Initial audio capturing via virtual pipewire sink

1 files changed, 279 insertions, 0 deletions

diff --git a/audio.c b/audio.c
new file mode 100644
index 0000000..358382a
--- /dev/null
+++ b/audio.c
@@ -0,0 +1,279 @@
+/*
+ * Copyright (C) 2024 Mikhail Burakov. This file is part of streamer.
+ *
+ * streamer 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * streamer 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 streamer.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "audio.h"
+
+#include <errno.h>
+#include <pipewire/pipewire.h>
+#include <spa/param/audio/raw-utils.h>
+#include <spa/utils/result.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "buffer_queue.h"
+#include "toolbox/utils.h"
+
+#define STATUS_OK 0
+#define STATUS_ERR 1
+
+struct AudioContext {
+  const struct AudioContextCallbacks* callbacks;
+  void* user;
+
+  int waker[2];
+  struct BufferQueue* buffer_queue;
+  struct pw_thread_loop* pw_thread_loop;
+  struct pw_stream* pw_stream;
+};
+
+static void WakeClient(const struct AudioContext* audio_context, char status) {
+  if (write(audio_context->waker[1], &status, sizeof(status)) !=
+      sizeof(status)) {
+    // TODO(mburakov): Then what?..
+    abort();
+  }
+}
+
+static void OnStreamStateChanged(void* data, enum pw_stream_state old,
+                                 enum pw_stream_state state,
+                                 const char* error) {
+  (void)data;
+  LOG("Stream state change %s->%s, error is %s", pw_stream_state_as_string(old),
+      pw_stream_state_as_string(state), error);
+}
+
+static void OnStreamParamChanged(void* data, uint32_t id,
+                                 const struct spa_pod* param) {
+  struct AudioContext* audio_context = data;
+  if (param == NULL || id != SPA_PARAM_Format) return;
+
+  struct spa_audio_info audio_info;
+  if (spa_format_parse(param, &audio_info.media_type,
+                       &audio_info.media_subtype) < 0) {
+    LOG("Failed to parse stream format");
+    goto failure;
+  }
+  if (audio_info.media_type != SPA_MEDIA_TYPE_audio ||
+      audio_info.media_subtype != SPA_MEDIA_SUBTYPE_raw) {
+    LOG("Unexpected stream format");
+    goto failure;
+  }
+  if (spa_format_audio_raw_parse(param, &audio_info.info.raw) < 0) {
+    LOG("Faield to parse audio stream format");
+    goto failure;
+  }
+
+  LOG("Capturing rate: %u, channels: %u", audio_info.info.raw.rate,
+      audio_info.info.raw.channels);
+  return;
+
+failure:
+  pw_thread_loop_stop(audio_context->pw_thread_loop);
+  WakeClient(audio_context, STATUS_ERR);
+}
+
+static void OnStreamProcess(void* data) {
+  struct AudioContext* audio_context = data;
+  struct pw_buffer* pw_buffer =
+      pw_stream_dequeue_buffer(audio_context->pw_stream);
+  if (!pw_buffer) {
+    LOG("Failed to dequeue stream buffer");
+    goto failure;
+  }
+
+  for (uint32_t i = 0; i < pw_buffer->buffer->n_datas; i++) {
+    const struct spa_data* spa_data = pw_buffer->buffer->datas + i;
+    const void* buffer = (const uint8_t*)spa_data->data +
+                         spa_data->chunk->offset % spa_data->maxsize;
+    uint32_t size = MIN(spa_data->chunk->size, spa_data->maxsize);
+    struct BufferQueueItem* buffer_queue_item =
+        BufferQueueItemCreate(buffer, size);
+    if (!buffer_queue_item) {
+      LOG("Failed to copy stream buffer");
+      goto failure;
+    }
+    if (!BufferQueueQueue(audio_context->buffer_queue, buffer_queue_item)) {
+      LOG("Failed to queue stream buffer copy");
+      BufferQueueItemDestroy(buffer_queue_item);
+      goto failure;
+    }
+  }
+
+  pw_stream_queue_buffer(audio_context->pw_stream, pw_buffer);
+  WakeClient(audio_context, STATUS_OK);
+  return;
+
+failure:
+  pw_thread_loop_stop(audio_context->pw_thread_loop);
+  WakeClient(audio_context, STATUS_ERR);
+}
+
+struct AudioContext* AudioContextCreate(
+    const struct AudioContextCallbacks* callbacks, void* user) {
+  pw_init(0, NULL);
+  struct AudioContext* audio_context = malloc(sizeof(struct AudioContext));
+  if (!audio_context) {
+    LOG("Failed to allocate audio context (%s)", strerror(errno));
+    return NULL;
+  }
+  *audio_context = (struct AudioContext){
+      .callbacks = callbacks,
+      .user = user,
+  };
+
+  if (pipe(audio_context->waker)) {
+    LOG("Failed to create pipe (%s)", strerror(errno));
+    goto rollback_audio_context;
+  }
+
+  audio_context->buffer_queue = BufferQueueCreate();
+  if (!audio_context->buffer_queue) {
+    LOG("Failed to create buffer queue (%s)", strerror(errno));
+    goto rollback_waker;
+  }
+
+  audio_context->pw_thread_loop = pw_thread_loop_new("audio-capture", NULL);
+  if (!audio_context->pw_thread_loop) {
+    LOG("Failed to create pipewire thread loop");
+    goto rollback_buffer_queue;
+  }
+
+  pw_thread_loop_lock(audio_context->pw_thread_loop);
+  int err = pw_thread_loop_start(audio_context->pw_thread_loop);
+  if (err) {
+    LOG("Failed to start pipewire thread loop (%s)", spa_strerror(err));
+    pw_thread_loop_unlock(audio_context->pw_thread_loop);
+    goto rollback_thread_loop;
+  }
+
+  // TOOD(mburakov): Read these from the commandline?
