diff --git a/src/header.c b/src/header.c
index b479a8a1..78e05a77 100644
--- a/src/header.c
+++ b/src/header.c
@@ -5,106 +5,3 @@
 #include "streamtypes.h"
 #include "util.h"
 
-/**
- * checks if the stream filename is one of the extensions (comma-separated, ex. "adx" or "adx,aix")
- *
- * returns 0 on failure
- */
-int header_check_extensions(STREAMFILE *streamFile, const char * cmpexts) {
-    char filename[PATH_LIMIT];
-    const char * ext = NULL;
-    const char * cmpext = NULL;
-    size_t ext_len;
-
-    streamFile->get_name(streamFile,filename,sizeof(filename));
-    ext = filename_extension(filename);
-    ext_len = strlen(ext);
-
-    cmpext = cmpexts;
-    do {
-        if (strncasecmp(ext,cmpext, ext_len)==0 )
-            return 1;
-        cmpext = strstr(cmpext, ",");
-        if (cmpext != NULL)
-            cmpext = cmpext + 1; /* skip comma */
-    } while (cmpext != NULL);
-
-    return 0;
-}
-
-
-/**
- * opens a stream at offset
- *
- * returns 0 on failure
- */
-int header_open_stream(VGMSTREAM * vgmstream, STREAMFILE *streamFile, off_t start_offset) {
-    STREAMFILE * file;
-    char filename[PATH_LIMIT];
-    int ch;
-    int buffer_size = STREAMFILE_DEFAULT_BUFFER_SIZE;
-
-#ifdef VGM_USE_FFMPEG
-    if (vgmstream->coding_type == coding_FFmpeg) /* not needed */
-        return 1;
-#endif
-
-    /* minor optimizations */
-    if (vgmstream->layout_type == layout_interleave
-            &&vgmstream->interleave_block_size > 0
-            && vgmstream->interleave_block_size > buffer_size) {
-        buffer_size = vgmstream->interleave_block_size;
-    }
-
-    if (buffer_size > 0x8000) {
-        buffer_size = 0x8000;
-        /* todo if interleave is big enough open one streamfile per channel so each uses it's own buffer */
-    }
-
-
-    streamFile->get_name(streamFile,filename,sizeof(filename));
-    /* open the file for reading by each channel */
-    {
-        file = streamFile->open(streamFile,filename,buffer_size);
-        if (!file) return 0;
-
-        for (ch=0; ch < vgmstream->channels; ch++) {
-
-            vgmstream->ch[ch].streamfile = file;
-
-            if (vgmstream->layout_type == layout_none
-#ifdef VGM_USE_MPEG
-                    || vgmstream->layout_type == layout_mpeg //todo simplify using flag "start offset"
-#endif
-                    ) { /* no appreciable difference for mpeg */
-                /* for some codecs like IMA where channels work with the same bytes */
-                vgmstream->ch[ch].channel_start_offset =
-                        vgmstream->ch[ch].offset = start_offset;
-            }
-            else {
-                vgmstream->ch[ch].channel_start_offset =
-                        vgmstream->ch[ch].offset = start_offset
-                        + vgmstream->interleave_block_size*ch;
-            }
-        }
-    }
-
-
-    return 1;
-}
-
-
-#if 0
-/**
- * Converts a data offset (without headers) to sample, so full datasize would be num_samples
- *
- * return -1 on failure
- */
-int data_offset_to_samples(layout_t layout, int channels, size_t interleave, size_t data_offset) {
-    // todo get samples per block
-    // VAG: datasize * 28 / 16 / channels;
-    // IMA: (datasize / 0x24 / channels) * ((0x24-4)*2);//0x24 = interleave?
-    // DSP:  datasize / 8 / channel_count * 14;
-}
-
-#endif
diff --git a/src/header.h b/src/header.h
index d5cd44ce..9c652972 100644
--- a/src/header.h
+++ b/src/header.h
@@ -10,8 +10,5 @@
 #include "vgmstream.h"
 
