Video: RAVENNA AM824 & SMPTE ST 2110-31 Applications



Audio has a long heritage in IP compared to video, so there’s plenty of overlap and there are edge cases abound when working between RAVENNA, AES67 and SMPTE ST 2110-30 and -31. SMPTE’s 2110 suite of standards currently holds two methods of carrying audio including a way of carrying encoded audio such as Dolby AC4 and Dolby E.

RAVENNA Evangelist Andreas Hildebrand is joined by Dolby Labs architect James Cowdrey to discuss the compatibility of -30 and -31 with AES67 and how non-PCM data can be carried in -31 whether that be lightly compressed audio, object audio for immersive experiences or even just pure metadata.

Andreas starts by revising the key differences between AES67 and RAVENNA. The core of AES67 fits neatly within RAVENNA’s capabilities including the transport of up to 24-bit linear PCM with 48 samples per packet and up to 8 channels of 48kHz audio. RAVENNA offers more sample rates, more channels and adds discovery and redundancy with modes such as ‘MADI’ and ‘High performance’ which help constrain and select the relevant parameters.

SMPTE ST 2110-30 is based on AES67 but adds its own constraints such that any -30 stream can be received by an AES67 decoder, however, an AES67 sender needs to be aware of -30’s constraints for it to be correctly decoded by a -30 receiver. Andreas says that all AES67 senders now have this capability.


In contrast to 2110-30, 2110-31 is all about AES3 and the ability of AES3 to carry both linear PCM and non-PCM data. We look at the structure of the AES3 which contains audio blocks each of which has 192 Frames. These frames are split into 2, in the case of stereo, 64 in the case of MADI. Within each of these subframes, we finally find the preamble and the 24-bit data. Andreas explains how this is linked to AM824 and the SDP details needed.

James Cowdery leads the second part of today’s talk first talking about SMPTE ST 337 which details how to send non-PCM audio and data in an AES3 serial digital audio interface. It can carry AC-3, AC-4 for object audio delivering immersive audio experiences, Dolby E and also the metadata standards KLV and Serial ADM.

‘Why use Dolby E?’ asks James. Dolby E has a number of advantages although as bandwidth has become more available, it is increasingly replaced by uncompressed audio. However legacy workflows may now be reliant on IP infrastructure between the receiver and decoder, so it’s important to be able to carry it. Dolby E also packs a whole set of surround sound within a single data stream removing any problems of relative phase and can be carried over MPEG-2 transport streams so it still has plenty of flexibility and uses cases.

Its strength can bring fragility and one way which you can destroy a Dolby E feed is by switching between two videos containing Dolby E in the middle of the data rather than waiting for the gap between packets which is called the guardband. Dolby E needs to be aligned to the video so that you can crossfade and switch between videos without breaking the audio. James makes the point that one reason to use -31 and not -30 to carry Dolby E, or any other non-PCM data, is that -30 assumes that a sample rate converter can be used and so there is usually little control over when an SRC is brought in to use. A sample rate converter, of course, would destroy any non-PCM data.

RAVENNA 824 and 2110-31 gateways will preserver the line position of Dolby data. Can support Dolby E transport can therefore be supported by a vendor without Dolby support. James notes that your Dolby E packets need to be 125 microseconds to achieve packet-level switching without missing a guardband and corrupting data.

Immersive audio requires metadata. sADM is an open specification for metadata interchange, the aim of which is to help interoperability between vendors. sADM metadata can be embedded in SDI, transported uncompressed as SMPTE 302 in MPEG-2 Transport Streams and for 2110, is carried in -31. It’s based on XML description of metadata from the Audio Definition Model and James advises using the GZip compression mode to reduce the bitrate as it can be sent per-frame. An alternative metadata standard is SMPTE ST 336 which is an open format providing a binary payload which makes it a lower-latency method for sending Metadata. These methods of sending metadata made sense in the past, but now, with SMPTE ST 2110 having its own section for metadata essences, we see 2110-41 taking shape to allow data like this to be carried on its own.

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Speakers

James Cowdery James Cowdery
Senior Staff Architect
Dolby Laboratories
Andreas Hildebrand Andreas Hildebrand
RAVENNA Evangelist,
ALC NetworX

Video: 5 Myths About Dolby Vision & HDR debunked

There seem no let up in the number of technologies coming to market and whilst some, like HDR, have been slowly advancing on us for many years, the technologies that enable them such as Dolby Vision, HDR10+ and the metadata handling technologies further upstream are more recent. So it’s no surprise that there is some confusion over what’s possible and what’s not.

In this video, Bitmovin and Dolby the truth behind 5 myths surrounding the implementation and financial impact of Dolby Vision and HDR in general. Bitmovin sets the scene by with Sean McCarthy giving an overview on their research into the market. He explains why quality remains important, simply put to either keep up with competitors or be a differentiator. Sean then gives an overview of the ‘better pixels’ principle underlining that improving the pixels themselves is often more effective than higher resolution, technologies such as wide colour gamut (WCG) and HDR.

