sample rate is exposed as a list of min/max pairs

README.md

@@ -249,16 +249,10 @@ view `coverage/index.html` in a browser.
 
 ## Roadmap
 
- 0. ALSA backend for microphone example is broken
- 0. Add some builtin channel layouts from
-    https://developer.apple.com/library/mac/documentation/MusicAudio/Reference/CoreAudioDataTypesRef/#//apple_ref/doc/constant_group/Audio_Channel_Layout_Tags
- 0. Make sure sending bogus device id results in "SoundIoErrorNoSuchDevice" on each backend
- 0. Make sure PulseAudio can handle refresh devices crashing before
-    block_until_have_devices
- 0. CoreAudio exposes a list of min/max pairs of supported sample rates. libsoundio
-    should do the same.
  0. implement WASAPI (Windows) backend, get examples working
  0. implement ASIO (Windows) backend, get examples working
+ 0. Make sure PulseAudio can handle refresh devices crashing before
+    block_until_have_devices
  0. Do we really want `period_duration` in the API?
  0. Integrate into libgroove and test with Groove Basin
  0. clear buffer maybe could take an argument to say how many frames to not clear

example/sio_list_devices.c

@@ -50,8 +50,12 @@ static void print_device(struct SoundIoDevice *device, bool is_default) {
             fprintf(stderr, "\n");
         }
 
-        fprintf(stderr, "  min sample rate: %d\n", device->sample_rate_min);
+        fprintf(stderr, "  sample rates:\n");
-        fprintf(stderr, "  max sample rate: %d\n", device->sample_rate_max);
+        for (int i = 0; i < device->sample_rate_count; i += 1) {
+            struct SoundIoSampleRateRange *range = &device->sample_rates[i];
+            fprintf(stderr, "    %d - %d\n", range->min, range->max);
+
+        }
         if (device->sample_rate_current)
             fprintf(stderr, "  current sample rate: %d\n", device->sample_rate_current);
         fprintf(stderr, "  formats: ");

example/sio_microphone.c

@@ -39,6 +39,14 @@ static enum SoundIoFormat prioritized_formats[] = {
     SoundIoFormatInvalid,
 };
 
+static int prioritized_sample_rates[] = {
+    48000,
+    44100,
+    96000,
+    24000,
+    0,
+};
+
 
 __attribute__ ((cold))
 __attribute__ ((noreturn))
@@ -274,11 +282,15 @@ int main(int argc, char **argv) {
     if (!layout)
         panic("channel layouts not compatible");
 
-
+    int *sample_rate;
-    int sample_rate = 48000;
+    for (sample_rate = prioritized_sample_rates; *sample_rate; sample_rate += 1) {
-    if (in_device->sample_rate_max < sample_rate) sample_rate = in_device->sample_rate_max;
+        if (soundio_device_supports_sample_rate(in_device, *sample_rate) &&
-    if (out_device->sample_rate_max < sample_rate) sample_rate = out_device->sample_rate_max;
+            soundio_device_supports_sample_rate(out_device, *sample_rate))
-    if (in_device->sample_rate_min > sample_rate || out_device->sample_rate_min > sample_rate)
+        {
+            break;
+        }
+    }
+    if (!*sample_rate)
         panic("incompatible sample rates");
 
     enum SoundIoFormat *fmt;
@@ -296,7 +308,7 @@ int main(int argc, char **argv) {
     if (!instream)
         panic("out of memory");
     instream->format = *fmt;
-    instream->sample_rate = sample_rate;
+    instream->sample_rate = *sample_rate;
     instream->layout = *layout;
     instream->period_duration = microphone_latency / 4.0;
     instream->read_callback = read_callback;
@@ -308,7 +320,7 @@ int main(int argc, char **argv) {
     if (!outstream)
         panic("out of memory");
     outstream->format = *fmt;
-    outstream->sample_rate = sample_rate;
+    outstream->sample_rate = *sample_rate;
     outstream->layout = *layout;
     outstream->buffer_duration = microphone_latency;
     outstream->write_callback = write_callback;

soundio/soundio.h

@@ -238,7 +238,13 @@ struct SoundIoChannelLayout {
     enum SoundIoChannelId channels[SOUNDIO_MAX_CHANNELS];
 };
 
