feat: SpliceInfoSection: add methods TimeSpecifiedFlag, SpliceTimePTS (#86)

This adds two methods to SpliceInfoSection.

TimeSpecifiedFlag returns true if the splice command is either SpliceInsert or TimeSignal and a splice time (PTSTime) is specified.

SpliceTimePTS returns the splice time PTS, adjusted by PTSAdjustment. If no time is specified, 0 is returned.

Co-authored-by: Jeff Bailey <[email protected]>

Author: julijane

pkg/scte35/splice_info_section.go

@@ -44,6 +44,9 @@ const (
 	SAPType3 = uint32(0x2)
 	// SAPTypeNotSpecified indicates the type of SAP, if any, is not signaled.
 	SAPTypeNotSpecified = uint32(0x3)
+
+	// MaxPTS is the maximum value for a 33-bit PTS value.
+	MaxPTS = 1<<33 - 1
 )
 
 // SpliceInfoSection shall be carried in transport packets whereby only one
@@ -210,6 +213,40 @@ func (sis *SpliceInfoSection) Durations() []Duration {
 	return durations
 }
 
+// TimeSpecifiedFlag returns true if the SpliceInfoSection contains a splice
+// command for a splice event for which the splice time is specified.
+func (sis *SpliceInfoSection) TimeSpecifiedFlag() bool {
+	switch sc := sis.SpliceCommand.(type) {
+	case *SpliceInsert:
+		return sc.TimeSpecifiedFlag()
+	case *TimeSignal:
+		return sc.SpliceTime.TimeSpecifiedFlag()
+	default:
+		return false
+	}
+}
+
+// SpliceTimePTS returns the final PTS time of the splice event, i.e. the
+// splice time of the command adjusted by the PTS adjustment. If the splice
+// command does not have a splice even for which splice time is specified,
+// this method returns 0.
+func (sis *SpliceInfoSection) SpliceTimePTS() uint64 {
+	switch sc := sis.SpliceCommand.(type) {
+	case *SpliceInsert:
+		if !sc.TimeSpecifiedFlag() {
+			return 0
+		}
+		return (*sc.Program.SpliceTime.PTSTime + sis.PTSAdjustment) & MaxPTS
+	case *TimeSignal:
+		if !sc.SpliceTime.TimeSpecifiedFlag() {
+			return 0
+		}
+		return (*sc.SpliceTime.PTSTime + sis.PTSAdjustment) & MaxPTS
+	default:
+		return 0
+	}
+}
+
 // Encode returns the binary representation of this SpliceInfoSection as a
 // byte array.
 func (sis *SpliceInfoSection) Encode() ([]byte, error) {

pkg/scte35/splice_info_section_test.go

@@ -391,3 +391,163 @@ func TestDurations(t *testing.T) {
 		})
 	}
 }
+
+func Test_TimeSpecifiedFlag(t *testing.T) {
+	cases := map[string]struct {
+		sis      scte35.SpliceInfoSection
+		expected bool
+	}{
+		"SpliceInsert": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{
+						SpliceTime: scte35.SpliceTime{
+							PTSTime: ptr(uint64(90000)),
+						},
+					},
+				},
+			},
+			expected: true,
+		},
+		"SpliceInsertNoProgramSplice": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{},
+			},
+			expected: false,
+		},
+		"SpliceInsertNoSpliceTime": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{},
+				},
+			},
+			expected: false,
+		},
+		"TimeSignal": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{PTSTime: ptr(uint64(90000))},
+				},
+			},
+			expected: true,
+		},
+		"TimeSignalNoSpliceTime": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{},
+				},
+			},
+			expected: false,
+		},
+	}
+
+	for k, c := range cases {
+		t.Run(k, func(t *testing.T) {
+			require.Equal(t, c.expected, c.sis.TimeSpecifiedFlag())
+		})
+	}
+}
+
+func Test_SpliceTimePTS(t *testing.T) {
+	cases := map[string]struct {
+		sis      scte35.SpliceInfoSection
+		expected uint64
+	}{
+		"SpliceInsert": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{
+						SpliceTime: scte35.SpliceTime{
+							PTSTime: ptr(uint64(90000)),
+						},
+					},
+				},
+			},
+			expected: 90000,
+		},
+		"SpliceInsertPtsAdjustment": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{
+						SpliceTime: scte35.SpliceTime{
+							PTSTime: ptr(uint64(90000)),
+						},
+					},
+				},
+				PTSAdjustment: 90000,
+			},
+			expected: 180000,
+		},
+		"SpliceInsertPtsAdjustmentWrapping": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{
+						SpliceTime: scte35.SpliceTime{
+							PTSTime: ptr(uint64(8589844592)),
+						},
+					},
+				},
+				PTSAdjustment: 180000,
+			},
+			expected: 90000,
+		},
+		"SpliceInsertNoProgramSplice": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{},
+			},
+			expected: 0,
+		},
+		"SpliceInsertNoSpliceTime": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.SpliceInsert{
+					Program: &scte35.SpliceInsertProgram{},
+				},
+			},
+			expected: 0,
+		},
+		"TimeSignal": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{PTSTime: ptr(uint64(90000))},
+				},
+			},
+			expected: 90000,
+		},
+		"TimeSingalPtsAdjustment": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{
+						PTSTime: ptr(uint64(90000)),
+					},
+				},
+				PTSAdjustment: 90000,
+			},
+			expected: 180000,
+		},
+		"TimeSignalPtsAdjustmentWrapping": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{
+						PTSTime: ptr(uint64(8589844592)),
+					},
+				},
+				PTSAdjustment: 180000,
+			},
+			expected: 90000,
+		},
+		"TimeSignalNoSpliceTime": {
+			sis: scte35.SpliceInfoSection{
+				SpliceCommand: &scte35.TimeSignal{
+					SpliceTime: scte35.SpliceTime{},
+				},
+			},
+			expected: 0,
+		},
+	}
+
+	for k, c := range cases {
+		t.Run(k, func(t *testing.T) {
+			require.Equal(t, c.expected, c.sis.SpliceTimePTS())
+		})
+	}
+}