As popular new OTT and VOD services offered by conventional DTH providers become increasingly popular, video providers are able to scale quickly and introduce new features, thanks to the agility that is unique to the software.
By Keith Wymbs
The software's abstraction of video processing functions from the fundamental hardware infrastructure enables the logical configuration of encoders, transcoders, multiplexer source servers as virtual modules without the need for manual cabling. Entire systems can be managed and controlled to achieve network optimization and reliability through a unified operator interface. New live-to-OVD and targeted multi-screen advertising services can be implemented, along with traditional and linear workflows to further drive efficiency in resource management.
Software-defined video encoding, multiplexing, and system management can enable operators to extract more capacity from their networks, increase quality of service, and improve the reliability of live linear TV networks through full system redundancy, streamlined workflows, and advanced configuration options. Elemental's video solutions can integrate both linear and OTT video streaming into a unified workflow.
The problem of static infrastructure
Most current linear television operations include older video processing equipment employed for specific tasks such as coding, splicing, and multiplexing. While these workflows may perform well, their functions are still tied to specific hardware components, often even down to the chip level.
Currently, to support the distribution of content in most traditional subscription television networks, advanced compression and statistical multiplexing methodologies are required. Because the QAM (quadrature amplitude modulation) bandwidth for transmitting these channels is fixed, one method of allocating it is to simply divide the total available bandwidth by the number of subchannels and then uniformly assign CBR (constant bitrate) encoding levels. However, this method of static allocation is extremely inefficient since the bandwidth is distributed equally between simple and more complex video scenes.
Conversely, a more efficient method is to pool the bandwidth available for multiple subchannels and apply an active VBR (variable bitrate) encoding per subchannel, in order to increase overall image quality and free up bandwidth for the channels that require it most at any given time.
The flexibility of a software-based solution
Software-defined video solutions differ, in part, by the ability to migrate changes and improvements between different codecs, such as MPEG-2 and H.264. This is not possible with hardware-based solutions for video compression.
For more aggressive unified header strategies, encoders can ingest 4K UHD HD content and transcode it in parallel to 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 combination of codecs, an optimal linear video transmission solution is designed to adapt and grow in tandem with the rapidly evolving requirements of terrestrial, cable and satellite networks.
On a global level, multi-screen video broadcasting requires coding, content protection, and monetization in terms very similar to the requirements of traditional subscription television. The encoding functions differ in the ways of handling metadata and in the types and number of outputs required, but the requirements for input, redundancy, and reliability are similar.
However, as for the specific details, many parts of the two broadcast workflows are significantly different, have different technologies for encryption, different broadcast protocols, and many different types of metadata. Added to these differences is the frenetic pace of change driven by a heavy reliance on consumer devices, which are usually updated every year and broadcast standards that are updated more or less every six months. Support for multi-screen video broadcast requires software-based solutions that are agile enough to accommodate rapid changes, while maintaining the reliability required for the provision of services 24 hours a day, 7 days a week.
The evolution of data transfer protocols and monetization strategies for OTT services usually necessitates an advanced source server, such as Elemental's® Delta, to perform just-in-time packaging, data transfer, and DRM. With an advanced source solution, content can be encoded once, stored in a transmissible mezzanine format, and uniquely repackaged and encrypted to fit new devices and changing customer expectations.
To offer services 24 hours a day, 7 days a week, regardless of the implementation model or workflow, it is necessary to understand well the possibility of failure at any point in the signal path, implementing measures that allow to reach the lowest possible level of interruption. All this experience can also be applied to conventional video operations where the pace of change has to be on par with that of innovative multi-screen services.
Statistical multiplexing, multicodec and multi-resolution
A statistical multiplexer is used to analyze the frame-by-frame complexity of incoming video across multiple subchannels while a bitrate controller sets the desirable bitrate levels of each encoder so that its total matches the total available bandwidth.
Elemental's® Statmux is a statistical multiplexer designed to adapt to current linear television flows, but always keeping an eye on future developments.
