[IIO] Enable/Disable buffer at correct state

Enabling/Disabling buffer when going from PAUSED to PLAYING state.
This might lead to higher latency but provides latest and correct data.
Enabling in READY to PAUSED can lead to accumulation of frames before playing
and result in unreal latency as well as old data.
This commit will also sync gst timing with iio device time.

Signed-off-by: Parichay Kapoor <pk.kapoor@samsung.com>

diff --git a/gst/nnstreamer/tensor_source/tensor_src_iio.c b/gst/nnstreamer/tensor_source/tensor_src_iio.c
index fc3206c..58ba063 100644 (file)
--- a/gst/nnstreamer/tensor_source/tensor_src_iio.c
+++ b/gst/nnstreamer/tensor_source/tensor_src_iio.c
@@ -23,7 +23,6 @@
  * @author     Parichay Kapoor <pk.kapoor@samsung.com>
  * @bug                No known bugs except for NYI items
  * @todo  support specific channels as input
- * @todo  support/sync buffer timestamps based on IIO channel timestamp
  * @todo  handle timestamp received from device
  *
  *
@@ -242,6 +241,8 @@ static void gst_tensor_src_iio_finalize (GObject * object);
 /** GstBaseSrc method implementation */
 static gboolean gst_tensor_src_iio_start (GstBaseSrc * src);
 static gboolean gst_tensor_src_iio_stop (GstBaseSrc * src);
+static GstStateChangeReturn gst_tensor_src_iio_change_state (GstElement *
+    element, GstStateChange transition);
 static gboolean gst_tensor_src_iio_event (GstBaseSrc * src, GstEvent * event);
 static gboolean gst_tensor_src_iio_query (GstBaseSrc * src, GstQuery * query);
 static gboolean gst_tensor_src_iio_set_caps (GstBaseSrc * src, GstCaps * caps);
@@ -346,6 +347,8 @@ gst_tensor_src_iio_class_init (GstTensorSrcIIOClass * klass)
 
   /** pad template */
   gst_element_class_add_static_pad_template (gstelement_class, &src_factory);
+  gstelement_class->change_state =
+      GST_DEBUG_FUNCPTR (gst_tensor_src_iio_change_state);
 
   /** GstBaseSrcIIO methods */
   bsrc_class->start = GST_DEBUG_FUNCPTR (gst_tensor_src_iio_start);
@@ -1682,17 +1685,6 @@ gst_tensor_src_iio_setup_device_buffer (GstTensorSrcIIO * self)
   }
   g_free (dirname);
 
-  /** enable the buffer for the data to be captured */
-  dirname = g_build_filename (self->device.base_dir, BUFFER, NULL);
-  if (G_UNLIKELY (!gst_tensor_write_sysfs_int (self, "enable", dirname, 1))) {
-    GST_ERROR_OBJECT (self,
-        "Cannot enable the IIO device buffer for device: %s.\n",
-        self->device.name);
-    g_free (dirname);
-    goto error_return;
-  }
-  g_free (dirname);
-
   /** open the buffer to read and ready the file descriptor */
   device_name = g_strdup_printf ("%s%d", DEVICE_PREFIX, self->device.id);
   filename = g_build_filename (IIO_DEV_DIR, device_name, NULL);
@@ -1798,15 +1790,6 @@ gst_tensor_src_restore_iio_device (GstTensorSrcIIO * self)
   gchar *filename = NULL, *dirname = NULL, *file_contents = NULL;
   GstTensorSrcIIOChannelProperties *channel_prop = NULL;
 
-  /** disable the buffer */
-  dirname = g_build_filename (self->device.base_dir, BUFFER, NULL);
-  if (G_UNLIKELY (!gst_tensor_write_sysfs_int (self, "enable", dirname, 0))) {
-    GST_ERROR_OBJECT (self,
-        "Error in disabling the IIO device buffer for device: %s.\n",
-        self->device.name);
-  }
-  g_free (dirname);
-
   /** reset enabled channels */
   for (ch_list = self->channels; ch_list != NULL; ch_list = ch_list->next) {
     channel_prop = (GstTensorSrcIIOChannelProperties *) ch_list->data;
@@ -2009,6 +1992,65 @@ gst_tensor_src_iio_fixate (GstBaseSrc * src, GstCaps * caps)
 }
 
 /**
+ * @brief Perform state change.
+ */
+static GstStateChangeReturn
+gst_tensor_src_iio_change_state (GstElement * element,
+    GstStateChange transition)
+{
+  GstTensorSrcIIO *self;
+  GstStateChangeReturn ret;
+  gboolean buffer_state_change_success = TRUE;
+  gchar *dirname = NULL;
+
+  self = GST_TENSOR_SRC_IIO (element);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
+    {
+      /** enable the buffer for the data to be captured */
+      dirname = g_build_filename (self->device.base_dir, BUFFER, NULL);
+      if (G_UNLIKELY (!gst_tensor_write_sysfs_int (self, "enable", dirname, 1))) {
+        GST_ERROR_OBJECT (self,
+            "Cannot enable the IIO device buffer for device: %s.\n",
+            self->device.name);
+        buffer_state_change_success = FALSE;
+      }
+      g_free (dirname);
+      break;
+    }
+    default:
+      break;
+  }
+
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
+    {
+      /** disable the buffer */
+      dirname = g_build_filename (self->device.base_dir, BUFFER, NULL);
+      if (G_UNLIKELY (!gst_tensor_write_sysfs_int (self, "enable", dirname, 0))) {
+        GST_ERROR_OBJECT (self,
+            "Error in disabling the IIO device buffer for device: %s.\n",
+            self->device.name);
+        buffer_state_change_success = FALSE;
+      }
+      g_free (dirname);
+      break;
+    }
+    default:
+      break;
+  }
+
+  if (buffer_state_change_success == FALSE) {
+    ret = GST_STATE_CHANGE_FAILURE;
+  }
+
+  return ret;
+}
+
+/**
  * @brief check if source supports seeking
  */
 static gboolean