Scte35.Net 0.3.0

Scte35.Net

<p align="center"> <img alt="Scte35.Net logo" src="./logo.png" width="400" />

</p>

A .NET 8 library for parsing and generating SCTE‑35 cue messages, adapted to idiomatic C# with guardrails around binary parsing and validation.

Based in part on Comcast's scte35-go, with C#/.NET adaptations and additional validation.

• Source: src/Scte35.Net
• Tests: tests/Scte35.Net.Tests
• License: Apache 2.0

Features

• Decode/encode SCTE‑35 splice_info_section to/from bytes, Hex, and Base64.
• High-level helpers: FromHex, FromBase64, TryDecode, ToHex, ToBase64.
• Commands: SpliceNull, SpliceSchedule, SpliceInsert, TimeSignal, BandwidthReservation, Private (unknown → preserved).
• Descriptors: Avail, DTMF, Segmentation, Time, Audio, plus opaque Private descriptors.
• CRC32 (MPEG‑2) computed/validated via Crc32Valid.
• .NET 8 target, nullable enabled.

Install

• NuGet (package id: Scte35.Net):
  • dotnet add package Scte35.Net
• From source: open Scte35.Net.sln, then dotnet restore and dotnet build.

Quick Start

Decode from Base64/Hex/Bytes

using Scte35.Net;
using Scte35.Net.Model;

// Base64
SpliceInfoSection section = Scte35.FromBase64("/DABAAAAAAAAAP/wFAUAAABf+/w==");

// Hex ("0x" prefix optional)
section = Scte35.FromHex("FC300000000000000FFF0140500000017FEFF");

// Raw bytes
if (Scte35.TryDecode(mySpan, out var parsed)) {
    // parsed.SpliceCommandType, parsed.SpliceDescriptors, parsed.Crc32Valid, ...
}

Create a Basic Time Signal and Encode

using Scte35.Net;
using Scte35.Net.Model;
using Scte35.Net.Model.Enums;
using Scte35.Net.Model.SpliceCommand;

var section = new SpliceInfoSection {
    SapType = SapType.NotSpecified,
    Tier = 0x0FFF,
    SpliceCommand = new TimeSignalCommand {
        TimeSpecifiedFlag = true,
        // 10 seconds in 90kHz ticks
        PtsTime90K = 10UL * 90_000
    }
};

byte[] wire = Scte35.Encode(section);
string b64 = Scte35.ToBase64(section);
string hex = Scte35.ToHex(section);

Create a Basic Splice Insert (Program Immediate)

using Scte35.Net.Model.SpliceCommand;

var insert = new SpliceInsertCommand {
    SpliceEventId = 1,
    OutOfNetworkIndicator = true,
    ProgramSpliceFlag = true,
    SpliceImmediateFlag = true,
    DurationFlag = false,
    UniqueProgramId = 1,
    AvailNum = 0,
    AvailsExpected = 0
};

var msg = new SpliceInfoSection { SpliceCommand = insert };
string insertHex = Scte35.ToHex(msg);

Tests

• Run: dotnet test -c Release
• Suite: xUnit; tests mirror source (e.g., tests/Scte35.Net.Tests/Model/SpliceInsertTests.cs).
• Focus areas: bit‑exact encode/decode, CRC32 validation, descriptor loops, and edge cases (e.g., 33‑bit PTS masking).
• Includes conformance/spec vector coverage under tests/Scte35.Net.Tests/Conformance.

Advanced

• Private Commands: pass a recognizer to skip unknown PrivateCommand identifiers during decode: Scte35.FromHex(hex, privateId => privateId == 0x43554549 /* CUEI */);
• Hex/Base64 helpers are available via Scte35.ToHex/ToBase64 and Bytes utilities.

Contributing

Use Conventional Commits; include tests for new behavior. Ensure dotnet build and dotnet test pass locally. CI builds, tests, and packs.