Index: xine-lib-1.1.1/src/demuxers/demux_matroska.c
===================================================================
--- xine-lib-1.1.1.orig/src/demuxers/demux_matroska.c
+++ xine-lib-1.1.1/src/demuxers/demux_matroska.c
@@ -1750,12 +1750,13 @@ static int parse_block (demux_matroska_t
         /* size of each frame */
         for (i = 0; i < lace_num; i++) {
           int size = 0;
-          while (*data == 255) {
-            size += *data;
+          int partial_size;
+          do
+          {
+            partial_size = *data;
+            size += partial_size;
             data++; block_size_left--;
-          }
-          size += *data;
-          data++; block_size_left--;
+          } while (partial_size == 255);
           frame[i] = size;
           block_size_left -= size;
         }
@@ -1765,14 +1766,19 @@ static int parse_block (demux_matroska_t
       }
       break;
 
-      case MATROSKA_FIXED_SIZE_LACING:
+      case MATROSKA_FIXED_SIZE_LACING: {
+        int frame_size;
+
         lprintf("fixed size lacing\n");
+        
+        frame_size = block_size_left / (lace_num + 1);
         for (i = 0; i < lace_num; i++) {
-          frame[i] = block_size / (lace_num + 1);
-          block_size_left -= frame[i];
+          frame[i] = frame_size;
         }
-        frame[lace_num] = block_size_left;
-        break;
+        frame[lace_num] = block_size_left - (lace_num * frame_size);
+        block_size_left = 0;
+      }
+      break;
 
       case MATROSKA_EBML_LACING: {
         int64_t tmp;
Index: xine-lib-1.1.1/src/xine-engine/demux.c
===================================================================
--- xine-lib-1.1.1.orig/src/xine-engine/demux.c
+++ xine-lib-1.1.1/src/xine-engine/demux.c
@@ -525,7 +525,8 @@ void _x_demux_send_data(fifo_buffer_t *f
 
   decoder_flags |= BUF_FLAG_FRAME_START;
 
-  while (fifo && size) {
+  _x_assert(size > 0);
+  while (fifo && size > 0) {
 
     buf = fifo->buffer_pool_alloc (fifo);