diff --git a/core/cd_hw/cdd.c b/core/cd_hw/cdd.c
index d20aa87..6c53b07 100644
--- a/core/cd_hw/cdd.c
+++ b/core/cd_hw/cdd.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  CD drive processor & CD-DA fader
  *
- *  Copyright (C) 2012-2016  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2017  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -157,6 +157,19 @@ static const char extensions[SUPPORTED_EXT][16] =
 };
 
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
+
+static int seek64_wrap(void *f,ogg_int64_t off,int whence){
+  return cdStreamSeek(f,off,whence);
+}
+
+static ov_callbacks cb =
+{ 
+  (size_t (*)(void *, size_t, size_t, void *))  cdStreamRead,
+  (int (*)(void *, ogg_int64_t, int))           seek64_wrap,
+  (int (*)(void *))                             cdStreamClose,
+  (long (*)(void *))                            cdStreamTell
+};
+
 #ifdef DISABLE_MANY_OGG_OPEN_FILES
 static void ogg_free(int i)
 {
@@ -170,9 +183,10 @@ static void ogg_free(int i)
   cdd.toc.tracks[i].vf.seekable = 1;
 
   /* reset file reading position */
-  fseek(cdd.toc.tracks[i].fd, 0, SEEK_SET);
+  cdStreamSeek(cdd.toc.tracks[i].fd, 0, SEEK_SET);
 }
 #endif
+
 #endif
 
 void cdd_init(int samplerate)
@@ -255,21 +269,21 @@ int cdd_context_load(uint8 *state)
   if (cdd.toc.sub)
   {
     /* 96 bytes per sector */
-    fseek(cdd.toc.sub, lba * 96, SEEK_SET);
+    cdStreamSeek(cdd.toc.sub, lba * 96, SEEK_SET);
   }
 
   /* seek to current track position */
   if (cdd.toc.tracks[cdd.index].type)
   {
     /* DATA track */
-    fseek(cdd.toc.tracks[cdd.index].fd, lba * cdd.sectorSize, SEEK_SET);
+    cdStreamSeek(cdd.toc.tracks[cdd.index].fd, lba * cdd.sectorSize, SEEK_SET);
   }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
   else if (cdd.toc.tracks[cdd.index].vf.seekable)
   {
 #ifdef DISABLE_MANY_OGG_OPEN_FILES
     /* VORBIS file need to be opened first */
-    ov_open(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0);
+    ov_open_callbacks(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0,cb);
 #endif
     /* VORBIS AUDIO track */
     ov_pcm_seek(&cdd.toc.tracks[cdd.index].vf, (lba * 588) - cdd.toc.tracks[cdd.index].offset);
@@ -278,7 +292,7 @@ int cdd_context_load(uint8 *state)
   else if (cdd.toc.tracks[cdd.index].fd)
   {
     /* PCM AUDIO track */
-    fseek(cdd.toc.tracks[cdd.index].fd, (lba * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
+    cdStreamSeek(cdd.toc.tracks[cdd.index].fd, (lba * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
   }
 
   return bufferptr;
@@ -289,7 +303,7 @@ int cdd_load(char *filename, char *header)
   char fname[256+10];
   char line[128];
   char *ptr, *lptr;
-  FILE *fd;
+  cdStream *fd;
   
   /* assume CD image file by default */
   int isCDfile = 1;
@@ -298,7 +312,7 @@ int cdd_load(char *filename, char *header)
   cdd_unload();
 
   /* open file */
-  fd = fopen(filename, "rb");
+  fd = cdStreamOpen(filename);
   if (!fd) return (-1);
 
   /* save a copy of base filename */
@@ -310,7 +324,7 @@ int cdd_load(char *filename, char *header)
     int len;
 
     /* read first 16 bytes */
-    fread(header, 0x10, 1, fd);
+    cdStreamRead(header, 0x10, 1, fd);
 
     /* look for valid CD image identifier */
     if (!memcmp("SEGADISCSYSTEM", header, 14))
@@ -321,7 +335,7 @@ int cdd_load(char *filename, char *header)
     else
     {    
       /* read next 16 bytes */
-      fread(header, 0x10, 1, fd);
+      cdStreamRead(header, 0x10, 1, fd);
 
