[client] audio: initial addition of PipeWire audio support via SPICE

.github/workflows/build.yml

@@ -44,6 +44,7 @@ jobs:
           -DCMAKE_LINKER:FILEPATH=/usr/bin/ld \
           -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
           -DENABLE_LIBDECOR=${{ matrix.wayland_shell == 'libdecor' }}  \
+          -DENABLE_PIPEWIRE=0 \
           ..
     - name: Build client
       run: |

client/CMakeLists.txt

@@ -51,6 +51,9 @@ add_feature_info(ENABLE_WAYLAND ENABLE_WAYLAND "Wayland support.")
 option(ENABLE_LIBDECOR "Build with libdecor support" OFF)
 add_feature_info(ENABLE_LIBDECOR ENABLE_LIBDECOR "libdecor support.")
 
+option(ENABLE_PIPEWIRE "Build with PipeWire audio output support" ON)
+add_feature_info(ENABLE_PIPEWIRE ENABLE_PIPEWIRE "PipeWire audio support.")
+
 if (NOT ENABLE_X11 AND NOT ENABLE_WAYLAND)
   message(FATAL_ERROR "Either ENABLE_X11 or ENABLE_WAYLAND must be on")
 endif()
@@ -144,6 +147,7 @@ add_subdirectory("${PROJECT_TOP}/repos/cimgui"    "${CMAKE_BINARY_DIR}/cimgui" E
 
 add_subdirectory(displayservers)
 add_subdirectory(renderers)
+add_subdirectory(audiodevs)
 
 add_executable(looking-glass-client ${SOURCES})
 
@@ -158,6 +162,7 @@ target_link_libraries(looking-glass-client
 	purespice
 	renderers
 	cimgui
+	audiodevs
 )
 
 install(TARGETS looking-glass-client

client/audiodevs/CMakeLists.txt

@@ -0,0 +1,43 @@
+cmake_minimum_required(VERSION 3.0)
+project(audiodevs LANGUAGES C)
+
+set(AUDIODEV_H "${CMAKE_BINARY_DIR}/include/dynamic/audiodev.h")
+set(AUDIODEV_C "${CMAKE_BINARY_DIR}/src/audiodev.c")
+
+file(WRITE  ${AUDIODEV_H} "#include \"interface/audiodev.h\"\n\n")
+file(APPEND ${AUDIODEV_H} "extern struct LG_AudioDevOps * LG_AudioDevs[];\n\n")
+
+file(WRITE  ${AUDIODEV_C} "#include \"interface/audiodev.h\"\n\n")
+file(APPEND ${AUDIODEV_C} "#include <stddef.h>\n\n")
+
+set(AUDIODEVS "_")
+set(AUDIODEVS_LINK "_")
+function(add_audiodev name)
+  set(AUDIODEVS      "${AUDIODEVS};${name}" PARENT_SCOPE)
+  set(AUDIODEVS_LINK "${AUDIODEVS_LINK};audiodev_${name}" PARENT_SCOPE)
+  add_subdirectory(${name})
+endfunction()
+
+# Add/remove audiodevs here!
+if(ENABLE_PIPEWIRE)
+  add_audiodev(PipeWire)
+endif()
+
+list(REMOVE_AT AUDIODEVS      0)
+list(REMOVE_AT AUDIODEVS_LINK 0)
+
+list(LENGTH AUDIODEVS AUDIODEV_COUNT)
+file(APPEND ${AUDIODEV_H} "#define LG_AUDIODEV_COUNT ${AUDIODEV_COUNT}\n")
+
+foreach(audiodev ${AUDIODEVS})
+  file(APPEND ${AUDIODEV_C} "extern struct LG_AudioDevOps LGAD_${audiodev};\n")
+endforeach()
+
+file(APPEND ${AUDIODEV_C} "\nconst struct LG_AudioDevOps * LG_AudioDevs[] =\n{\n")
+foreach(audiodev ${AUDIODEVS})
+  file(APPEND ${AUDIODEV_C} "  &LGAD_${audiodev},\n")
+endforeach()
+file(APPEND ${AUDIODEV_C} "  NULL\n};")
+
+add_library(audiodevs STATIC ${AUDIODEV_C})
+target_link_libraries(audiodevs ${AUDIODEVS_LINK})

