Video: CPAC Case Study – Replacement of a CWDM System with an IP System

Posted on by Adam K

For a long time now, broadcasters have been using dark fibre and CWDM (Coarse Wavelength Division Multiplexing) for transmission of multiple SDI feeds to and from remote sites. As an analogue process, WDM is based on a concept called Frequency Division Multiplexing (FDM). The bandwidth of a fibre is divided into multiple channels and each channel occupies a part of the large frequency spectrum. Each channel operates at a different frequency and at a different optical wavelength. All these wavelengths (i.e., colours) of laser light are combined and de-combined using a passive prism and optical filters.

In this presentation Roy Folkman from Embrionix shows what advantages can be achieved by moving from CWDM technology to real-time media-over-IP system. The recent project for CPAC (Cable Public Affairs Channel) in Canada has been used as an example. The scope of this project was to replace an aging CWDM system connecting government buildings and CPAC Studios which could carry 8 SDI signals in each direction with a single dark fibre pair. The first idea was to use a newer CWDM system which would allow up to 18 SDI signals, but quite quickly it became apparent that an IP system could be implemented at similar cost.

As this was an SDI replacement, SMPTE ST 2022-6 was used in this project with a upgrade path to ST 2110 possible. Roy explains that, from CPAC point of view, using ST 2022-6 was a comfortable first step into real-time media-over-IP which allowed for cost reduction and simplification (no PTP generation and distribution required, re-use of existing SDI frame syncs and routing with audio breakaway capability). The benefits of using IP were: increased capacity, integrated routing (in-band control) and ease of future expansion.

A single 1RU 48-port switch on each side and a single dark fibre pair gave the system a capacity of 48 HD SDI signals in each direction. SFP gateways with small Embronix enclosures have been used to convert SDI outs of cameras to IP fibre – that also allowed to extend the distance between the cameras and the switch above SDI cabling limit of 100 meters. SFP gateway modules converting IP to SDI have been installed directly in the switches in both sites.

Roy finishes his presentation with possible future expansion of the system, such as migration to ST 2110 (firmware upgrade for SFP modules), increased capacity (by adding additional dark fibres ands switches), SDI and IP routing integration with unified control system (NMOS), remote camera control and addition of processing functions to SFP modules (Multiviewers, Up/Down/CrossConversion, Compression).

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Download the slides.

Speaker

Roy Folkman 
VP of Sales
Embrionix

Video: ABA IP Fundamentals For Broadcast

Posted on by Russell Trafford-Jones

IP explained from the fundamentals here in this in this talk from Wayne Pecena building up a picture of networking from the basics. This talk discusses not just the essentials for uncompressed video over IP, SMPTE ST 2110 for instance, but for any use of IP within broadcast even if just for management traffic. Networking is a fundamental skill, so even if you know what an IP address is, it’s worth diving down and shoring up the foundations by listening to this talk from the President of SBE and long-standing Director of Engineering at Texas A&M University.

This talk covers what a Network is, what elements make up a network and an insight into how the internet developed out of a small number of these elements. Wayne then looks at the different standards organisations that specify protocols for use in networking and IP. He explains what they do and highlights the IETF’s famous RFCs as well as the IEEE’s 802-series of ethernet standards including 802.11 for Wi-Fi.

The OSI model is next, which is an important piece of the puzzle for understanding networking. Once you understand, as the OSI model lays out, that different aspects of networking are built on top of, but operate separately from other parts, fault-finding, desiring networks and understanding the individual technologies becomes much easier. The OSI model explains how the standards that define the physical cables work underneath those for Ethernet as separate layers. There are layers all the way up to how your software works but much of broadcasting that takes place in studios and MCRs can be handled within the first 4, out of 7 layers.

The last section of the talk deals with how packets are formed by adding information from each layer to the data payload. Wayne then finishes off with a look at fibre interfaces, different types of SFP and the fibres themselves.

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Speaker

Wayne Pecena Wayne Pecena
Director of Engineering, KAMU TV/FM at Texas A&M University
President, Society of Broadcast Engineers AKA SBE

Video: Video Caching Best Practices

Posted on by Russell Trafford-Jones

Caching is a critical element of the streaming video delivery infrastructure. By storing objects as close to the viewer as possible, you can reduce round-trip times, cut bandwidth costs, and create a more efficient delivery chain.

This video brings together Disney, Qwilt and Verizon to understand their best-practices and look at the new Open Caching Network (OCN) working group from the Streaming Video Alliance. This recorded webinar is a discussion on the different aspects of caching and the way the the OCN addresses this.