       /* look for valid CD image identifier */
       if (!memcmp("SEGADISCSYSTEM", header, 14))
@@ -335,7 +349,7 @@ int cdd_load(char *filename, char *header)
     if (cdd.sectorSize)
     {
       /* read CD image header + security code */
-      fread(header + 0x10, 0x200, 1, fd);
+      cdStreamRead(header + 0x10, 0x200, 1, fd);
 
       /* initialize first track file descriptor */
       cdd.toc.tracks[0].fd = fd;
@@ -344,8 +358,8 @@ int cdd_load(char *filename, char *header)
       cdd.toc.tracks[0].type = TYPE_CDROM;
 
       /* DATA track end LBA (based on DATA file length) */
-      fseek(fd, 0, SEEK_END);
-      cdd.toc.tracks[0].end = ftell(fd) / cdd.sectorSize;
+      cdStreamSeek(fd, 0, SEEK_END);
+      cdd.toc.tracks[0].end = cdStreamTell(fd) / cdd.sectorSize;
 
       /* DATA track length should be at least 2s (BIOS requirement) */
       if (cdd.toc.tracks[0].end < 150)
@@ -354,7 +368,7 @@ int cdd_load(char *filename, char *header)
       }
         
       /* DATA track start LBA (logical block 0) */
-      fseek(fd, 0, SEEK_SET);
+      cdStreamSeek(fd, 0, SEEK_SET);
       cdd.toc.tracks[0].start = 0;
 
       /* initialize TOC */
@@ -367,14 +381,14 @@ int cdd_load(char *filename, char *header)
       isCDfile = 0;
 
       /* close file */
-      fclose(fd);
+      cdStreamClose(fd);
     }
 
     /* automatically try to mount CD associated CUE file */
     len = strlen(fname);
     while ((len && (fname[len] != '.')) || (len > 251)) len--;
     strcpy(&fname[len], ".cue");
-    fd = fopen(fname, "rb");
+    fd = cdStreamOpen(fname);
   }
 
   /* parse CUE file */
@@ -386,7 +400,7 @@ int cdd_load(char *filename, char *header)
     if (cdd.toc.last)
     {
       /* skip first track */
-      while (fgets(line, 128, fd))
+      while (cdStreamGets(line, 128, fd))
       {
         if (strstr(line, "INDEX 01") && !strstr(line, "INDEX 1"))
           break;
@@ -394,7 +408,7 @@ int cdd_load(char *filename, char *header)
     }
 
     /* read lines until end of file */
-    while (fgets(line, 128, fd))
+    while (cdStreamGets(line, 128, fd))
     {
       /* skip any SPACE characters */
       lptr = line;
@@ -431,7 +445,7 @@ int cdd_load(char *filename, char *header)
         *ptr = 0;
 
         /* open current track file descriptor */
-        cdd.toc.tracks[cdd.toc.last].fd = fopen(fname, "rb");
+        cdd.toc.tracks[cdd.toc.last].fd = cdStreamOpen(fname);
         if (!cdd.toc.tracks[cdd.toc.last].fd)
         {
           /* error opening file */
@@ -449,32 +463,32 @@ int cdd_load(char *filename, char *header)
         {
           /* read file header */
           unsigned char head[28];
-          fseek(cdd.toc.tracks[cdd.toc.last].fd, 8, SEEK_SET);
-          fread(head, 28, 1, cdd.toc.tracks[cdd.toc.last].fd);
-          fseek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
+          cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 8, SEEK_SET);
+          cdStreamRead(head, 28, 1, cdd.toc.tracks[cdd.toc.last].fd);
+          cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
       
