Introduction to Zixi Broadcaster

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 or is 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/HDS/MPEG-DASH/RTMP/FLV
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 and HDS 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)
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.
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.

ZiXi Technology

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

Zixi Platform Architecture

The Zixi Universe diagram shows how a Zixi embedded (ZiXi EcoZystem OEM partners) device initiates a ZiXi stream at Acquisition or how ZiXi Feeder running on an appliance or mobile device enables non-Zixi embedded devices to initiate a live stream. Zixi Feeder encapsulates the stream in the ZiXi transport protocol and delivers point to point or point to multi-point over standard IP connections. Zixi 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 capable of transcoding, recording, and more in a clustered environment that supports reliability and scalability.

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
Transport stream files from local file system

Output:

ZiXi protected transport
MPEG-TS over UDP and/or RTP with SMPTE-2022
RTMP 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
Transport stream files to local file system
Re-multiplex output streams to strict CBR for extensive compatibility with Integrated Receiver- Decoders (IRDs)

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
Video Encoding – MPEG2, H.264/AVC , H.265/HEVC
Audio Decoding – AAC, MPEG-1 Audio Layer I / II / III, MPEG-2 Audio Layer I / II / III
Audio Encoding – AAC only, AAC only; Pass through – any audio codec (MPEG1/2 / AAC / AC-3)

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 end point. 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 benefit from one frame (30ms), while increasing the latency will provide more robustness for the error-recovery.

In low latency (below 1500ms) the error recovery is based on hybrid approach of FEC and ARQ. FEC will add overhead of up to 30%(adaptive–without congesting the network) .

For getting sufficient error-recovery we are recommending to set the Latency at least 3 times larger than the RTT (i.e Latency >= 3* RTT)

Latency can be set to any value, we can propose two common modes:

Interactive mode - 500ms
Non-interactive mode – 4000ms

Latency below 1500ms will add an FEC overhead of up to 30%