 
-int header_check_extensions(STREAMFILE *streamFile, const char * cmpexts);
-
-int header_open_stream(VGMSTREAM * vgmstream, STREAMFILE *streamFile, off_t start_offset);
 
 #endif /* _HEADER_H_ */
diff --git a/src/meta/baf.c b/src/meta/baf.c
index 8ef6f822..dff1503f 100644
--- a/src/meta/baf.c
+++ b/src/meta/baf.c
@@ -1,9 +1,6 @@
 #include "meta.h"
-#include "../util.h"
-#include "../header.h"
 
 /* .BAF - Bizarre Creations (Blur, James Bond 007: Blood Stone, etc) */
-
 VGMSTREAM * init_vgmstream_baf(STREAMFILE *streamFile) {
     VGMSTREAM * vgmstream = NULL;
     off_t WAVE_size, DATA_size;
@@ -17,7 +14,7 @@ VGMSTREAM * init_vgmstream_baf(STREAMFILE *streamFile) {
     int loop_flag = 0;
 
     /* check extensions */
-    if ( !header_check_extensions(streamFile, "baf") )
+    if ( !check_extensions(streamFile, "baf") )
         goto fail;
 
     /* check WAVE */
@@ -57,7 +54,7 @@ VGMSTREAM * init_vgmstream_baf(STREAMFILE *streamFile) {
     vgmstream->meta_type = meta_BAF;
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
diff --git a/src/meta/bgw.c b/src/meta/bgw.c
index 4656fbe5..12830685 100644
--- a/src/meta/bgw.c
+++ b/src/meta/bgw.c
@@ -1,12 +1,7 @@
 #include "meta.h"
-#include "../util.h"
-#include "../header.h"
 
-/**
- * BGW - Final Fantasy XI (PC) music files.
- *
- * Some info from POLUtils
- */
+/* BGW - from Final Fantasy XI (PC) music files
+ * Some info from POLUtils */
 VGMSTREAM * init_vgmstream_bgw(STREAMFILE *streamFile) {
     VGMSTREAM * vgmstream = NULL;
     uint32_t codec, filesize, blocksize, sample_rate;
@@ -17,7 +12,7 @@ VGMSTREAM * init_vgmstream_bgw(STREAMFILE *streamFile) {
     int channel_count, loop_flag = 0;
 
     /* check extensions */
-    if ( !header_check_extensions(streamFile, "bgw") )
+    if ( !check_extensions(streamFile, "bgw") )
         goto fail;
 
     /* check header */
@@ -74,7 +69,7 @@ VGMSTREAM * init_vgmstream_bgw(STREAMFILE *streamFile) {
 
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
@@ -84,9 +79,7 @@ fail:
     return NULL;
 }
 
-/**
- * SPW (SEWave), PlayOnline viewer for Final Fantasy XI (PC)
- */
+/* SPW (SEWave) - from  PlayOnline viewer for Final Fantasy XI (PC) */
 VGMSTREAM * init_vgmstream_spw(STREAMFILE *streamFile) {
     VGMSTREAM * vgmstream = NULL;
     uint32_t codec, filesize, blocksize, sample_rate;
@@ -97,7 +90,7 @@ VGMSTREAM * init_vgmstream_spw(STREAMFILE *streamFile) {
     int channel_count, loop_flag = 0;
 
 	/* check extensions */
-	if ( !header_check_extensions(streamFile, "spw") )
+	if ( !check_extensions(streamFile, "spw") )
         goto fail;
 
     /* check header */
@@ -168,7 +161,7 @@ VGMSTREAM * init_vgmstream_spw(STREAMFILE *streamFile) {
 
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
diff --git a/src/meta/fsb.c b/src/meta/fsb.c
index f7ddaa74..29e3a89e 100644
--- a/src/meta/fsb.c
+++ b/src/meta/fsb.c
@@ -1,7 +1,5 @@
 #include "meta.h"
 #include "../coding/coding.h"
-#include "../util.h"
-#include "../header.h"
 
