Microsoft Announces Support for MPEG-DASH in Microsoft Media Platform
Microsoft Media Platform will support MPEG-DASH, a recently ratified ISO/IEC standard for dynamic adaptive streaming over HTTP. Microsoft plans to support DASH and other open standards as part of an industry-wide initiative to establish reliable video delivery to Internet connected devices and enable true interoperability between adaptive streaming technologies from different vendors.
Much like Smooth Streaming, DASH uses Extensible Markup Language (XML) to describe media presentations in a manifest file which references media streams stored in ISO Base Media File Format. Combined with the standard HTTP protocol and existing Web content delivery networks, the DASH standard enables a better video experience for end users by automatically adapting to varying client and network conditions during playback.
Taking advantage of similarities between Smooth Streaming and DASH, Windows Azure Media Services will add support for DASH Live Profile later this year so that both Smooth Streaming and DASH devices can access the same live and on-demand video presentations using either manifest format. This will enable a smooth transition to DASH for millions of devices and services currently using Smooth Streaming.
In addition to server-side support, Microsoft will also add support for DASH to all its Smooth Streaming client development kits. The first step will be to enable DASH support in the Smooth Streaming Client for Silverlight, followed by support in Smooth Streaming Client SDKs for Windows 8, iOS, Xbox, Windows Phone and Smooth Streaming Client Porting Kit for embedded devices.
Microsoft is also contributing to W3C efforts to standardize adaptive streaming APIs in HTML5 so that DASH Web applications may also be written in HTML5 and ECMAScript (JavaScript) in the future without requiring browser plug-ins such as Silverlight and Flash to enable advanced streaming media scenarios.
Microsoft has contributed to the development of the DECE UltraViolet video format which enables download and adaptive streaming of premium movie and TV content; and to various international broadcast standards and consortia so that a common protected video format based on DECE Common File Format, MPEG Common Encryption, and MPEG-DASH specifications will be supported by all adaptive streaming services and devices to enable reliable interoperability for consumers, just like broadcast TV and DVD.
What Microsoft services will have DASH support?
Windows Azure Media Services will provide encoding, encryption, and streaming support for Application Profiles based on DASH “ISO Base Media Live Profile” this year. Both DASH manifests and Smooth Streaming manifests will be generated to allow the same media to be streamed by DASH clients and Smooth Streaming clients. The primary media format will conform to the PIFF 1.3 specification in addition to Live Profile, will include several features and constraints compatible with the DECE Common File Format, and may optionally include MPEG Common Encryption with PlayReady DRM support. Windows Azure Media Services will also be capable of live transformation to multiple streaming formats, including MPEG-2 Transport Streams for use with DASH M2TS Simple Profile manifests or M3U8 playlists.
What Microsoft client technologies will have DASH support?
Microsoft plans to add MPEG-DASH support to all client development kits that currently support Smooth Streaming. These are: Smooth Streaming Client for Silverlight; Smooth Streaming Client for Windows Phone; Smooth Streaming Client SDK for Windows 8 Metro-style applications; Xbox LIVE Application Development Kit; Smooth Streaming SDK for iOS Devices with PlayReady; and Smooth Streaming Client Porting Kit.
Is Microsoft discontinuing Smooth Streaming?
No. Microsoft will continue to invest in Smooth Streaming as an established technology and brand while ensuring its Smooth Streaming services, clients, tools and workflows are DASH compatible. The Smooth Streaming file format (PIFF 1.3) is already compatible with the DASH specification (ISO Base Media Live Profile) so customers and partners who are investing into creation of Smooth Streaming content today will have a clear path to making that content deliverable to DASH clients in the future.
What is Common Encryption?
Common Encryption is an MPEG standard using AES-128 media encryption that enables a single protected ISO Base Media file or adaptive streaming presentation to be used with any DRM system supported by a device and the publisher. The standard is designated ISO/IEC 23001-7 “Information technology – MPEG systems technologies – Part 7: Common encryption in ISO base media file format files”. Prior to this standard, a different set of files was required for each different DRM type, and interchange of files between authorized devices was generally not possible because of different DRMs.
What is Common File Format?
Common File Format (CFF) is a DECE video specification titled “Common File Format & Media Formats Specification” used for content download. It specifies video files based on fragmented ISO Base Media files (MPEG-4 Part 12), optionally using Common Encryption, containing AVC video, AAC audio, SMPTE Timed Text and Graphics subtitles, metadata, and several optional audio formats. All parameters required for interoperability are sufficiently specified to allow independently implemented encoders, publishers, delivery services, and devices to reliably interchange and play the same files. Different “media profiles” are specified for high definition, standard definition, and “portable” definition devices.
The CFF requirement to use short movie fragments makes these files and compatible decoders forward compatible with DASH adaptive streaming using movie fragments as DASH Media Segments. DECE is currently in the process of specifying “Common Streaming Format” and considering DASH Application Profiles.
What about HTML5 playback?
The current working draft of HTML5 does not include specific support for either adaptive streaming or DRM protection. It is possible to indicate a playlist or manifest file as the source of the <video> tag, but a publisher would have no control over the behavior and presentation that each device or browser would execute in response to that manifest. There are no standard APIs to integrate the presentation decisions made by the platform with a presentation application running in the browser.
However, there is work underway in W3C to add both adaptive streaming and content protection APIs so that a script application will be able to run in any HTML5 browser to perform DRM license acquisition and DASH adaptive streaming under the control of the script application. This will allow the script application to control adaptive heuristics, authorization, load balancing, performance reporting, targeted ad insertion, and interactive presentation and navigation of one or more adaptive presentations. These script APIs will make HTML5/JavaScript DASH applications a viable alternative to Silverlight and Flash across the full range of devices … in the future.
