baseparse: handle streamheaders by prepending them to the stream

Add a first_buffer boolean state flag to have baseparse do actions
before pushing data. This is used to check the caps for streamheader
buffers that are prepended to the stream, but only if the first buffer
isn't already marked with the _HEADER flag. In this case, it is assumed
that the _HEADER marked buffer is the same as the streamheader.

https://bugzilla.gnome.org/show_bug.cgi?id=735070

diff --git a/libs/gst/base/gstbaseparse.c b/libs/gst/base/gstbaseparse.c
index fdc2673..8fd1103 100644 (file)
--- a/libs/gst/base/gstbaseparse.c
+++ b/libs/gst/base/gstbaseparse.c
@@ -350,6 +350,9 @@ struct _GstBaseParsePrivate
   GList *detect_buffers;
   guint detect_buffers_size;
 
+  /* True when no buffers have been received yet */
+  gboolean first_buffer;
+
   /* if TRUE, a STREAM_START event needs to be pushed */
   gboolean push_stream_start;
 };
@@ -856,6 +859,8 @@ gst_base_parse_reset (GstBaseParse * parse)
 
   parse->priv->new_frame = TRUE;
 
+  parse->priv->first_buffer = TRUE;
+
   g_list_foreach (parse->priv->detect_buffers, (GFunc) gst_buffer_unref, NULL);
   g_list_free (parse->priv->detect_buffers);
   parse->priv->detect_buffers = NULL;
@@ -2714,6 +2719,53 @@ gst_base_parse_check_sync (GstBaseParse * parse)
 }
 
 static GstFlowReturn
+gst_base_parse_process_streamheader (GstBaseParse * parse)
+{
+  GstCaps *caps;
+  GstStructure *str;
+  const GValue *value;
+  GstFlowReturn ret = GST_FLOW_OK;
+
+  caps = gst_pad_get_current_caps (GST_BASE_PARSE_SINK_PAD (parse));
+  if (caps == NULL)
+    goto notfound;
+
+  str = gst_caps_get_structure (caps, 0);
+  value = gst_structure_get_value (str, "streamheader");
+  if (value == NULL)
+    goto notfound;
+
+  GST_DEBUG_OBJECT (parse, "Found streamheader field on input caps");
+
+  if (GST_VALUE_HOLDS_ARRAY (value)) {
+    gint i;
+    gsize len = gst_value_array_get_size (value);
+
+    for (i = 0; i < len; i++) {
+      GstBuffer *buffer =
+          gst_value_get_buffer (gst_value_array_get_value (value, i));
+      ret =
+          gst_base_parse_chain (GST_BASE_PARSE_SINK_PAD (parse),
+          GST_OBJECT_CAST (parse), gst_buffer_ref (buffer));
+    }
+
+  } else if (GST_VALUE_HOLDS_BUFFER (value)) {
+    GstBuffer *buffer = gst_value_get_buffer (value);
+    ret =
+        gst_base_parse_chain (GST_BASE_PARSE_SINK_PAD (parse),
+        GST_OBJECT_CAST (parse), gst_buffer_ref (buffer));
+  }
+
+  return ret;
+
+notfound:
+  {
+    GST_DEBUG_OBJECT (parse, "No streamheader on caps");
+    return GST_FLOW_OK;
+  }
+}
+
+static GstFlowReturn
 gst_base_parse_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
 {
   GstBaseParseClass *bclass;
@@ -2730,6 +2782,20 @@ gst_base_parse_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
   parse = GST_BASE_PARSE (parent);
   bclass = GST_BASE_PARSE_GET_CLASS (parse);
 
+  if (G_UNLIKELY (parse->priv->first_buffer)) {
+    parse->priv->first_buffer = FALSE;
+    if (!GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_HEADER)) {
+      /* this stream has no header buffers, check if we just prepend the
+       * streamheader from caps to the stream */
+      GST_DEBUG_OBJECT (parse, "Looking for streamheader field on caps to "
+          "prepend to the stream");
+      gst_base_parse_process_streamheader (parse);
+    } else {
+      GST_DEBUG_OBJECT (parse, "Stream has header buffers, not prepending "
+          "streamheader from caps");
+    }
+  }
+
   if (parse->priv->detecting) {
     GstBuffer *detect_buf;