client/audiodevs/PipeWire/CMakeLists.txt

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.0)
+project(audiodev_PipeWire LANGUAGES C)
+
+find_package(PkgConfig)
+pkg_check_modules(AUDIODEV_PipeWire REQUIRED IMPORTED_TARGET
+	libpipewire-0.3
+)
+
+add_library(audiodev_PipeWire STATIC
+	pipewire.c
+)
+
+target_link_libraries(audiodev_PipeWire
+	PkgConfig::AUDIODEV_PipeWire
+	lg_common
+)
+
+target_include_directories(audiodev_PipeWire
+	PRIVATE
+		src
+)

client/audiodevs/PipeWire/pipewire.c

@@ -0,0 +1,220 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "interface/audiodev.h"
+
+#include <spa/param/audio/format-utils.h>
+#include <pipewire/pipewire.h>
+
+#include "common/debug.h"
+#include "common/ringbuffer.h"
+
+struct PipeWire
+{
+  struct pw_loop        * loop;
+  struct pw_thread_loop * thread;
+  struct pw_stream      * stream;
+  int    channels;
+  int    stride;
+
+  RingBuffer buffer;
+};
+
+static struct PipeWire pw = {0};
+
+static void pipewire_on_process(void * userdata)
+{
+  struct pw_buffer * pbuf;
+
+  const int avail = ringbuffer_getCount(pw.buffer);
+  if (!avail)
+    return;
+
+  if (!(pbuf = pw_stream_dequeue_buffer(pw.stream))) {
+    DEBUG_WARN("out of buffers");
+    return;
+  }
+
+  struct spa_buffer * sbuf = pbuf->buffer;
+  uint8_t * dst;
+
+  if (!(dst = sbuf->datas[0].data))
+    return;
+
+  int frames = sbuf->datas[0].maxsize / pw.stride;
+  if (frames > avail)
+    frames = avail;
+
+  for(int i = 0; i < frames; ++i)
+  {
+    ringbuffer_shift(pw.buffer, dst);
+    dst += pw.stride;
+  }
+
+  sbuf->datas[0].chunk->offset = 0;
+  sbuf->datas[0].chunk->stride = pw.stride;
+  sbuf->datas[0].chunk->size   = frames * pw.stride;
+
+  pw_stream_queue_buffer(pw.stream, pbuf);
+}
+
+static bool pipewire_init(void)
+{
+  pw_init(NULL, NULL);
+
+  pw.loop = pw_loop_new(NULL);
+  struct pw_context * context = pw_context_new(pw.loop, NULL, 0);
+  if (!context)
+  {
+    DEBUG_ERROR("Failed to create a context");
+    goto err;
+  }
+
+  /* this is just to test for PipeWire availabillity */
+  struct pw_core * core = pw_context_connect(context, NULL, 0);
+  if (!core)
+    goto err_context;
+
+  pw_context_destroy(context);
+
+  /* PipeWire is available so create the loop thread and start it */
+  pw.thread = pw_thread_loop_new_full(pw.loop, "Playback", NULL);
+  if (!pw.thread)
+  {
+    DEBUG_ERROR("Failed to create the thread loop");
+    goto err;
+  }
+
+  pw_thread_loop_start(pw.thread);
+  return true;
+
+err_context:
+  pw_context_destroy(context);
+
+err:
+  pw_deinit();
+  return false;
+}
+
+static void pipewire_free(void)
+{
+  if (pw.thread)
+  {
+    pw_thread_loop_lock(pw.thread);
+    if (pw.stream)
+    {
+      pw_stream_destroy(pw.stream);
+      pw.stream = NULL;
+    }
+
+    pw_thread_loop_signal(pw.thread, true);
+    pw_thread_loop_destroy(pw.thread);
+    pw.loop = NULL;
+  }
+
+  ringbuffer_free(&pw.buffer);
+  pw_deinit();
+}
+
+static void pipewire_start(int channels, int sampleRate)
+{
+  const struct spa_pod * params[1];
+  uint8_t buffer[1024];
+  struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
+  static const struct pw_stream_events events =
+  {
+    .version = PW_VERSION_STREAM_EVENTS,
+    .process = pipewire_on_process
+  };
+
+  pw.channels = channels;
+  pw.stride   = sizeof(uint16_t) * channels;
+  pw.buffer   = ringbuffer_new(sampleRate, channels * sizeof(uint16_t));
+
+  pw_thread_loop_lock(pw.thread);
+  pw.stream = pw_stream_new_simple(
+    pw.loop,
+    "LookingGlass",
+    pw_properties_new(
+      PW_KEY_MEDIA_TYPE    , "Audio",
+      PW_KEY_MEDIA_CATEGORY, "Playback",
+      PW_KEY_MEDIA_ROLE    , "Music",
+      NULL
+    ),
+    &events,
+    NULL
+  );
+
+  if (!pw.stream)
+  {
+    pw_thread_loop_unlock(pw.thread);
+    DEBUG_ERROR("Failed to create the stream");
+    return;
+  }
+
+  params[0] = spa_format_audio_raw_build(&b, SPA_PARAM_EnumFormat,
+      &SPA_AUDIO_INFO_RAW_INIT(
+        .format   = SPA_AUDIO_FORMAT_S16,
+        .channels = channels,
+        .rate     = sampleRate
+        ));
+
+  pw_stream_connect(
+      pw.stream,
+      PW_DIRECTION_OUTPUT,
+      PW_ID_ANY,
+      PW_STREAM_FLAG_AUTOCONNECT |
+      PW_STREAM_FLAG_MAP_BUFFERS |
+      PW_STREAM_FLAG_RT_PROCESS,
+      params, 1);
+
+  pw_thread_loop_unlock(pw.thread);
+}
+
+static void pipewire_play(uint8_t * data, int size)
+{
+  if (!pw.stream)
+    return;
+
+  for(int i = 0; i < size; i += pw.stride)
+    ringbuffer_push(pw.buffer, data + i);
+}
+
+static void pipewire_stop(void)
+{
+  if (!pw.stream)
+    return;
+
+  pw_thread_loop_lock(pw.thread);
+  pw_stream_flush(pw.stream, true);
+  pw_stream_destroy(pw.stream);
+  pw.stream = NULL;
+  pw_thread_loop_unlock(pw.thread);
+}
+
+struct LG_AudioDevOps LGAD_PipeWire =
+{
+  .name  = "PipeWire",
+  .init  = pipewire_init,
+  .free  = pipewire_free,
+  .start = pipewire_start,
+  .play  = pipewire_play,
+  .stop  = pipewire_stop
+};

