commit c0a87bbed2f0947fe30ae80a5466bdae4de7621b
parent f2aae646ea349e196c882dea120da8243efb37f6
Author: Oliver Lowe <o@olowe.co>
Date: Fri, 31 May 2024 13:51:31 +1000
scte35: Add most important docs
Still more to go but these are the most crucial bits that most users
of the package - including us! - would need. In particuclar:
- package overview
- all fields of Splice
- example encoding splice
Diffstat:
2 files changed, 62 insertions(+), 3 deletions(-)
diff --git a/scte35/codec_test.go b/scte35/codec_test.go
@@ -33,3 +33,38 @@ func Example() {
// 28980000
// /DA0AAAAAAAA///wBQb+cr0AUAAeAhxDVUVJSAAAjn/PAAG6MyAICAAAAAAsoKGKNAIAQO/SuQ==
}
+
+func ExampleEncode() {
+ when := uint64(12 * 60 * 60 * 90000) // 12 hours since midnight UTC as 90KHz ticks
+ duration := uint64(60 * 90000) // 60 seconds as 90KHz ticks
+ splice := scte35.Splice{
+ SAPType: scte35.SAPNone,
+ Tier: 0x0fff,
+ Command: &scte35.Command{
+ Type: scte35.TimeSignal,
+ TimeSignal: &when,
+ },
+ Descriptors: []scte35.SpliceDescriptor{
+ scte35.SegmentationDescriptor{
+ EventID: 1234,
+ Restrictions: scte35.NoRegionalBlackout | scte35.ArchiveAllowed | scte35.DeviceRestrictionsNone,
+ Duration: &duration,
+ UPID: scte35.UPID{
+ Type: scte35.UPIDTI,
+ Value: []byte{0x00, 0x00, 0x00, 0x00, 0x2c, 0xa0, 0xa1, 0x8a},
+ },
+ Type: 0x34,
+ Number: 2,
+ Expected: 0,
+ },
+ },
+ }
+ b, err := scte35.Encode(&splice)
+ if err != nil {
+ // handle error...
+ }
+ // SCTE 35 time_signal() commands can be inserted into HLS playlists using the
+ // EXT-X-DATERANGE tag. See "Mapping SCTE-35 into EXT-X-DATERANGE"
+ // RFC 8216 section 4.3.2.7.1.
+ fmt.Printf("#EXT-X-DATERANGE:ID=\"example\",SCTE35-CMD=%#x\n", b)
+}
diff --git a/scte35/splice.go b/scte35/splice.go
@@ -1,3 +1,8 @@
+// Package scte35 implements a subset of the
+// Digital Program Insertion Cueing Message standard
+// as specified in [ANSI/SCTE 35].
+//
+// [ANSI/SCTE 35]: https://www.scte.org/standards/library/catalog/scte-35-digital-program-insertion-cueing-message/
package scte35
import (
@@ -33,15 +38,34 @@ func (t SAPType) String() string {
type Splice struct {
SAPType SAPType
+
+ // If true, indicates that the contents of Command,
+ // Descriptors and CRC32 are encrypted with Cipher.
+ // TODO(otl): encoding and decoding of encrypted splices is not supported.
Encrypted bool
Cipher Cipher
- // Holds a 33-bit unsigned integer representing the number of ticks of a 90KHz clock.
- PTSAdjustment uint64
+ // The control word (key) used to decrypt the message.
CWIndex uint8
- // Holds a 12-bit field representing an authorization tier.
+
+ // Holds a 33-bit unsigned integer representing the number of
+ // ticks of a 90KHz clock. The value is an offset added to
+ // timestamps in Descriptors by splice devices when executing the
+ // provided Command.
+ PTSAdjustment uint64
+
+ // Holds a 12-bit field representing an authorization tier. In
+ // most cases, its value should be 0x0fff for backwards
+ // compatibility. See 'tier' in SCTE 35 section 9.6.1.
Tier uint16
+
+ // Command points to this splice's specific instruction for splice devices.
Command *Command
+ // Descriptors holds zero or more parameters to Command.
Descriptors []SpliceDescriptor
+
+ // A checksum of the encoded splice. Splices returned from
+ // Decode() will hold a non-zero value. Splices passed to
+ // Encode() will have their checksums calculated automatically.
CRC32 uint32
}