 #define FAKE_RIFF_BUFFER_SIZE           100
 
@@ -122,7 +120,7 @@ VGMSTREAM * init_vgmstream_fsb_offset(STREAMFILE *streamFile, off_t offset) {
     FSB_HEADER fsbh;
 
     /* check extensions */
-    if ( !header_check_extensions(streamFile, "fsb,wii") )
+    if ( !check_extensions(streamFile, "fsb,wii") )
         goto fail;
 
     h_off = offset;
@@ -396,7 +394,7 @@ VGMSTREAM * init_vgmstream_fsb_offset(STREAMFILE *streamFile, off_t offset) {
 
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
diff --git a/src/meta/ps2.c b/src/meta/ps2.c
index efaa0290..dd29f9c8 100644
--- a/src/meta/ps2.c
+++ b/src/meta/ps2.c
@@ -1,6 +1,4 @@
 #include "meta.h"
-#include "../util.h"
-#include "../header.h"
 
 /* VDS/VDM - from Grafitti Kingdom / Rakugaki Oukoku 2 */
 VGMSTREAM * init_vgmstream_ps2_vds_vdm(STREAMFILE *streamFile) {
@@ -9,7 +7,7 @@ VGMSTREAM * init_vgmstream_ps2_vds_vdm(STREAMFILE *streamFile) {
     int loop_flag, channel_count;
 
     /* check extension, case insensitive */
-    if ( !header_check_extensions(streamFile,"vds,vdm"))
+    if ( !check_extensions(streamFile,"vds,vdm"))
         goto fail;
 
     if (read_32bitBE(0x00,streamFile) != 0x56445320 && /* "VDS " (music)*/
@@ -40,7 +38,7 @@ VGMSTREAM * init_vgmstream_ps2_vds_vdm(STREAMFILE *streamFile) {
     /*0x23: 02=VDS 04=VDM? */
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
     return vgmstream;
 
diff --git a/src/meta/ps2_vag.c b/src/meta/ps2_vag.c
index 8703a317..6f7b7eba 100644
--- a/src/meta/ps2_vag.c
+++ b/src/meta/ps2_vag.c
@@ -1,6 +1,4 @@
 #include "meta.h"
-#include "../util.h"
-#include "../header.h"
 
 
 static int vag_find_loop_offsets(STREAMFILE *streamFile, off_t start_offset, off_t * loop_start, off_t * loop_end);
@@ -22,16 +20,16 @@ VGMSTREAM * init_vgmstream_ps2_vag(STREAMFILE *streamFile) {
     int is_swag = 0;
 
     /* check extension, case insensitive */
-    if ( !header_check_extensions(streamFile,"vag,swag") )
+    if ( !check_extensions(streamFile,"vag,swag") )
+        goto fail;
+
+    /* check VAG Header */
+    if (((read_32bitBE(0x00,streamFile) & 0xFFFFFF00) != 0x56414700) && /* "VAG" */
+        ((read_32bitLE(0x00,streamFile) & 0xFFFFFF00) != 0x56414700))
         goto fail;
 
     /* Frantix VAGp .swag: some (not all) fields in LE + 2 VAGp in the same file (full interleave) */
-    is_swag = header_check_extensions(streamFile,"swag");
-
-    /* check VAG Header */
-    if (((read_32bitBE(0x00,streamFile) & 0xFFFFFF00) != 0x56414700) && /* "VAG\0" */
-        ((read_32bitLE(0x00,streamFile) & 0xFFFFFF00) != 0x56414700))
-        goto fail;
+    is_swag = check_extensions(streamFile,"swag");
 
     filesize = get_streamfile_size(streamFile);
 
