Merged in add-findpid (pull request #145)

stream/mts: added general FindPID func and FindPAT func.

stream/mts/mpegts.go

@@ -30,6 +30,7 @@ package mts
 
 import (
 	"errors"
+	"fmt"
 )
 
 // General mpegts packet properties.
@@ -157,20 +158,32 @@ type Packet struct {
 	Payload  []byte // Mpeg ts Payload
 }
 
-// FindPMT will take a clip of mpegts and try to find a PMT table - if one
+// FindPmt will take a clip of mpegts and try to find a PMT table - if one
 // is found, then it is returned along with its index, otherwise nil, -1 and an error is returned.
-func FindPMT(d []byte) (p []byte, i int, err error) {
+func FindPmt(d []byte) ([]byte, int, error) {
+	return FindPid(d, PmtPid)
+}
+
+// FindPat will take a clip of mpegts and try to find a PAT table - if one
+// is found, then it is returned along with its index, otherwise nil, -1 and an error is returned.
+func FindPat(d []byte) ([]byte, int, error) {
+	return FindPid(d, PatPid)
+}
+
+// FindPid will take a clip of mpegts and try to find a packet with given PID - if one
+// is found, then it is returned along with its index, otherwise nil, -1 and an error is returned.
+func FindPid(d []byte, pid uint16) (pkt []byte, i int, err error) {
 	if len(d) < PacketSize {
 		return nil, -1, errors.New("Mmpegts data not of valid length")
 	}
 	for i = 0; i < len(d); i += PacketSize {
-		pid := (uint16(d[i+1]&0x1f) << 8) | uint16(d[i+2])
-		if pid == pmtPid {
-			p = d[i+4 : i+PacketSize]
+		p := (uint16(d[i+1]&0x1f) << 8) | uint16(d[i+2])
+		if p == pid {
+			pkt = d[i+4 : i+PacketSize]
 			return
 		}
 	}
-	return nil, -1, errors.New("Could not find pmt table in mpegts data")
+	return nil, -1, fmt.Errorf("could not find packet with pid: %d", pid)
 }
 
 // FillPayload takes a channel and fills the packets Payload field until the