Work on sink

Remove _remove from properties, we can do the same with set of a NULL
value.
Add signals to the stream API to manage the buffers. Wrap those buffers
in a GstBuffer in the pinossrc and pinossink elements and pool them in a
bufferpool.
Remove SPA_EVENT_TYPE_PULL_INPUT, we can do the same with NEED_INPUT and
by using a ringbuffer.
Do more complete allocation of buffers in the link. Use the buffer
allocator if none of the nodes can allocate.
Follow the node state to trigger negotiation and allocation.
Remove offset and size when refering to buffers, we want to always deal
with the complete buffer and use a ringbuffer for ranges or change the
offset/size in the buffer data when needed.
Serialize port_info structures as part of the port_update
Print both the enum number and the name when debuging properties or
formats.

pinos/gst/gstpinospool.c

@@ -0,0 +1,149 @@
+/* GStreamer
+ * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
+ * Boston, MA 02110-1335, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gst/gst.h>
+
+#include "gstpinospool.h"
+
+GST_DEBUG_CATEGORY_STATIC (gst_pinos_pool_debug_category);
+#define GST_CAT_DEFAULT gst_pinos_pool_debug_category
+
+G_DEFINE_TYPE (GstPinosPool, gst_pinos_pool, GST_TYPE_BUFFER_POOL);
+
+GstPinosPool *
+gst_pinos_pool_new (void)
+{
+  GstPinosPool *pool;
+
+  pool = g_object_new (GST_TYPE_PINOS_POOL, NULL);
+
+  return pool;
+}
+
+gboolean
+gst_pinos_pool_add_buffer (GstPinosPool *pool, GstBuffer *buffer)
+{
+  g_return_val_if_fail (GST_IS_PINOS_POOL (pool), FALSE);
+  g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
+
+  GST_OBJECT_LOCK (pool);
+  g_queue_push_tail (&pool->available, buffer);
+  g_cond_signal (&pool->cond);
+  GST_OBJECT_UNLOCK (pool);
+
+  return TRUE;
+}
+
+gboolean
+gst_pinos_pool_remove_buffer (GstPinosPool *pool, GstBuffer *buffer)
+{
+  g_return_val_if_fail (GST_IS_PINOS_POOL (pool), FALSE);
+  g_return_val_if_fail (GST_IS_BUFFER (buffer), FALSE);
+
+  GST_OBJECT_LOCK (pool);
+  g_queue_remove (&pool->available, buffer);
+  GST_OBJECT_UNLOCK (pool);
+
+  return TRUE;
+}
+
+static GstFlowReturn
+acquire_buffer (GstBufferPool * pool, GstBuffer ** buffer,
+        GstBufferPoolAcquireParams * params)
+{
+  GstPinosPool *p = GST_PINOS_POOL (pool);
+
+  GST_OBJECT_LOCK (pool);
+  while (p->available.length == 0) {
+    g_cond_wait (&p->cond, GST_OBJECT_GET_LOCK (pool));
+  }
+  *buffer = g_queue_pop_head (&p->available);
+  GST_OBJECT_UNLOCK (pool);
+  GST_DEBUG ("acquire buffer %p", *buffer);
+
+  return GST_FLOW_OK;
+}
+
+static void
+release_buffer (GstBufferPool * pool, GstBuffer *buffer)
+{
+  GstPinosPool *p = GST_PINOS_POOL (pool);
+
+  GST_DEBUG ("release buffer %p", buffer);
+  GST_OBJECT_LOCK (pool);
+  g_queue_push_tail (&p->available, buffer);
+  GST_OBJECT_UNLOCK (pool);
+}
+
+static gboolean
+do_start (GstBufferPool * pool)
+{
+  GstPinosPool *p = GST_PINOS_POOL (pool);
+  PinosProperties *props = NULL;
+  GstStructure *config;
+  GstCaps *caps;
+  guint size;
+  guint min_buffers;
+  guint max_buffers;
+
+  config = gst_buffer_pool_get_config (pool);
+  gst_buffer_pool_config_get_params (config, &caps, &size, &min_buffers, &max_buffers);
+
+
+  pinos_stream_start_allocation (p->stream, props);
+
+  return TRUE;
+}
+
+static void
+gst_pinos_pool_finalize (GObject * object)
+{
+  GstPinosPool *pool = GST_PINOS_POOL (object);
+
+  GST_DEBUG_OBJECT (pool, "finalize");
+
+  G_OBJECT_CLASS (gst_pinos_pool_parent_class)->finalize (object);
+}
+
+static void
+gst_pinos_pool_class_init (GstPinosPoolClass * klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GstBufferPoolClass *bufferpool_class = GST_BUFFER_POOL_CLASS (klass);
+
+  gobject_class->finalize = gst_pinos_pool_finalize;
+
+  bufferpool_class->start = do_start;
+  bufferpool_class->acquire_buffer = acquire_buffer;
+  bufferpool_class->release_buffer = release_buffer;
+
+  GST_DEBUG_CATEGORY_INIT (gst_pinos_pool_debug_category, "pinospool", 0,
+      "debug category for pinospool object");
+}
+
+static void
+gst_pinos_pool_init (GstPinosPool * pool)
+{
+  g_cond_init (&pool->cond);
+  g_queue_init (&pool->available);
+}