@@ -211,7 +209,7 @@ VGMSTREAM * init_vgmstream_ps2_vag(STREAMFILE *streamFile) {
 
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
diff --git a/src/meta/ps3_vawx.c b/src/meta/ps3_vawx.c
index 4acb14f9..28e74922 100644
--- a/src/meta/ps3_vawx.c
+++ b/src/meta/ps3_vawx.c
@@ -1,6 +1,4 @@
 #include "meta.h"
-#include "../util.h"
-#include "../header.h"
 #include "../coding/coding.h"
 
 #define FAKE_RIFF_BUFFER_SIZE           100
@@ -15,7 +13,7 @@ VGMSTREAM * init_vgmstream_vawx(STREAMFILE *streamFile) {
     int loop_flag = 0, channel_count, type;
 
     /* check extensions */
-    if ( !header_check_extensions(streamFile, "vawx,xwv") )
+    if ( !check_extensions(streamFile, "vawx,xwv") )
         goto fail;
 
     /* check header */
@@ -115,7 +113,7 @@ VGMSTREAM * init_vgmstream_vawx(STREAMFILE *streamFile) {
 
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
 
     return vgmstream;
diff --git a/src/meta/x360.c b/src/meta/x360.c
index c75c11d6..311cdbc9 100644
--- a/src/meta/x360.c
+++ b/src/meta/x360.c
@@ -1,5 +1,4 @@
 #include "meta.h"
-#include "../header.h"
 #include "../coding/coding.h"
 
 /* CXS - found in Eternal Sonata (Xbox 360) */
@@ -9,7 +8,7 @@ VGMSTREAM * init_vgmstream_x360_cxs(STREAMFILE *streamFile) {
     int loop_flag, channel_count;
 
     /* check extension, case insensitive */
-    if ( !header_check_extensions(streamFile,"cxs"))
+    if ( !check_extensions(streamFile,"cxs"))
         goto fail;
 
     if (read_32bitBE(0x00,streamFile) != 0x43585320)   /* "CXS " */
@@ -57,7 +56,7 @@ VGMSTREAM * init_vgmstream_x360_cxs(STREAMFILE *streamFile) {
 #endif
 
     /* open the file for reading */
-    if ( !header_open_stream(vgmstream, streamFile, start_offset) )
+    if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
     return vgmstream;
 
diff --git a/src/streamfile.c b/src/streamfile.c
index 0e5f1e68..354eebc7 100644
--- a/src/streamfile.c
+++ b/src/streamfile.c
@@ -1,9 +1,9 @@
 #ifndef _MSC_VER
 #include <unistd.h>
 #endif
-#include "vgmstream.h"
 #include "streamfile.h"
 #include "util.h"
+#include "vgmstream.h"
 
 typedef struct {
     STREAMFILE sf;
@@ -391,3 +391,31 @@ fail:
 
     return 0;
 }
+
+
+/**
+ * checks if the stream filename is one of the extensions (comma-separated, ex. "adx" or "adx,aix")
+ *
+ * returns 0 on failure
+ */
+int check_extensions(STREAMFILE *streamFile, const char * cmp_exts) {
+    char filename[PATH_LIMIT];
+    const char * ext = NULL;
+    const char * cmp_ext = NULL;
+    size_t ext_len;
+
+    streamFile->get_name(streamFile,filename,sizeof(filename));
+    ext = filename_extension(filename);
+    ext_len = strlen(ext);
+
+    cmp_ext = cmp_exts;
+    do {
+        if (strncasecmp(ext,cmp_ext, ext_len)==0 )
+            return 1;
+        cmp_ext = strstr(cmp_ext, ",");
+        if (cmp_ext != NULL)
+            cmp_ext = cmp_ext + 1; /* skip comma */
+    } while (cmp_ext != NULL);
+
+    return 0;
+}
diff --git a/src/streamfile.h b/src/streamfile.h
index f0347744..1127c995 100644
--- a/src/streamfile.h
+++ b/src/streamfile.h
@@ -146,11 +146,12 @@ static inline STREAMFILE * open_stdio_streamfile(const char * const filename) {
     return open_stdio_streamfile_buffer(filename,STREAMFILE_DEFAULT_BUFFER_SIZE);
 }
 
