Software-defined video encoding, multiplexing, and system management can enable operators to extract additional capacity from their networks, increase the QoS, and reliability of linear TV delivery networks through full system redundancy, simplified workflows and advanced configuration options. Elemental video solutions can integrate both linear and OTT video delivery within a single unified workflow.
The Problem with Static Infrastructure
Most linear television operationstoday include legacy video processing equipment dedicated to specific tasks such as encoding, splicing and multiplexing. Althoughthese workflowsmay perform well, their functions remain tied to specific hardware components, many times all the way to the chip level. Today’s digital TV systems typically rely predominantly on two video compression formats: MPEG 2 and H.264. The emergence of HEVC promises greater encoding efficiencies and supports higher picture quality and differentiated new services in the form of 4K Ultra HD TV. HEVC efficiencies can also extend to benefit video providers with limited bandwidth, such as IPTV operators. However, H.264 encoding is required for satellite and IPTV as well as multiscreen OTT and VOD streaming. Simultaneous provisionfor all three of these compression formats within workflows and delivery networks is often the goal as it allows for more seamless migration of technology through an operator’s network.
Today, support for content distribution across most traditional pay TV networks requires advanced compression and statistical multiplexing methodologies. Since QAM bandwidth for delivering these channels is fixed, one approachto allocating bandwidth is to simply divide the total available bandwidth by the number of sub-channels and then evenly allocate constant bitrate (CBR) encoding levels. However, this static allocation method is extremely inefficient as bandwidth is equally spread across simple and more complex video scenes. Instead,a more efficient method is to pool together the available bandwidth for several sub-channels and apply active variable bitrate (VBR) encoding per sub-channel in order to increase overall picture quality and free up bandwidth for the channels that need it most at any point in time.
The Flexibility of a Software Approach
Software-defined video solutions are in part differentiated by the ability to migrate changes and improvements amongst different codecs such as MPEG-2 and H.264. This is not possible with hardware-based solutions for video compression. For more aggressive unified headend strategies, encoders can ingest 4K UHD or HD content and transcode it into parallel HEVC UHD and MPEG-2 or H.264 HD and SD streams, allowing a single system to create multi-resolution channel outputs from a single source. Whatever the codec combination, an optimal linear video delivery solution is designed to adapt and grow with rapidly evolving cable, satellite and terrestrial network requirements.
At a high level, multiscreen video delivery requires encoding, content protection and monetization in terms very similar to traditional pay TV requirements. Encoding functions differ in the ways metadata is handled and in the types and number of outputs required, but input, redundancy and reliability requirements are similar.
Down in the details, however, many parts of the two delivery workflow are significantly different, with alternate technologies for encryption, alternate delivery protocols and many different types of metadata. Adding to these differences is the frantic pace of change driven by a heavy dependence on consumer devices that are typically updated yearly and delivery standards updating roughly every six months. Support for multiscreen video delivery requires software-based solutions that are nimble enough to accommodate rapid change while simultaneously maintaining the reliability required for 24/7 services. The evolution of streaming protocols and monetization strategies for over–the-top services generally makes required an advanced origin server, such as Elemental® Delta, to perform just-in-time packaging, streaming and DRM. Through an advanced origin solution, content can be encoded once, stored in a deliverable mezzanine format, and repackaged and encrypted uniquely for new devices and evolving customer expectations.
For a 24/7 service, regardless of the deployment model or workflow, the possibility of failure at any point in the signal path needs to be well understood, with counter measures in place to provide the shortest interruption possible. All of this experience can also be applied to traditional video operations where the pace of change needs to match that of disruptive multiscreen services.
Multi-Codec, Multi-Resolution Statistical Multiplexing
A statistical multiplexer is used to analyze the frame-by-frame complexity of incoming video across multiple sub-channels while a bitrate controller sets the target bitrate levels of each encoder so that theirtotalmatches the full bandwidth available.
Elemental®Statmux is a statistical multiplexer designed to accommodate current linear TV workflows with a close eye on the future.
With Elemental Statmux and encoding from Elemental® Live, new choices and opportunities arise for determining an ideal mux pool. Support for mux pools that contain mixed codecs such as MPEG-2 and HEVC or H.264 and HEVC allow QAM optimization for both existing services as well as new services. The addition of multi-resolution support advances the idea of statistical multiplexing by enabling new services, including the creation of mux pools containing UHD 4K channels along with HD and SD channels, allowing network operators to thoroughly optimize bandwidth usage.
In contrast to most hardware-based equipment, Elemental Statmux can potentially operate as part of a linear TV solution embedded within the encoder or as a standalone system. The advantage of having an embedded statmux is that it not only requires minimal rack space, but can also be easily duplicated to a standby system for full redundancy..
Full-System Redundancy for Maximum Up-Time
In traditional linear TV deployments, failures were historically limited to a single channel because a single hardware encoder was used for each individual channel. More recent and powerful encoders support multiple channels in a single system. Channels from a multi-channel encoder system with an input or power failure must be switched over to redundant systems, manually or automatically, with minimal or no signal loss depending on the system design. Due to the timing and complexity of failover situations, it’s extremely important to eliminate dependence on the content characteristics of the channels. However, redundancy usually comes at the cost of configuration complexity, rack space requirements, and operating expenses.
With software-defined video processing, linear TV processing, network and storage resources can be dynamically provisioned for video encoding, muxing, and other linear TV delivery functions. Service upgrades, channel line-up changes and system maintenance tasks can be performed without any downtime by switching live functions over to redundant hardware or virtual machines. Elemental software runs on Linux and has been deployed by more than 600 Elemental customers. The Linux operating system eliminates the need for the occasional restarts required by Windows solutions while simultaneously reducing the deployment time for spinning up additional software-based nodes.
The flexibility and scalability of Elemental software provides many other types of redundancy configurations including 1+1, N+1, and M+N, which are required for more advanced services and complex use cases. Redundancy solutions are designed to cover all services from traditional managed network delivery to multiscreen delivery and for all resolutions from SD to UHD. The result is maximum reliability and minimized costs for on-going maintenance.
Advanced Configuration and Node Management
Elemental Conductor management software offers the features and functionality required by pay TV operators for live workflows. New capabilities such as bulk actions that allow multiple channels to be stopped, started and edited simultaneously simplifies management of hundreds of channels while ensuring configurations are synchronized. The combined capabilities of template-based channel configuration and secure authentication capabilities provide confidence that all channels are configured with the desired settings by authorized users. Likewise, audit logs provide insight into the changes made by authorized users. Manual or automatic failover switching with customer-defined conditions add a layer of redundancy control required for maximum reliability and is one of the layers of redundancy control implemented within the Elemental solution ecosystem.