15 Jul 2016

Unified Content Across Platforms, Are We There Yet?

tl;dr; For content that doesn’t require DRM, we’re there. If you need DRM there’s still some work ahead.
At WWDC 2016 Apple had some big news for the video streaming community. They announced two big changes that move us closer to a world where media files can truly be shared. Announcement one was that the HLS (HTTP Live Streaming) specification would be expanded to allow for use of fMP4 (fragmented MP4) media segments. The second announcement was that FairPlay would support fMP4 segments that are encrypted with CENC. Unfortunately as is often the case, the devil is in the details.
Let’s start with the good news. fMP4 support in HLS means that content libraries that do not require DRM can use a single set of content to serve most (if not all) clients. You will need an MPEG-DASH manifest and an HLS manifest, but the segments referenced by those manifests can be shared. This is huge! This has a major impact on the cache-ability of assets and on storage costs for media libraries. The open question here is what versions of iOS will support this new version of HLS? Will there be an update to old versions of iOS or will this be an iOS 10+ feature?
Now for the news that turned out to be a pretty big letdown. Apple announced “Sample encryption uses part of ISO/IEC 23001:7 2016” (that specification is for Common Encryption, a draft version can be obtained from mpeg). The next line in the slide says “MPEG standard—“Common Encryption”, this is looking great. However that was followed by “‘cbcs’ mode” which made it clear something fishy was going on. The language they used should also have made it clear something was up “uses part of” is not a good sign for implementing a standard.
To understand what is going on here we need to understand the CENC spec and the new HLS spec a bit better. The new versions of the CENC spec define 4 separate protection schemes for content. The 4 protection schemes defined in section 4.2 of that specification are ‘cenc’, ‘cbc1’, ‘cens’, and ‘cbcs’ (yes, one of the schemes has the same name as the overall spec). Of these 4 protection schemes only the first, cenc, is required for implementors to support. The other three are optional.
Now we need to better understand what was added to HLS. The new spec in section says “fMP4 Media Segments are encrypted using the ‘cbcs’ scheme of Common Encryption”. They’ve added support for the optional ‘cbcs’ protection scheme, without adding support for CENC spec required ‘cenc’ protection scheme. This means that if you need to protect your content with DRM you cannot use the same fMP4 fragments for FairPlay as you use for PlayReady or WideVine.
Why would Apple choose to “use part of” the CENC spec and not implement the one required protection scheme? We don’t know all of the answers, but one key point that Roger Pantos drove home in one of his presentations “Content Protection for HTTP Live Streaming”[4] was that battery life is king. He even said “every choice we made was predicated on giving you good battery life”. So what does the ‘cbcs’ protection scheme have to do with good battery life?
Of the 4 protection schemes defined in CENC the first two (‘cenc’ and ‘cbc1’) are Full Sample Encryption. As the name implies these protection schemes encrypt the entirety of the protected segment. The two newer protection schemes (‘cens’ and ‘cbcs’) use Subsample Encryption. In subsample encryption only a portion of the protected segment is encrypted. The spec says “Each Subsample SHALL have an unprotected part followed by a protected part”, so about half of the segment ends up being encrypted. This means that there is less work that needs to be done on the client as only about half as much data needs to be decrypted. In addition the ‘cbcs’ protection scheme treats each subsample as an independent encrypted block, this means that subsamples can be decrypted in parallel allowing for faster decryption of streams.
The ‘cbcs’ protection scheme is a great approach allowing for faster and more efficient protection of content, however the lack of support for ‘cenc’ within FairPlay means that DRM protected content must still be fragmented. We’ve come much closer to an ecosystem where we can use a single set of content files to deliver high quality protected video content, but we’re not quite there yet.
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02 Oct 2015

Material with LESS

In this post we are going to create a dynamic style-sheet that can be altered to fit any web application project while keeping inline with Material standards. This project is a great way to familiarize yourself with Material design while creating a style-sheet that can be recycled over and over again to create unique looking designs by just changing a few lines of code.

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24 Sep 2015
10 Sep 2015

Getting Your Feet Wet with Angular Animations

Imagine you get into a car start the engine, touch the acceleration and go from 0 to 60 in the blink of an eye. You then take the wheel to turn right and instead of a smooth turn the car takes an immediate 90 degree turn.

This is how interface design feels without smooth transitions. It works, but it does not feel natural to the user. Animations can give your design the illusion of depth and lifelike motion, creating a more 3D space and giving the user the feeling of being inside the design.

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19 Aug 2015

Different uses for the HTML5 Canvas tool

One of my co-workers suggested I look into the HTML5 Canvas as a possible solution. After looking into the canvas element I realized it was not only the perfect solution to my current problem, but it could also be a very useful tool for future projects involving graphical elements that need to changed based on user interaction.

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17 Nov 2014

Nesting SVG Charts From a Single Data Source with the Magic of D3JS Selections

Recently I was challenged with creating a series of nested pie-charts from a single set of data as a Proof of Concept for a client. A colleague suggested using the D3 javascript library and it has proven itself extremely useful for its ability to transform data into visual SVG elements with a minimum of coding. The real magic is in D3’s ‘selectAll’ method – as we will see!

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28 Oct 2014
01 Oct 2014
23 Sep 2014

HTML Video – Changes to Alternate Audio Track Access in iOS 8

Since iOS 8 went live on the 17th and I updated a few of my devices over the weekend, I decided to do some quick testing of web video playback. I wanted to see if there were any little, undocumented changes that would affect our custom, cross-platform video player, or our general approach to working with HTML video – like the changes to exiting fullscreen video that came in the update from iOS 6 -> iOS 7.

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17 Sep 2014

Alternate Audio Streams in HTML Video – Part 1

As streaming video continues to mature and become a more widely used medium for delivering major events, it is becoming more important to not only deliver a clear, reliable video, but to begin augmenting it with some of the extra possibilities it affords. One of those extras is the possibility of including alternate audio tracks that can be selected during playback. These can be used to offer video in multiple languages, provide a commentary track, and in many other creative ways.

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