Introduction to Zixi Broadcaster

Owned by Copy Space for Confluence
Last updated: 20 May 2021 by Alon Men
8 min read

The Zixi Broadcaster is the central component in the Zixi Video Network. Zixi Broadcaster takes video streams from Zixi Feeder, and can process the stream, enabling transcoding, transmuxing, recording, and distribution in multiple bit rates and protocols to any device anywhere. The Zixi Broadcaster is an intelligent and versatile video distribution component that may reside on premise at a customers’ site, on the customer's cloud, or offered by Zixi as a cloud service.

Zixi Broadcaster offers the following features:

  • Robust content delivery over IP - communicates with Zixi Feeder and Zixi Receiver over UDP-based, video-optimized protocols on private and public IP networks for maximal quality at a predictable latency
  • Adaptive Bit Rate - Dynamically adjusts stream rate to adapt to changing network conditions, using unicast or multicast, to meet specific application requirements
  • Transcoding - transcodes to a variety of different profiles and bit rates
  • Format conversion – supports Internet protocols: HLS/MPEG-DASH/RTMP/FLV/MPEG-TS over HTTP
  • Recording - store streams as MPEG-TS files.
  • Time-shifting – records the stream to delay its broadcasting
  • Secure and rapid file transfer – accelerated and secure file transfers delivered at wire speed and accelerated HTTP delivery including optimized playback of HLS over UDP.
  • VOD - stored files can be accessed on demand in multiple formats.
  • Clustering and load balancing – supports cluster architectures to provide continuous uptime.
  • Transport Stream Analyzer – MPEG-TS ETSI TR 101-290 analyzer (priorities 1 and 2)
  • Content Analysis - analysis of the stream's audio and video content, including audio levels, audio silence detection, frozen video detection, and more.
  • Monitoring - captures network and content specific statistical information in real-time.
  • Supports many to many and any to any - gateway platform between UDP (unicast/multicast), Zixi protected stream (unicast/multicast), RTMP, or other supported formats.
  • Network bonding with hit-less fail-over – reunites divided streams coming from multiple network channels into a single stream, enabling simultaneous load balancing between multiple networks and ensuring high availability of the stream.
  • Hitless failover - hitless failover for inputs enables undisrupted streaming when switching from one source to another. Zixi's new hitless failover feature is based on the SMPTE 2022-7 standard, which specifies “seamless” or hitless failover between binary-identical streams with synchronized RTP headers.
  • IFB Support - a monitoring and cueing system for one-way communication from the director or assistant director to on-air talent or a remote location. IFB support has been implemented in Zixi Broadcaster Pull and UDP outputs, allowing the decoder with a Zixi Receiver to send audio back to the encoder with a Zixi Feeder.
  • AES stream encryption and decryption - UDP, File and RTMP input streams can be encrypted by Zixi Broadcaster using a fixed key (AES 128, AES 192, AES 256), which can be entered into the input settings or automatically generated. Zixi Broadcaster can also decrypt contribution streams using a matching key, or securely forward encrypted streams to receivers, without being able to see or analyze the traffic.
  • MPTS demuxing - MPTS streams can be demuxed into single SPTS input streams for specific programs.
  • SCTE-35 - SCTE-35 markers found in the source input will be used to segment the stream and the #EXT-X-CUE-IN/#EXT-X-CUE-OUT tags will be added to the manifest.
  • Low-latency HLS - Zixi Broadcaster supports low latency HLS delivery using chunked transfer encoding, which starts sending an HTTP response as chunks of data when they are ready before the complete response is available.  Chunked transfer encoding can be use with transport stream (TS) segments and with fragmented MP4 (fMP4), which is also called Common Media Application Format (CMAF). For low latency HLS and DASH, Zixi Broadcaster must be used as an origin server.

Zixi Software-Defined Video Platform (SDVP)

Zixi’s proprietary Software-Defined Video Platform or SDVP is the tight integration of four components that enable broadcast-quality live video workflows to be intelligently and centrally provisioned, deployed, managed, and monitored using software and integrated devices, regardless of the underlying network infrastructure. Employed by traditional broadcasters, OTT broadcast services, service providers to source, manage, and distribute live events and 24/7 live linear channels over any IP network, protocol, cloud provider, and/or edge device.

