Chris Knowlton's Blog

The Importance of the File Format for Adaptive Streaming

chriskno — Fri, 18 Nov 2011 23:15:00 GMT

When it comes to adaptive bitrate streaming over HTTP, file format really does matter. The fragmented MP4 (fMP4) file format, first used by Microsoft, is the basis of IIS Smooth Streaming, Adobe HTTP Dynamic Streaming, and two industry streaming standards. fMP4 files have some distinct advantages over adaptive streaming solutions based on MPEG-2 Transport Streams, such as the proprietary HTTP Live Streaming (HLS) format developed by Apple.

HLS is based on a derivative of the MPEG-2 Transport Stream (M2TS), which was developed nearly two decades ago for broadcast TV. On the other hand, the fMP4 file format was specifically designed to address the needs of modern streaming to computers, televisions, and mobile devices. fMP4 offers a number of key benefits over M2TS solutions, such as:

Trickplay capabilities (e.g., fast-forward, pause, instant replay)
Seamless stream adaptation to local conditions
Reduced storage requirements
Backwards compatibility with M2TS-based solutions
Integrated digital rights management (DRM)

When Microsoft first developed IIS Smooth Streaming, we built the fMP4 format on Part 12 of the MPEG-4 standard, which defines the ISO Base Media File Format. We released the specification for the fMP4 format under the name "Protected Interoperable File Format" (PIFF). In addition to IIS Smooth Streaming, this format has become the basis for streaming for Netflix, Comcast XFINITY, and two industry standards: the UltraViolet digital-rights management and delivery standard, which based their Common File Format on PIFF; and the upcoming MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard.

Tim Siglin, a well-known digital media consultant and writer with Transitions, Inc., has just released an excellent white paper that explores the fMP4 file format and what it means for the future of streaming video. A unique aspect of this paper is that teams from Microsoft and Adobe worked together with Tim on it, a first-time collaboration that provides hope for a standardized media streaming format in the near future. To get the Adobe perspective on this, please refer to Kevin Towes' blog post.

To learn more about fMP4 and read the white paper, titled "Unifying Global Video Strategies - MP4 File Fragmentation for Broadcast, Mobile and Web Delivery," please see Tim's blog post.

Expression Encoder 4 SP2 released

chriskno — Thu, 03 Nov 2011 06:42:00 GMT

Service Pack 2 (SP2) for Expression Encoder 4 was released today, and comes with some great updates. For example, SP2 adds the ability to do GPU encoding with Intel Sandy Bridge processors, and there are new multi-channel audio options including AAC and SRS support. For live scenarios, you can now control IIS Smooth Streaming publishing points from Expression Encoder. There have also been improvements in screen capture encoding, the built-in player templates, and new SDK samples to help you get started faster with building encoding applications.

There are over 300 improvements and fixes in SP2. Get more detailed information on the Expression Encoder team blog.

Microsoft Media Platform Content Manager 1.1 Released

chriskno — Sat, 29 Oct 2011 05:36:00 GMT

An update to the Microsoft Media Platform (MMP) Content Manager has been released. Content Manager provides an end-to-end video workflow that allows you to create live streaming events, transcode on-demand content, manage and publish video, edit video, and insert mid-roll advertisements.

Content Manager 1.1 of addresses provides the following changes:

Now includes some source code projects that were inadvertently omitted in version 1.0;
Content Manager can now be installed on Windows Vista and Windows 7.

To learn more about the MMP Content Manager, please see my Content Manager 1.0 blog post from June 30, 2011.

Microsoft Media Platform Content Manager 1.0 Released

chriskno — Fri, 01 Jul 2011 06:30:00 GMT

The newly released Microsoft Media Platform Content Manager pulls together an end-to-end video workflow that allows you to create live streaming events, transcode on-demand content, manage and publish video, edit video, and insert mid-roll advertisements. This open-source release can be used by enterprises, educational institutions, and broadcasting companies to manage their video assets using a lightweight and highly-customizable solution built on Microsoft SharePoint 2010 and Microsoft Media Platform (MMP) technologies, including Silverlight 4, IIS Media Services 4.0, and Expression Encoder 4.

