Encryption Archives – The Broadcast Knowledge

Video: When USB meets Pay-TV – an overview of DVB CI Plus

Posted on 21st May 2021 by Russell Trafford-Jones

Content protection needs to evolve not only to new attacks but also to the technology landscape around it. While the PCMCIA form factor has been successfully used now for CAMs, it is an old technology that takes up a lot of space. This video looks at the move to USB interfaces and feature updates to the DVB CI standards,

To lead us through, TP Vision’s Nicholas Frame joins DVB’s Emily Dubs ad starts by explaining how all the different specifications and standards connect to provide the decryption ecosystem. This video centres on CI Plus 1.4 and CI Plus 2.0 which are standardised as ETSI TS 103 205 and ETSI TS 103 605 respectively.

CI Plus 1.4, Nicholas continues, introduces two main features. The first is the introduction of a negotiation mechanism to get a list and choose to use optional features in much the same way as a browser and server negotiate when they set up a secure HTTPS connection using TLS. Nicholas walks us through the negotiation process and explains that the first of these optional features is Overt Watermarking.

Watermarking is the practice of embedding data within a media stream which helps in tracking the source for use in copyright protection. This can be done with hidden data or overtly and works by defining a layer that is composited on top of the base video layer. This is not unlike the way that the decoder would also show the application GUI however the watermark layer is controlled by the CAM which says when to show or hide the watermark. The protocol is kept simple with the watermark itself comprising just ASCII text of a chosen colour at a defined position. Naturally, communication between the CAM and decoder is encrypted and the decoder provides confirmation back to the CAM when the watermark is shown which allows the CAM to take action if it believes the watermark isn’t being respected.

Moving on to CI Plus 2.0, Nicholas explains that it’s an evolution, not a new standard. It’s based on the previous mature, trusted work in the CI Plus standard and adds additional functionality with a modern interface. There’s no loss of features nor change in signalling. It does change the interface, however, which brings with it a whole raft of improvements and possibilities.

USB A is probably the most universally used physical interface which means it’s well known by the public and is a tried and tested, robust connector. It avoids being inserted the wrong way round and has no possibility of bent pins. In terms of manufacturing, space will be saved on circuit boards and manufacturing with USB components is very well understood. Nicholas sees this as opening up new possibilities such as decoders with different form factors or a move to virtualisation.

Although the lower layers defined by USB will change, the upper layers which are specific to CI and DVB won’t change. Nicholas finishes the video explaining how the USB interface (either 2.0 or 3.x) can use bulk transfer and will group MPEG TS packets into fragments for onwards transmission.

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Speakers

	Nicholas Frame Standardisation Manager, TP Vision
	Moderator: Emily Dubs Head of Technology, DVB Project

Video: CMAF And The Future Of OTT

Posted on 12th October 2020 by Russell Trafford-Jones

Why is CMAF still ‘the future’ of OTT? Published in 2018, CMAF’s been around for a while now so what are the challenges and hurdles holding up implementation? Are there reasons not to use it at all? CMAF is a way of encoding and packaging media which then can be sent using MPEG DASH and HLS, the latter being the path Disney+ has chosen, for instance.

This panel from Streaming Media West Connect, moderated by Jan Ozer, discusses CMAF use within Akami, Netflix, Disney+, and Hulu. Peter Chave from Akamai starts off making the point that CMAF is important to CDNs because if companies are able to use just one CMAF file as the source for different delivery formats, this reduces storage costs for consumers and makes each individual file more popular thus increasing the chance of having a file available in the CDN (particularly at the edge) and reducing cache misses. They’ve had to do some work to ensure that CMAF is carried throughout the CDN efficiently and ensuring the manifests are correctly checked.

Disney+, explains Bill Zurat, is 100% HLS CMAF. Benefiting from the long experience of the Disney Streaming Services teams (formerly BAMTECH), but also from setting up a new service, Disney were able to bring in CMAF from the start. There are issues ensuring end-device support, but as part of the launch, a number were sunsetted which didn’t have the requirements necessary to support either the protocol or the DRM needed.

Hulu is an aggregator so they have strong motivation to normalise inputs, we hear from Hulu’s Nick Brookins. But they also originate programming along with live streaming so CMAF has an important to play on the way in and the way out. Hulu dynamically regenerates their manifests so can iterate as they roll out easily. They are currently part the way through the rollout and will achieve full CMAF compatibility within the next 18 months.

The conversation turns to DRM. CMAF supports two methods of DRM known as CTR (adopted by Apple) and CBC (also known as CBCS) which has been adopted by others. AV1 supports both, but the recommendation has been to use CBC which appears have been universally followed to date explains Netflix’s Cyril Concolato. Netflix have been using AV1 since it was finalised and are aiming to have most titles transitioned by 2021 to CMAF.

Peter comments from Akamai’s position that they see a number of customers who, like Disney+ and Peacock, have been able to enter the market recently and move straight into CMAF, but there is a whole continuum of companies who are restricted by their workflows and viewer’s devices in moving to CMAF.

