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Document the multi-channel mixers
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h4yn0nnym0u5e committed Feb 20, 2022
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146 changes: 145 additions & 1 deletion gui/index.html
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Expand Up @@ -493,7 +493,11 @@ <h5 id="node-help-label">Keyboard Shortcuts <span style="float: right;"><a href=
{"type":"AudioOutputUSB","data":{"defaults":{"name":{"value":"new"}},"shortName":"usb","inputs":2,"outputs":0,"category":"output-function","color":"#E6E0F8","icon":"arrow-in.png"}},

{"type":"AudioAmplifier","data":{"defaults":{"name":{"value":"new"}},"shortName":"amp","inputs":1,"outputs":1,"category":"mixer-function","color":"#E6E0F8","icon":"arrow-in.png"}},
{"type":"AudioMixer4","data":{"defaults":{"name":{"value":"new"}},"shortName":"mixer","inputs":4,"outputs":1,"category":"mixer-function","color":"#E6E0F8","icon":"arrow-in.png"}},
{"type":"AudioMixer4","data":{"defaults":{"name":{"value":"new"}},"shortName":"mixer4","inputs":4,"outputs":1,"category":"mixer-function","color":"#E6E0F8","icon":"arrow-in.png"}},

{"type":"AudioMixer","data":{"defaults":{"name":{"value":"new"}},"shortName":"mixer","inputs":1,"outputs":1,"category":"mixer-function","color":"#E6E0F8","icon":"arrow-in.png"}},
{"type":"AudioMixerStereo","data":{"defaults":{"name":{"value":"new"}},"shortName":"mixerS","inputs":1,"outputs":2,"category":"mixer-function","color":"#E6E0F8","icon":"arrow-in.png"}},

{"type":"AudioPlayMemory","data":{"defaults":{"name":{"value":"new"}},"shortName":"playMem","inputs":0,"outputs":1,"category":"play-function","color":"#E6E0F8","icon":"arrow-in.png"}},
{"type":"AudioPlaySdWav","data":{"defaults":{"name":{"value":"new"}},"shortName":"playSdWav","inputs":0,"outputs":2,"category":"play-function","color":"#E6E0F8","icon":"arrow-in.png"}},
{"type":"AudioPlaySdRaw","data":{"defaults":{"name":{"value":"new"}},"shortName":"playSdRaw","inputs":0,"outputs":1,"category":"play-function","color":"#E6E0F8","icon":"arrow-in.png"}},
Expand Down Expand Up @@ -2550,6 +2554,7 @@ <h3>Notes</h3>
</div>
</script>

<!-------------------------------------------------------------------------- -->
<script type="text/x-red" data-help-name="AudioMixer4">
<h3>Summary</h3>
<div class=tooltipinfo>
Expand Down Expand Up @@ -2599,6 +2604,145 @@ <h3>Notes</h3>
<input type="text" id="node-input-name" placeholder="Name">
</div>
</script>
<!-------------------------------------------------------------------------- -->


<!-------------------------------------------------------------------------- -->
<script type="text/x-red" data-help-name="AudioMixer">
<h3>Summary</h3>
<div class=tooltipinfo>
<p>Combine up to 255 audio signals together, each with adjustable gain.
All channels support signal attenuation or amplification.</p>
<p> REQUIRES Audio System Design Tool++</p>
<p>In order to add an input, drop the connecting "cable" onto the body of the
mixer, rather than onto an existing input node: a new node will be added
and the connection made to that.
</p>
</div>
<h3>Audio Connections</h3>
<table class=doc align=center cellpadding=3>
<tr class=top><th>Port</th><th>Purpose</th></tr>
<tr class=odd><td align=center>In N</td><td>Input signal #N</td></tr>
<tr class=odd><td align=center>Out 0</td><td>Sum of all inputs</td></tr>
</table>
<h3>Functions</h3>
<p class=func><span class=keyword>gain</span>(channel, level);</p>
<p class=desc>Adjust the amplification or attenuation. "channel" must
be 0 to N-1. "level" may be any floating point number from 0 to 32767.0.
1.0 passes the signal through directly. Level of 0 shuts the channel
off completely. Between 0 to 1.0 attenuates the signal, and above
1.0 amplifies it. Negative numbers may also be used, to invert the
signal. All channels have separate gain settings.
</p>
<p class=func><span class=keyword>gain</span>(level);</p>
<p class=desc>Adjust the amplification or attenuation for all channels at once.
</p>
<p class=func><span class=keyword>setSoftKnee</span>(startPoint);</p>
<p class=desc>Changes the "overload" characteristic of the mixer to provide a
soft roll-off at high amplitude. startPoint should be set to a value between 0.0 and
0.97 to enable this: values outside this range will revert to the original
overload behaviour.<br/><br/>
When the summed amplitude is above the "startPoint" level, it is scaled back using
a quadratic curve so the saturation point is reached more gradually. Because the initial
mixing is done using 32-bit rather than 16-bit accumulation, this can result in
radically different output.
</p>
<p align=center><img src="img/mixer-soft-knee.png"><br><small>Example with triangle wave</small></p>
<h3>Examples</h3>
TBD
</p>
<h3>Notes</h3>
<p>Signal clipping can occur when any channel has gain greater than 1.0,
or when multiple signals add together to greater than 1.0. The "soft knee"
behaviour may be used to smooth the transition.
</p>
</script>
<script type="text/x-red" data-template-name="AudioMixer4">
<div class="form-row">
<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
<input type="text" id="node-input-name" placeholder="Name">
</div>
</script>
<!-------------------------------------------------------------------------- -->

