audio{en,de}coder: Add optional open/close vfuncs

This can be used to do something in NULL->READY, like checking
if a hardware codec is actually available and to error out early.

gst-libs/gst/audio/gstaudiodecoder.c

@@ -2070,12 +2070,18 @@ static GstStateChangeReturn
 gst_audio_decoder_change_state (GstElement * element, GstStateChange transition)
 {
   GstAudioDecoder *codec;
+  GstAudioDecoderClass *klass;
   GstStateChangeReturn ret;
 
   codec = GST_AUDIO_DECODER (element);
+  klass = GST_AUDIO_DECODER_GET_CLASS (codec);
 
   switch (transition) {
     case GST_STATE_CHANGE_NULL_TO_READY:
+      if (klass->open) {
+        if (!klass->open (codec))
+          goto open_failed;
+      }
       break;
     case GST_STATE_CHANGE_READY_TO_PAUSED:
       if (!gst_audio_decoder_start (codec)) {
@@ -2099,6 +2105,10 @@ gst_audio_decoder_change_state (GstElement * element, GstStateChange transition)
       }
       break;
     case GST_STATE_CHANGE_READY_TO_NULL:
+      if (klass->close) {
+        if (!klass->close (codec))
+          goto close_failed;
+      }
       break;
     default:
       break;
@@ -2116,6 +2126,16 @@ stop_failed:
     GST_ELEMENT_ERROR (codec, LIBRARY, INIT, (NULL), ("Failed to stop codec"));
     return GST_STATE_CHANGE_FAILURE;
   }
+open_failed:
+  {
+    GST_ELEMENT_ERROR (codec, LIBRARY, INIT, (NULL), ("Failed to open codec"));
+    return GST_STATE_CHANGE_FAILURE;
+  }
+close_failed:
+  {
+    GST_ELEMENT_ERROR (codec, LIBRARY, INIT, (NULL), ("Failed to close codec"));
+    return GST_STATE_CHANGE_FAILURE;
+  }
 }
 
 GstFlowReturn

gst-libs/gst/audio/gstaudiodecoder.h

@@ -201,6 +201,12 @@ struct _GstAudioDecoder
  *                  Called just prior to pushing (encoded data) buffer downstream.
  *                  Subclass has full discretionary access to buffer,
  *                  and a not OK flow return will abort downstream pushing.
+ * @open:           Optional.
+ *                  Called when the element changes to GST_STATE_READY.
+ *                  Allows opening external resources. Since: 0.10.37.
+ * @close:          Optional.
+ *                  Called when the element changes to GST_STATE_NULL.
+ *                  Allows closing external resources. Since: 0.10.37.
  *
  * Subclasses can override any of the available virtual methods or not, as
  * needed. At minimum @handle_frame (and likely @set_format) needs to be
@@ -237,8 +243,12 @@ struct _GstAudioDecoderClass
   gboolean      (*event)              (GstAudioDecoder *dec,
                                        GstEvent *event);
 
+  gboolean      (*open)               (GstAudioDecoder *dec);
+  
+  gboolean      (*close)              (GstAudioDecoder *dec);
+
   /*< private >*/
-  gpointer       _gst_reserved[GST_PADDING_LARGE];
+  gpointer       _gst_reserved[GST_PADDING_LARGE-2];
 };
 
 GType             gst_audio_decoder_get_type (void);

gst-libs/gst/audio/gstaudioencoder.c

@@ -301,6 +301,9 @@ static void gst_audio_encoder_set_property (GObject * object,
 static void gst_audio_encoder_get_property (GObject * object,
     guint prop_id, GValue * value, GParamSpec * pspec);
 
+static GstStateChangeReturn gst_audio_encoder_change_state (GstElement *
+    element, GstStateChange transition);
+
 static gboolean gst_audio_encoder_sink_activate_push (GstPad * pad,
     gboolean active);
 
@@ -317,8 +320,10 @@ static void
 gst_audio_encoder_class_init (GstAudioEncoderClass * klass)
 {
   GObjectClass *gobject_class;
+  GstElementClass *gstelement_class;
 
   gobject_class = G_OBJECT_CLASS (klass);
+  gstelement_class = GST_ELEMENT_CLASS (klass);
   parent_class = g_type_class_peek_parent (klass);
 
   GST_DEBUG_CATEGORY_INIT (gst_audio_encoder_debug, "audioencoder", 0,
@@ -349,6 +354,9 @@ gst_audio_encoder_class_init (GstAudioEncoderClass * klass)
           "Consider discontinuity if timestamp jitter/imperfection exceeds tolerance (ns)",
           0, G_MAXINT64, DEFAULT_TOLERANCE,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  gstelement_class->change_state =
+      GST_DEBUG_FUNCPTR (gst_audio_encoder_change_state);
 }
 
 static void
@@ -460,6 +468,49 @@ gst_audio_encoder_finalize (GObject * object)
   G_OBJECT_CLASS (parent_class)->finalize (object);
 }
 
+static GstStateChangeReturn
+gst_audio_encoder_change_state (GstElement * element, GstStateChange transition)
+{
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+  GstAudioEncoder *enc = GST_AUDIO_ENCODER (element);
+  GstAudioEncoderClass *klass = GST_AUDIO_ENCODER_GET_CLASS (enc);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      if (klass->open) {
+        if (!klass->open (enc))
+          goto open_failed;
+      }
+    default:
+      break;
+  }
+
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+
+  switch (transition) {
+    case GST_STATE_CHANGE_READY_TO_NULL:
+      if (klass->close) {
+        if (!klass->close (enc))
+          goto close_failed;
+      }
+    default:
+      break;
+  }
+
+  return ret;
+
+open_failed:
+  {
+    GST_ELEMENT_ERROR (enc, LIBRARY, INIT, (NULL), ("Failed to open codec"));
+    return GST_STATE_CHANGE_FAILURE;
+  }
+close_failed:
+  {
+    GST_ELEMENT_ERROR (enc, LIBRARY, INIT, (NULL), ("Failed to close codec"));
+    return GST_STATE_CHANGE_FAILURE;
+  }
+}
+
 /**
  * gst_audio_encoder_finish_frame:
  * @enc: a #GstAudioEncoder

gst-libs/gst/audio/gstaudioencoder.h

@@ -151,6 +151,12 @@ struct _GstAudioEncoder {
  *                  for multichannel input specification).  If not implemented,
  *                  default returns gst_audio_encoder_proxy_getcaps
  *                  applied to sink template caps.
+ * @open:           Optional.
+ *                  Called when the element changes to GST_STATE_READY.
+ *                  Allows opening external resources. Since: 0.10.37.
+ * @close:          Optional.
+ *                  Called when the element changes to GST_STATE_NULL.
+ *                  Allows closing external resources. Since: 0.10.37.
  *
  * Subclasses can override any of the available virtual methods or not, as
  * needed. At minimum @set_format and @handle_frame needs to be overridden.
@@ -183,8 +189,12 @@ struct _GstAudioEncoderClass {
 
   GstCaps *     (*getcaps)            (GstAudioEncoder *enc);
 
+  gboolean      (*open)               (GstAudioEncoder *enc);
+
+  gboolean      (*close)              (GstAudioEncoder *enc);
+
   /*< private >*/
-  gpointer       _gst_reserved[GST_PADDING_LARGE];
+  gpointer       _gst_reserved[GST_PADDING_LARGE-2];
 };
 
 GType           gst_audio_encoder_get_type         (void);