The MMP Content Manager is one of four MMP frameworks optimized around IIS Smooth Streaming and its open-specification adaptive streaming file format, known as PIFF (the Protected Interoperable File Format, adopted by the likes of Ultraviolet and Netflix). It greatly simplifies the workflow for complex video streaming events, such as PDC 2010 and the types shown on the IIS Media Case Studies page.

To learn more about the MMP Content Manager, see the following resources…

Microsoft Media Platform Content Manager Download Page (code and documentation)
Steven Woodward's MIX11 session "Introducing MMP Content Manager" (slides and video)

Update (October 28, 2011): Content Manager 1.1 has been released - read more about it.

IIS Transform Manager 1.0 Beta Released

chriskno — Mon, 09 May 2011 16:01:00 GMT

The long-awaited Beta release of IIS Transform Manager is now available! With this release, we’ve incorporated some great feature requests from a large number of customers who have been running the Alpha release in commercial production for months. In addition to the previous ability to almost instantly convert Smooth Streaming content for use on Apple iOS devices, Transform Manager now also enables you to convert segmented .mp4 files to Smooth Streaming presentations and then apply DRM encryption. Add to this the new ability to scale out across multi-core HPC clusters, plus improved monitoring and management controls, and you have one very high-performance media transform engine at a very low price point.

Features

Here is a quick list of some of the major feature changes:

Capability	Status
Apply Digital Rights Management	New!
Apply fine-grained logging controls & log rollover	New!
Auditing of all file movements and copies	New!
Configure auto-cleanup of Watch Folders	New!
Manage credentials on each Watch Folder	New!
Monitor Watch Folders via notifications	New!
Run as a non-administrator, even after logging off	New!
Scale out with multi-core HPC clusters	New!
Transmux MP4 files into Smooth Streaming	New!
Chain Tasks together to create unique workflows	Improved
Convert an existing content library to Smooth Streaming	Improved
Create custom tasks using the updated Task API	Improved
Maintain constant ingest / transcode rates	Improved
Transmux Smooth content for Apple iOS devices	Improved
User interfaces, file filtering, overall stability	Improved

Workflow

Several of the Transform Manager 1.0 Beta features listed above are represented in the workflow diagram for the Expression Encoder 4 task shown in the following figure.

Customer Praise

Many customers find that Transform Manager uniquely addresses their on-demand batch processing needs. Here are two examples…

iStreamPlanet

“We have been using Expression Encoder to edit and transcode assets for the past 2 years. Prior to Transform Manager and HPC, we found the task of managing a large number of concurrent encoding jobs to be challenging. By integrating Transform Manager and HPC into our Video Workflow Automation Platform, iStreamPlanet is able to scale and manage multiple Expression Encoder nodes across multiple servers while also tracking the progress through the entire transcoding cycle from our own CMS.”

Bhavesh Upadhyaya, Vice President of Operations, iStreamPlanet

Twofour Digital

“IIS Transform manager has quickly become a core part of our video services platform ‘MediaFreedom’ and allowed us to quickly get running with complex custom workflows in critical business situations, even in its Alpha and pre-Beta versions. Communication and support from Microsoft has been excellent, and we’ve managed to leverage our existing infrastructure and build a transcode and video processing farm for a fraction of the price of competing solutions. We look forward to growing MediaFreedom alongside this valuable tool of the Microsoft Media Platform.

The plug-in architecture allows us to be flexible and deliver unique solutions to our customers, differentiating ourselves from the competition. Although the bundling of Expression Encoder control into IIS Transform Manager helps us get off the ground in record time, we appreciate the vendor-neutral aspect of Transform Manager, allowing us to be confident in our capital investments and their longevity.

The compute clustering capabilities of IIS Transform Manager allows us to scale our solutions according to our needs, and have a single point of configuration. The lack of a homogeneity requirement also allows us to scale down and redistribute our hardware when the time comes.”

