diff --git a/example/sine.c b/example/sine.c
index d8cccfc..be9a9e7 100644
--- a/example/sine.c
+++ b/example/sine.c
@@ -25,6 +25,12 @@ static void panic(const char *format, ...) {
     abort();
 }
 
+static int usage(char *exe) {
+    fprintf(stderr, "Usage: %s [--dummy] [--alsa] [--pulseaudio]\n", exe);
+    return 1;
+}
+
+
 static const float PI = 3.1415926535f;
 static float seconds_offset = 0.0f;
 static void write_callback(struct SoundIoOutStream *outstream, int requested_frame_count) {
@@ -69,12 +75,29 @@ static void error_callback(struct SoundIoOutStream *device, int err) {
 }
 
 int main(int argc, char **argv) {
+    char *exe = argv[0];
+    enum SoundIoBackend backend = SoundIoBackendNone;
+    for (int i = 1; i < argc; i += 1) {
+        char *arg = argv[i];
+        if (strcmp("--dummy", arg) == 0) {
+            backend = SoundIoBackendDummy;
+        } else if (strcmp("--alsa", arg) == 0) {
+            backend = SoundIoBackendAlsa;
+        } else if (strcmp("--pulseaudio", arg) == 0) {
+            backend = SoundIoBackendPulseAudio;
+        } else {
+            return usage(exe);
+        }
+    }
+
     struct SoundIo *soundio = soundio_create();
     if (!soundio)
         panic("out of memory");
 
-    int err;
-    if ((err = soundio_connect(soundio)))
+    int err = (backend == SoundIoBackendNone) ?
+        soundio_connect(soundio) : soundio_connect_backend(soundio, backend);
+
+    if (err)
         panic("error connecting: %s", soundio_strerror(err));
 
     int default_out_device_index = soundio_get_default_output_device_index(soundio);
diff --git a/src/dummy.cpp b/src/dummy.cpp
index fa3f7fa..f9854ab 100644
--- a/src/dummy.cpp
+++ b/src/dummy.cpp
@@ -138,7 +138,7 @@ static int outstream_open_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os)
     }
     os->backend_data = osd;
 
-    osd->buffer_size = outstream->bytes_per_frame * outstream->buffer_duration;
+    osd->buffer_size = outstream->bytes_per_frame * outstream->sample_rate * outstream->buffer_duration;
 
     soundio_ring_buffer_init(&osd->ring_buffer, osd->buffer_size);
 
@@ -185,13 +185,19 @@ static int outstream_begin_write_dummy(SoundIoPrivate *si,
     int byte_count = *frame_count * outstream->bytes_per_frame;
     assert(byte_count <= osd->buffer_size);
 
-    char *write_ptr = soundio_ring_buffer_write_ptr(&osd->ring_buffer);
-    for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
-        osd->areas[ch].ptr = write_ptr + outstream->bytes_per_sample * ch;
-        osd->areas[ch].step = outstream->bytes_per_frame;
-    }
+    int free_byte_count = soundio_ring_buffer_free_count(&osd->ring_buffer);
+    int free_frame_count = free_byte_count / outstream->bytes_per_frame;
+    *frame_count = min(*frame_count, free_frame_count);
 
-    *out_areas = osd->areas;
+    if (free_frame_count) {
+        char *write_ptr = soundio_ring_buffer_write_ptr(&osd->ring_buffer);
+        for (int ch = 0; ch < outstream->layout.channel_count; ch += 1) {
+            osd->areas[ch].ptr = write_ptr + outstream->bytes_per_sample * ch;
+            osd->areas[ch].step = outstream->bytes_per_frame;
+        }
+
+        *out_areas = osd->areas;
+    }
     return 0;
 }
 
@@ -319,14 +325,15 @@ int soundio_dummy_init(SoundIoPrivate *si) {
             destroy_dummy(si);
             return SoundIoErrorNoMem;
         }
-        device->layout_count = 1;
-        device->layouts = allocate<SoundIoChannelLayout>(1);
+        device->layout_count = soundio_channel_layout_builtin_count();
+        device->layouts = allocate<SoundIoChannelLayout>(device->layout_count);
         if (!device->layouts) {
             soundio_device_unref(device);
             destroy_dummy(si);
             return SoundIoErrorNoMem;
         }
-        device->layouts[0] = *soundio_channel_layout_get_builtin(SoundIoChannelLayoutIdMono);
+        for (int i = 0; i < device->layout_count; i += 1)
+            device->layouts[i] = *soundio_channel_layout_get_builtin(i);
 
         int err;
         if ((err = set_all_device_formats(device))) {
@@ -371,14 +378,15 @@ int soundio_dummy_init(SoundIoPrivate *si) {
             return SoundIoErrorNoMem;
         }
 
-        device->layout_count = 1;
-        device->layouts = allocate<SoundIoChannelLayout>(1);
+        device->layout_count = soundio_channel_layout_builtin_count();
+        device->layouts = allocate<SoundIoChannelLayout>(device->layout_count);
         if (!device->layouts) {
             soundio_device_unref(device);
             destroy_dummy(si);
             return SoundIoErrorNoMem;
         }
-        device->layouts[0] = *soundio_channel_layout_get_builtin(SoundIoChannelLayoutIdMono);
+        for (int i = 0; i < device->layout_count; i += 1)
+            device->layouts[i] = *soundio_channel_layout_get_builtin(i);
 
         int err;
         if ((err = set_all_device_formats(device))) {