> 0</td><td>-22.5</td><td> -23.5</td></tr>
<tr><th>ATSC A/85 </th><td>false</td><td> true</td><td> true</td><td> true</td><td>false</td><td> 0</td><td>-2.0</td><td>-24</td><td> 0</td><td> 0</td><td>-22.0</td><td> -26.0</td></tr>
<tr><th>AES Streaming </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-18</td><td> 0</td><td> 0</td><td>-16.0</td><td> -20.0</td></tr>
<tr><th>ASWG-R001 HOME </th><td>false</td><td> true</td><td> true</td><td> true</td><td>false</td><td> 0</td><td>-1.0</td><td>-24</td><td> 0</td><td> 0</td><td>-22.0</td><td> -26.0</td></tr>
<tr><th>Digital Peak </th><td> true</td><td>false</td><td>false</td><td>false</td><td>false</td><td> 0</td><td> 0.0</td><td> 0</td><td> 0</td><td> 0</td><td> 0.0</td><td>-200.0</td></tr>
<tr><th>CD/DVD </th><td> true</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-0.1</td><td> -9</td><td> 0</td><td> 0</td><td> 0.0</td><td>-200.0</td></tr>
<tr><th>Amazon Music </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-2.0</td><td>-14</td><td> 0</td><td> 0</td><td> -9.0</td><td> -19.0</td></tr>
<tr><th>Apple Music </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-16</td><td> 0</td><td> 0</td><td>-15.0</td><td> -17.0</td></tr>
<tr><th>Deezer </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-15</td><td> 0</td><td> 0</td><td>-14.0</td><td> -16.0</td></tr>
<tr><th>Soundcloud </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-10</td><td> 0</td><td> 0</td><td> -8.0</td><td> -13.0</td></tr>
<tr><th>Spotify </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-14</td><td> 0</td><td> 0</td><td> -8.0</td><td> -20.0</td></tr>
<tr><th>Spotify Loud </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-2.0</td><td>-11</td><td> 0</td><td> 0</td><td> -5.0</td><td> -17.0</td></tr>
<tr><th>Youtube </th><td>false</td><td> true</td><td> true</td><td>false</td><td>false</td><td> 0</td><td>-1.0</td><td>-14</td><td> 0</td><td> 0</td><td>-13.0</td><td> -15.0</td></tr>
</tbody>
</table>
<p>
New presets can be created at will and saved/removed using the <kbd>Save</kbd>
and <kbd>Remove</kbd> buttons next to the preset choice. The Standard
presets listed above can not be removed or edited.
</p>
<p>
The <kbd>Analysis Report</kbd> button allows to visually represent
the analysis with a graph in a very similar window to the one in the
Post-<a href="@@export-dialog">Export</a> analysis.
</p>
<h2>The Conformity Analysis Panel</h2>
<p>
At the lower right end of the window is a <em>Conformity Analysis</em>
info panel indicating, for each of the presets above, if the corrected
gain would fit the required values:
</p>
<ul>
<li><span style="color:red;">&#10006;</span>: the signal is too loud</li>
<li><span style="color:orange;">&#10004;</span>: the signal is too quiet, but satisfies the max. loudness spec</li>
<li><span style="color:green;">&#10004;</span>: signal loudness is within the spec.</li>
</ul>
<p>
Lastly, the gain correction is, by default, applied after all the processors
of the master bus. This can also be changed, either by checking the
<kbd>Custom Amplifier Position</kbd> temporaty button in this window, or in the Master
strip, by <kbd class="mouse">Right</kbd>-clicking the gain slider and
checking <kbd class="option">Custom LAN Amp Position</kbd>. The gain
normalizer then becomes a processor in the processors box of the Master
strip, that can be moved as needed like any processor/effect.
</p>