Iain Ballard, Senior Developer, Twofour Digital

Resources

IIS Transform Manager webpage

IIS Transform Manager 1.0 Beta, 32-bit download

IIS Transform Manager 1.0 Beta, 64-bit download

IIS Transform Manager 1.0 Beta Readme File

MSDN API Reference and Documentation

TechNet Help Docs

IIS.net Learning Center Section on Transform Manager

Free Passes to the Microsoft workshops at Streaming Media East

chriskno — Thu, 05 May 2011 21:19:07 GMT

At the Streaming Media East show next week, we are holding two half-day workshops on Monday, May 9^th, entitled "Upgrading From Windows Media to The Next Generation Microsoft Media Platform" and "Using SharePoint for Video Delivery and Content Management". These workshops normally cost $245 to attend, but we have a few seats to fill, so are giving away five free passes to attendees who work at enterprise companies and are tasked with deploying video.

Some of the topics that will be covered include:

Learn how to easily upgrade your Windows Media infrastructure to the next-generation Microsoft Media Platform, which includes Silverlight, Expression Encoder, and IIS Media Services.
See how to easily deliver your existing audio and video content (including Windows Media, MP3, Flash, QuickTime, and other formats) and learn how to create new content at higher quality and with smaller file sizes.
Learn how to deliver video adaptively, cross-platform and cross-device, at the highest possible quality for each user.
Learn how to use SharePoint to deliver live and on-demand audio and video and see how you can serve content directly from your SharePoint database or from your media servers, and make that content easily searchable.
Find out about your options for managing and delivering your content using Windows Azure.

If you are interested in getting a free pass to either (or both) of the workshops, please email me and I'll provide you with more details.

-Chris

Live Webcasting Master Class

chriskno — Thu, 17 Mar 2011 05:31:00 GMT

Join Microsoft, Adobe, Highwinds, and Conviva for a free Master Class webcast on Live Webcasting. Going beyond production values and product descriptions, this session gets into the "how-to" of delivering cost-effective high quality live events with streaming media. The live webcast will be on March 17th, 2011, at 11:00 AM Pacific Time; the on-demand version of the event will be available starting March 18th.

Each presenter in this roundtable web event brings deep live webcasting knowledge from various perspectives. Jason Suess (pictured at right), a Principal Technical Evangelist at Microsoft, will provide insights into how we delivered the Microsoft Professional Developers Conference 2010 (PDC10) to an on-line audience in more than 150 countries. Over 500,000 hours of video was streamed to 100,000 developers during the two-day event, and many more have watched the archived on-demand content since then.

Watch the webcast to learn more about the PDC10 interactive media player experience, streaming architecture, measures implemented to assure high quality, cost containment, and the partners we worked with. In case you are interested, the Microsoft technologies used included Windows Azure, IIS Smooth Streaming, the Silverlight Media Framework, Expression Encoder, SharePoint, the Silverlight Rough Cut Editor, and a new lightweight Content Management System for Smooth Streaming that was built on SharePoint.

Interested in learning more? Here are some resources to help…

To watch the webcast, either live or on-demand, Register at StreamingMedia.com
To learn more about what made the PDC10 streaming experience compelling for end users (besides the great content), read my blog post about the event
To read the White Paper about delivering PDC10 as a Global Conference, find the download at the Windows Azure blog post
To try the PDC10 player yourself, visit the PDC website and select some on-demand content from the sessions list using the Play buttons

Expression Encoder 4 SP1 released with new IIS Smooth Streaming features

chriskno — Tue, 15 Feb 2011 23:21:43 GMT

The Microsoft Expression Encoder team recently announced the release of Expression Encoder 4 Service Pack 1 (SP1), containing some great new features for live and on-demand IIS Smooth Streaming. As you probably know, Smooth Streaming is a technology that dynamically adjusts playback rates and quality to provide each end user with the highest quality content that their bandwidth and playback device will allow.

