MPEG Dynamic Adaptive Streaming over HTTP (MPEG-DASH) / DASH-264 2016

Whenever a new technology is emerging, especially the one that can give some order to the mess, lots of people pray the technology would be the final ONE. While H.265 and HTML5 are lurking on the horizon, let's look at one of the new technology that could clean-up the mess caused by lots of codecs, containers, and streaming protocols.

MPEG DASH is an ISO standard for dynamic adaptive streaming over HTTP. It could potentially supersede the proprietary DASHs such as Microsoft's Smooth Streaming, Adobe's Dynamic Streaming, and Apple's HTTP Live Streaming. With the emergence of various competing HTTP-based adaptive streaming solutions over the past several years as listed above, it quickly became obvious that multiple competing adaptive streaming technologies were contributing to the fragmentation of the streaming media market, increasing storage and bandwidth costs, and impairing customer reach. So, efforts to standardize HTTP-based adaptive streaming beganvn 3GPP in 2009, and DASH was ratified by ISO/IEC as a standard in November 2011.

Adaptive streaming defines Segments that are a few seconds long and a playlist format that describes alternative encodings of each Segment with different bitrates, resolutions, codecs, etc. Devices can download a sequence of Segments of compatible types with a particular video bitrate and resolution, and audio language from a set of alternatives typically stored on Web servers.

Dynamic adaptation is the ability of each device to automatically switch the next Segment selection to an alternative resolution and bitrate so that it can adapt to changes in network bandwidth and client conditions. The video quality will only be as good as the effective network bandwidth allows, but will be the best possible quality rather than some lowest common denominator fixed bitrate that still causes paused for rebuffering errors when bandwidth temporarily reduces.

Because the adaptive intelligence is inside each device, and Web servers and Content Delivery Networks (CDNs) are stateless HTTP servers, with only a small increase in server load, DASH can allow the number of clients for a particular presentation to scale to large numbers.

DASH uses XML to describe media presentations in a manifest file. It references media streams stored in ISO Base Media File Format. With the HTTP protocol and existing CDNs, the DASH enables a better video experience for end users by automatically adapting to varying client and network conditions during playback.

DASH has the potential to give content publishers access to any consumer on any video device capable of Internet access. generate a single set of files (based on DASH's standardized manifest) that would play on all devices, reducing both technical headaches and transcoding costs rather than preparing several servers and sets of content to reach different types of devices.

Picture from MPEG's Dynamic Adaptive Streaming over HTTP (DASH) - Enabling Formats for Video Streaming over the Open Internet

A DASH client retrieves and plays the video content using these steps: howstuffworks.com

1. The client downloads and reads the Media Presentation Description (MPD) to get important information, such as the content locations, segment encodings, resolution, minimum and maximum bandwidths, accessibility features like closed captioning and content restrictions (such as DRM).
2. The client selects an appropriate segment encoding and begins streaming the content through a series of HTTP requests. The server creates and encodes each segments on demand for each request, all from the same source.
3. The client buffers data as it's downloaded, while also keeping track of fluctuations in the connection bandwidth. If necessary, the client automatically changes to a different segment encoding (from those listed by the MPD) that's more compatible with the current bitrate. This ensures the client maintains a sufficient buffer throughout the video without downloading more data than you need.

Adobe/Akamai MPEG-DASH Demo in Adobe Flash with the Prototype player.

Adobe/Akamai MPEG-DASH Demo

At NAB 2012, Andy Plesser of BeetTV about DASH

1. Work on DASH started in 2010
2. Draft International Standard in January 2011
3. Ratified by ISO/IEC as a standard in November 2011.
4. The MPEG-DASH standard was published as ISO/IEC 23009-1 in April 2012.
5. In July 2013, the second edition of MPEG-DASH has been approved incorporating first amendment and corrigenda including support for event messages and media presentation anchors.

Netflix sees hope in MPEG-DASH. Please watch:

These Streaming Media Red Carpet Interviews are sponsored by Front Porch Digital.

1. MPEG-DASH uses standard HTTP protocol.
   It can be deployed using standard web servers and it work with existing Internet infrastructures, including CDNs, caches, firewalls and NATs.
2. On-demand, live and time-shift applications.
   MPEG-DASH supports on-demand, live and time-shift applications and services with a single framework.
3. Switching and selectable streams.
   The Media Presentation Description (MPD) provides adequate information to the client for selecting and switching between streams, such as selecting one audio stream from different languages, selecting video between different camera angles, selecting the subtitles from provided languages, and dynamically switching between different bitrates of the same video camera.
4. Ad insertion.
   Advertisements can be inserted as a period between periods or segment between segments in both on-demand and live cases.
5. Compact manifest.
   The segments' address URLs can be signaled using a template scheme resulting in a compact MPD.
6. Fragmented manifest.
   The MPD can be divided into multiple parts or some of its elements can be externally referenced, enabling downloading MPD in multiple steps.
7. Common Encryption and Multiple DRM support.
   The content can be encrypted once and delivered to client supporting various DRM schemes. The supported DRM schemes can be signaled in MPD including UltraViolet(UV).
8. Segments with variable durations.
   The duration of segments can be varied. With live streaming, the duration of the next segment can also be signaled with the delivery of the current segment.
9. Multiple base URLs.
   The same content can be available at multiple URLs, at different servers or CDNs-and the client can stream from any of them to maximize the available network bandwidth.
10. Clock-drift control for live sessions.
    The UTC time can be included with each segment to enable the client to control its clock drift. Scalable Video Coding (SVC) and Multiview Video Coding (MVC) support. The MPD provides adequate information regarding the decoding dependencies between representations, which can be used for streaming any multilayer coded streams such as SVC and MVC.
11. A flexible set of descriptors.
    These describe content rating, components' roles, accessibility features, camera views, frame packing, and audio channels' configuration.
12. Subsetting adaptation sets into groups.
    Grouping occurs according to the content author's guidance. Quality metrics for reporting the session experience. The standard has a set of well-defined quality metrics for the client to measure and report back to a reporting server.