           /* autodetect WAVE file header (44.1KHz 16-bit stereo format only) */
           if (!memcmp(head, waveHeader, 28))
           {
             /* look for 'data' chunk id */
             int dataOffset = 0;
-            fseek(cdd.toc.tracks[cdd.toc.last].fd, 36, SEEK_SET);
-            while (fread(head, 4, 1, cdd.toc.tracks[cdd.toc.last].fd))
+            cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 36, SEEK_SET);
+            while (cdStreamRead(head, 4, 1, cdd.toc.tracks[cdd.toc.last].fd))
             {
               if (!memcmp(head, "data", 4))
               {
-                dataOffset = ftell(cdd.toc.tracks[cdd.toc.last].fd) + 4;
-                fseek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
+                dataOffset = cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) + 4;
+                cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
                 break;
               }
-              fseek(cdd.toc.tracks[cdd.toc.last].fd, -2, SEEK_CUR);
+              cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, -2, SEEK_CUR);
             }
 
             /* check if 'data' chunk has not been found */
             if (!dataOffset)
             {
               /* invalid WAVE file */
-              fclose(cdd.toc.tracks[cdd.toc.last].fd);
+              cdStreamClose(cdd.toc.tracks[cdd.toc.last].fd);
               cdd.toc.tracks[cdd.toc.last].fd = 0;
               break;
             }
@@ -483,7 +497,7 @@ int cdd_load(char *filename, char *header)
             cdd.toc.tracks[cdd.toc.last].offset -= dataOffset;
           }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
-          else if (!ov_open(cdd.toc.tracks[cdd.toc.last].fd,&cdd.toc.tracks[cdd.toc.last].vf,0,0))
+          else if (!ov_open_callbacks(cdd.toc.tracks[cdd.toc.last].fd,&cdd.toc.tracks[cdd.toc.last].vf,0,0,cb))
           {
             /* retrieve stream infos */
             vorbis_info *info = ov_info(&cdd.toc.tracks[cdd.toc.last].vf,-1);
@@ -499,7 +513,7 @@ int cdd_load(char *filename, char *header)
           else
           {
             /* unsupported audio file */
-            fclose(cdd.toc.tracks[cdd.toc.last].fd);
+            cdStreamClose(cdd.toc.tracks[cdd.toc.last].fd);
             cdd.toc.tracks[cdd.toc.last].fd = 0;
             break;
           }
@@ -515,7 +529,7 @@ int cdd_load(char *filename, char *header)
           /* close any opened file */
           if (cdd.toc.tracks[cdd.toc.last].fd)
           {
-            fclose(cdd.toc.tracks[cdd.toc.last].fd);
+            cdStreamClose(cdd.toc.tracks[cdd.toc.last].fd);
             cdd.toc.tracks[cdd.toc.last].fd = 0;
           }
 
@@ -538,7 +552,7 @@ int cdd_load(char *filename, char *header)
             cdd.sectorSize = 2352;
 
             /* skip 16-byte header */
-            fseek(cdd.toc.tracks[0].fd, 0x10, SEEK_SET);
+            cdStreamSeek(cdd.toc.tracks[0].fd, 0x10, SEEK_SET);
           }
 
           if (cdd.sectorSize)
@@ -547,8 +561,8 @@ int cdd_load(char *filename, char *header)
             cdd.toc.tracks[0].type = TYPE_CDROM;
 
             /* read CD image header + security code */
-            fread(header, 0x210, 1, cdd.toc.tracks[0].fd);
-            fseek(cdd.toc.tracks[0].fd, 0, SEEK_SET);
+            cdStreamRead(header, 0x210, 1, cdd.toc.tracks[0].fd);
+            cdStreamSeek(cdd.toc.tracks[0].fd, 0, SEEK_SET);
           }
         }
         else
@@ -638,18 +652,18 @@ int cdd_load(char *filename, char *header)
 #endif
           {
             /* current track end time */
-            fseek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_END);
+            cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_END);
             if (cdd.toc.tracks[cdd.toc.last].type)
             {
               /* DATA track length */
-              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((ftell(cdd.toc.tracks[cdd.toc.last].fd) + cdd.sectorSize - 1) / cdd.sectorSize);
+              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) + cdd.sectorSize - 1) / cdd.sectorSize);
             }
             else
             {
               /* AUDIO track length */
-              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((ftell(cdd.toc.tracks[cdd.toc.last].fd) + 2351) / 2352);
+              cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((cdStreamTell(cdd.toc.tracks[cdd.toc.last].fd) + 2351) / 2352);
             }
-            fseek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
+            cdStreamSeek(cdd.toc.tracks[cdd.toc.last].fd, 0, SEEK_SET);
           }
 