First of all, Expression Encoder now supports encoding using NVIDIA CUDA-accelerated graphics processing units (GPUs). For encoding offline files, this can mean cutting encoding time by half. If you are using Expression Encoder 4 Pro to do live Smooth Streaming, expect to see significant increases in the number of simultaneous streams that a single encoder can produce. In other words, with Expression Encoder SP1 installed on a NVIDIA CUDA-accelerated laptop or workstation, you can now create more content at higher bit rates with less computer effort.

Second, Expression Encoder 4 Pro SP1 now includes templates for live Smooth Streaming. This includes auto-generation and publishing of media players for Silverlight as well as Apple iPhone® and iPad® devices. You will also find new encoding presets for Windows Phone 7. With these features, you can now set up to do live adaptive streaming for a live event that reaches PC, Mac, Windows Phone 7, and iOS devices in just a few minutes.

Third, SP1 adds some other new features that enable customer-requested Smooth Streaming scenarios. For live events, Expression Encoder 4 now supports live screen capture encoding and simultaneous live push/pull streaming. Other improvements include support for the HE-AAC codec and Digital Rights Management (DRM) content keys, improved de-interlacing, and captioning updates.

The bottom line is that you now get great new features and the performance of a hardware encoder for a software price, taking encoding for IIS Smooth Streaming to a new level of simplicity, reach, and cost-effectiveness.

Resources

Official Release Announcement
Expression Encoder Website
Expression Encoder 4 Service Pack 1 download site
Expression Encoder Forum
Expression Encoder Blog
Expression Encoder Whitepaper: Step-by-step guidelines and best practices on GPU encoding with Expression Encoder Pro
Expression Encoder Report: Comparisons of recommended PC configurations and associated performance numbers

IIS Media Services 4.0 Released

chriskno — Mon, 01 Nov 2010 13:23:00 GMT

IIS Media Services 4.0 was released yesterday, just in time for Streaming Media West. Coming just one year after the previous major release, IIS Media Services 4.0 allows you to encode once and deliver adaptive streaming content to three screens across multiple file formats and protocols. Keep reading to learn more about the new features, or install it now.

What's Included

This IIS Media Services release centers on new functionality for the live and on-demand IIS Smooth Streaming components. Building on over two years of industry usage, IIS Smooth Streaming has become the primary HTTP adaptive streaming technology for delivering content online. Broadcasters worldwide have used it to deliver on-demand content and live events, such as the World Cup, Sunday Night Football, the Tour de France, and the 2010 Winter Olympics.

With another year of customer wins and input on what would make it even better, the feature set in IIS Media Services 4.0 addresses some specific themes, focusing primarily on expanded iPhone support and a broad set of new live streaming features. Some specifics follow…

One Encoding Format, One Server, Many Devices – including iPhone

Using the same live H.264 streams you encode for Silverlight and other Smooth Streaming players running on PCs, Macs, Linux, Nokia S60 phones, Windows Phone 7, and set-top-boxes, IIS Media Services can now re-package those streams in real time for delivery to iPhone, iPad, and other Apple^® iOS devices. It's as simple as clicking a checkbox. Under the hood, IIS Media Services re-packages (transmuxes) the H.264 and AAC content into the Apple HTTP Live Streaming format, which iOS devices natively understand.

New advanced capabilities are also available for iOS devices, including:

Live DVR – Pause, Rewind, Seek
Archiving – saves the live content for DVR use or later on-demand playback
Archive Segmentation – breaks a long broadcast archive into shorter clips for storage purposes
AES Encryption – keeps your content safe while streaming
B-frame support – provides better picture quality
Compatibility mode for iOS3 devices

Low-Latency Live Streaming and more

There are times when you need to see video in near real-time, such as for financial market news, surveillance video, and on-line gaming (gambling) sites. With low-latency (sometimes referred to as low-delay) streaming, you can reduce the time it takes from when an event actually occurs to when a viewer sees it from a typical latency of 15 seconds to under 2 seconds.

