[client] audio: add transport provider interface

Route audio through a provider interface. Connected transports take
priority while SPICE remains the fallback.

Carry explicit sample formats, rates, channel layouts, and source clocks
through playback and recording. Add optional presentation clock feedback
for active synchronization.

client/src/main.c

@@ -58,6 +58,9 @@
 #include "core.h"
 #include "app.h"
 #include "audio.h"
+#if ENABLE_AUDIO
+#include "audio_spice.h"
+#endif
 #include "keybind.h"
 #include "clipboard.h"
 #include "kb.h"
@@ -1025,9 +1028,15 @@ static int renderThread(void * unused)
 
   if (g_state.transport &&
       g_state.transportOps->sessionValid(g_state.transport))
+  {
     lgInput_setTransport(NULL, NULL);
+    lgAudio_setTransport(NULL, NULL);
+  }
   else
+  {
     lgInput_dropTransport();
+    lgAudio_dropTransport();
+  }
 
   core_stopCursorThread();
   core_stopFrameThread();
@@ -1075,7 +1084,10 @@ int main_cursorThread(void * unused)
       }
 
       if (status == LG_TRANSPORT_DISCONNECTED)
+      {
         lgInput_dropTransport();
+        lgAudio_dropTransport();
+      }
       app_setState(status == LG_TRANSPORT_DISCONNECTED ?
         APP_STATE_RESTART : APP_STATE_SHUTDOWN);
       if (status != LG_TRANSPORT_DISCONNECTED)
@@ -1216,6 +1228,7 @@ int main_frameThread(void * unused)
       if (status == LG_TRANSPORT_DISCONNECTED)
       {
         lgInput_dropTransport();
+        lgAudio_dropTransport();
         app_setState(APP_STATE_RESTART);
       }
       else if (status == LG_TRANSPORT_END)
@@ -1503,6 +1516,13 @@ void spiceReady(void)
   atomic_store_explicit(&g_state.spiceReady, true, memory_order_release);
   if (g_params.useSpiceInput)
     lgInput_setFallback(&LGI_Spice, NULL);
+#if ENABLE_AUDIO
+  if (g_params.useSpiceAudio)
+  {
+    lgaSpice_setAvailable(true);
+    lgAudio_setFallback(&LGA_Spice, NULL);
+  }
+#endif
 
   if (atomic_load_explicit(&g_state.spiceDisplayRequested,
         memory_order_acquire))
@@ -1687,9 +1707,6 @@ static void spice_setCursorState(bool visible, int x, int y)
 
 int spiceThread(void * arg)
 {
-  if (g_params.useSpiceAudio)
-    audio_init();
-
   const struct PSConfig config =
   {
     .host      = g_params.spiceHost,
@@ -1730,22 +1747,22 @@ int spiceThread(void * arg)
 #if ENABLE_AUDIO
     .playback =
     {
-      .enable      = audio_supportsPlayback(),
+      .enable      = g_params.useSpiceAudio && lgAudio_supportsPlayback(),
       .autoConnect = true,
-      .start       = audio_playbackStart,
-      .volume      = audio_playbackVolume,
-      .mute        = audio_playbackMute,
-      .stop        = audio_playbackStop,
-      .data        = audio_playbackData
+      .start       = lgaSpice_playbackStart,
+      .volume      = lgaSpice_playbackVolume,
+      .mute        = lgaSpice_playbackMute,
+      .stop        = lgaSpice_playbackStop,
+      .data        = lgaSpice_playbackData
     },
     .record =
     {
-      .enable      = audio_supportsRecord(),
+      .enable      = g_params.useSpiceAudio && lgAudio_supportsRecord(),
       .autoConnect = true,
-      .start       = audio_recordStart,
-      .volume      = audio_recordVolume,
-      .mute        = audio_recordMute,
-      .stop        = audio_recordStop
+      .start       = lgaSpice_recordStart,
+      .volume      = lgaSpice_recordVolume,
+      .mute        = lgaSpice_recordMute,
+      .stop        = lgaSpice_recordStop
     }
 #endif
   };
@@ -1770,12 +1787,19 @@ int spiceThread(void * arg)
   }
 
   lgInput_setFallback(NULL, NULL);
+  lgAudio_setFallback(NULL, NULL);
+#if ENABLE_AUDIO
+  lgaSpice_setAvailable(false);
+#endif
   purespice_disconnect();
 
 end:
 
   lgInput_setFallback(NULL, NULL);
-  audio_free();
+  lgAudio_setFallback(NULL, NULL);
+#if ENABLE_AUDIO
+  lgaSpice_setAvailable(false);
+#endif
 
   // if the connection was disconnected intentionally we don't want to shutdown
   // so that the user can see the message box and take action
@@ -1886,6 +1910,7 @@ static int lg_run(void)
   LG_LOCK_INIT(l_cursorRepaint.lock);
   frameTimingInit();
   lgInput_init();
+  lgAudio_init();
 
 #ifdef ENABLE_TESTS
   memset(&l_testCapture, 0, sizeof(l_testCapture));
@@ -2356,6 +2381,11 @@ restart:
     g_state.transportOps->getInputOps(g_state.transport, &inputOpaque) : NULL;
   lgInput_setTransport(inputOps, inputOpaque);
 
+  void              * audioOpaque = NULL;
+  const LG_AudioOps * audioOps    = g_state.transportOps->getAudioOps ?
+    g_state.transportOps->getAudioOps(g_state.transport, &audioOpaque) : NULL;
+  lgAudio_setTransport(audioOps, audioOpaque);
+
   if (inputOps || lgInput_available())
     keybind_inputRegister();
   checkUUID();
@@ -2373,6 +2403,7 @@ restart:
     if (unlikely(!g_state.transportOps->sessionValid(g_state.transport)))
     {
       lgInput_dropTransport();
+      lgAudio_dropTransport();
       atomic_store_explicit(
           &g_state.lgHostConnected, false, memory_order_release);
       DEBUG_INFO("Waiting for the host to restart...");
@@ -2394,6 +2425,7 @@ restart:
     core_stopFrameThread();
     core_stopCursorThread();
     lgInput_dropTransport();
+    lgAudio_dropTransport();
     g_state.transportOps->disconnect(g_state.transport);
 
     app_setState(APP_STATE_RUNNING);
@@ -2440,10 +2472,16 @@ static void lg_shutdown(void)
   if (g_state.transportOps)
   {
     lgInput_dropTransport();
+    if (g_state.transport &&
+        g_state.transportOps->sessionValid(g_state.transport))
+      lgAudio_setTransport(NULL, NULL);
+    else
+      lgAudio_dropTransport();
     g_state.transportOps->destroy(&g_state.transport);
   }
 
   lgInput_free();
+  lgAudio_free();
 
   if (g_state.frameEvent)
   {