  • Protocols & Containers – The SDVP accepts over 17 industry protocols and containers, advancing the market leading Zixi protocol while adding additional value to tangential offerings from other vendors, standards, and open-sourced initiatives. Most customers rely on the Zixi protocol for transport as it is congestion and network-aware and can dynamically adjust to varying network conditions and employ forward error correction techniques for error-free video delivery.
  • Video Solutions Stack – Zixi’s Video Solutions Stack provides essential tools and core media processing functions for broadcast-quality transport that corrects for packet loss and jitter. Patented Hitless Failover techniques provide 99.9999%+ reliable transport between sources and receivers. The Video Solutions Stack also provides broadcasters with enhanced tools to streamline workflows including protocol switching, analytics, live 4K transcoding and repackaging, recording, time shifted delivery, and auto-slating.
  • Intelligent Data Platform – Zixi is constantly incorporating analytics, event correlation, AI and Machine Learning tools in its platform to aggregate a user’s historical and real-time metadata and present it back to them to help better predict downtime, content quality, trends, and more in the form of alerts, notifications, and background monitoring.
  • ZEN Master – With Zixi’s ZEN Master control plane, cost-effectively manage and monitor complex deployments at scale and configure and orchestrate live broadcast channels across protocols and the Zixi Enabled Network. ZEN Master allows for control of the edge, network, and cloud with full telemetry visualization of network streams. It offers essential monitoring and management tools like workflow visualization, alerting, history, automation, scheduling, reporting, and root cause analysis across complex media supply chains.

Seamless protocol switching between 17 protocols 

Once users adopt the SDVP and install the software components, they can choose to send or receive live video streams using the Zixi protocol or one of the 16 supported protocols. With the SDVP, users can conduct protocol switching, handle up to 5Gb+ streams in 4K and now 8K video, and change stream parameters without stopping the stream. SDVP allows for high availability with high redundancy and can run on premise or on any cloud.

Hitless failover and analytics and bonding

Users can take advantage of its Video Solutions Stack capabilities such as analytics, hitless failover and bonding across diverse ISPs to ensure high reliability and encrypt content with AES 256 encryption and DTLS for best-in-class security. The Video Solutions Stack’s unique patented hitless failover techniques ensure reliability, and its robust analytics suite provides atomic-level telemetry on stream health that allows users to address any issues impacting QoS before the consumer’s QoE is affected. The analytics solution employs machine learning techniques to provide a real-time estimated PSNR (ePSNR) with no reference video required, helping the user determine if content providers are meeting SLAs for contribution stream quality.

ZEN Master control plane

ZEN Master integration allows remote access to the UIs of Zixi-integrated devices and software across the Zixi Enabled Network for optimal monitoring and control from one centralized control plane. With the ZEN Master control plane, users have extensive visibility into and control over workflows that go across Zixi-enabled multi-party supply chains, with the ability to leverage alerting, extensive history graphs, automated toolsets, and scheduling and reporting capabilities that abstract complexity to reduce engineering requirements and allow media organizations to leverage operational resources, providing democratized access with geographic agility.


SDVP Architecture

The Zixi SDVP architecture shows how a live linear broadcast or event is ingested through a Zixi Feeder (ZF) or Zixi embedded device running Zixi Feeder at acquisition. Zixi Feeder encapsulates the stream in the Zixi transport protocol and delivers point to point or point to multi-point over standard IP connections to Zixi Broadcaster (ZB). Zixi Broadcaster can be deployed on premise or in the cloud with the ability to monitor streams anywhere along the path. For management, processing and larger scale distribution capabilities, Zixi can support complex production workflows for live events, including transcoding, recording, and more, all in a clustered environment that supports reliability and scalability. The stream is distributed through a CDN, OTT, or endpoint device, running Zixi Receiver (ZR) to any device.  

Zixi Transport Stream Protocol

Zixi’s transport stream protocol is a content and network-aware protocol that dynamically adjusts to varying network conditions and employs error correction techniques for error-free video streaming over IP. With minimum overhead to physical bandwidth, this dynamic mechanism provides low end-to-end latency, removes jitter, recovers and re-orders packets, smooths video delivery and regenerates video to its original form, all in real-time.

Zixi delivers outstanding performance (at low predictable latency), superior reliability (no packet loss) and broadcast-grade video quality (SD, HD, and UHD) with no tradeoffs to delay, resolution or stutter. 