           /* adjust track start time (based on current file start time + index absolute time) */
@@ -687,11 +701,11 @@ int cdd_load(char *filename, char *header)
 #endif
     if (cdd.toc.tracks[cdd.toc.last].fd)
     {
-      fclose(cdd.toc.tracks[cdd.toc.last].fd);
+      cdStreamClose(cdd.toc.tracks[cdd.toc.last].fd);
     }
 
     /* close CUE file */
-    fclose(fd);
+    cdStreamClose(fd);
   }
   else
   {
@@ -705,7 +719,7 @@ int cdd_load(char *filename, char *header)
     {
       /* auto-detect wrong initial track index */
       sprintf(ptr, extensions[i], cdd.toc.last);
-      fd = fopen(fname, "rb");
+      fd = cdStreamOpen(fname);
       if (fd)
       {
         offset = 0;
@@ -713,7 +727,7 @@ int cdd_load(char *filename, char *header)
       }
 
       sprintf(ptr, extensions[i], cdd.toc.last + 1);
-      fd = fopen(fname, "rb");
+      fd = cdStreamOpen(fname);
       if (fd) break;
     }
 
@@ -722,31 +736,31 @@ int cdd_load(char *filename, char *header)
     {
       /* read file HEADER */
       unsigned char head[28];
-      fseek(fd, 8, SEEK_SET);
-      fread(head, 28, 1, fd);
-      fseek(fd, 0, SEEK_SET);
+      cdStreamSeek(fd, 8, SEEK_SET);
+      cdStreamRead(head, 28, 1, fd);
+      cdStreamSeek(fd, 0, SEEK_SET);
       
       /* check if this is a valid WAVE file (44.1KHz 16-bit stereo format only) */
       if (!memcmp(head, waveHeader, 28))
       {
         /* look for 'data' chunk id */
         int dataOffset = 0;
-        fseek(fd, 36, SEEK_SET);
-        while (fread(head, 4, 1, fd))
+        cdStreamSeek(fd, 36, SEEK_SET);
+        while (cdStreamRead(head, 4, 1, fd))
         {
           if (!memcmp(head, "data", 4))
           {
-            dataOffset = ftell(fd) + 4;
+            dataOffset = cdStreamTell(fd) + 4;
             break;
           }
-          fseek(fd, -2, SEEK_CUR);
+          cdStreamSeek(fd, -2, SEEK_CUR);
         }
 
         /* check if 'data' chunk has not been found */
         if (!dataOffset)
         {
           /* invalid WAVE file */
-          fclose(fd);
+          cdStreamClose(fd);
           break;
         }
 
@@ -760,16 +774,16 @@ int cdd_load(char *filename, char *header)
         cdd.toc.tracks[cdd.toc.last].start += 150;
 
         /* current track end time */
-        fseek(fd, 0, SEEK_END);
-        cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((ftell(fd) - dataOffset + 2351) / 2352);
+        cdStreamSeek(fd, 0, SEEK_END);
+        cdd.toc.tracks[cdd.toc.last].end = cdd.toc.tracks[cdd.toc.last].start + ((cdStreamTell(fd) - dataOffset + 2351) / 2352);
 
         /* initialize file read offset for current track */
         cdd.toc.tracks[cdd.toc.last].offset = cdd.toc.tracks[cdd.toc.last].start * 2352;
 
         /* auto-detect PAUSE within audio files */
-        fseek(fd, 100 * 2352, SEEK_SET);
-        fread(head, 4, 1, fd);
-        fseek(fd, 0, SEEK_SET);
+        cdStreamSeek(fd, 100 * 2352, SEEK_SET);
+        cdStreamRead(head, 4, 1, fd);
+        cdStreamSeek(fd, 0, SEEK_SET);
         if (*(int32 *)head == 0)
         {
           /* assume 2s PAUSE is included at the beginning of the file */
@@ -787,7 +801,7 @@ int cdd_load(char *filename, char *header)
         cdd.toc.last++;
       }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
-      else if (!ov_open(fd,&cdd.toc.tracks[cdd.toc.last].vf,0,0))
+      else if (!ov_open_callbacks(fd,&cdd.toc.tracks[cdd.toc.last].vf,0,0,cb))
       {
         /* retrieve stream infos */
         vorbis_info *info = ov_info(&cdd.toc.tracks[cdd.toc.last].vf,-1);
@@ -852,7 +866,7 @@ int cdd_load(char *filename, char *header)
       else
       {
         /* unsupported audio file format */
-        fclose(fd);
+        cdStreamClose(fd);
         break;
       }
 
