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Archives for January 2012

Implementing startOffsetTime for HTML5

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Sean O'Halpin | 14:45 UK time, Tuesday, 31 January 2012

In this first of two technical blog posts on our recent work on P2P Next, we explain why and how we implemented the HTML5 media element attribute startOffsetTime in Firefox to enable accurate synchronisation of out-of-band timestamped metadata with media streamed live to a browser over the internet.

First we'll explain our rationale for why we need the functionality this attribute makes possible. Then, we'll go into some technical detail as to how Firefox and Chrome currently interpret the specification. We'll explain how we built a proof of concept implementation in Firefox. Finally we'll state our position on the interpretation of the specification and highlight some challenges in getting this implemented more generally.

The reason for setting this out is that we'd like to see consistent support for startOffsetTime across all commonly used codecs and for browser vendors to bring their implementations into line with the published HTML5 media elements specification. There are ambiguities in the specification itself, such as the interpretation of 'earliest seekable position', which could be clarified, especially with respect to continuous live streaming media. Browser vendors need to agree on a common interpretation of attributes such as currentTime so others can experiment with the exciting possibilities this new technology is opening up.

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Prototyping weeknotes #93

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Pete Warren Pete Warren | 16:19 UK time, Monday, 30 January 2012

The project focus for these weeknotes is LIMO where we have been investigating timed interactive media to support video using HTML5. This work was conducted as part of the collaborative project in which ´óÏó´«Ã½ R&D is a partner.

LIMO screenshot

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2D compatible 3D broadcasts

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Ant Miller Ant Miller | 10:00 UK time, Tuesday, 24 January 2012

The Digital Service Development group led by Phil Layton in ´óÏó´«Ã½ R&D was involved in the previous trial of 3D at the Wimbledon Tennis Championships this year and also the recently broadcast Strictly Come Dancing Grand Final. In this post Dr Peter Cherriman outlines the work to produce 2D compatible 3D broadcasts for Freeview and Freesat receivers.

The ´óÏó´«Ã½ has been trialling 3D broadcasting over the last year. While 3D content is an interesting development in television, it creates a number of challenging problems for existing 2D receivers in the market.

In order to allow the introduction of 3D broadcasting with the minimum changes to existing systems and receivers, the DVB broadcasting specifications allow 3D content to be broadcast as HD video. The stereoscopic video is merged into a single HD frame by anamorphically compressing the view for each eye into half of the HD frame. This 'frame compatible' video can then be transmitted on a separate 3D channel or broadcast as part of a 2D HD channel.

Launching a separate 3D channel does reduce some of the legacy 2D receiver issues. However, such a channel would require a significant amount of 3D content and the cost of finding additional capacity. The ´óÏó´«Ã½ has broadcast its 3D trials on an existing 2D channel, the ´óÏó´«Ã½ HD channel.

Our trial 3D broadcasts started with the Wimbledon Singles Finals and then the Strictly Come Dancing Final before Christmas. These programmes were all broadcast in 3D on the ´óÏó´«Ã½ HD channel. Viewers without 3D televisions were able to watch a simulcast in 2D on ´óÏó´«Ã½ One or ´óÏó´«Ã½ One HD.

However, scheduling a 2D simulcast of a 3D broadcast will not always be possible. We have been looking for solutions to allow viewers with a existing HD receiver and a 2D television to watch the 3D content in 2D. It is possible to generate a 2D view from the frame compatible 3D content, by showing the 2D viewers a stretched version of either the left or right eye view.

With the current broadcasting standards this 2D view results in a loss of resolution, to something less than HD resolution but higher than standard definition.

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Prototyping weeknotes #92

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Tristan Ferne | 11:00 UK time, Monday, 23 January 2012

We're starting a new format for our weeknotes this week to make them a bit easier to read. We'll feature one project in detail each time and just give a quick summary of our other projects. This week the project in focus is The Programme List.

New GEL-based design for The Programme List

The forthcoming release of The Programme List has a simplified interface based on GEL

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An Affective Interface for Mood-Based Navigation

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Rosie Campbell Rosie Campbell | 12:00 UK time, Monday, 16 January 2012

Sometimes we need 'cheering up', 'calming down' or 'a bit of excitement'. Whether we notice it or not, we use affective (i.e. mood-based) language pervasively in life. Yet when we browse for media, we find content categorised into rigid, traditional genres, with searching restricted to factual metadata such as title or director. There is little allowance for relative scales or subjectivity.

