Try to support > 2 output channels with PulseAudio.

2 files changed, 102 insertions, 4 deletions

diff --git a/RtAudio.cpp b/RtAudio.cpp
index 3e78f75..bea68a8 100644
--- a/RtAudio.cpp
+++ b/RtAudio.cpp
@@ -8436,6 +8436,7 @@ static void *alsaCallbackHandler( void *ptr )
 
 #include <pulse/error.h>
 #include <pulse/simple.h>
+#include <pulse/pulseaudio.h>
 #include <cstdio>
 
 static const unsigned int SUPPORTED_SAMPLERATES[] = { 8000, 16000, 22050, 32000,
@@ -8472,8 +8473,33 @@ unsigned int RtApiPulse::getDeviceCount( void )
   return 1;
 }
 
+void RtApiPulse::sinkInfoCallback(pa_context*, const pa_sink_info* info, int, void* arg)
+{
+  RtApiPulse* api = (RtApiPulse *) arg;
+  if (info) {
+    api->channels_ = info->sample_spec.channels;
+  }
+  pa_threaded_mainloop_signal(api->mainloop_, 0);
+}
+
+void RtApiPulse::contextStateCallback(pa_context* c, void* arg)
+{
+  pa_threaded_mainloop* mainloop = (pa_threaded_mainloop*) arg;
+
+  switch (pa_context_get_state(c)) {
+  case PA_CONTEXT_READY:
+  case PA_CONTEXT_TERMINATED:
+  case PA_CONTEXT_FAILED:
+    pa_threaded_mainloop_signal(mainloop, 0);
+    break;
+  default:
+    break;
+  }
+}
+
 RtAudio::DeviceInfo RtApiPulse::getDeviceInfo( unsigned int /*device*/ )
 {
+  /* Set up some defaults in case we crash and burn */
   RtAudio::DeviceInfo info;
   info.probed = true;
   info.name = "PulseAudio";
@@ -8489,6 +8515,72 @@ RtAudio::DeviceInfo RtApiPulse::getDeviceInfo( unsigned int /*device*/ )
   info.preferredSampleRate = 48000;
   info.nativeFormats = RTAUDIO_SINT16 | RTAUDIO_SINT32 | RTAUDIO_FLOAT32;
 
+  /* Get the number of output channels from pulseaudio.  A simple task, you say?
+     "What is your mainloop?" */
+  mainloop_ = pa_threaded_mainloop_new();
+  if (!mainloop_) {
+    return info;
+  }
+
+  pa_threaded_mainloop_start(mainloop_);
+  pa_threaded_mainloop_lock(mainloop_);
+
+  /* "And what is your context?" */
+  pa_context* context = pa_context_new(pa_threaded_mainloop_get_api(mainloop_), "RtAudio");
+  if (!context) {
+    pa_threaded_mainloop_unlock(mainloop_);
+    pa_threaded_mainloop_stop(mainloop_);
+    pa_threaded_mainloop_free(mainloop_);
+    mainloop_ = 0;
+    return info;
+  }
+
+  pa_context_set_state_callback(context, contextStateCallback, mainloop_);
+
+  pa_context_connect(context, 0, (pa_context_flags_t) 0, 0);
+
+  /* "And what is your favourite colour?" */
+  int connected = 0;
+  pa_context_state_t state = pa_context_get_state(context);
+  for (; !connected; state = pa_context_get_state(context)) {
+    switch (state) {
+    case PA_CONTEXT_READY:
+      connected = 1;
+      continue;
+    case PA_CONTEXT_FAILED:
+    case PA_CONTEXT_TERMINATED:
+      /* Blue! No, I mean red! */
+      pa_threaded_mainloop_unlock(mainloop_);
+      pa_context_disconnect(context);
+      pa_context_unref(context);
+      pa_threaded_mainloop_stop(mainloop_);
+      pa_threaded_mainloop_free(mainloop_);
+      mainloop_ = 0;
+      return info;
+    default:
+      pa_threaded_mainloop_wait(mainloop_);
+      break;
+    }
+  }
+
+  pa_operation* op = pa_context_get_sink_info_by_index(context, 0, sinkInfoCallback, this);
+
+  if (op) {
+    pa_operation_unref(op);
+  }
+
+  pa_threaded_mainloop_wait(mainloop_);
+  pa_threaded_mainloop_unlock(mainloop_);
+
+  pa_context_disconnect(context);
+  pa_context_unref(context);
+
+  pa_threaded_mainloop_stop(mainloop_);
+  pa_threaded_mainloop_free(mainloop_);
+  mainloop_ = 0;
+
+  info.outputChannels = channels_;
+  
   return info;
 }
 
@@ -8763,10 +8855,6 @@ bool RtApiPulse::probeDeviceOpen( unsigned int device, StreamMode mode,
 
   if ( device != 0 ) return false;
   if ( mode != INPUT && mode != OUTPUT ) return false;
-  if ( channels != 1 && channels != 2 ) {
-    errorText_ = "RtApiPulse::probeDeviceOpen: unsupported number of channels.";
-    return false;
-  }
   ss.channels = channels;
 
   if ( firstChannel != 0 ) return false;
diff --git a/RtAudio.h b/RtAudio.h
index d4f9f38..5a19f99 100644
--- a/RtAudio.h
+++ b/RtAudio.h
@@ -1099,15 +1099,25 @@ public:
                         unsigned int firstChannel, unsigned int sampleRate,
                         RtAudioFormat format, unsigned int *bufferSize,
                         RtAudio::StreamOptions *options );
+
+  static void sinkInfoCallback(pa_context* c, const pa_sink_info* info, int eol, void* arg);
+  static void contextStateCallback(pa_context* c, void* arg);
+  pa_threaded_mainloop* mainloop_;
+  int channels_;
 };
 
 #endif
 
 #if defined(__LINUX_PULSE__)
 
+struct pa_context;
+struct pa_sink_info;
+struct pa_threaded_mainloop;
+
 class RtApiPulse: public RtApi
 {
 public:
+  RtApiPulse() : mainloop_(0), channels_(2) {}
   ~RtApiPulse();
   RtAudio::Api getCurrentApi() { return RtAudio::LINUX_PULSE; }
   unsigned int getDeviceCount( void );