@@ -861,7 +875,7 @@ int cdd_load(char *filename, char *header)
 
       /* try to open next audio track file */
       sprintf(ptr, extensions[i], cdd.toc.last + offset);
-      fd = fopen(fname, "rb");
+      fd = cdStreamOpen(fname);
     }
   }
 
@@ -976,7 +990,7 @@ int cdd_load(char *filename, char *header)
 
     /* Automatically try to open associated subcode data file */
     strncpy(&fname[strlen(fname) - 4], ".sub", 4);
-    cdd.toc.sub = fopen(fname, "rb");
+    cdd.toc.sub = cdStreamOpen(fname);
 
     /* return 1 if loaded file is CD image file */
     return (isCDfile);
@@ -1014,13 +1028,13 @@ void cdd_unload(void)
         else
         {
           /* close file */
-          fclose(cdd.toc.tracks[i].fd);
+          cdStreamClose(cdd.toc.tracks[i].fd);
         }
       }
     }
 
     /* close any opened subcode file */
-    if (cdd.toc.sub) fclose(cdd.toc.sub);
+    if (cdd.toc.sub) cdStreamClose(cdd.toc.sub);
 
     /* CD unloaded */
     cdd.loaded = 0;
@@ -1042,16 +1056,16 @@ void cdd_read_data(uint8 *dst)
     if (cdd.sectorSize == 2048)
     {
       /* Mode 1 COOKED data (ISO) */
-      fseek(cdd.toc.tracks[0].fd, cdd.lba * 2048, SEEK_SET);
+      cdStreamSeek(cdd.toc.tracks[0].fd, cdd.lba * 2048, SEEK_SET);
     }
     else
     {
       /* Mode 1 RAW data (skip 16-byte header) */
-      fseek(cdd.toc.tracks[0].fd, cdd.lba * 2352 + 16, SEEK_SET);
+      cdStreamSeek(cdd.toc.tracks[0].fd, cdd.lba * 2352 + 16, SEEK_SET);
     }
 
     /* read sector data (Mode 1 = 2048 bytes) */
-    fread(dst, 2048, 1, cdd.toc.tracks[0].fd);
+    cdStreamRead(dst, 2048, 1, cdd.toc.tracks[0].fd);
   }
 }
 
@@ -1139,7 +1153,7 @@ void cdd_read_audio(unsigned int samples)
 #else
       uint8 *ptr = cdc.ram;
 #endif
-      fread(cdc.ram, 1, samples * 4, cdd.toc.tracks[cdd.index].fd);
+      cdStreamRead(cdc.ram, 1, samples * 4, cdd.toc.tracks[cdd.index].fd);
 
       /* process 16-bit (little-endian) stereo samples */
       for (i=0; i<samples; i++)
@@ -1217,7 +1231,7 @@ static void cdd_read_subcode(void)
   index = (scd.regs[0x68>>1].byte.l + 0x100) >> 1;
 
   /* read interleaved subcode data from .sub file (12 x 8-bit of P subchannel first, then Q subchannel, etc) */
-  fread(subc, 1, 96, cdd.toc.sub);
+  cdStreamRead(subc, 1, 96, cdd.toc.sub);
 