client/include/interface/audiodev.h

@@ -0,0 +1,63 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _H_I_AUDIODEV_
+#define _H_I_AUDIODEV_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+struct LG_AudioDevOps
+{
+  /* internal name of the audio for debugging */
+  const char * name;
+
+  /* called very early to allow for option registration, optional */
+  void (*earlyInit)(void);
+
+  /* called to initialize the audio backend */
+  bool (*init)(void);
+
+  /* final free */
+  void (*free)(void);
+
+  /* setup the playback audio stream
+   * Note: currently SPICE only supports S16 samples so always assume so
+   */
+  void (*start)(int channels, int sampleRate);
+
+  /* called for each packet of output audio to play
+   * Note: size is the size of data in bytes, not frames/samples
+   */
+  void (*play)(uint8_t * data, int size);
+
+  /* called when SPICE reports the audio stream has stopped */
+  void (*stop)(void);
+};
+
+#define ASSERT_LG_AUDIODEV_VALID(x) \
+  DEBUG_ASSERT((x)->name  ); \
+  DEBUG_ASSERT((x)->init  ); \
+  DEBUG_ASSERT((x)->free  ); \
+  DEBUG_ASSERT((x)->start ); \
+  DEBUG_ASSERT((x)->play  ); \
+  DEBUG_ASSERT((x)->stop  );
+
+#endif

client/src/config.c

@@ -428,6 +428,13 @@ static struct Option options[] =
     .type           = OPTION_TYPE_BOOL,
     .value.x_bool   = true
   },
+  {
+    .module         = "spice",
+    .name           = "audio",
+    .description    = "Enable SPICE audio support",
+    .type           = OPTION_TYPE_BOOL,
+    .value.x_bool   = true
+  },
   {
     .module         = "spice",
     .name           = "scaleCursor",
@@ -609,6 +616,7 @@ bool config_load(int argc, char * argv[])
 
     g_params.useSpiceInput     = option_get_bool("spice", "input"    );
     g_params.useSpiceClipboard = option_get_bool("spice", "clipboard");
+    g_params.useSpiceAudio     = option_get_bool("spice", "audio"    );
 
     if (g_params.useSpiceClipboard)
     {

client/src/main.c

@@ -846,6 +846,66 @@ static void reportBadVersion()
   DEBUG_ERROR("Please install the matching host application for this client");
 }
 
