diff --git a/src/liboggplay/oggplay_callback.c b/src/liboggplay/oggplay_callback.c
index f3e2339..39380e7 100644
--- a/src/liboggplay/oggplay_callback.c
+++ b/src/liboggplay/oggplay_callback.c
@@ -109,6 +109,15 @@ oggplay_callback_theora (OGGZ * oggz, ogg_packet * op, long serialno,
   int                     musec;
 #endif
 
+  if ( (granulepos > 0) && (common->last_granulepos > granulepos)) {
+    /* 
+     * the granule position is not monotonically increasing,
+     * something wrong with the page!
+     * skipping this page..... 
+     */
+    return 0;
+  }
+
   /*
    * always decode headers
    */
@@ -174,10 +183,19 @@ oggplay_callback_theora (OGGZ * oggz, ogg_packet * op, long serialno,
 #endif
 
   if (granulepos != -1) {
+    /* 
+     * save last granule position in order to be able to validate
+     * that it's monotonically increasing
+     */
+    common->last_granulepos = granulepos;
+
+    /* calculate the frame number */
     granuleshift = oggz_get_granuleshift(oggz, serialno);
     frame = (granulepos >> granuleshift);
     frame += (granulepos & ((1 << granuleshift) - 1));
-    common->current_loc = frame * common->granuleperiod;
+    
+    /* calculate the current location in the stream */
+    common->current_loc = frame * common->granuleperiod;    
   } else {
     common->current_loc = -1;
   }
diff --git a/src/liboggplay/oggplay_private.h b/src/liboggplay/oggplay_private.h
index fb73f1d..1455c68 100644
--- a/src/liboggplay/oggplay_private.h
+++ b/src/liboggplay/oggplay_private.h
@@ -142,22 +142,22 @@ struct _OggPlayCallbackInfo {
  *                              track
  */
 typedef struct {
-  long                  serialno;
-  int                   content_type;
-  const char          * content_type_name;
-  OggPlayDataType       decoded_type;
-  ogg_int64_t           granuleperiod;
-  ogg_int64_t           last_granulepos;
-  ogg_int64_t           offset;
-  ogg_int64_t           current_loc;
-  int                   active;
-  ogg_int64_t           final_granulepos;
-  struct _OggPlay     * player;
-  OggPlayDataHeader   * data_list;
-  OggPlayDataHeader   * end_of_data_list;
-  OggPlayDataHeader   * untimed_data_list;
-  OggPlayStreamInfo     stream_info;
-  int                   preroll;
+  long                  serialno;           /**< identifies the logical bit stream */
+  int                   content_type;       
+  const char          * content_type_name;  
+  OggPlayDataType       decoded_type;       /**< type of the track @see OggPlayDataType */
+  ogg_int64_t           granuleperiod;      
+  ogg_int64_t           last_granulepos;    /**< last seen granule position */
+  ogg_int64_t           offset;             /**<  */
+  ogg_int64_t           current_loc;        /**< current location in the stream (in ) */
+  int                   active;             /**< indicates whether the track is active or not */
+  ogg_int64_t           final_granulepos;   /**<  */
+  struct _OggPlay     * player;             /**< reference to the OggPlay handle */
+  OggPlayDataHeader   * data_list;          
+  OggPlayDataHeader   * end_of_data_list;   
+  OggPlayDataHeader   * untimed_data_list;  
+  OggPlayStreamInfo     stream_info;        /**< @see OggPlayStreamInfo */
+  int                   preroll;            /**< num. of past content packets to take into account when decoding the current Ogg page */
 } OggPlayDecode;
 
 typedef struct {
@@ -190,6 +190,9 @@ typedef struct {
   int             granuleshift;
 } OggPlayCmmlDecode;
 
+/**
+ * OggPlaySkeletonDecode
+ */
 typedef struct {
   OggPlayDecode   decoder;
   ogg_int64_t     presentation_time;
diff --git a/src/liboggplay/oggplay_seek.c b/src/liboggplay/oggplay_seek.c
index e74c136..ef150b8 100644
--- a/src/liboggplay/oggplay_seek.c
+++ b/src/liboggplay/oggplay_seek.c
@@ -133,6 +133,7 @@ oggplay_seek_cleanup(OggPlay* me, ogg_int64_t milliseconds)
     track->data_list = track->end_of_data_list = NULL;
     track->untimed_data_list = NULL;
     track->current_loc = -1;
+    track->last_granulepos = -1;
     track->stream_info = OGGPLAY_STREAM_JUST_SEEKED;
   }