1. The MPEG-DASH Standard for Multimedia Streaming Over the Internet
2. MPEG's Dynamic Adaptive Streaming over HTTP (DASH)- An Enabling Standard for InternetTV
3. Scalable Video Coding based DASH for efficient usage of network resources
4. DASH-IEEE-multimedia-preprint.pdf
5. Dynamic Adaptive Streaming over HTTP - Design Principles and Standards by Thomas Stockhammer, Qualcomm
   
6. Short Tutorial on MPEG-DASH
7. OTT Streaming
8. Guidelines for Implementation: DASH264 Interoperability Points - DASH Industry Forum, 2013

1. Here is an excerpts from MPEG DASH's Future: Unified Format or DASHed Hopes?

   Unless MPEG DASH considers a few key issues during ratification and implementation, it "has more issues than Lindsay Lohan." Among them is that while Microsoft and Adobe have indicated their plans to support MPEG DASH in practice as well as in theory, Apple hasn't. Given Apple's aversion to embracing any technology that limits its ability to tightly control the iOS/iDevice ecosystem, it's not unreasonable to think that Apple will refrain.

   The bigger issue is that even though MPEG DASH standardizes a single delivery protocol, it supports two video codecs, H.264 and WebM, and two file formats, MPEG-2 Transport Stream (M2TS) and a fragmented MPEG-4 version of the ISO Base Media File Format known as the Common File Format (CFF). CFF is royalty-free, but if MPEG DASH includes H.264, Mozilla won't support it in Firefox, a browser that still holds more than 20 percent of the browser market share.

   Even if DASH is implemented correctly, content producers will still have to deliver content in both DASH-compliant players (with H.264 and either M2TS or fMP4(fragmented MP4)) as well as a WebM-compliant player, as DASH does not yet include profiles for WebM. Without WebM support, content producers might not be able to reach Firefox users at all. And Apple's iOS with HLS delivery will likely remain a world unto itself. All of which means that MPEG DASH's promise of total interoperability will likely never become a reality.

2. Another one related to licensing, MPEG DASH Gains Industry Support As "Streaming Media Standard"
   From a licensing standpoint, there is a requirement to notify ISO of their intent to license; Qualcomm and Cisco have announced they'll offer royalty-free since HTTP adaptive streaming has been done for a number of years but to get to a standard we need to see a path forward to royalty-free licensing.



3. What aspects of DASH could hinder widespread adoption?
   

   First, there are some unresolved intellectual property rights with DASH. Normally, IP introduced into MPEG standards is accepted only if the IP owner agrees to Reasonable and Non-Discriminatory (RAND) terms. In the case of DASH, it is not clear that all IPR in the standard is covered by RAND terms. Second, while DASH has one name, it is a collection of different, non-interoperable profiles. So DASH doesn't solve the problem of different, non-interoperable implementations unless DASH clients support all profiles. And this is basically equivalent to having a client that supports HLS and HDS and Smooth Streaming (which incidentally would also address the interoperability problem).

   Time will tell if MPEG DASH will coexist or supersede existing adaptive streaming formats. Certainly, DASH provides quite a flexible framework for delivering streaming media content. As usual, it will depend on what the major vendors do, and whether VSPs see the benefits of augmenting or changing trajectory of in-process deployments and content offerings.



4. MPEG DASH's Future Is Fractured, Says VideoRX, July 9, 2012
   

   MPEG DASH offers a promise of simplified endoding and delivery for adapative streaming, but that promise is still years away. Speaking in a red carpet interview at the recent Streaming Media East conference, Robert Reinhardt, inventor for VideoRX, says the problem is getting the major players to agree.

   "Let's just say Apple continues with HLS and that's all they do for adaptive streaming and they are like "Eh, MPEG DASH, we don't really need it, we've got our own solution already." But then we still have this environment where we have two streaming standards," noted Reinhardt. "Two is better than what we currently have, which is Adobe, Microsoft, and Apple all sort of pushing their own adaptive streaming manifest "

1. RGB Networks Is First With TV Everywhere Packager Support for MPEG DASH and All Other Leading Adaptive Streaming Protocols.
   

   RGB Networks, the leading provider of scalable multiscreen IP video delivery solutions, today announced that its award-winning TransAct Packager now supports the MPEG Dynamic Adaptive Streaming over HTTP (MPEG DASH) protocol.

   Adding this to its support for Apple HTTP Live Streaming (HLS), Microsoft Smooth Streaming and Adobe HTTP Dynamic Streaming (HDS), RGB's TransAct Packager is the only packager to support all four protocols in live and on-demand environments. With this broad support, video service providers (VSP) can continue to deliver video to any IP-enabled device, even as the industry continues to evolve.

2. MPEG-DASH: Making Tracks Toward Widespread Adoption.
   

   The need to reach multiple platforms and consumer electronics devices has long presented a technical and business headache, not to mention a cost for service providers looking to deliver online video. the holy grail of a common file format that would rule them all always seemed a quest too far.

   Enter MPEG-DASH, a technology with the scope to significantly improve the way content is delivered to any device by cutting complexity and providing a common ecosystem of content and services.

   The MPEG-DASH standard was ratified in December 2011 and tested in 2012, with deployments across the world now underway. Yet just as MPEG-DASH is poised to become a universal point for interoperable OTT delivery comes concern that slower-than-expected initial uptake will dampen wider adoption.

   -July 2013, Streaming Media

3. The Current State of MPEG-DASH In The Industry - Aug. 2013