+static int find_sync_word(unsigned char *buf, int nBytes)
+{
+ unsigned char *p, *pe;
+
+ /* find byte-aligned syncword - need 12 (MPEG 1,2) or 11 (MPEG 2.5) matching bits */
+ for (p = buf, pe = buf + nBytes - 4; p < pe; p++)
+ {
+ int pn;
+ if (p[0] != 0xff) continue;
+ pn = p[1];
+ if ((pn & 0xf8) != 0xf8 || // currently must be MPEG1
+ (pn & 6) == 0) { // invalid layer
+ p++; continue;
+ }
+ pn = p[2];
+ if ((pn & 0xf0) < 0x20 || (pn & 0xf0) == 0xf0 || // bitrates
+ (pn & 0x0c) != 0) { // not 44kHz
+ continue;
+ }
+
+ return p - buf;
+ }
+
+ return -1;
+}
+
+