+  struct pw_properties* pw_properties = pw_properties_new(
+#define _(...) __VA_ARGS__
+      _(PW_KEY_AUDIO_FORMAT, "S16LE"), _(PW_KEY_AUDIO_RATE, "48000"),
+      _(PW_KEY_AUDIO_CHANNELS, "2"), _(SPA_KEY_AUDIO_POSITION, "[ FL FR ]"),
+      _(PW_KEY_NODE_NAME, "streamer-sink"), _(PW_KEY_NODE_VIRTUAL, "true"),
+      _(PW_KEY_MEDIA_CLASS, "Audio/Sink"), NULL
+#undef _
+  );
+  if (!pw_properties) {
+    LOG("Failed to create pipewire properties");
+    pw_thread_loop_unlock(audio_context->pw_thread_loop);
+    goto rollback_thread_loop;
+  }
+
+  static const struct pw_stream_events kPwStreamEvents = {
+      .version = PW_VERSION_STREAM_EVENTS,
+      .state_changed = OnStreamStateChanged,
+      .param_changed = OnStreamParamChanged,
+      .process = OnStreamProcess,
+  };
+  audio_context->pw_stream = pw_stream_new_simple(
+      pw_thread_loop_get_loop(audio_context->pw_thread_loop), "audio-capture",
+      pw_properties, &kPwStreamEvents, audio_context);
+  if (!audio_context->pw_stream) {
+    LOG("Failed to create pipewire stream");
+    pw_thread_loop_unlock(audio_context->pw_thread_loop);
+    goto rollback_thread_loop;
+  }
+
+  uint8_t buffer[1024];
+  struct spa_pod_builder spa_pod_builder =
+      SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
+  const struct spa_pod* params[] = {
+      spa_format_audio_raw_build(
+          &spa_pod_builder, SPA_PARAM_EnumFormat,
+          &SPA_AUDIO_INFO_RAW_INIT(.format = SPA_AUDIO_FORMAT_S16_LE,
+                                   .rate = 48000, .channels = 2,
+                                   .position = {SPA_AUDIO_CHANNEL_FL,
+                                                SPA_AUDIO_CHANNEL_FR})),
+  };
+  static const enum pw_stream_flags kPwStreamFlags =
+      PW_STREAM_FLAG_AUTOCONNECT | PW_STREAM_FLAG_MAP_BUFFERS |
+      PW_STREAM_FLAG_RT_PROCESS;
+  if (pw_stream_connect(audio_context->pw_stream, PW_DIRECTION_INPUT, PW_ID_ANY,
+                        kPwStreamFlags, params, LENGTH(params))) {
+    LOG("Failed to connect pipewire stream");
+    pw_stream_destroy(audio_context->pw_stream);
+    pw_thread_loop_unlock(audio_context->pw_thread_loop);
+    goto rollback_thread_loop;
+  }
+
+  pw_thread_loop_unlock(audio_context->pw_thread_loop);
+  return audio_context;
+
+rollback_thread_loop:
+  pw_thread_loop_destroy(audio_context->pw_thread_loop);
+rollback_buffer_queue:
+  BufferQueueDestroy(audio_context->buffer_queue);
+rollback_waker:
+  close(audio_context->waker[1]);
+  close(audio_context->waker[0]);
+rollback_audio_context:
+  free(audio_context);
+  pw_deinit();
+  return NULL;
+}
+
+int AudioContextGetEventsFd(struct AudioContext* audio_context) {
+  return audio_context->waker[0];
+}
+
+bool AudioContextProcessEvents(struct AudioContext* audio_context) {
+  char status;
+  if (read(audio_context->waker[0], &status, sizeof(status)) !=
+      sizeof(status)) {
+    // TODO(mburakov): Then what?..
+    abort();
+  }
+
+  switch (status) {
+    case STATUS_OK:
+      break;
+    case STATUS_ERR:
+      LOG("Error reported from audio thread");
+      return false;
+    default:
+      __builtin_unreachable();
+  }
+
+  for (;;) {
+    struct BufferQueueItem* buffer_queue_item;
+    if (!BufferQueueDequeue(audio_context->buffer_queue, &buffer_queue_item)) {
+      LOG("Failed to dequeue stream buffer copy");
+      return false;
+    }
+    if (!buffer_queue_item) return true;
+    audio_context->callbacks->OnAudioReady(
+        audio_context->user, buffer_queue_item->data, buffer_queue_item->size);
+    BufferQueueItemDestroy(buffer_queue_item);
+  }
+}
+
+void AudioContextDestroy(struct AudioContext* audio_context) {
+  pw_thread_loop_lock(audio_context->pw_thread_loop);
+  pw_stream_destroy(audio_context->pw_stream);
+  pw_thread_loop_unlock(audio_context->pw_thread_loop);
+  pw_thread_loop_destroy(audio_context->pw_thread_loop);
+  BufferQueueDestroy(audio_context->buffer_queue);
+  close(audio_context->waker[1]);
+  close(audio_context->waker[0]);
+  free(audio_context);
+  pw_deinit();
+}