-// The size of this struct is not part of the API or ABI.
+// The size of this struct is OK to use.
+struct SoundIoSampleRateRange {
+    int min;
+    int max;
+};
+
+// The size of this struct is OK to use.
 struct SoundIoChannelArea {
     // Base address of buffer.
     char *ptr;
@@ -336,10 +342,11 @@ struct SoundIoDevice {
     // Sample rate is the number of frames per second.
     // Sample rate is handled very similar to sample format; see those docs.
     // If sample rate information is missing due to a probe error, the field
-    // will be set to zero.
+    // will be set to 0 or NULL.
-    // Devices are guaranteed to have at least 1 sample rate available.
+    // Devices which have `probe_error` set to `SoundIoErrorNone` are
-    int sample_rate_min;
+    // guaranteed to have at least 1 sample rate available.
-    int sample_rate_max;
+    struct SoundIoSampleRateRange *sample_rates;
+    int sample_rate_count;
     int sample_rate_current;
 
     // Buffer duration in seconds. If `buffer_duration_current` is unknown or
@@ -705,6 +712,16 @@ bool soundio_device_supports_format(struct SoundIoDevice *device,
 bool soundio_device_supports_layout(struct SoundIoDevice *device,
         const struct SoundIoChannelLayout *layout);
 
+// Convenience function. Returns whether `sample_rate` is included in the
+// device's supported sample rates.
+bool soundio_device_supports_sample_rate(struct SoundIoDevice *device,
+        int sample_rate);
+
+// Convenience function. Returns the available sample rate nearest to
+// `sample_rate`, rounding up.
+int soundio_device_nearest_sample_rate(struct SoundIoDevice *device,
+        int sample_rate);
+
 
 
 // Output Streams

src/alsa.cpp

@@ -252,6 +252,7 @@ static int set_access(snd_pcm_t *handle, snd_pcm_hw_params_t *hwparams, snd_pcm_
 static int probe_open_device(SoundIoDevice *device, snd_pcm_t *handle, int resample,
         int *out_channels_min, int *out_channels_max)
 {
+    SoundIoDevicePrivate *dev = (SoundIoDevicePrivate *)device;
     int err;
 
     snd_pcm_hw_params_t *hwparams;
@@ -286,8 +287,10 @@ static int probe_open_device(SoundIoDevice *device, snd_pcm_t *handle, int resam
     if ((err = snd_pcm_hw_params_set_rate_last(handle, hwparams, &rate_max, nullptr)) < 0)
         return SoundIoErrorOpeningDevice;
 
-    device->sample_rate_min = rate_min;
+    device->sample_rate_count = 1;
-    device->sample_rate_max = rate_max;
+    device->sample_rates = &dev->prealloc_sample_rate_range;
+    device->sample_rates[0].min = rate_min;
+    device->sample_rates[0].max = rate_max;
 
     double one_over_actual_rate = 1.0 / (double)rate_max;
 
@@ -437,8 +440,8 @@ static int probe_device(SoundIoDevice *device, snd_pcm_chmap_query_t **maps) {
     maps = nullptr;
 
     if (!device->is_raw) {
-        if (device->sample_rate_min == device->sample_rate_max)
+        if (device->sample_rates[0].min == device->sample_rates[0].max)
-            device->sample_rate_current = device->sample_rate_min;
+            device->sample_rate_current = device->sample_rates[0].min;
 
         if (device->buffer_duration_min == device->buffer_duration_max)
             device->buffer_duration_current = device->buffer_duration_min;

src/coreaudio.cpp

@@ -642,6 +642,14 @@ static int refresh_devices(struct SoundIoPrivate *si) {
             }
             rd.device->sample_rate_current = (int)floored_value;
 
+            // If you try to open an input stream with anything but the current
+            // nominal sample rate, AudioUnitRender returns an error.
+            if (aim == SoundIoDeviceAimInput) {
+                device->sample_rate_count = 1;
+                device->sample_rates = &dev->prealloc_sample_rate_range;
+                device->sample_rates[0].min = rd.device->sample_rate_current;
+                device->sample_rates[0].max = rd.device->sample_rate_current;
+            } else {
                 prop_address.mSelector = kAudioDevicePropertyAvailableNominalSampleRates;
                 prop_address.mScope = aim_to_scope(aim);
                 prop_address.mElement = kAudioObjectPropertyElementMaster;
@@ -666,20 +674,26 @@ static int refresh_devices(struct SoundIoPrivate *si) {
                     return SoundIoErrorOpeningDevice;
                 }
 