<!-------------------------------------------------------------------------- -->
<script type="text/x-red" data-help-name="AudioMixerStereo">
<h3>Summary</h3>
<div class=tooltipinfo>
<p>Combine up to 255 audio signals together, each with adjustable gain, to
a stereo output.
All channels support signal attenuation or amplification, pan or balance.</p>
<p> REQUIRES Audio System Design Tool++</p>
<p>In order to add an input, drop the connecting "cable" onto the body of the
mixer, rather than onto an existing input node: a new node will be added
and the connection made to that.
</p>
</div>
<h3>Audio Connections</h3>
<table class=doc align=center cellpadding=3>
<tr class=top><th>Port</th><th>Purpose</th></tr>
<tr class=odd><td align=center>In N</td><td>Input signal #N</td></tr>
<tr class=odd><td align=center>Out 0</td><td>Left output channel</td></tr>
<tr class=odd><td align=center>Out 1</td><td>Right output channel</td></tr>
</table>
<h3>Functions</h3>
<p class=func><span class=keyword>gain</span>(channel, level);</p>
<p class=desc>Adjust the amplification or attenuation. "channel" must
be 0 to N-1. "level" may be any floating point number from 0 to 32767.0.
1.0 passes the signal through directly. Level of 0 shuts the channel
off completely. Between 0 to 1.0 attenuates the signal, and above
1.0 amplifies it. Negative numbers may also be used, to invert the
signal. All channels have separate gain settings.
</p>
<p class=func><span class=keyword>gain</span>(level);</p>
<p class=desc>Adjust the amplification or attenuation for all channels at once.
</p>
<p class=func><span class=keyword>setSoftKnee</span>(startPoint);</p>
<p class=desc>Changes the "overload" characteristic of the mixer to provide a
soft roll-off at high amplitude. startPoint should be set to a value between 0.0 and
0.97 to enable this: values outside this range will revert to the original
overload behaviour.<br/><br/>
When the summed amplitude is above the "startPoint" level, it is scaled back using
a quadratic curve so the saturation point is reached more gradually. Because the initial
mixing is done using 32-bit rather than 16-bit accumulation, this can result in
radically different output.
</p>
<p align=center><img src="img/mixer-soft-knee.png"><br><small>Example with triangle wave</small></p>
<p class=func><span class=keyword>pan</span>(channel, position);</p>
<p class=desc>Pan a mono input channel to an apparent position in the stereo field. The
position parameter should be between -1.0 (fully left) and +1.0 (fully right).
<p class=func><span class=keyword>balance</span>(chLeft, chRight, position);</p>
<p class=desc>Balance a pair of input channels within the stereo field. Note that unlike
the pan() control, none of the left channel signal ever appears on the right output, and vice versa.
</p>
<p class=func><span class=keyword>balance</span>(chLeft, position);</p>
<p class=desc>Balance a pair of input channels within the stereo field. The right channel is
taken from the next channel number up from the left channel parameter.
</p>
<p class=func><span class=keyword>setPanLaw</span>(law);</p>
<p class=desc>Changes the mapping between pan position value and the relative (linear) levels
of the left and right outputs. A small "law" value will push a given "position" value wider
in the stereo field. Defaults to 0.22, values between 0.70 and 0.01 seem to give reasonable
results.
<h3>Examples</h3>
TBD
</p>
<h3>Notes</h3>
<p>Signal clipping can occur when any channel has gain greater than 1.0,
or when multiple signals add together to greater than 1.0. The "soft knee"
behaviour may be used to smooth the transition.
</p>
An input channel can either be regarded as a panned mono channel, or
one channel of a balanced stereo pair, but not both at the same time.
</script>
<script type="text/x-red" data-template-name="AudioMixer4">
<div class="form-row">
<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
<input type="text" id="node-input-name" placeholder="Name">
</div>
</script>
<!-------------------------------------------------------------------------- -->


<script type="text/x-red" data-help-name="AudioPlayMemory">
<h3>Summary</h3>
Expand Down

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