/**
* gst_event_new_stream_start:
+ * @stream_id: Identifier for this stream
*
* Create a new STREAM_START event. The stream start event can only
* travel downstream synchronized with the buffer flow. It is expected
* combining multiple streams must ensure that this event is only forwarded
* downstream once and not for every single input stream.
*
+ * The @stream_id should be a unique string that consists of the upstream
+ * stream-id, / as separator and a unique stream-id for this specific
+ * stream. A new stream-id should only be created for a stream if the upstream
+ * stream is split into (potentially) multiple new streams, e.g. in a demuxer,
+ * but not for every single element in the pipeline.
+ * gst_util_create_stream_id() can be used to create a stream-id.
+ *
* Returns: (transfer full): the new STREAM_START event.
*/
GstEvent *
-gst_event_new_stream_start (void)
+gst_event_new_stream_start (const gchar * stream_id)
+{
+ GstStructure *s;
+
+ g_return_val_if_fail (stream_id != NULL, NULL);
+
+ s = gst_structure_new_id (GST_QUARK (EVENT_STREAM_START),
+ GST_QUARK (STREAM_ID), G_TYPE_STRING, stream_id, NULL);
+
+ return gst_event_new_custom (GST_EVENT_STREAM_START, s);
+}
+
+/**
+ * gst_event_parse_stream_start:
+ * @event: a stream-start event.
+ * @stream_id: (out): pointer to store the stream-id
+ *
+ * Parse a stream-id @event and store the result in the given @stream_id location.
+ */
+void
+gst_event_parse_stream_start (GstEvent * event, const gchar ** stream_id)
{
- return gst_event_new_custom (GST_EVENT_STREAM_START, NULL);
+ const GstStructure *structure;
+
+ g_return_if_fail (event != NULL);
+ g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_STREAM_START);
+
+ structure = gst_event_get_structure (event);
+
+ if (stream_id)
+ gst_structure_id_get (structure,
+ GST_QUARK (STREAM_ID), G_TYPE_STRING, stream_id, NULL);
}
/**
/* Should not happen because a_d and b_d are not 0 */
g_return_val_if_reached (0);
}
+
+/** gst_pad_create_stream_id:
+ * @pad: A source #GstPad
+ * @parent: Parent #GstElement of @pad
+ * @stream_id: (allow-none): The stream-id
+ * @var_args: parameters for the @stream_id format string
+ *
+ * Creates a stream-id for the source #GstPad @pad by combining the
+ * upstream information with the optional @stream_id of the stream
+ * of @pad. @pad must have a parent #GstElement and which must have zero
+ * or one sinkpad. @stream_id can only be %NULL if the parent element
+ * of @pad has only a single source pad.
+ *
+ * This function generates an unique stream-id by getting the upstream
+ * stream-start event stream ID and appending @stream_id to it. If the
+ * element has no sinkpad it will generate an upstream stream-id by
+ * doing an URI query on the element and in the worst case just uses
+ * a random number. Source elements that don't implement the URI
+ * handler interface should ideally generate a unique, deterministic
+ * stream-id manually instead.
+ *
+ * Returns: A stream-id for @pad. g_free() after usage.
+ */
+gchar *
+gst_pad_create_stream_id_printf_valist (GstPad * pad, GstElement * parent,
+ const gchar * stream_id, va_list var_args)
+{
+ GstEvent *upstream_event;
+ gchar *upstream_stream_id = NULL, *new_stream_id;
+ GstPad *sinkpad;
+
+ g_return_val_if_fail (GST_IS_PAD (pad), NULL);
+ g_return_val_if_fail (GST_PAD_IS_SRC (pad), NULL);
+ g_return_val_if_fail (GST_IS_ELEMENT (parent), NULL);
+
+ g_return_val_if_fail (parent->numsinkpads <= 1, NULL);
+
+ /* If the element has multiple source pads it must
+ * provide a stream-id for every source pad, otherwise
+ * all source pads will have the same and are not
+ * distinguishable */
+ g_return_val_if_fail (parent->numsrcpads == 1 || stream_id, NULL);
+
+ /* First try to get the upstream stream-start stream-id from the sinkpad.