   /* convert back to raw subcode format (96 bytes with 8 x P-W subchannel bits per byte) */
   for (i=0; i<96; i+=2)
@@ -1345,7 +1359,7 @@ void cdd_update(void)
       {
 #ifdef DISABLE_MANY_OGG_OPEN_FILES
         /* VORBIS file need to be opened first */
-        ov_open(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0);
+        ov_open_callbacks(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0,cb);
 #endif
         ov_pcm_seek(&cdd.toc.tracks[cdd.index].vf, (cdd.toc.tracks[cdd.index].start * 588) - cdd.toc.tracks[cdd.index].offset);
       }
@@ -1353,7 +1367,7 @@ void cdd_update(void)
 #endif 
       if (cdd.toc.tracks[cdd.index].fd)
       {
-        fseek(cdd.toc.tracks[cdd.index].fd, (cdd.toc.tracks[cdd.index].start * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
+        cdStreamSeek(cdd.toc.tracks[cdd.index].fd, (cdd.toc.tracks[cdd.index].start * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
       }
     }
   }
@@ -1431,14 +1445,14 @@ void cdd_update(void)
     /* seek to current subcode position */
     if (cdd.toc.sub)
     {
-      fseek(cdd.toc.sub, cdd.lba * 96, SEEK_SET);
+      cdStreamSeek(cdd.toc.sub, cdd.lba * 96, SEEK_SET);
     }
 
     /* seek to current track position */
     if (cdd.toc.tracks[cdd.index].type)
     {
       /* DATA track */
-      fseek(cdd.toc.tracks[0].fd, cdd.lba * cdd.sectorSize, SEEK_SET);
+      cdStreamSeek(cdd.toc.tracks[0].fd, cdd.lba * cdd.sectorSize, SEEK_SET);
     }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
     else if (cdd.toc.tracks[cdd.index].vf.seekable)
@@ -1448,7 +1462,7 @@ void cdd_update(void)
       if (!cdd.toc.tracks[cdd.index].vf.datasource)
       {
         /* VORBIS file need to be opened first */
-        ov_open(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0);
+        ov_open_callbacks(cdd.toc.tracks[cdd.index].fd,&cdd.toc.tracks[cdd.index].vf,0,0,cb);
       }
 #endif
       /* VORBIS AUDIO track */
@@ -1458,7 +1472,7 @@ void cdd_update(void)
     else if (cdd.toc.tracks[cdd.index].fd)
     {
       /* PCM AUDIO track */
-      fseek(cdd.toc.tracks[cdd.index].fd, (cdd.lba * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
+      cdStreamSeek(cdd.toc.tracks[cdd.index].fd, (cdd.lba * 2352) - cdd.toc.tracks[cdd.index].offset, SEEK_SET);
     }
   }
 }
@@ -1641,7 +1655,7 @@ void cdd_process(void)
         /* open current track VORBIS file */
         if (cdd.toc.tracks[index].vf.seekable)
         {
-          ov_open(cdd.toc.tracks[index].fd,&cdd.toc.tracks[index].vf,0,0);
+          ov_open_callbacks(cdd.toc.tracks[index].fd,&cdd.toc.tracks[index].vf,0,0,cb);
         }
       }
 #endif
@@ -1659,14 +1673,14 @@ void cdd_process(void)
       /* seek to current subcode position */
       if (cdd.toc.sub)
       {
-        fseek(cdd.toc.sub, lba * 96, SEEK_SET);
+        cdStreamSeek(cdd.toc.sub, lba * 96, SEEK_SET);
       }
       
       /* seek to current track position */
       if (cdd.toc.tracks[index].type)
       {
         /* DATA track */
-        fseek(cdd.toc.tracks[0].fd, lba * cdd.sectorSize, SEEK_SET);
+        cdStreamSeek(cdd.toc.tracks[0].fd, lba * cdd.sectorSize, SEEK_SET);
       }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
       else if (cdd.toc.tracks[index].vf.seekable)
@@ -1678,7 +1692,7 @@ void cdd_process(void)
       else if (cdd.toc.tracks[index].fd)
       {
         /* PCM AUDIO track */
-        fseek(cdd.toc.tracks[index].fd, (lba * 2352) - cdd.toc.tracks[index].offset, SEEK_SET);
+        cdStreamSeek(cdd.toc.tracks[index].fd, (lba * 2352) - cdd.toc.tracks[index].offset, SEEK_SET);
       }
 
