configure: Add configure option to pack OpenMAX structures

This is required to set to 4 for the Raspberry Pi for example.

configure.ac

@@ -167,6 +167,16 @@ AC_ARG_ENABLE(Bsymbolic,
                            enable_Bsymbolic=no)
                LDFLAGS="${SAVED_LDFLAGS}"])
 
+
+AC_ARG_WITH([omx-struct-packing],
+        AS_HELP_STRING([--with-omx-struct-packing],[Force OpenMAX struct packing, (default is none)]),
+        [ac_cv_omx_struct_packing="$withval"], [ac_cv_omx_struct_packing="none"])
+
+if test x"$ac_cv_omx_struct_packing" != x"none"; then
+  AC_MSG_NOTICE([Using $ac_cv_omx_struct_packing as OpenMAX struct packing])
+  AC_DEFINE_UNQUOTED(GST_OMX_STRUCT_PACKING, $ac_cv_omx_struct_packing, [The struct packing used for OpenMAX structures])
+fi
+
 dnl *** set variables based on configure arguments ***
 
 dnl set license and copyright notice

omx/gstomx.h

@@ -27,9 +27,31 @@
 #include <gst/video/video.h>
 #include <string.h>
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#ifdef GST_OMX_STRUCT_PACKING
+# if GST_OMX_STRUCT_PACKING == 1
+#  pragma pack(1)
+# elif GST_OMX_STRUCT_PACKING == 2
+#  pragma pack(2)
+# elif GST_OMX_STRUCT_PACKING == 4
+#  pragma pack(4)
+# elif GST_OMX_STRUCT_PACKING == 8
+#  pragma pack(8)
+# else
+#  error "Unsupported struct packing value"
+# endif
+#endif
+
 #include <OMX_Core.h>
 #include <OMX_Component.h>
 
+#ifdef GST_OMX_STRUCT_PACKING
+#pragma pack()
+#endif
+
 #include "gstomxrecmutex.h"
 
 G_BEGIN_DECLS