Other new live Smooth Streaming features help improve manageability and increase performance, including:

Publishing point runtime status – provides real-time stats via APIs and the UI
Manifest compression – reduces the size of the manifest sent to clients
Metadata delivery support – delivers RDF format metadata from encoder to the client
Reduced memory usage – handles even higher server loads
Smarter disk access – provides higher consistency server performance
Dedicated fragment caching – reduces disk access during live sessions

Next Steps

Whether you are trying to reach a broader set of endpoints, actively monitor your Smooth Streaming presentations, or increase server performance and scalability, IIS Media Services 4.0 has something for you.

Install and try IIS Media Services 4.0 today
Stay tuned for other IIS Media releases in the weeks and months ahead…
- IIS Smooth Streaming Client
- IIS Transform Manager
- IIS Smooth Multicast

Big Buck Bunny images © copyright Blender Foundation | www.bigbuckbunny.org

Microsoft PDC 2010 – Streaming Now using IIS Smooth Streaming

chriskno — Thu, 28 Oct 2010 20:27:00 GMT

Today is the start of the Microsoft Professional Developer Conference (PDC) 2010, and you can view it now – live or on-demand – at www.microsoftpdc.com. Powering the streaming at PDC is IIS Smooth Streaming, part of IIS Media Services.

As usual, there will be plenty of big announcements at PDC, including new information about Windows Phone 7 and Windows Azure. Two announcements, made by Bob Muglia during the keynote (see the video or the transcript), affect IIS Media Services:

Windows Azure will soon support a VM role so you can run a full Windows Server 2008 R2 image
Full IIS and IIS Smooth Streaming support will soon be enabled natively on Azure!

With this year's event, we have taken the media experience up another level. Not only are we providing live Smooth Streaming of the keynotes, but also concurrent live streaming of all sessions. All of this content will be available for on-demand viewing after the live event ends.

The player experience, built on Silverlight Media Framework 2.0 and hosted on Windows Azure, has some great new functionality. As you can see from the screenshot below, there are a number of cool and useful features built in, including:

Swappable large and small video feeds, one for the presenter, and one for the on-screen content (slides and demonstrations – shown here in the upper right)
A live Twitter feed, and a Q&A tab for the PDC sessions
The ability to copy or Tweet a link to the current session
Download Materials available for some sessions
Related Content links
Live Closed Captions

When you hover your mouse over the player, you also see a two-row overlay set of standard and advanced player controls. From left to right, top to bottom, these include:

Clickable Seek bar
Current play position and estimated video duration
A "Live" button, so if you have paused or replayed some content, you can rejoin the live broadcast
A Bookmark button, allowing you to denote key events in the video and then share the URL to point in the video with others
Volume control
Video quality meter
The "Like" button and "Like" counter
15-second instant replay
Rewind, Pause, and Fast Forward controls (full live DVR!)
Closed Captioning toggle
Audio menu – some PDC sessions, such as the keynotes, are available with live audio in five languages
Full Screen – which overlays the secondary video over the main window as Picture-in-Picture

Especially useful for viewing any of the live or on-demand sessions is the Guide tab. This provides a full schedule of PDC sessions, organized by channels, and lets you access more information and video feeds (during or after the event) for each item.

We hope you enjoy participating in PDC through this Silverlight + IIS Smooth Streaming experience!

-Chris

Encoding Workshop: Best Practices and Strategies

chriskno — Thu, 16 Sep 2010 05:48:01 GMT

On Thursday, September 16, StreamingMedia.com is sponsoring an online workshop on Encoding Best Practices and Strategies that will include Allan Poore from the Microsoft Expression Encoder 4 Pro team. Delivery technologies such as IIS Smooth Streaming really improve the playback experience, but they assume that you start with high-quality video. The focus of the workshop will be a discussion on the latest tips, tricks, and technologies for making your video look the best it can.

In this workshop, you will learn more about how to effectively balance issues such as format, codec, bit rate, and aspect ratio to get the best solution. You also need your encoding and transcoding processes to be efficient and cost-effective, and you will learn more about new technology options that can help.

