Partially segregate access_demux V4L2 code

modules/access/Modules.am

@@ -132,6 +132,7 @@ libvlc_LTLIBRARIES += $(LTLIBaccess_shm)
 
 libv4l2_plugin_la_SOURCES = \
 	v4l2/video.c \
+	v4l2/demux.c \
 	v4l2/access.c \
 	v4l2/controls.c \
 	v4l2/v4l2.h

modules/access/v4l2/v4l2.h

@@ -71,11 +71,24 @@ struct demux_sys_t
 #endif
 };
 
+struct buffer_t
+{
+    void *  start;
+    size_t  length;
+};
+
 /* video.c */
 void ParseMRL(vlc_object_t *, const char *);
 int OpenVideo(vlc_object_t *, demux_sys_t *, bool);
 block_t* GrabVideo(vlc_object_t *, demux_sys_t *);
 
+/* demux.c */
+int DemuxOpen(vlc_object_t *);
+void DemuxClose(vlc_object_t *);
+float GetAbsoluteMaxFrameRate(vlc_object_t *, int fd, uint32_t fmt);
+void GetMaxDimensions(vlc_object_t *, int fd, uint32_t fmt, float fps_min,
+                      uint32_t *pwidth, uint32_t *pheight);
+
 /* access.c */
 int AccessOpen(vlc_object_t *);
 void AccessClose(vlc_object_t *);