---
title: Understanding Transport Streams and IP Delivery Protocols
slug: product-features/understanding-transport-streams-and-ip-delivery-protocols
docTags: 
createdAt: 2026-01-07T14:20:31.362Z
---

# Overview

Modern broadcast and streaming workflows rely on **MPEG Transport Streams (TS)** for reliable delivery of video, audio, and metadata across diverse networks. This document explains:

- How video and audio are encoded into transport streams.
- How receivers extract and decode these streams.
- How IP delivery protocols (SRT, RIST, Zixi) ensure resilience and quality.

Here's a basic architectural diagram of the encoding - decoding flow:

::Image[]{src="https://api.archbee.com/api/optimize/mzxtTQEvCNIdUNgF2kuwJ/R7V9DspVG3WArdS4rN20c-20260107-144815.png" size="80" width="1536" height="1024" position="center" alt="Transport Stream Encoding/Decoding" showCaption="false"}

We will look at a more complete diagram after looking at some of the details of the process.

## Encoding Pipeline

### Step-by-Step Process

1. **Compression** 
   - Video: H.264/AVC, HEVC (H.265), or MPEG-2.
   - Audio: AAC, AC-3.
2. **Packetization** 
   - Compressed streams become **Elementary Streams (ES)**.
   - ES wrapped into **Packetized Elementary Streams (PES)** with timing info ( PTS/DTS)
   - **Transport Stream Packetization** 
     - PES split into **188-byte TS packets**.
     - Each packet includes: 
       - **Sync byte (0x47)** for alignment.
       - PID** (Packet Identifier)** for stream identification.
       - Optional **adaptation field** for timing (PCR \[Program Clock Reference]).
3. **Multiplexing** 
   - Video, audio, and metadata interleaved into one TS.
   -  PAT**/**PMT** tables** describe program structure.
4. **Metadata & Signaling** 
   - SCTE-35 markers for ad insertion.
   - Timing references (PTS/DTS, PCR) for synchronization.

## Decoding Pipeline

1. **Demultiplexing** 
   - Receiver uses PAT/PMT to identify PIDs.
2. **Depacketization** 
   - TS packets → PES → ES.
3. **Decoding** 
   - Video/audio are decoded using original codecs.
4. **Rendering** 
   - Frames and audio are synchronized for playback.

## IP Delivery Protocols

### Why IP Delivery?

Traditional satellite/cable links are being augmented or replaced by IP-based transport for flexibility and cost efficiency. However, IP introduces packet loss, jitter, and latency challenges.

### Protocols

- **Zixi Protocol** 
  - ARQ (Automatic Repeat reQuest) for packet recovery.
  - FEC (Forward Error Correction) for proactive error handling.
  - Bonding across multiple paths for resilience.
  - AES-256 encryption and DTLS security.
  - Integrated orchestration via **ZEN Master**.
- **SRT (Secure Reliable Transport)** 
  - ARQ-based recovery.
  - AES encryption.
  - Designed for low-latency contribution feeds.
- **RIST (Reliable Internet Stream Transport)** 
  - Standards-based.
  - ARQ with optional FEC.
  - Ideal for broadcast-grade reliability.

### Error Correction Layers

- **ARQ**: Retransmits lost packets based on NACKs.
- **FEC (Forward Error Correction)**: Adds redundant data for recovery without retransmission.
- **Bonding**: Distributes traffic across multiple links for hitless failover.
- **Jitter Buffers**: Smooth out packet arrival variations.

## Timing & Signaling

- **PTS/DTS**: Presentation and decoding timestamps.
- **PCR**: Program Clock Reference for sync.
- **SCTE-35**: Ad signaling for dynamic ad insertion.

## End-to-End Architecture

**Source → Contribution → Core → Distribution → Affiliate**

- Transport Stream encapsulated in IP packets.
- Delivered via SRT, RIST, or Zixi with error correction.
- Monitored via ZEN Master for SLA compliance.

### Diagram

Here is a more complete diagram:

::Image[]{src="https://api.archbee.com/api/optimize/mzxtTQEvCNIdUNgF2kuwJ/mHJXG2KjpF8UlfG8PSGFs-20260112-155215.png" size="80" width="1536" height="1024" position="center" alt="Transport Stream Processing End-to-End" showCaption="false"}

## Key Benefits Zixi Provides

- **Reliability**: >99.999% uptime with bonding and error correction.
- **Security**: AES-256 encryption and DTLS.
- **Flexibility**: Multi-protocol support for diverse workflows.
- **Visibility**: Real-time telemetry and analytics via ZEN Master.

## Related Topics

[Zixi Transport Stream Protocol](docId\:jdVs1L_ZSEjBtnf2oKaV9) 

[Improving Stream Resiliency: Error Correction and Concealment](docId:9_OLo1Argk_2aDoSHYFBb)