Low latency streaming is one topic which invigorates minds and debates for many in the industry. Netflix, being purely video on demand, they are not interested in low-latency streaming. However, Hulu is as is Disney Streaming Services, but Bill cautions us on rushing to the bottom in terms of latency. Quality of experience is improved with extra latency both in terms of reduced rebuffering and, in some cases, picture quality. Much of Disney Streaming Services’ output needs to match cable, rather than meeting over-the-air latencies or less.

The panel session finishes with a quick-fire round of questions from Jan and the audience covering codec strategy, whether their workflows have changed to incorporate CMAF, just-in-time vs static packaging, and what customers get out of CMAF.

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Speakers

	Cyril Concolato Senior Software Engineer, Netflix
	Peter Chave Principal Architect, Akamai
	Nick Brookins VP, Platform Services Group, Hulu
	Bill Zurat VP, Core Technology Disney Streaming Services
	Moderator: Jan Ozer Contributing Editor, Streaming Media Owner, StreamingLearningCenter.com

Video: Encoding and packaging for DVB-I services

Posted on 2nd April 2020 by Adam K

There are many ways of achieving a hybrid of OTT-delivered and broadcast-delivered content, but they are not necessarily interoperable. DVB aims to solve the interoperability issue, along with the problem of service discovery with DVB-I. This specification was developed to bring linear TV over the internet up to the standard of traditional broadcast in terms of both video quality and user experience.

DVB-I supports any device with a suitable internet connection and media player, including TV sets, smartphones, tablets and media streaming devices. The medium itself can still be satellite, cable or DTT, but services are encapsulated in IP. Where both broadband and broadcast connections are available, devices can present an integrated list of services and content, combining both streamed and broadcast services.

DVB-I standard relies on three components developed separately within DVB: the low latency operation, multicast streaming and advanced service discovery. In this webinar, Rufael Mekuria from Unified Streaming focuses on low latency distributed workflow for encoding and packaging.

The process starts with an ABR (adaptive bit rate) encoder responsible for producing streams with multiple bit rates and clear segmentation – this allows clients to automatically choose the best video quality depending on available bandwidth. Next step is packaging where streaming manifests are added and content encryption is applied, then data is distributed through origin servers and CDNs.

Rufael explains that low latency mode is based on an enhancement to the DVB-DASH streaming specification known as DVB Bluebook A168. This incorporates the chunked transfer encoding of the MPEG CMAF (Common Media Application Format), developed to enable co-existence between the two principle flavors of adaptive bit rate streaming: HLS and DASH. Chunked transfer encoding is a compromise between segment size and encoding efficiency (shorter segments make it harder for encoders to work efficiently). The encoder splits the segments into groups of frames none of which requires a frame from a later group to enable decoding. The DASH packager then puts each group of frames into a CMAF chunk and pushes it to the CDN. DVB claims this approach can cut end-to-end stream latency from a typical 20-30 seconds down to 3-4 seconds.

The other topics covered are: encryption (exhanging key parameters using CPIX), content insertion, metadata, supplemental descriptors, TTML subitles and MPD proxy.

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Download the slides.

Speaker

Rufael Mekuria
Head of Research & Standardization
Unified Streaming

Video: Integrating CMAF Into A VOD Workflow

Posted on 20th February 2020 by Russell Trafford-Jones

CMAF is often seen as the best hope for streaming to match the latency of broadcast. Fully standards based, many see this as the best route over Apple’s LL-HLS. Another benefit of it over LL-HLS is that it’s already a completed standard with growing support.

This talk from Tomas Bacik starts by explaining CMAF to us. Standing for the Common Media Application Format, it’s based on the standardised ISOBMFF container format and whilst CMAF isn’t by default low-latency, it is flexible enough to deliver just that. However, as Tomas from CDN77 points out, there are other major benefits in terms of its use of the Common Encryption format, reduces storage fees and more.

MPEG DASH is a commonly found streaming format based on ISO BMFF. It has always had the benefit of supporting other codecs such as HEVC and AV1 over HLS which is an AVC-only specification. CMAF is an extension of MPEG DASH which goes one step further in that it can deal with both HLS-style manifest files (.hls) as well as MPEG DASH format (.mpd) inheriting, of course, the multi-codec ability of DASH itself.

Next is central theme of the talk, looking at VoD workflows showing how CMAF fits in and, indeed, changes workflows for the better. CMAF directly impacts packaging, storage and CDN which is where we focus now. Given that some devices can play HLS and some can play DASH, if you try to serve both, you will double your requirements of packaging, storage etc. Dynamic packaging allows for immediately repackaging your chunks into either HLS or DASH as needed. Whilst this reduces the storage requirements, it increases processing and also increases the time to first byte. As you might expect, using CMAF throughout, Tomas explains in this talk, allows you to package once and store once which solves these problems.

Tomas continues by explaining the DRM abilities of CMAF including AES-CBC and finishes by taking questions from the audience.

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See Streamflow’s blog post supporting the talk
Speakers