-size_t get_streamfile_dos_line(int dst_length, char * dst, off_t offset,
-                STREAMFILE * infile, int *line_done_ptr);
+size_t get_streamfile_dos_line(int dst_length, char * dst, off_t offset, STREAMFILE * infile, int *line_done_ptr);
 
 int read_key_file(uint8_t * buf, size_t bufsize, STREAMFILE *streamFile);
 
 int read_pos_file(uint8_t * buf, size_t bufsize, STREAMFILE *streamFile);
 
+int check_extensions(STREAMFILE *streamFile, const char * cmp_exts);
+
 #endif
diff --git a/src/vgmstream.c b/src/vgmstream.c
index d7366e8b..9249a5a9 100644
--- a/src/vgmstream.c
+++ b/src/vgmstream.c
@@ -2234,3 +2234,59 @@ int get_vgmstream_average_bitrate(VGMSTREAM * vgmstream)
     
     return bitrate;
 }
+
+
+int vgmstream_open_stream(VGMSTREAM * vgmstream, STREAMFILE *streamFile, off_t start_offset) {
+    STREAMFILE * file;
+    char filename[PATH_LIMIT];
+    int ch;
+    int buffer_size = STREAMFILE_DEFAULT_BUFFER_SIZE;
+
+#ifdef VGM_USE_FFMPEG
+    if (vgmstream->coding_type == coding_FFmpeg) /* not needed */
+        return 1;
+#endif
+
+    /* minor optimizations */
+    if (vgmstream->layout_type == layout_interleave
+            &&vgmstream->interleave_block_size > 0
+            && vgmstream->interleave_block_size > buffer_size) {
+        buffer_size = vgmstream->interleave_block_size;
+    }
+
+    if (buffer_size > 0x8000) {
+        buffer_size = 0x8000;
+        /* todo if interleave is big enough open one streamfile per channel so each uses it's own buffer */
+    }
+
+
+    streamFile->get_name(streamFile,filename,sizeof(filename));
+    /* open the file for reading by each channel */
+    {
+        file = streamFile->open(streamFile,filename,buffer_size);
+        if (!file) return 0;
+
+        for (ch=0; ch < vgmstream->channels; ch++) {
+
+            vgmstream->ch[ch].streamfile = file;
+
+            if (vgmstream->layout_type == layout_none
+#ifdef VGM_USE_MPEG
+                    || vgmstream->layout_type == layout_mpeg //todo simplify using flag "start offset"
+#endif
+                    ) { /* no appreciable difference for mpeg */
+                /* for some codecs like IMA where channels work with the same bytes */
+                vgmstream->ch[ch].channel_start_offset =
+                        vgmstream->ch[ch].offset = start_offset;
+            }
+            else {
+                vgmstream->ch[ch].channel_start_offset =
+                        vgmstream->ch[ch].offset = start_offset
+                        + vgmstream->interleave_block_size*ch;
+            }
+        }
+    }
+
+
+    return 1;
+}
diff --git a/src/vgmstream.h b/src/vgmstream.h
index 8725cded..696eb3f6 100644
--- a/src/vgmstream.h
+++ b/src/vgmstream.h
@@ -994,4 +994,9 @@ int vgmstream_do_loop(VGMSTREAM * vgmstream);
  * If a suitable file is found, open it and change opened_stream to a stereo stream. */
 void try_dual_file_stereo(VGMSTREAM * opened_stream, STREAMFILE *streamFile);
 
+
+/* Open the stream for reading at offset (standarized taking into account layouts, channels and so on).
+ * returns 0 on failure */
+int vgmstream_open_stream(VGMSTREAM * vgmstream, STREAMFILE *streamFile, off_t start_offset);
+
 #endif