+ * This will only work for non-source elements */
+ sinkpad = gst_element_get_static_pad (parent, "sink");
+ if (sinkpad) {
+ upstream_event =
+ gst_pad_get_sticky_event (sinkpad, GST_EVENT_STREAM_START, 0);
+ if (upstream_event) {
+ const gchar *tmp;
+
+ gst_event_parse_stream_start (upstream_event, &tmp);
+ if (tmp)
+ upstream_stream_id = g_strdup (tmp);
+ gst_event_unref (upstream_event);
+ }
+ gst_object_unref (sinkpad);
+ }
+
+ /* The only case where we don't have an upstream start-start event
+ * here is for source elements */
+ if (!upstream_stream_id) {
+ GstQuery *query;
+
+ /* Try to generate one from the URI query and
+ * if it fails take a random number instead */
+ query = gst_query_new_uri ();
+ if (gst_element_query (parent, query)) {
+ GChecksum *cs;
+ gchar *uri;
+
+ gst_query_parse_uri (query, &uri);
+
+ /* And then generate an SHA256 sum of the URI */
+ cs = g_checksum_new (G_CHECKSUM_SHA256);
+ g_checksum_update (cs, (const guchar *) uri, strlen (uri));
+ g_free (uri);
+ upstream_stream_id = g_strdup (g_checksum_get_string (cs));
+ g_checksum_free (cs);
+ } else {
+ /* Just get some random number if the URI query fails */
+ GST_WARNING_OBJECT (pad, "Creating random stream-id, consider "
+ "implementing a deterministic way of creating a stream-id");
+ upstream_stream_id =
+ g_strdup_printf ("%08x%08x%08x%08x", g_random_int (), g_random_int (),
+ g_random_int (), g_random_int ());
+ }
+
+ gst_query_unref (query);
+ }
+
+ if (stream_id) {
+ gchar *expanded = g_strdup_vprintf (stream_id, var_args);
+ new_stream_id = g_strconcat (upstream_stream_id, "/", expanded, NULL);
+ g_free (expanded);
+ } else {
+ new_stream_id = g_strdup (upstream_stream_id);
+ }
+
+ g_free (upstream_stream_id);
+
+ return new_stream_id;
+}
+
+/** gst_pad_create_stream_id:
+ * @pad: A source #GstPad
+ * @parent: Parent #GstElement of @pad
+ * @stream_id: (allow-none): The stream-id
+ * @...: parameters for the @stream_id format string
+ *
+ * Creates a stream-id for the source #GstPad @pad by combining the
+ * upstream information with the optional @stream_id of the stream
+ * of @pad. @pad must have a parent #GstElement and which must have zero
+ * or one sinkpad. @stream_id can only be %NULL if the parent element
+ * of @pad has only a single source pad.
+ *
+ * This function generates an unique stream-id by getting the upstream
+ * stream-start event stream ID and appending @stream_id to it. If the
+ * element has no sinkpad it will generate an upstream stream-id by
+ * doing an URI query on the element and in the worst case just uses
+ * a random number. Source elements that don't implement the URI
+ * handler interface should ideally generate a unique, deterministic
+ * stream-id manually instead.
+ *
+ * Returns: A stream-id for @pad. g_free() after usage.
+ */
+gchar *
+gst_pad_create_stream_id_printf (GstPad * pad, GstElement * parent,
+ const gchar * stream_id, ...)
+{
+ va_list var_args;
+ gchar *new_stream_id;
+
+ va_start (var_args, stream_id);
+ new_stream_id =
+ gst_pad_create_stream_id_printf_valist (pad, parent, stream_id, var_args);
+ va_end (var_args);
+
+ return new_stream_id;
+}
+
+/** gst_pad_create_stream_id:
+ * @pad: A source #GstPad
+ * @parent: Parent #GstElement of @pad
+ * @stream_id: (allow-none): The stream-id
+ *
+ * Creates a stream-id for the source #GstPad @pad by combining the
+ * upstream information with the optional @stream_id of the stream
+ * of @pad. @pad must have a parent #GstElement and which must have zero
+ * or one sinkpad. @stream_id can only be %NULL if the parent element
+ * of @pad has only a single source pad.
+ *
+ * This function generates an unique stream-id by getting the upstream
+ * stream-start event stream ID and appending @stream_id to it. If the
+ * element has no sinkpad it will generate an upstream stream-id by
+ * doing an URI query on the element and in the worst case just uses
+ * a random number. Source elements that don't implement the URI
+ * handler interface should ideally generate a unique, deterministic
+ * stream-id manually instead.
+ *
+ * Returns: A stream-id for @pad. g_free() after usage.
+ */
+gchar *
+gst_pad_create_stream_id (GstPad * pad, GstElement * parent,
+ const gchar * stream_id)
+{
+ return gst_pad_create_stream_id_printf (pad, parent, stream_id, NULL);
+}
projects / platform / upstream / gstreamer.git / commitdiff