+void audioStart(int channels, int sampleRate, PSAudioFormat format,
+  uint32_t time)
+{
+  /*
+   * we probe here so that the audiodev is operating in the context of the SPICE
+   * thread/loop to avoid any audio API threading issues
+   */
+  static int probed = false;
+  if (!probed)
+  {
+    probed = true;
+
+    // search for the best audiodev to use
+    for(int i = 0; i < LG_AUDIODEV_COUNT; ++i)
+      if (LG_AudioDevs[i]->init())
+      {
+        g_state.audioDev = LG_AudioDevs[i];
+        DEBUG_INFO("Using AudioDev: %s", g_state.audioDev->name);
+        break;
+      }
+
+    if (!g_state.audioDev)
+      DEBUG_WARN("Failed to initialize an audio backend");
+  }
+
+  if (g_state.audioDev)
+  {
+    static int lastChannels   = 0;
+    static int lastSampleRate = 0;
+
+    if (g_state.audioStarted)
+    {
+      if (channels != lastChannels || sampleRate != lastSampleRate)
+        g_state.audioDev->stop();
+      else
+        return;
+    }
+
+    lastChannels   = channels;
+    lastSampleRate = sampleRate;
+    g_state.audioStarted = true;
+
+    DEBUG_INFO("%d channels @ %dHz", channels, sampleRate);
+    g_state.audioDev->start(channels, sampleRate);
+  }
+}
+
+void audioStop(void)
+{
+  if (g_state.audioDev)
+    g_state.audioDev->stop();
+  g_state.audioStarted = false;
+}
+
+void audioData(uint8_t * data, size_t size)
+{
+  if (g_state.audioDev)
+    g_state.audioDev->play(data, size);
+}
+
 static int lg_run(void)
 {
   g_cursor.sens = g_params.mouseSens;
@@ -921,7 +981,9 @@ static int lg_run(void)
   }
 
   // try to connect to the spice server
-  if (g_params.useSpiceInput || g_params.useSpiceClipboard)
+  if (g_params.useSpiceInput     ||
+      g_params.useSpiceClipboard ||
+      g_params.useSpiceAudio)
   {
     if (g_params.useSpiceClipboard)
       spice_set_clipboard_cb(
@@ -930,7 +992,14 @@ static int lg_run(void)
           cb_spiceRelease,
           cb_spiceRequest);
 
-    if (!spice_connect(g_params.spiceHost, g_params.spicePort, ""))
+    if (g_params.useSpiceAudio)
+      spice_set_audio_cb(
+          audioStart,
+          audioStop,
+          audioData);
+
+    if (!spice_connect(g_params.spiceHost, g_params.spicePort, "",
+          g_params.useSpiceAudio))
     {
       DEBUG_ERROR("Failed to connect to spice server");
       return -1;

client/src/main.h

@@ -24,6 +24,7 @@
 
 #include "dynamic/displayservers.h"
 #include "dynamic/renderers.h"
+#include "dynamic/audiodev.h"
 
 #include "common/thread.h"
 #include "common/types.h"
@@ -133,6 +134,9 @@ struct AppState
   bool     resizeDone;
 
   bool     autoIdleInhibitState;
+
+  struct LG_AudioDevOps * audioDev;
+  bool audioStarted;
 };
 
 struct AppParams
@@ -154,6 +158,7 @@ struct AppParams
   LG_RendererRotate winRotate;
   bool              useSpiceInput;
   bool              useSpiceClipboard;
+  bool              useSpiceAudio;
   const char *      spiceHost;
   unsigned int      spicePort;
   bool              clipboardToVM;

doc/build.rst

@@ -93,6 +93,9 @@ feature is disabled when running :ref:`cmake <client_building>`.
    -  libwayland-dev
    -  wayland-protocols
 
+-  Disable with ``cmake -DENABLE_PIPEWIRE=no ..``
+
+   -  libpipewire-0.3-dev
 
 .. _client_deps_recommended:
 

doc/words.txt

@@ -6,6 +6,7 @@ cmake
 config
 dejavu
 deuteranope
+dev
 dir
 distros
 dmabuf
@@ -19,6 +20,7 @@ ini
 kvmfr
 laggy
 libdecor
+libpipewire
 libvirt
 linux
 LookingGlass