Update portaudio to upstream r1885

lib-src/portaudio-v19/qa/loopback/README.txt

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+README for PortAudio Loopback Test
+
+Copyright (c) 1999-2010 Phil Burk and Ross Bencina
+See complete license at end of file.
+
+This folder contains code for a single executable that does a standalone test of PortAudio.
+It does not require a human to listen to the result. Instead it listens to itself using
+a loopback cable connected between the audio output and the audio input. Special pop detectors
+and phase analysers can detect errors in the audio stream.
+
+This test can be run from a script as part of a nightly build and test.
+
+--- How to Build the Loopback Test ---
+
+The loopback test is not normally built by the makefile.
+To build the loopback test, enter:
+
+  ./configure && make loopback
+  
+This will build the "bin/paloopback" executable.
+  
+--- How To Run Test ---
+
+Connect stereo cables from one or more output audio devices to audio input devices. 
+The test will scan all the ports and find the cables.
+
+Adjust the volume levels of the hardware so you get a decent signal that will not clip.
+
+Run the test from the command line with the following options:
+
+  -i# Input device ID. Will scan for loopback if not specified.
+  -o# Output device ID. Will scan for loopback if not specified.
+  -r# Sample Rate in Hz. Will use multiple common rates if not specified.
+  -s# Size of callback buffer in frames, framesPerBuffer.
+  -w  Save bad recordings in a WAV file.
+  -dDir  Path for Directory for WAV files. Default is current directory.
+  -m  Just test the DSP Math code and not the audio devices.
+
+If the -w option is set then any tests that fail will save the recording of the broken
+channel in a WAV file. The files will be numbered and shown in the report.
+
+--- ToDo ---
+
+* Add check for harmonic and enharmonic distortion.
+* Measure min/max peak values.
+* Detect DC bias.
+* Test against matrix of devices/APIs and settings.
+* Detect mono vs stereo loopback.
+* More command line options
+   --quick
+   --latency
+   --duration
+* Automated build and test script with cron job.
+* Test on Windows.
+
+
+/*
+ * PortAudio Portable Real-Time Audio Library
+ * Latest Version at: http://www.portaudio.com
+ *
+ * Copyright (c) 1999-2008 Phil Burk and Ross Bencina
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * The text above constitutes the entire PortAudio license; however, 
+ * the PortAudio community also makes the following non-binding requests:
+ *
+ * Any person wishing to distribute modifications to the Software is
+ * requested to send the modifications to the original developer so that
+ * they can be incorporated into the canonical version. It is also 
+ * requested that these non-binding requests be included along with the 
+ * license above.
+ */