The talk starts simply by answering “What is a caching server and how does it work?” which helps everyone get on to the same page whilst listening to the answers to “What are some of the data points to collect from the cache?” hearing ‘cache:hit-ratio’, ‘latency’, ‘cache misses’, ‘data coming from the CDN vs the origin server’ as some of the answers.

This video continues by exploring how caching nodes are built, optimising different caching solutions, connecting a cache to the Open Caching Network, and how bettering cache performance and interoperability can improve your overall viewer experience.

The Live Streaming Working Group is mentioned covered as they are working out the parameters such as ‘needed memory’ for live streaming servers and moves quickly into discussing some tricks-of-the-trade, which often lead to a better cache.

There are lots of best practices which can be shared and the an open caching network one great way to do this. The aim is to create some interoperability between companies, allowing small-scale start-up CDNs to talk to larger CDNs. A way for a streaming company to understand that it can interact with ‘any’ CDN. As ever, the idea comes down to ‘interoperability’. Have a listen and judge for yourself!

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Speakers

Eric Klein Eric Klein
Director, Content Distribution – Disney+/ESPN+, Disney Streaming Services
Co-Chair, Open Cache Working Group, Streaming Video Alliance
Yoav Gressel Yoav Gressel
Vice President of R&D,
Qwilt
Sanjay Mishra Sanjay Mishra
Director, Technology
Verizon
Jason Thibeault Jason Thibeault
Executive Director,
Streaming Media Alliance

Video: A Forensic Approach to Video

Posted on by Russell Trafford-Jones

Unplayable media is everyone’s nightmare, made all the worse if it could be key evidence in a crimnial case. This is daily fight that Gareth Harbord from the Metropolitan Police has as he tries to render old CCTV footage and files from crashed dash cams playable, files from damaged SD cards and hard drives readable and recover video from old tape formats which have been obselete for years.

In terms of data recovery, there are two main elments: Getting the data off the device and then fixing the data to make it playable. Getting the data off a device tends to be difficult because either the device is damaged and/or connecting to the device requires some proprietary hardware/software which simply isn’t available any more. Pioneers in a field often have to come up with their own way of interfacing which, when the market becomes bigger, is often then improved by a standard way of doing things. Take, as an example, mobile phone cables. They used to be all sorts of shapes and sizes but are now much more uniform with 3 main types. The same was initially true with hard drives, however the first hard drives were so long ago that osolecence is much more of an issue.

Once you have the data on your own system, it’s then time to start analysing it to see why it won’t play. It may play because the data itself is of an old or proprietary format, which Gareth says is very common with CCTV manufacturers. While there are some poular formats, there are many variations from different companies including putting all, say, 4 cameras onto one image or into one file, running the data for the four cameras in parallel. After a while, you start to be able to get a feel for the formats but not without many hours of previous trial and error.

Gareth starts his talk explaining that he works in the download and data receovery function which is different from the people who make the evidence ready for presentation in a trial. Their job is to find the best way to show the relevant parts both in terms of presentation but also technically making sure it is easy to play for the technically uninitiated in court and that it is robust and reliable. Presentation covers the effort behind combining multiple sources of video evidence into one timeline and ensuring the correct chronology. Other teams also deal with enhancing the video and Gareth shows examples of deblurring an image and also using frame averaging to enhance the intelligability of the picture.

Gareth spends some time discussing CCTV where he calls the result of the lack of standardisation “a myriad of madness.” He says it’s not uncommon to have 15-year-old systems which are brought in but, since the hard drives have been spinning for one and half decades, don’t start again when they are repowered. On the otherhand the newer IP cameras are more complicated whereby each camera is generating its own time-stampped video going into a networked video recorder which also has a timestamp. What happens when all of the timestamps disagree?

Mobile devices cause problems due to variable frame rates which are used to deal with dim scenes, non-conformance with standards and who can forget the fun of CMOS videos where the CMOS sensors lead to wobbling of the image when the phone is panned left or right. Gareth highlights a few of the tools he and his colleagues use such as the ever-informative MediaInfo and FFProbe before discussing the formats that they transode to in order to share the videos internally.

Gareth walks us through an example file looking at the how data can be lined up to start understanding the structure and start to decode it. This can lead to the need to write some simple code in C#, or similar, to rework the data. When it’s not possible to get hold of the data in a partiular format to be playable in VLC, or similar, a proprietary player may be the only way forward. When this is the case, often a capture of the computer screen is the only way to excerpt the clip. Gareth looks at the pros and cons of this method.

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Speakers

Gareth Harbord Gareth Harbord
Senior Digital Forensic Specialist (Video)
Metropolitan Police Service