Multi-vendor IP network schema
It is clear that the risks associated with IP’s resilience compared to SDI are exaggerated and that the real concern with using IP infrastructure to deliver time-critical broadcast signals lies in the lack of a common approach and operability between vendors. The broadcast and post production industry has lived with this issue for decades but perhaps the time has come to thrust that paradigm aside to offer true cross-vendor software-based compatibility? Ed Calverley, VP Products at Suitcase TV certainly thinks so in his views on this vital topic heading into IBC 2015.
Broadcast Bridge: Is Live over IP ready for primetime?
Ed Calverley: IP transport of high-quality live video over standard COTS hardware is itself perfectly possible, the complication comes at the interface points between systems from different vendors or on networks where bandwidth cannot be guaranteed.
Broadcast Bridge: Is IT technology opaque to broadcast engineers and is real-time switching over IP guaranteed to work?
EC: The importance of ‘real-time switching’ in IP networks distracts from the real issue of multi-vendor compatibility. IP network will always introduce latency and timing jitter, the important thing is that the overall average frame timing is consistent and suitable buffering is introduced at any edge-points to ensure stable output signals.
Due to this distraction you can argue that other risks with moving to IP are being under-exaggerated. Unlike SDI, the standards for exchange of real-time video data over IP are much more prone to incompatibilities and break-up. Very often it is up to the end-customer or system integrator to accept these risks or go through the expense and time consuming ‘proof of concept’ testing; something that simply wasn’t necessary when working with SDI.
Broadcast Bridge: No one company has all the pieces of the IP live puzzle. How can broadcasters be confident that your workflow will operate seamlessly in practice?
EC: At Suitcase TV we acknowledged this problem some time ago which is why we are proud to be a member of a new consortium of vendors called IPPG (IP Production Group) who will facilitate multi-vendor collaboration and help introduce standard structures for exchanging media data in file-based and real-time environments.
Broadcast Bridge: Is SMPTE 2022 the best standard for video over IP in the long term?
EC: Transferring video data as a continuous stream (and in only one direction) is an old fashioned way of thinking about video signals where one process always follows another. Modern software based systems provide an opportunity to do media signal operations in parallel which necessitates bi-directional communication between processes – to allow interoperability of processes from different vendors new standards will be needed and that is something that the IPPG consortium will be focussing on with Open Media Stream v1.0 being the first step in the right direction.
The range of SMPTE 2022 standards are certainly a useful framework for agreeing different levels of real-time video signal transfer over IP but on their own they do nothing to guarantee interoperability. SMPTE 2022 formats are suited to transferring video signals between systems that are clearly separated. They don’t provide anything more than a way to replace SDI cables with network infrastructure; introducing complexity and risk for very little gain.
Broadcast Bridge: How long will SDI remain part of the chain for most broadcasters?
EC: SDI will be around for quite some time – even in systems running software-based solutions. Until IP connected systems truly offer a compelling reason to simply replace SDI with network infrastructure the risks will still outweigh any benefits. The desire for broadcasters to make more use of virtual server platforms will help drive the move away from SDI but the real step-change will come when IP-based systems are able to offer something that simply wasn’t possible in a traditional architecture.
Broadcast Bridge: Will 4K accelerate the move towards IP?
EC: 4K production so far is very much dependent on IP, with the success stories so far relying on a lot of proprietary systems. The move to 4K production seems unstoppable and with the introduction of higher bit-depths and higher frame rates we may see a resurgence in hardware based devices for processing signals in real time. But as time ticks on and processor and network speeds further increase the flexibility of software solutions will quickly provide new tools that engineers not burdened by traditional thinking will be quick to adopt.
Broadcast Bridge: Is the lack of standards and vendor interoperability a long term barrier to adoption of video over IP?
EC: Vendor interoperability is a major risk for customers and vendors alike. Reducing this risk will increase choice for customers and allow purchasing decisions to be made quickly with confidence. Vendors who want to own all parts of the chain may see their customers moving to smaller best-of-breed suppliers who realise it is essential to work with others to provide assurances of interoperability.
Broadcast Bridge: What is the best compression technology for working with video over IP at 4K or higher resolutions?
EC: The choice of compression depends on where you are in the broadcast chain. Transferring uncompressed 4K/UHD signals between systems over IP is unlikely to be practical but production and post-production operations will require lossless or at least visually-lossless compression, for this there are a few suitable solutions such as TICO which at the moment are only available on dedicated hardware interfaces. Moving down the chain to contribution links some form of H.264-Intra may be more suitable with higher compression ratios provided by codecs like HEVC being used for distribution.
You can see Suitecase TV at IBC 2015 stand 2.C10.
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