       /* no audio track playing (yet) */
@@ -1739,7 +1753,7 @@ void cdd_process(void)
         /* open current track VORBIS file */
         if (cdd.toc.tracks[index].vf.seekable)
         {
-          ov_open(cdd.toc.tracks[index].fd,&cdd.toc.tracks[index].vf,0,0);
+          ov_open_callbacks(cdd.toc.tracks[index].fd,&cdd.toc.tracks[index].vf,0,0,cb);
         }
       }
 #endif
@@ -1758,7 +1772,7 @@ void cdd_process(void)
       if (cdd.toc.tracks[index].type)
       {
         /* DATA track */
-        fseek(cdd.toc.tracks[0].fd, lba * cdd.sectorSize, SEEK_SET);
+        cdStreamSeek(cdd.toc.tracks[0].fd, lba * cdd.sectorSize, SEEK_SET);
       }
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
       else if (cdd.toc.tracks[index].vf.seekable)
@@ -1770,13 +1784,13 @@ void cdd_process(void)
       else if (cdd.toc.tracks[index].fd)
       {
         /* PCM AUDIO track */
-        fseek(cdd.toc.tracks[index].fd, (lba * 2352) - cdd.toc.tracks[index].offset, SEEK_SET);
+        cdStreamSeek(cdd.toc.tracks[index].fd, (lba * 2352) - cdd.toc.tracks[index].offset, SEEK_SET);
       }
 
       /* seek to current subcode position */
       if (cdd.toc.sub)
       {
-        fseek(cdd.toc.sub, lba * 96, SEEK_SET);
+        cdStreamSeek(cdd.toc.sub, lba * 96, SEEK_SET);
       }
 
       /* no audio track playing */
diff --git a/core/cd_hw/cdd.h b/core/cd_hw/cdd.h
index 59d998c..bd09677 100644
--- a/core/cd_hw/cdd.h
+++ b/core/cd_hw/cdd.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  CD drive processor & CD-DA fader
  *
- *  Copyright (C) 2012-2016  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2012-2017  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -64,7 +64,7 @@
 /* CD track */
 typedef struct
 {
-  FILE *fd;
+  cdStream *fd;
 #if defined(USE_LIBTREMOR) || defined(USE_LIBVORBIS)
   OggVorbis_File vf;
 #endif
@@ -80,7 +80,7 @@ typedef struct
   int end;
   int last;
   track_t tracks[CD_MAX_TRACKS];
-  FILE *sub;
+  cdStream *sub;
 } toc_t; 
 
 /* CDD hardware */
diff --git a/core/macros.h b/core/macros.h
index 6f8969f..9b4223c 100644
--- a/core/macros.h
+++ b/core/macros.h
@@ -39,7 +39,7 @@
 
 /* Set to your compiler's static inline keyword to enable it, or
  * set it to blank to disable it.
- * If you define INLINE in the makefile, it will override this value.
+ * If you define INLINE in makefile or osd.h, it will override this value.
  * NOTE: not enabling inline functions will SEVERELY slow down emulation.
  */
 #ifndef INLINE
@@ -53,4 +53,18 @@
 #define ALIGNED_(x) __attribute__ ((aligned(x)))
 #endif
 
+/* Default CD image file access (read-only) functions */
+/* If you need to override default stdio.h functions with custom filesystem API,
+   redefine following macros in platform specific include file (osd.h) or Makefile
+*/
+#ifndef cdStream
+#define cdStream            FILE
+#define cdStreamOpen(fname) fopen(fname, "rb")
+#define cdStreamClose       fclose
+#define cdStreamRead        fread
+#define cdStreamSeek        fseek
+#define cdStreamTell        ftell
+#define cdStreamGets        fgets
+#endif
+
 #endif /* _MACROS_H_ */
diff --git a/core/shared.h b/core/shared.h
index 959f289..3ab1a33 100644
--- a/core/shared.h
+++ b/core/shared.h
@@ -7,8 +7,8 @@
 #include <math.h>
 
 #include "types.h"
-#include "macros.h"
 #include "osd.h"
+#include "macros.h"
 #include "loadrom.h"
 #include "m68k.h"
 #include "z80.h"