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Update StreamSwitchSignalId() to support single-UPID descriptors #179

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Merged
laba2346 merged 1 commit into from
May 6, 2026
Merged

Update StreamSwitchSignalId() to support single-UPID descriptors #179

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13 changes: 7 additions & 6 deletions scte35/segmentationdescriptor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -374,12 +374,13 @@ func (d *segmentationDescriptor) UPID() []byte {
func (d *segmentationDescriptor) StreamSwitchSignalId() (string, error) {
var signalId string
var err error
// The VSS SignalId is present in the MID of len 2.
// SignalId is the UPID value in the MID which has
// delivery_not_restricted flag = 0 and
// contains "BLACKOUT" at UpidType of 0x09 and
// comcast:linear:licenserotation at 0x0E
if len(d.mid) == 2 &&
// The VSS SignalId can be found either in the top level `segmentation_upid` when the UPID type is 0x09, or
// in the MID of len 2 when the first UPID has type 0x09 and the second UPID has type 0x0E.
if d.upidType == SegUPIDADI &&
!d.deliveryNotRestricted &&
strings.Contains(string(d.upid), "BLACKOUT") {
signalId = strings.TrimPrefix(string(d.upid), "BLACKOUT:")
} else if len(d.mid) == 2 &&
!d.deliveryNotRestricted &&
(d.mid[0].upidType == SegUPIDADI) &&
(strings.Contains(string(d.mid[0].upid), "BLACKOUT")) &&
Expand Down
30 changes: 30 additions & 0 deletions scte35/segmentationdescriptor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,15 @@ var vss = []byte{
0x00, 0x00, 0x00, 0x09, 0x7f, 0x97, 0x00, 0x00, 0x41, 0x00, 0x00, 0x7a, 0xd7, 0xa4, 0x65,
}

var vssSingleUPID = []byte{
0x00, 0xfc, 0x30, 0x59, 0x00, 0x01, 0xa1, 0xe9, 0xbe, 0xfa, 0xff, 0xff, 0xf0, 0x05, 0x06, 0xfe,
0x00, 0x00, 0x00, 0x00, 0x00, 0x43, 0x02, 0x30, 0x43, 0x55, 0x45, 0x49, 0xfd, 0x88, 0x9d, 0x22,
0x7f, 0x97, 0x09, 0x21, 0x42, 0x4c, 0x41, 0x43, 0x4b, 0x4f, 0x55, 0x54, 0x3a, 0x55, 0x52, 0x53,
0x64, 0x44, 0x67, 0x43, 0x59, 0x64, 0x5f, 0x5f, 0x68, 0x5f, 0x61, 0x77, 0x59, 0x4d, 0x44, 0x41,
0x77, 0x4d, 0x41, 0x41, 0x41, 0x40, 0x00, 0x00, 0x02, 0x0f, 0x43, 0x55, 0x45, 0x49, 0xfd, 0x88,
0x9d, 0x22, 0x7f, 0x97, 0x00, 0x00, 0x41, 0x00, 0x00, 0x36, 0xd9, 0x86, 0xac,
}

func TestNoInRules(t *testing.T) {
out, err := NewSCTE35(poOpen1)
if err != nil {
Expand Down Expand Up @@ -270,3 +279,24 @@ func TestVSSSignalId(t *testing.T) {
t.FailNow()
}
}

func TestVSSSignalIdSingleUPID(t *testing.T) {
expectedSignalId := "URSdDgCYd__h_awYMDAwMAAA"
vssScte35, err := NewSCTE35([]byte(vssSingleUPID))

if err != nil {
t.Error("NewSCTE35(vssSingleUPID) returned err:", err.Error())
t.FailNow()
}

signalID, err := vssScte35.Descriptors()[0].StreamSwitchSignalId()
if err != nil {
t.Fatal(err)
}

// Compare against the Signal ID we should see in the vssScte35 signal.
if strings.Compare(signalID, expectedSignalId) != 0 {
t.Error("SignalID parsed, not as expected")
t.FailNow()
}
}
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