From 763f4c3fc3bf6ece9f747e4e5bd8c26a807d01fb Mon Sep 17 00:00:00 2001
From: David Corvoysier <david.corvoysier@orange.com>
Date: Wed, 17 Oct 2012 15:50:33 +0200
Subject: [PATCH] Added a typefind helper for DASH: this commit should be
 reverted as soon as a proper patch has been submitted to gst-plugins-base

---
 ext/dash/Makefile.am |  2 +-
 ext/dash/gstplugin.c | 85 ++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 83 insertions(+), 4 deletions(-)

diff --git a/ext/dash/Makefile.am b/ext/dash/Makefile.am
index b0f72e4d0f..f0489ee058 100644
--- a/ext/dash/Makefile.am
+++ b/ext/dash/Makefile.am
@@ -18,7 +18,7 @@ noinst_HEADERS =             \
 
 # compiler and linker flags used to compile this plugin, set in configure.ac
 libgstdashdemux_la_CFLAGS = $(GST_CFLAGS) 
-libgstdashdemux_la_LIBADD = $(GST_LIBS)
+libgstdashdemux_la_LIBADD = $(GST_LIBS) $(GST_BASE_LIBS)
 libgstdashdemux_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
 libgstdashdemux_la_LIBTOOLFLAGS = --tag=disable-static
 
diff --git a/ext/dash/gstplugin.c b/ext/dash/gstplugin.c
index f6712c6baf..9e7361869a 100644
--- a/ext/dash/gstplugin.c
+++ b/ext/dash/gstplugin.c
@@ -2,6 +2,8 @@
 #  include <config.h>
 #endif
 
+#include <string.h>
+
 #include <gst/gst.h>
 
 #include "gstfragmented.h"
@@ -9,14 +11,93 @@
 
 GST_DEBUG_CATEGORY (fragmented_debug);
 
+#define XML_BUFFER_SIZE 16
+#define XML_INC_BUFFER {                                                \
+  pos++;                                                                \
+  if (pos == XML_BUFFER_SIZE) {                                         \
+    pos = 0;                                                            \
+    offset += XML_BUFFER_SIZE;                                          \
+    data = gst_type_find_peek (tf, offset, XML_BUFFER_SIZE);            \
+    if (data == NULL) return FALSE;                                     \
+  } else {                                                              \
+    data++;                                                             \
+  }                                                                     \
+}
+
+static gboolean
+xml_check_first_element (GstTypeFind * tf, const gchar * element, guint elen,
+    gboolean strict)
+{
+  gboolean got_xmldec;
+  const guint8 *data;
+  guint offset = 0;
+  guint pos = 0;
+
+  data = gst_type_find_peek (tf, 0, XML_BUFFER_SIZE);
+  if (!data)
+    return FALSE;
+
+  /* look for the XMLDec
+   * see XML spec 2.8, Prolog and Document Type Declaration
+   * http://www.w3.org/TR/2004/REC-xml-20040204/#sec-prolog-dtd */
+  got_xmldec = (memcmp (data, "<?xml", 5) == 0);
+
+  if (strict && !got_xmldec)
+    return FALSE;
+
+  /* skip XMLDec in any case if we've got one */
+  if (got_xmldec) {
+    pos += 5;
+    data += 5;
+  }
+
+  /* look for the first element, it has to be the requested element. Bail
+   * out if it is not within the first 4kB. */
+  while (data && (offset + pos) < 4096) {
+    while (*data != '<' && (offset + pos) < 4096) {
+      XML_INC_BUFFER;
+    }
+
+    XML_INC_BUFFER;
+    if (!g_ascii_isalpha (*data)) {
+      /* if not alphabetic, it's a PI or an element / attribute declaration
+       * like <?xxx or <!xxx */
+      XML_INC_BUFFER;
+      continue;
+    }
+
+    /* the first normal element, check if it's the one asked for */
+    data = gst_type_find_peek (tf, offset + pos, elen + 1);
+    return (data && element && strncmp ((char *) data, element, elen) == 0);
+  }
+
+  return FALSE;
+}
+
+/*** application/dash+xml typefind helper ***/
+
+static GstStaticCaps dash_caps = GST_STATIC_CAPS ("application/dash+xml");
+
+#define DASH_CAPS gst_static_caps_get (&dash_caps)
+
+static void
+dash_type_find (GstTypeFind * tf, gpointer unused)
+{
+  if (xml_check_first_element (tf, "MPD", 3, FALSE) ||
+      xml_check_first_element (tf, "mpd", 3, FALSE)) {
+    gst_type_find_suggest (tf, GST_TYPE_FIND_MAXIMUM, DASH_CAPS);
+  }
+}
+
 static gboolean
 fragmented_init (GstPlugin * plugin)
 {
   GST_DEBUG_CATEGORY_INIT (fragmented_debug, "dashdemux", 0, "dashdemux");
-
   if (!gst_element_register (plugin, "dashdemux", GST_RANK_PRIMARY,
           GST_TYPE_DASH_DEMUX) || FALSE)
     return FALSE;
+  gst_type_find_register (plugin, "application/dash+xml",
+      GST_RANK_SECONDARY, dash_type_find, NULL, DASH_CAPS, NULL, NULL);
   return TRUE;
 }
 
@@ -25,5 +106,3 @@ GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
     "fragmented",
     "Fragmented streaming plugins",
     fragmented_init, VERSION, "LGPL", PACKAGE_NAME, "http://www.gstreamer.org/")
-
-