DOC: show how to set the Pd path (#364)

Author: mgeier

doc/manual/images/src/hrirs_fabian_min_phase_eq.wav

@@ -0,0 +1 @@
+../../../../data/impulse_responses/hrirs/hrirs_fabian_min_phase_eq.wav

doc/manual/images/src/ssr_binaural_pd.pd

@@ -0,0 +1,24 @@
+#N canvas 634 36 431 229 12;
+#X declare -path ssr;
+#X obj 9 16 declare -path ssr;
+#X obj 17 155 ssr_binaural~ 2 hrirs_fabian_min_phase_eq.wav;
+#X obj 18 187 dac~;
+#X text 142 190 SOFA files can also be used!;
+#X obj 358 106 *~ 0.1;
+#X obj 359 82 noise~;
+#X obj 289 82 osc~ 440;
+#X obj 289 106 *~ 0.2;
+#X msg 35 53 src 1 pos -2 0;
+#X msg 36 83 src 1 pos -1 3;
+#X msg 156 53 src 2 pos 2 0;
+#X msg 157 83 src 2 pos 1 3;
+#X connect 1 0 2 0;
+#X connect 1 1 2 1;
+#X connect 4 0 1 1;
+#X connect 5 0 4 0;
+#X connect 6 0 7 0;
+#X connect 7 0 1 0;
+#X connect 8 0 1 0;
+#X connect 9 0 1 0;
+#X connect 10 0 1 0;
+#X connect 11 0 1 0;

doc/manual/images/ssr_binaural_pd.png

@@ -33,12 +33,20 @@ SSR in Pure Data
 ^^^^^^^^^^^^^^^^
 
 The SSR renderers are available as externals in `Pure Data <https://puredata
-.info/>`_. Install them in Pd via Help -> Find externals, then search for
+.info/>`_ (Pd). Install them in Pd via
+:menuselection:`Help --> Find externals`,
+then search for
 'ssr'. This is available on both Linux and macOS, whereby the macOS version
 for Macs with Apple silicon is experimental. If this one does not work for you,
 use Pd for Intel processors with
 `Rosetta <https://en.wikipedia.org/wiki/Rosetta_(software)>`_.
 
+Each renderer is available as a separate external, namely
+``ssr_binaural~``, ``ssr_brs~``, ``ssr_dca~``,
+``ssr_aap~``, ``ssr_wfs~`` and ``ssr_vbap~``.
+The externals have to be added to Pure Data's path,
+for example by creating an object ``[declare -path ssr]`` in your patch.
+
 Here is a screenshot of what it looks like when using SSR's binaural renderer
 with the minimum-phase EQ'd HRIRs of the FABIAN manikin and 2 virtual sound
 sources in Pd, whereby the signal that feeds source 1 is a sine of 440 Hz, and
@@ -47,6 +55,10 @@ the signal that feeds source 2 is noise:
 .. figure:: images/ssr_binaural_pd.png
    :align: center
 
+The source positions, orientations and many other things
+can be changed by sending messages to the external.
+See the help patch for all available messages.
+
 The computational performance of SSR in Pd is somewhat lower than that of the
 standalone version because we have not got it to work in Pd with internal
 block sizes that are larger than 64. Such short blocks cause filters to be