The Multimedia Classification project in Archives Research is attempting to address this by answering the question of how we can use mood as a meaningful navigation tool. It certainly isn’t a feckless pursuit: if the ´óÏó´«Ã½ archive is ever to be made available to the public, we’re going to need some help finding what we want. From hundreds of thousands of hours of programmes spanning over 75 years, simply searching for ‘comedy’ isn’t going to get you very far! In fact, in our recent study, the majority of people said they would find it useful to be able to search by mood. I understand if you’re sceptical, we’re so used to conventional searching, it’s hard to imagine a useful alternative. However we’re not suggesting this approach will replace conventional methods, more that it will augment and improve them. It may even turn out that searching by mood is something people didn’t realise they wanted it, but once it’s there they’ll wonder how they ever managed without it!

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Prototyping weeknotes #91

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Barbara Zambrini | 10:28 UK time, Monday, 16 January 2012

After a well-deserved Christmas break, we are ready for another great year! We continue making good progress on current projects as well as looking at exciting new opportunities.

The Programme List project is proceeding towards the final spike of the current development with Andrew and Theo giving it a visual makeover to use the ´óÏó´«Ã½ Global Experience Language (GEL) using the Ruby gem, which makes easy to integrate into a ruby application. Duncan has reworked the whole thing from a web app to a website and has been plotting graphs with the usage data to understand strengths and weaknesses.

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Easier, faster, smoother, better ... but first we need a few details

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Joanne Moore | 10:22 UK time, Monday, 9 January 2012

Online services frequently gather data from users – users explicitly disclose some of it, and other data is implicitly captured; but different services have differing amounts of access and openness on the data they hold. Users are not always given the opportunity to view the collected data or manage how it will be used. With emerging technologies, more user data will be gathered, often with the intention to enhance the user experience; but gathering user data opens up issues of privacy and security to the detriment of the user experience it was intended to enhance. This literature review aims to explore issues around personal data from the perspective of users, and is part of our work on the .

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Drawing of a person holding a box with an arrow pointing at it labelled 'Your data'

Security and privacy considerations for end users are complex and ever changing

Privacy and security are complex concepts, they change constantly depending on the context the user is in. Security and privacy cannot be looked at in isolation, people cannot consider them out of context, rather decisions are made as part of another task with a different purpose - for example keeping up to date with friends, or buying some groceries. Users approach each situation depending on past experience and current expectations. There is a recognised paradox between what users say they are comfortable disclosing and what they actually disclose – this is partly because some studies asked security questions out of context or without a purpose for users to relate to; another explanation is that users can be enticed into decisions based on the potential benefits rather than the costs associated with the disclosure. Even when users are less comfortable disclosing information, if the benefits are compelling enough they sometimes find hacks and workarounds to maintain some sense of their privacy while using the system.Ìý

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CVMP 2011

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Oliver Grau Oliver Grau | 15:42 UK time, Tuesday, 3 January 2012

held at the BFI at London's south bank aims to bridge cutting edge research with best practice in media production. This year marked the 8th edition of the event, chaired by the author of this post.

A number of keynotes and invited talks were setting the industrial scene, with Google's Jeremy Doig talking about challenges of delivering video in the internet age. Nicola Hoyle from gave some insides into the special effects on the movie 'Inception' together with tips how to get from University into post-production industry. Roberto Cipola, Professor at Cambridge University and Director at gave an overview of vision-based 3D modelling techniques. Sylvain Paris, Researcher at demonstrated latest research work on automatic stylisation of home-made photos.

The mainly industrial invited talks were complemented by with reviewed paper submissions mostly coming from academia. This year's best paper prize sponsored by ´óÏó´«Ã½ R&D went to (University of Cambridge) For his paper entitled

What attendees seem to like most is the compact programme and the fact that 'you get the same high calibers as at SIGGRAPH, but you can actually talk to them'. We hope to keep this familiarity and close contact for all attendees as CVMP grows and looks for a bigger venue for next year.

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