With Elemental's Statmux and Elemental's® Live coding, new options and opportunities arise to establish an optimal multiplexing group. Support for multiplexing groups containing mixed codecs such as MPEG-2 and HEVC or H.264 and HEVC enables QAM optimization in both existing and new services. The addition of multi-resolution support enhances statistical multiplexing, allowing the provision of new services, among others, the creation of multiplexing groups containing 4K UHD channels along with HD SD channels, which allows network operators to fully optimize the use of bandwidth.
In contrast to most hardware-based equipment, Elemental's Statmux can function as part of a linear television solution embedded within the encoder or as a standalone system. The advantage of having an embedded statmux is that it only requires minimal rack space, but it can also be easily duplicated in a standalone system for full redundancy.
Full system redundancy for maximum uptime
In traditional linear television installations, historically failures were limited to a single channel because a single hardware encoder was used for each individual channel. The latest and most powerful encoders support multiple channels in a single system. The channels of a multi-channel encoder system with an input failure or a power failure must be transferred to redundant systems, either manually or automatically, thus achieving a minimum or no level of signal loss depending on the system design. Due to the timing and complexity of failover situations, it is extremely important to eliminate dependency on channel content characteristics. However, redundancy generally entails complexity in terms of configuration, rack space requirements, and operating expenses.
With software-defined video processing, linear TELEVISION, network, and storage processing resources can be dynamically supplied for video encoding, multiplexing, and other linear streaming functions for TV. Service upgrades, channel offering changes, and system maintenance can be performed without downtime, thanks to the transfer of live functions to redundant hardware or virtual machines. Elemental's software runs on Linux and has been implemented by over 600 customers of 600 Elemental. Thanks to the Linux operating system, the sporadic reboots required with Windows operating system solutions are no longer necessary, while reducing installation time to speed up additional software-based nodes.
The flexibility and scalability of Elemental's software offers many other types of redundancy configurations, including 1+1, N+1, and M+N, which are required to deliver the most advanced services and in complex use cases. Redundancy solutions are designed to cover all services, from conventional manageable network transmission to multi-screen transmission and for all resolutions, from SD to UHD. The result is maximum reliability and minimization of costs that allows continuous maintenance.
Advanced configuration and node management
Elemental's Driver Management Software delivers the features and functionality required by subscription TV operators in live workflows. New features such as bulk actions that allow you to stop, start and edit several channels simultaneously, simplify the management of hundreds of channels, while ensuring the synchronization of configurations. Combined template-based channel configuration capabilities and secure authentication capabilities provide confidence that all channels have been configured to the configurations desired by authorized users.
In the same way, audit logs allow you to know the changes made by authorized users. Manual or automatic failover with customer-defined conditions incorporates a level of redundancy control necessary for maximum reliability and is one of the levels of redundancy control implemented within the Elemental solution system.
The Growing Demand for Software-Defined Video Infrastructures
There are many reasons why linear TV providers may be forced to improve their infrastructure, including natural and cyclical equipment upgrades or the introduction of new services such as 4K HD TV broadcasts or advanced live-to-VOD services. Relying on specialized hardware is becoming an increasingly complicated and unattractive strategy for most vendors, in contrast to using software platforms that are more flexible and scale as demand for service expansion increases.
Elemental's software solutions support MPEG-2, H.264 and HEVC and include statistical multiplexing, with the ability to mix resolutions and codecs in the same multiplexing channel. This opens up numerous possibilities for subscription TV operators and allows for a smooth migration of existing standards.
Major cable and satellite operators are using software-defined video processing to enable multi-screen television as well as traditional linear transmission. Unifying these workflows to leverage synergies in operations and processing is the next logical step. As the price-performance ratio of commercial hardware has improved and cloud IT capabilities have matured, the case for migrating traditional video encoding and multiplexing to a software-defined infrastructure has increased, as has the number of operators adopting this solution.
*Keith Wymbs is director of linear marketing for Elemental.
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