+                if (avr_array_len == 1) {
+                    device->sample_rate_count = 1;
+                    device->sample_rates = &dev->prealloc_sample_rate_range;
+                    device->sample_rates[0].min = ceil(avr->mMinimum);
+                    device->sample_rates[0].max = floor(avr->mMaximum);
+                } else {
+                    device->sample_rate_count = avr_array_len;
+                    device->sample_rates = allocate<SoundIoSampleRateRange>(avr_array_len);
+                    if (!device->sample_rates) {
+                        deinit_refresh_devices(&rd);
+                        return SoundIoErrorNoMem;
+                    }
                     for (int i = 0; i < avr_array_len; i += 1) {
                         AudioValueRange *avr = &rd.avr_array[i];
                         int min_val = ceil(avr->mMinimum);
                         int max_val = floor(avr->mMaximum);
-                if (rd.device->sample_rate_min == 0 || min_val < rd.device->sample_rate_min)
+                        device->sample_rates[i].min = min_val;
-                    rd.device->sample_rate_min = min_val;
+                        device->sample_rates[i].max = max_val;
-                if (rd.device->sample_rate_max == 0 || max_val > rd.device->sample_rate_max)
+                    }
-                    rd.device->sample_rate_max = max_val;
                 }
-            // If you try to open an input stream with anything but the current
-            // nominal sample rate, AudioUnitRender returns an error.
-            if (aim == SoundIoDeviceAimInput) {
-                rd.device->sample_rate_min = rd.device->sample_rate_current;
-                rd.device->sample_rate_max = rd.device->sample_rate_current;
             }
 
             prop_address.mSelector = kAudioDevicePropertyBufferFrameSize;

src/dummy.cpp

@@ -363,6 +363,14 @@ static int set_all_device_formats(SoundIoDevice *device) {
     return 0;
 }
 
+static void set_all_device_sample_rates(SoundIoDevice *device) {
+    SoundIoDevicePrivate *dev = (SoundIoDevicePrivate *)device;
+    device->sample_rate_count = 1;
+    device->sample_rates = &dev->prealloc_sample_rate_range;
+    device->sample_rates[0].min = 8000;
+    device->sample_rates[0].max = 5644800;
+}
+
 static int set_all_device_channel_layouts(SoundIoDevice *device) {
     device->layout_count = soundio_channel_layout_builtin_count();
     device->layouts = allocate<SoundIoChannelLayout>(device->layout_count);
@@ -429,12 +437,11 @@ int soundio_dummy_init(SoundIoPrivate *si) {
             destroy_dummy(si);
             return err;
         }
+        set_all_device_sample_rates(device);
 
         device->buffer_duration_min = 0.01;
         device->buffer_duration_max = 4;
         device->buffer_duration_current = 0.1;
-        device->sample_rate_min = 2;
-        device->sample_rate_max = 5644800;
         device->sample_rate_current = 48000;
         device->period_duration_min = 0.01;
         device->period_duration_max = 2;
@@ -479,11 +486,10 @@ int soundio_dummy_init(SoundIoPrivate *si) {
             destroy_dummy(si);
             return err;
         }
+        set_all_device_sample_rates(device);
         device->buffer_duration_min = 0.01;
         device->buffer_duration_max = 4;
         device->buffer_duration_current = 0.1;
-        device->sample_rate_min = 2;
-        device->sample_rate_max = 5644800;
         device->sample_rate_current = 48000;
         device->period_duration_min = 0.01;
         device->period_duration_max = 2;

src/jack.cpp

@@ -192,8 +192,10 @@ static int refresh_devices_bare(SoundIoPrivate *si) {
         device->format_count = 1;
         device->formats = allocate<SoundIoFormat>(1);
         device->current_format = SoundIoFormatFloat32NE;
-        device->sample_rate_min = sij->sample_rate;
+        device->sample_rate_count = 1;
-        device->sample_rate_max = sij->sample_rate;
+        device->sample_rates = &dev->prealloc_sample_rate_range;
+        device->sample_rates[0].min = sij->sample_rate;
+        device->sample_rates[0].max = sij->sample_rate;
         device->sample_rate_current = sij->sample_rate;
         device->period_duration_min = sij->period_size / (double) sij->sample_rate;
         device->period_duration_max = device->period_duration_min;

