Merged in packet-conv (pull request #462)

mts: added function for converting byte slice to Packet to use comcast/gots code

Approved-by: kortschak

container/mts/mpegts.go

@@ -6,11 +6,12 @@ NAME
 DESCRIPTION
   See Readme.md
 
-AUTHOR
+AUTHORS
   Saxon A. Nelson-Milton <saxon.milton@gmail.com>
+  Trek Hopton <trek@ausocean.org>
 
 LICENSE
-  mpegts.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)
+  mpegts.go is Copyright (C) 2017-2021 the Australian Ocean Lab (AusOcean)
 
   It is free software: you can redistribute it and/or modify them
   under the terms of the GNU General Public License as published by the
@@ -31,6 +32,7 @@ package mts
 
 import (
 	"fmt"
+	"unsafe"
 
 	"github.com/Comcast/gots/packet"
 	gotspsi "github.com/Comcast/gots/psi"
@@ -374,6 +376,16 @@ func asByte(b bool) byte {
 	return 0
 }
 
+// GotsPacket takes a byte slice and returns a Packet as defined in github.com/comcast/gots/packet.
+// TODO: replace this with a type conversion as described here: https://github.com/golang/go/issues/395
+// when it becomes available in Go 1.17.
+func GotsPacket(b []byte) *packet.Packet {
+	if len(b) != packet.PacketSize {
+		panic("invalid packet size")
+	}
+	return *(**packet.Packet)(unsafe.Pointer(&b))
+}
+
 type Option func(p *packet.Packet)
 
 // addAdaptationField adds an adaptation field to p, and applys the passed options to this field.
@@ -410,7 +422,7 @@ func resetAdaptation(p *packet.Packet) error {
 	return nil
 }
 
-// DiscontinuityIndicator returns and Option that will set p's discontinuity
+// DiscontinuityIndicator returns an Option that will set p's discontinuity
 // indicator according to f.
 func DiscontinuityIndicator(f bool) Option {
 	return func(p *packet.Packet) {
@@ -638,13 +650,13 @@ func SegmentForMeta(d []byte, key, val string) ([][]byte, error) {
 	// We've reached the end of the entire MTS clip so if we're segmenting we need
 	// to append current segment to res.
 	if segmenting {
-		res = append(res, d[start:len(d)])
+		res = append(res, d[start:])
 	}
 
 	return res, nil
 }
 
-// pid returns the packet identifier for the given packet.
+// PID returns the packet identifier for the given packet.
 func PID(p []byte) (uint16, error) {
 	if len(p) < PacketSize {
 		return 0, errors.New("packet length less than 188")

container/mts/mpegts_test.go

@@ -7,9 +7,10 @@ DESCRIPTION
 
 AUTHORS
   Saxon A. Nelson-Milton <saxon@ausocean.org>
+  Trek Hopton <trek@ausocean.org>
 
 LICENSE
-  Copyright (C) 2019 the Australian Ocean Lab (AusOcean)
+  Copyright (C) 2019-2021 the Australian Ocean Lab (AusOcean)
 
   It is free software: you can redistribute it and/or modify them
   under the terms of the GNU General Public License as published by the
@@ -768,3 +769,12 @@ func TestFindPSI(t *testing.T) {
 		}
 	}
 }
+
+func TestGotsPacket(t *testing.T) {
+	b := make([]byte, 188)
+	p := GotsPacket(b)
+	p.SetPID(PIDAudio)
+	if p.PID() != PIDAudio {
+		t.Error("failed to set PID in gots Packet")
+	}
+}