1 files changed, 129 insertions, 0 deletions
diff --git a/mpeglib/lib/splay/dxHead.cpp b/mpeglib/lib/splay/dxHead.cpp
new file mode 100644
index 00000000..a96bb553
--- /dev/null
+++ b/mpeglib/lib/splay/dxHead.cpp
@@ -0,0 +1,129 @@
+/*---- DXhead.c --------------------------------------------
+
+decoder MPEG Layer III
+handle Xing header
+mod 12/7/98 add vbr scale
+
+Copyright 1998 Xing Technology Corp.
+-----------------------------------------------------------*/
+#include <stdlib.h>
+#include <stdio.h>
+#include <float.h>
+#include <math.h>
+#include "dxHead.h"
+
+// 4   Xing
+// 4   flags
+// 4   frames
+// 4   bytes
+// 100 toc
+
+/*-------------------------------------------------------------*/
+static int ExtractI4(unsigned char *buf)
+{
+int x;
+// big endian extract
+
+x = buf[0];
+x <<= 8;
+x |= buf[1];
+x <<= 8;
+x |= buf[2];
+x <<= 8;
+x |= buf[3];
+
+return x;
+}
+/*-------------------------------------------------------------*/
+int GetXingHeader(XHEADDATA *X,  unsigned char *buf)
+{
+int i, head_flags;
+int h_id, h_mode, h_sr_index;
+static const int sr_table[4] = { 44100, 48000, 32000, 99999 };
+
+// get Xing header data
+
+
+X->flags = 0;     // clear to null incase fail
+
+
+// get selected MPEG header data
+h_id       = (buf[1] >> 3) & 1;
+h_sr_index = (buf[2] >> 2) & 3;
+h_mode     = (buf[3] >> 6) & 3;
+
+
+// determine offset of header
+if( h_id ) {        // mpeg1
+    if( h_mode != 3 ) buf+=(32+4);
+    else              buf+=(17+4);
+}
+else {      // mpeg2
+    if( h_mode != 3 ) buf+=(17+4);
+    else              buf+=(9+4);
+}
+
+if( buf[0] != 'X' ) return 0;    // fail
+if( buf[1] != 'i' ) return 0;    // header not found
+if( buf[2] != 'n' ) return 0;
+if( buf[3] != 'g' ) return 0;
+buf+=4;
+
+X->h_id = h_id;
+X->samprate = sr_table[h_sr_index];
+if( h_id == 0 ) X->samprate >>= 1;
+
+head_flags = X->flags = ExtractI4(buf); buf+=4;      // get flags
+
+if( head_flags & FRAMES_FLAG ) {X->frames   = ExtractI4(buf); buf+=4;}
+if( head_flags & BYTES_FLAG )  {X->bytes = ExtractI4(buf); buf+=4;}
+
+if( head_flags & TOC_FLAG ) {
+    if( X->toc != NULL ) {
+        for(i=0;i<100;i++) X->toc[i] = buf[i];
+    }
+    buf+=100;
+}
+
+X->vbr_scale = -1;
+if( head_flags & VBR_SCALE_FLAG )  {X->vbr_scale = ExtractI4(buf); buf+=4;}
+
+//if( X->toc != NULL ) {
+//for(i=0;i<100;i++) {
+//    if( (i%10) == 0 ) printf("\n");
+//    printf(" %3d", (int)(X->toc[i]));
+//}
+//}
+
+return 1;       // success
+}
+/*-------------------------------------------------------------*/
+int SeekPoint(unsigned char TOC[100], int file_bytes, float percent)
+{
+// interpolate in TOC to get file seek point in bytes
+int a, seekpoint;
+float fa, fb, fx;
+
+
+if( percent < 0.0f )   percent = 0.0f;
+if( percent > 100.0f ) percent = 100.0f;
+
+a = (int)percent;
+if( a > 99 ) a = 99;
+fa = TOC[a];
+if( a < 99 ) {
+    fb = TOC[a+1];
+}
+else {
+    fb = 256.0f;
+}
+
+fx = fa + (fb-fa)*(percent-a);
+//printf("%f  .......   %f ...... %f\n",fa,fb,fx);
+
+seekpoint = (int)((1.0f/256.0f)*fx*file_bytes); 
+
+
+return seekpoint;
+}
+/*-------------------------------------------------------------*/