src/pulseaudio.cpp

@@ -294,8 +294,10 @@ static void sink_info_callback(pa_context *pulse_context, const pa_sink_info *in
         device->sample_rate_current = info->sample_spec.rate;
         // PulseAudio performs resampling, so any value is valid. Let's pick
         // some reasonable min and max values.
-        device->sample_rate_min = min(8000, device->sample_rate_current);
+        device->sample_rate_count = 1;
-        device->sample_rate_max = max(5644800, device->sample_rate_current);
+        device->sample_rates = &dev->prealloc_sample_rate_range;
+        device->sample_rates[0].min = min(8000, device->sample_rate_current);
+        device->sample_rates[0].max = max(5644800, device->sample_rate_current);
 
         device->current_format = from_pulseaudio_format(info->sample_spec);
         // PulseAudio performs sample format conversion, so any PulseAudio
@@ -364,8 +366,10 @@ static void source_info_callback(pa_context *pulse_context, const pa_source_info
         device->sample_rate_current = info->sample_spec.rate;
         // PulseAudio performs resampling, so any value is valid. Let's pick
         // some reasonable min and max values.
-        device->sample_rate_min = min(8000, device->sample_rate_current);
+        device->sample_rate_count = 1;
-        device->sample_rate_max = max(5644800, device->sample_rate_current);
+        device->sample_rates = &dev->prealloc_sample_rate_range;
+        device->sample_rates[0].min = min(8000, device->sample_rate_current);
+        device->sample_rates[0].max = max(5644800, device->sample_rate_current);
 
         device->current_format = from_pulseaudio_format(info->sample_spec);
         // PulseAudio performs sample format conversion, so any PulseAudio

src/soundio.cpp

@@ -368,6 +368,9 @@ void soundio_device_unref(struct SoundIoDevice *device) {
         free(device->formats);
         free(device->layouts);
 
+        if (device->sample_rates != &dev->prealloc_sample_rate_range)
+            free(device->sample_rates);
+
         free(dev);
     }
 }
@@ -451,7 +454,7 @@ int soundio_outstream_open(struct SoundIoOutStream *outstream) {
     }
 
     if (!outstream->sample_rate)
-        outstream->sample_rate = clamp(device->sample_rate_min, 48000, device->sample_rate_max);
+        outstream->sample_rate = soundio_device_nearest_sample_rate(device, 48000);
 
     if (!outstream->name)
         outstream->name = "SoundIoOutStream";
@@ -537,7 +540,7 @@ int soundio_instream_open(struct SoundIoInStream *instream) {
     }
 
     if (!instream->sample_rate)
-        instream->sample_rate = clamp(device->sample_rate_min, 48000, device->sample_rate_max);
+        instream->sample_rate = soundio_device_nearest_sample_rate(device, 48000);
 
     if (!instream->name)
         instream->name = "SoundIoInStream";
@@ -687,3 +690,32 @@ bool soundio_device_supports_layout(struct SoundIoDevice *device,
     }
     return false;
 }
+
+bool soundio_device_supports_sample_rate(struct SoundIoDevice *device, int sample_rate) {
+    for (int i = 0; i < device->sample_rate_count; i += 1) {
+        SoundIoSampleRateRange *range = &device->sample_rates[i];
+        if (sample_rate >= range->min && sample_rate <= range->max)
+            return true;
+    }
+    return false;
+}
+
+int soundio_device_nearest_sample_rate(struct SoundIoDevice *device, int sample_rate) {
+    int best_rate = -1;
+    int best_delta = -1;
+    for (int i = 0; i < device->sample_rate_count; i += 1) {
+        SoundIoSampleRateRange *range = &device->sample_rates[i];
+        if (sample_rate < range->min) {
+            int delta = range->min - sample_rate;
+            if (best_delta == -1 || delta < best_delta) {
+                best_delta = delta;
+                best_rate = range->min;
+            }
+        } else if (best_rate == -1 && sample_rate > range->max) {
+            best_rate = range->max;
+        } else {
+            return sample_rate;
+        }
+    }
+    return best_rate;
+}

src/soundio.hpp

@@ -147,6 +147,7 @@ struct SoundIoDevicePrivate {
     SoundIoDevice pub;
     SoundIoDeviceBackendData backend_data;
     void (*destruct)(SoundIoDevicePrivate *);
+    SoundIoSampleRateRange prealloc_sample_rate_range;
 };
 
 void soundio_destroy_devices_info(struct SoundIoDevicesInfo *devices_info);