How to Package Video for Multiscreen Delivery
Most producers aim for their videos to play on every available platform. These platforms are presented in the pyramid on the right of Figure 1. To achieve this goal, producers can use a number of formats, which are shown in the table on the left in Figure 1. The color coding in the table shows the suitability of each format for each target platform in the familiar traffic light format: red means stop, green means go, yellow means caution.
Also shown in the pyramid are the major standards or players in each market. As you can see, in computers and notebooks, there are two major standards— Flash is the de facto, but waning, standard, while HTML5 is the up-and-comer but limited in features, at least as currently implemented. Not shown is the impact of the Media Source Extensions (MSE), which I’ll cover in a separate section below.
But where you can paint the computer market with a very broad brush, you have to approach the other markets on a platform-by-platform basis. For example, in mobile, HTML5 is universally supported for H.264 playback, but that only delivers single-file, not adaptive, playback, and doesn’t enable live streaming or DRM. For these features, you have to address the two major platforms separately. Apple is simple—all iOS versions support HLS, simplifying adaptive delivery to that platform. Android is not. Android 3.0 and later versions support HLS, though there are various issues that make this support problematic at best, unusable at worst. Android version 5, or Lollipop, supposedly addresses these issues, but it hasn’t shipped yet. So there isn’t one adaptive approach that achieves native, browser-based playback on iOS and Android.
As you climb the pyramid, the different markets become ever more fractured, and the company behind each platform chooses the format or formats that it supports. For example, in the Retail OTT market, Apple TV supports only HLS, and not DASH. Roku is the same. Chromecast supports DASH, as does the Amazon Fire TV, but only if you create your Fire TV media player with the VisualOn OnStream MediaPlayer+ SDK.
How Much Can You Afford?
The reference to the VisualOn OnStream MediaPlayer+ SDK brings up another key point. At most points in the pyramid, there are multiple ways to implement any specific technology. In the PC/notebook space, native browser-based playback is always easiest and cheapest because all you need are MP4/WebM files and the video tag and you’re in. A pervasive plug-in like Flash is next-easiest, because you can use any number of free or inexpensive off-the-shelf (OTS) players, or build your own.
However, other plug-ins or players can extend format support beyond that enabled in the Flash Player. For example, if you deploy the JW Player, a leading OTS player, you can deliver HLS to computers and notebooks, which gives you adaptive delivery to computers, notebooks, and iOS devices with a single format. Other alternatives, such as castLabs DASH Everywhere, enable DASH-based playback from a browser. Or you can create your own DASH- or HLS-compatible player from scratch.
The mobile side has its own design alternatives. Again, native playback is easiest because it doesn’t require any custom development, but then you’re limited to natively supported formats. If you create an app, however, you can implement virtually any technology: DASH, HLS, Flash, or even Smooth Streaming.
Taking it a step further, if you create an app, you can also replace dysfunctional components of a particular platform, such as the aforementioned flawed HLS playback in Android. Some well-heeled developers have taken this approach, as has Adobe in Primetime.
The bottom line is that you have enough cash, you can use virtually any technology in any platform. The permutations are too numerous to address, so I’ll focus primarily on browser-based playback in the scenarios presented below, either natively or via OTS players or SDKs.
Let’s start with single file delivery to desktops, notebooks, and mobile devices.
Single File Delivery via HTML5 With Flash Fallback
The simplest approach to reaching the bottom two levels of the pyramid is to use HTML5 delivery with Flash fallback. At this point, the vast majority of browsers are compatible with HTML5, though some sources estimate Internet Explorer 8, which is not, still had a 20 percent share or more as of July 2014. For this reason, most producers that deliver via HTML5 also fall back to Flash in legacy browsers.
Of course, not all HTML5-compatible browsers play the same codec; Apple Safari and Microsoft IE play H.264, while Mozilla Firefox and the Opera browser play WebM, and Google Chrome can play either. Some producers encode in both formats for HTML5 delivery; some encode in H.264 for delivery to Safari, IE, and Chrome and fall back to Flash for Opera and Firefox since Flash can play the same H.264-encoded file.
Figure 2 shows the HTML coding required for H.264/ WebM delivery with Flash fallback. This code was created in Sorenson Squeeze, which can produce H.264 and WebM output, plus the HTML5 code, a nice convenience for nontechnical users.
This approach delivers virtually all viewers in the bottom two levels of the pyramid, but comes with some pretty serious limitations. Specifically, it’s VOD-only (no live), single file-only (no adaptive), and progressive download-only (no streaming). Moreover, there is no standard schema for DRM. All that said, it’s enough for many web producers, and it’s simple and inexpensive to implement.
From Proprietary Technologies to Standards (Warts and All)
OK, so HTML5 with Flash fallback gives you single file progressive delivery of VOD files without DRM. What do you do if you need adaptive, live, true streaming, or DRM? You choose a different technology. Since we’re undergoing a fundamental shift in these technologies, let’s take a quick overview.
The streaming industry was founded on proprietary technologies that ebbed and flowed as different technologies achieved dominant market share—RealNetworks yielded to Microsoft Windows Media, which yielded to Adobe Flash. In the adaptive space, Microsoft produced Smooth Streaming for Silverlight and Adobe produced adaptive technologies for Flash, RTMP, and HTTP-based Dynamic Streaming, while Apple produced HTTP Live Streaming for iOS and Safari.
Proprietary technologies come with pros and cons. On the plus side, since one organization controls the format and player, it’s simple to add new features to the technology, whether it’s adaptive, or DRM, or captions. On the negative side, since many proprietary technologies must integrate with the browsers used to find and play the videos, they require plug-ins, which can cause security issues and instability.
Standards also have pros and cons. The key benefit of DASH is that you can deliver a single set of files to all compatible players, from the bottom to the tippy top of the pyramid. Standards also come with negatives, chief among them that you can’t force companies to adopt them. The poster child for this concept is Apple, which hasn’t yet indicated if and when it will support DASH in iOS. Microsoft isn’t helping either, only releasing support for the Media Source Extensions (MSE) required for DASH playback on Internet Explorer in Windows 8.1, which, at 12.2 percent share (per StatCounter), only recently surpassed Windows XP in worldwide installed base and is dwarfed by Windows 7 (43.9 percent). True, as mentioned above, you can implement DASH without browser support via plug-ins or custom development, but pervasive support simplifies matters and reduces development costs.
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