PulseAudio: fix microphone example

example/microphone.c

@@ -61,6 +61,7 @@ static void read_callback(struct SoundIoInStream *instream, int available_frame_
     int write_count = min_int(available_frame_count, free_count);
     int frames_left = write_count;
 
+
     for (;;) {
         int frame_count = frames_left;
 
@@ -115,6 +116,9 @@ static void write_callback(struct SoundIoOutStream *outstream, int requested_fra
     for (;;) {
         int frame_count = frames_left;
 
+        if (frame_count <= 0)
+            break;
+
         if ((err = soundio_outstream_begin_write(outstream, &areas, &frame_count)))
             panic("begin write error: %s", soundio_strerror(err));
 
@@ -133,9 +137,6 @@ static void write_callback(struct SoundIoOutStream *outstream, int requested_fra
             panic("end write error: %s", soundio_strerror(err));
 
         frames_left -= frame_count;
-
-        if (frames_left <= 0)
-            break;
     }
 
     soundio_ring_buffer_advance_read_ptr(ring_buffer, read_frames * outstream->bytes_per_frame);
@@ -289,6 +290,7 @@ int main(int argc, char **argv) {
     outstream->period_duration = 0.1;
     outstream->write_callback = write_callback;
     outstream->underflow_callback = underflow_callback;
+    outstream->prebuf_duration = 0.0;
 
     if ((err = soundio_outstream_open(outstream)))
         panic("unable to open output stream: %s", soundio_strerror(err));
@@ -297,6 +299,10 @@ int main(int argc, char **argv) {
     ring_buffer = soundio_ring_buffer_create(soundio, capacity);
     if (!ring_buffer)
         panic("unable to create ring buffer: out of memory");
+    char *buf = soundio_ring_buffer_write_ptr(ring_buffer);
+    int fill_count = 0.2 * outstream->sample_rate * outstream->bytes_per_frame;
+    memset(buf, 0, fill_count);
+    soundio_ring_buffer_advance_write_ptr(ring_buffer, fill_count);
 
     if ((err = soundio_instream_start(instream)))
         panic("unable to start input device: %s", soundio_strerror(err));

src/pulseaudio.cpp

@@ -698,7 +698,9 @@ static int outstream_begin_write_pa(SoundIoPrivate *si,
     SoundIoOutStream *outstream = &os->pub;
     SoundIoOutStreamPulseAudio *ospa = &os->backend_data.pulseaudio;
     pa_stream *stream = ospa->stream;
+
     size_t byte_count = *frame_count * outstream->bytes_per_frame;
+
     if (pa_stream_begin_write(stream, (void**)&ospa->write_ptr, &byte_count))
         return SoundIoErrorStreaming;
 

src/soundio.cpp

@@ -330,6 +330,7 @@ int soundio_outstream_begin_write(struct SoundIoOutStream *outstream,
     SoundIo *soundio = outstream->device->soundio;
     SoundIoPrivate *si = (SoundIoPrivate *)soundio;
     SoundIoOutStreamPrivate *os = (SoundIoOutStreamPrivate *)outstream;
+    assert(*frame_count > 0);
     return si->outstream_begin_write(si, os, areas, frame_count);
 }
 

src/soundio.h

@@ -368,7 +368,8 @@ struct SoundIoOutStream {
     // Defaults to NULL. Put whatever you want here.
     void *userdata;
     // In this callback, you call `soundio_outstream_begin_write` and
-    // `soundio_outstream_end_write`.
+    // `soundio_outstream_end_write`. `requested_frame_count` will always be
+    // greater than 0.
     void (*write_callback)(struct SoundIoOutStream *, int requested_frame_count);
     // This optional callback happens when the sound device runs out of buffered
     // audio data to play. After this occurs, the outstream waits until the
@@ -631,7 +632,8 @@ int soundio_outstream_start(struct SoundIoOutStream *outstream);
 //  * `areas` - (out) The memory addresses you can write data to. It is OK to
 //     modify the pointers if that helps you iterate.
 //  * `frame_count` - (in/out) Provide the number of frames you want to write.
-//    Returned will be the number of frames you actually can write.
+//    Returned will be the number of frames you actually can write. Must be
+//    greater than 0 frames.
 // It is your responsibility to call this function no more and no fewer than the
 // correct number of times as determined by `requested_frame_count` from
 // `write_callback`. See sine.c for an example.