Streaming from one Zixi-enabled device/server to another Zixi-enabled device/server protects the stream from quality degradations along the path. It enables the streaming of high-quality video over any distance, while overcoming the varying network conditions of the public Internet, where the amount of network errors, packet loss, jitter and out-of-order packets fluctuate "every second".

The Zixi transport stream protocol can be also deployed on part of the path. For example, from a ZiXi Feeder to a ZiXi Broadcaster (Zixi protected path) and on to the end user through UDP or RTMP. In this case, the path that has challenging conditions (e.g. long distance or unstable wireless conditions) will be protected by ZiXi and then delivered on to the end-user on a standard UDP or RTMP protocol.

Zixi’s transport stream technology includes the following features for ultimate quality and security:

  • Network sensing
  • Dynamic de-jitter
  • MPEG specific optimizations
  • Z-ARQ error recovery
  • Z-FEC - Dynamic content aware forward error correction
  • Active multi-path error recovery
  • Adaptive bitrate over UDP, unicast or multicast
  • Rate control and congestion avoidance
  • 256 bit AES transport encryption

Supported Protocols

Input:

  • Zixi protected transport
  • MPEG-TS over UDP and/or RTP with SMPTE-2022 
  • RTMP pull from CDNs and/or other sources
  • RTMP push
  • RTMPS
  • RTSP input
  • RIST (TR-06-1)
  • NDI
  • Transport stream files from local file system
  • SRT (configured via Zen Master or Zixi API)

Output:

  • Zixi protected transport
  • MPEG-TS over UDP and/or RTP with SMPTE-2022
  • RTMP and RTMPS push to CDNs and/or other media servers;
  • Apple HTTP Live Streaming (HLS)
  • Adobe HTTP Dynamic Streaming (HDS)
  • FLV over HTTP (HTTP pseudo-streaming)
  • MPEG-DASH (DASH264 profile)
  • SHOUTcast
  • NDI
  • Transport stream files to local file system
  • Re-multiplex output streams to strict CBR for extensive compatibility with Integrated Receiver- Decoders (IRDs)
  • SRT (configured via Zen Master or Zixi API)

Transcoding Options

Zixi Broadcaster can transcode a single input stream using multiple profiles. The transcoder supports the following options:

  • Video Decoding – MPEG2, H.264/AVC, H.265/HEVC, Raw
  • Video Encoding – MPEG2, H.264/AVC, H.265/HEVC, Raw

  • Audio Decoding – AAC, MPEG-1 Audio Layer I / II / III, MPEG-2 Audio Layer I / II / III, AC-3 (Dolby Digital), Opus.

    For AC-3, which can contain up to six discrete channels of sound, the transcoder only supports the left and right channels and will ignore the other channels.

  • Audio Encoding – AAC, AAC-HE (High Efficiency) and AAC-HEv2; Pass through (no encoding) – any audio codec (MPEG1/2 / AAC / AC-3, E-AC-3 (Dolby Digital Plus), Opus.

Recording Options

Live stream inputs can be stored as MPEG-TS files to a local disk drive or mounted drive.

Multicast Options

Multicast streams can be received or be sent by the Zixi Broadcaster. Zixi Broadcaster serves as a gateway between Unicast and Multicast streams, while allowing reliable streaming over multicast.

Adaptive Options

Zixi Broadcaster can create an adaptive group, subsequently editing, recording, or playing it in conjunction with DASH, HLS, HDS or Zixi. You can also set a Pre-roll video/screen that will be played before the live streaming begins.

VOD Options

Zixi Broadcaster supports VOD (Video on Demand) playback of stored files in multiple formats such as TS, MP4, HLS, FLV.

Latency Considerations

Latency defines the delay in which the video stream will be delivered to the endpoint. This delay is essentially a buffer that is used for additional processing, thereby improving the quality of video stream. The latency should be considered based on the importance of immediacy. For example, if the video requires interaction (e.g. between a reporter in the field and an anchor in the studio), the latency should be set to a minimum so that the interaction does not suffer from any delay.

Latency can vary from tens of milli-seconds to several seconds.

Zixi protocol can start providing benefit from one frame (30ms), while increasing the latency will provide more robustness for the error-recovery.