documentation: add references to RTP Tools' defconfigs

Added examples of using the RTP Tools (`rtpdump`, in particular)
to receive RTP packets and 1) print the data and/or 2) playback
audio content through I2S.

Documentation/guides/simulator.rst

@@ -91,6 +91,8 @@ Compiling
        $
        $ # we're back at the Linux prompt.
 
+.. _simulator_accessing_the_network:
+
 Accessing the Network
 ---------------------
 

Documentation/platforms/sim/sim/boards/sim/index.rst

@@ -1247,6 +1247,40 @@ the returned packet.
 
 See also the 'pktradio' configuration.
 
+rtptools
+--------
+
+**RTP Tools** is a set of small applications that can be used for processing RTP data.
+
+-  ``rtpplay``: playback RTP sessions recorded by ``rtpdump``
+-  ``rtpsend``: generate RTP packets from the textual description, generated by hand or ``rtpdump``
+-  ``rtpdump``: parse and print RTP packets, generating output files suitable for ``rtpplay`` and ``rtpsend``
+-  ``rtptrans``: RTP translator between unicast and multicast networks
+
+This configuration is based on the :ref:`sim:tcpblaster <simulator_accessing_the_network>` and
+builds the ``rtpdump``. This application is able to receive RTP packets and print the contents.
+As a real-world application, one could write the received content to a FIFO and play it with
+``nxplayer``.
+
+To build it, follow the instructions for :ref:`Accessing the Network <simulator_accessing_the_network>`.
+
+.. tip::
+  One can use ``pulseaudio`` to send RTP packets through the network::
+
+    pactl load-module module-null-sink sink_name=rtp format=s16le channels=2 rate=44100 sink_properties="device.description='RTP'"
+    pactl load-module module-rtp-send source=rtp.monitor format=s16le destination_ip=10.0.1.2 port=46998
+
+  The loaded sink ``RTP`` is used to send PC's audio to the ``10.0.1.2:46998`` address (SIM's IP).
+
+After being able to access the network through the simulator, run::
+
+  nsh> rtpdump -F short /46998 &
+  rtpdump [5:100]
+  nsh> 42949704.930000 1277462397 15308
+  42949704.930000 1277462714 15309
+
+For a real-world application, check :ref:`RTP Tools on ESP32-LyraT board <esp32-lyrat_rtptools>`.
+
 spiffs
 ------
 

Documentation/platforms/xtensa/esp32/boards/esp32-lyrat/index.rst

@@ -499,6 +499,80 @@ To record audio, execute the following commands::
 To play the recorded audio, import the raw data into Audacity and set the encoding to signed
 16-bit PCM, the sample rate to 44.1kHz and the number of channels to 2.
 
+.. _esp32-lyrat_rtptools:
+
+rtptools
+--------
+
+**RTP Tools** is a set of small applications that can be used for processing RTP data.
+
+-  ``rtpplay``: play back RTP sessions recorded by ``rtpdump``
+-  ``rtpsend``: generate RTP packets from the textual description, generated by hand or ``rtpdump``
+-  ``rtpdump``: parse and print RTP packets, generating output files suitable for ``rtpplay`` and ``rtpsend``
+-  ``rtptrans``: RTP translator between unicast and multicast networks
+
+This application is able to receive RTP packets and write the content to a FIFO. ``nxplayer`` then reads
+from the FIFO, enabling using NuttX as a RTP receiver for audio applications.
+
+This is particularly useful to stream uncompressed audio through Wi-Fi to remote speakers.
+
+**Connect to your Network**
+
+Connect the ESP32-LyraT board to your network in order to be able to receive RTP packets::
+
+    nsh> wapi psk wlan0 mypasswd 3
+    nsh> wapi essid wlan0 myssid 1
+    nsh> renew wlan0
+    nsh> ifconfig
+    wlan0   Link encap:Ethernet HWaddr aa:bb:cc:dd:ff:ee at RUNNING mtu 1504
+            inet addr:192.168.1.38 DRaddr:192.168.1.1 Mask:255.255.255.0
+
+                IPv4   TCP   UDP  ICMP
+    Received     00d5  0000  00d4  0000
+    Dropped      0001  0000  0000  0000
+    IPv4        VHL: 0000   Frg: 0000
+    Checksum   0000  0000  0000  ----
+    TCP         ACK: 0000   SYN: 0000
+                RST: 0000  0000
+    Type       0000  ----  ----  0000
+    Sent         0002  0000  0002  0000
+    Rexmit     ----  0000  ----  ----
+
+Please, check your device's IP (``192.168.1.38`` in this example):
+RTP packets will be sent to it.
+
+**Sending Audio through pulseaudio**
+
+``pulseaudio`` is able to send RTP packets through the network::
+
+    pactl load-module module-null-sink sink_name=rtp format=s16be channels=2 rate=44100 sink_properties="device.description='RTP'"
+    pactl load-module module-rtp-send source=rtp.monitor format=s16le destination_ip=192.168.1.38 port=46998
+
+The loaded sink is used to send PC audio through RTP, using the ``192.168.1.38:46998``
+(boards's IP in this example, please adjust accordingly).
+
+**Receiving the RTP packets**
+
+RTP packets will be written to a FIFO: create the FIFO and run ``rtpdump``
+on background::
+
+    nsh> mkfifo temp
+    nsh> rtpdump -F payload -o temp /46998 &
+    rtpdump [31:100]
+
+**Playing Audio**
+
+Finally, run ``nxplayer`` to play from the FIFO::
+
+    nsh> nxplayer
+    NxPlayer version 1.05
+    h for commands, q to exit
+
+    nxplayer> playraw temp 2 16 44100
+
+This board contains the ES8388 audio codec. Please attach your headphones to listen to the
+content streamed through the Wi-Fi in CD quality!
+
 wifi
 ----