Added an audio recording test program

test/Makefile.in

@@ -9,6 +9,7 @@ LIBS	= @LIBS@
 
 TARGETS = \
 	checkkeys$(EXE) \
+	loopbackaudio$(EXE) \
 	loopwave$(EXE) \
 	loopwavequeue$(EXE) \
 	testatomic$(EXE) \
@@ -75,6 +76,9 @@ Makefile: $(srcdir)/Makefile.in
 checkkeys$(EXE): $(srcdir)/checkkeys.c
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
 
+loopbackaudio$(EXE): $(srcdir)/loopbackaudio.c
+	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+
 loopwave$(EXE): $(srcdir)/loopwave.c
 	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
 

test/README

@@ -2,6 +2,7 @@
 These are test programs for the SDL library:
 
 	checkkeys	Watch the key events to check the keyboard
+	loopbackaudio	Audio test -- record from the microphone and play it back immediately
 	loopwave	Audio test -- loop playing a WAV file
 	loopwavequeue	Audio test -- loop playing a WAV file with SDL_QueueAudio
 	testaudioinfo	Lists audio device capabilities

test/loopbackaudio.c

@@ -0,0 +1,166 @@
+/*
+  Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely.
+*/
+
+/* Program to record audio from the microphone and play it back immediately */
+
+#include "SDL_config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#if HAVE_SIGNAL_H
+#include <signal.h>
+#endif
+
+#ifdef __EMSCRIPTEN__
+#include <emscripten/emscripten.h>
+#endif
+
+#include "SDL.h"
+
+static SDL_AudioDeviceID device;
+static SDL_AudioDeviceID capture;
+
+static void SDLCALL
+fillerup(void *unused, Uint8 * stream, int len)
+{
+	SDL_QueueAudio(device, stream, len);
+}
+
+/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
+static void
+quit(int rc)
+{
+    SDL_Quit();
+    exit(rc);
+}
+
+static void
+close_audio()
+{
+    if (capture != 0) {
+        SDL_CloseAudioDevice(capture);
+        capture = 0;
+    }
+    if (device != 0) {
+        SDL_CloseAudioDevice(device);
+        device = 0;
+    }
+}
+
+static void
+open_audio()
+{
+    SDL_AudioSpec spec;
+
+    SDL_zero(spec);
+    spec.freq = 44100;
+    spec.format = AUDIO_S16;
+    spec.channels = 1;
+    spec.samples = 1024;
+    spec.callback = fillerup;
+
+	capture = SDL_OpenAudioDevice(NULL, SDL_TRUE, &spec, &spec, SDL_AUDIO_ALLOW_ANY_CHANGE);
+	if (!capture) {
+		SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't open microphone: %s\n", SDL_GetError());
+		quit(2);
+	}
+
+	spec.callback = NULL;
+
+	device = SDL_OpenAudioDevice(NULL, SDL_FALSE, &spec, NULL, 0);
+    if (!device) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't open audio: %s\n", SDL_GetError());
+        quit(2);
+    }
+
+	/* Let the audio run */
+	SDL_PauseAudioDevice(capture, SDL_FALSE);
+    SDL_PauseAudioDevice(device, SDL_FALSE);
+}
+
+static void reopen_audio()
+{
+    close_audio();
+    open_audio();
+}
+
+
+static int done = 0;
+void
+poked(int sig)
+{
+    done = 1;
+}
+
+#ifdef __EMSCRIPTEN__
+void
+loop()
+{
+    if(done || (SDL_GetAudioDeviceStatus(capture) != SDL_AUDIO_PLAYING) || (SDL_GetAudioDeviceStatus(device) != SDL_AUDIO_PLAYING))
+        emscripten_cancel_main_loop();
+}
+#endif
+
+int
+main(int argc, char *argv[])
+{
+    int i;
+
+    /* Enable standard application logging */
+    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
+
+    /* Load the SDL library */
+    if (SDL_Init(SDL_INIT_AUDIO|SDL_INIT_EVENTS) < 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
+        return (1);
+    }
+
+    /* Show the list of available drivers */
+    SDL_Log("Available audio drivers:");
+    for (i = 0; i < SDL_GetNumAudioDrivers(); ++i) {
+        SDL_Log("%i: %s", i, SDL_GetAudioDriver(i));
+    }
+
+    SDL_Log("Using audio driver: %s\n", SDL_GetCurrentAudioDriver());
+
+    open_audio();
+
+    SDL_FlushEvents(SDL_AUDIODEVICEADDED, SDL_AUDIODEVICEREMOVED);
+
+#ifdef __EMSCRIPTEN__
+    emscripten_set_main_loop(loop, 0, 1);
+#else
+    while (!done) {
+        SDL_Event event;
+
+        while (SDL_PollEvent(&event) > 0) {
+            if (event.type == SDL_QUIT) {
+                done = 1;
+            }
+            if (event.type == SDL_AUDIODEVICEADDED ||
+                (event.type == SDL_AUDIODEVICEREMOVED && event.adevice.iscapture && event.adevice.which == capture) ||
+                (event.type == SDL_AUDIODEVICEREMOVED && !event.adevice.iscapture && event.adevice.which == device)) {
+                reopen_audio();
+            }
+        }
+        SDL_Delay(100);
+    }
+#endif
+
+    /* Clean up on signal */
+    close_audio();
+    SDL_Quit();
+    return (0);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */