manual/include/loudness-analyzer.html

<p>
  The Loudness Analyzer and 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-signal_flow">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>