David Brooks then explains why HDR looks better, explaining the biology and psychology behind the effect as well as the technology itself. The trick with HDR is that there are no extra brightness values for the pixels, rather the brightness of each pixel is mapped onto a larger range. It’s this mapping which is the strength of the technology, altering the mapping gives different results, ultimately allowing you to run SDR and HDR workflows in parallel. David explains how HDR can be mapped down to low-brightness displays,

The last half of this video is dedicated to the myths. Each myth has several slides of explanation, for instance, the one suggests that the workflows are very complex. Hangen Last walks through a number of scenarios showing how dual (or even three-way) workflows can be achieved. The other myths, and the questions at the end, talk about resolution, licensing cost, metadata, managing dual SDR/HDR assets and live workflows with Dolby Vision.

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Speakers

David Brooks David Brooks
Senior Director, Professional Solutions,
Dolby Laboratories
Hagan Last Hagan Last
Technology Manager, Content Distribution,
Dolby Laboratories
Sean McCarthy Sean McCarthy
Senior Technical Product Marketing Manager,
Bitmovin
Kieran Farr Moderator: Kieran Farr
VP Marketing,
Bitmovin

Video: UHD – commercial success or work in progress?

Where is UHD? Whilst the move to HD for US primetime slots happened very quickly, HD had actually taken many years to gain a hold on the market. Now, though SD services are still numerous, top tier channels all target HD and in terms of production, SD doesn’t really exist. Is UHD successfully building the momentum needed to dominate the market in the way that HD does or are there blockers? Is there the will but not the bandwidth? Can we show that UHD makes financial sense for a business? This video from the DVB Project and UltraHD Forum answers these questions.

Ian Nock takes the mic first and explains the UltraHD Forum’s role in the industry ahead of introducing Dolby’s Jason Power. Ian explains that the UltraHD Forum isn open organisation focused on all aspects of Ultra High Definition including HDR, Wide Colour Gamut (WCG), Next Generation Audio (NGA) and High Frame Rate (HFR). Jason Power is the chair of the DVB Commercial Module AVC. See starts by underlining the UHD-1 Phase 1 and Phase 2 specifications. Phase 1 defines the higher resolution and colour gamut, but phase 2 delivers higher frame rate, better audio and HDR. DVB works to produce standards that define how these can be used and the majority of UHD services available are DVB compliant.

On the topic of available services, Ben Schwarz takes the stand next to introduce the UltraHD Forum’s ‘Service Tracker‘ which tracks the UHD services available to the public around the world. Ben underlines there’s been a tripling of services available between 2018 to 2020. It allows you to order by country, look at resolution (from 2K to 8L) and more. Ben gives a demo and explains the future plans.

Paul Bray focusses on the global television set business. He starts looking at how the US and Europe have caught up with China in terms of shipments but the trend of buying a TV set – on average – an inch larger than the year before, shows little sign of abating. A positive for the industry, in light of Covid-19, is that the market is not predicted to shrink. Rather, the growth that was expected will be stunted. The US replaces TVs more often than other countries, so the share of TVs there which are UHD is higher than anywhere else. Europe still has a large proportion of people who are happy with 32″ TVs due to the size and HD is perfectly ok for them. Paul shows a great graph which shows the UHD Penetration of each market against the number of UHD services available. We see that Europe is notably in the lead and that China barely has any UHD services at all. Though it should be noted that Omdia are counting linear services only.

Graph showing UHD Penetration per geographical market Vs. Number of Linear UHD services in that Market

Graph showing UHD Penetration per geographical market Vs. Number of Linear UHD services.
Graph and Information ©Omdia

The next part of the video is a 40-minute Q&A which includes Virginie Drugeon who explains her work in defining the dynamic metadata that is sent to the receiver so that it can correctly adapt the picture, particularly for HDR, to the display itself. The Q&A covers the impacts of Covid-19, recording formats for delivery to broadcasters, bitrates on satellite, the UltraHD Forum’s foundational guidelines, new codecs within DVB, high frame rate content and many other topics.

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Download the presentations
Speakers

Jason Power Jason Power
Chair of the DVB Commercial Module AVC Working Group
Commercial Partnerships and Standards, Dolby Laboratories
Ben Schwarz Ben Schwarz
Chair of Ultra HD Forum Communication Working Group
Paul Gray Paul Gray
Research Director,
Omdia
Virginie Drugeon Virginie Drugeon
Senior Engineer, Digital Standardisation,
Panasonic
Ian Nock Moderator:Ian Nock
Chair of the Interoperability Working Group of the Ultra HD Forum
Principal Consultant & Founder, Fairmile West