Planned topics include:

Choosing video and audio formats
Optimizing bitrate for bandwidth
Transcoding content for multiple device delivery: PC, mobile, and TV
Encoding and transcoding best practices
Industry-leading transcoding technologies

Allan and other industry experts, including Dan Rayburn from Streaming Media.com, Rich Mavrogeanes from Discover Video, Coby Rich from Sorenson Media, and Andrew Karlin from Internap, will be on the workshop panel. The live event will have an interactive roundtable format, including direct answers to your questions. The workshop will also be available afterwards for on-demand viewing. To learn more or register, click here.

-Chris

IIS Smooth Streaming highlighted at IBC

chriskno — Thu, 09 Sep 2010 20:31:00 GMT

IIS Smooth Streaming, part of IIS Media Services, is one of the unifying themes in the "Digital Marketing & Experiences" section of the Microsoft exhibit at IBC this year. Held each September at the RAI Exhibition and Convention Centre in Amsterdam, IBC is billed as "the premier annual conference and exhibition for professionals engaged in the creation, management and delivery of entertainment and media content worldwide." Over 1,300 companies exhibit at the show, and over 45,000 attendees are expected during the event, which runs September 9^th – 14^th.

In today's media-rich society, bringing high quality media experiences to people when, where, and how they want vital. Microsoft delivers an end-to-end media platform, making it easier for content owners and broadcasters to reach consumers across devices and operating systems. Smooth Streaming is a key part of this platform and integrated throughout the Microsoft platform and partner ecosystem.

The Microsoft presence at IBC will be in a unique venue called the Topaz Lounge. In addition to demos of many technologies that support Microsoft digital media supply chains, there is informal meeting space to meet with Microsoft subject matter experts, and a coffee and refreshments bar open throughout the day. In-depth meetings will be held in an adjoining set of scheduled meeting rooms.

Four demonstration pods in this area will show IIS Smooth Streaming in action plus new technology innovations. One pod is about the Smooth Streaming Platform, and will highlight some of the features coming soon in IIS Media Services 4.0. Another pod will feature new developments in Live 3D Smooth Streaming. Two pods feature partners showing examples of Smooth Smoothing and Windows Phone 7 applications. In addition, several TV lounge areas will feature Smooth Streaming integrated in set-top boxes, built into Microsoft Mediaroom 2.0, and delivered with 5.1-channel surround sound.

If you are attending IBC, we look forward to seeing you there. If not, check back here later for more details about IIS Smooth Streaming at IBC.

Silverlight and Premium Media Experiences

chriskno — Fri, 03 Sep 2010 19:56:00 GMT

Given the speed at which web technologies seem to be evolving, partners and customers often ask about the roadmap for Silverlight, with many of those conversations centered around premium media experiences. Brad Becker, Director of Product Management, Developer Platforms, has written a blog post on The Future of Silverlight which addresses this and many other questions about Silverlight.

In short, there are many reasons why Silverlight will continue to extend the web by enabling rich experience scenarios in unique and high-value ways. These scenarios include premium media experiences with features such as:

Single-encode IIS Smooth Streaming delivery across computers, TVs, and mobile devices
Friction-free content protection with PlayReady DRM, coming soon as a built-in feature in IIS Media Services
Live webcasting with full DVR and Trick Play controls, such as seen during the 2010 French Open
Live webcasting with multiple camera angles, such as seen during the AVP Nivea Tour Hermosa Beach Open volleyball tournament
Live 1080p streaming of stereoscopic 3D video
Full analytics support with the Silverlight Analytics Framework

For more on Silverlight, read Brad's blog post. He talks about standards and innovation, "rich experience" categories, other considerations (performance, consistency, timing), and going beyond the browser.

To learn more about IIS Media Services, which will support premium media experiences on Silverlight as well as media experiences built using other technologies, see the Integrated Media Platform page.

Bit Rate Throttling and Smooth Streaming - Part 2

chriskno — Fri, 13 Aug 2010 06:50:00 GMT

This is Part 2 of a post on IIS Bit Rate Throttling and IIS Smooth Streaming. In Part 1, I provided a high-level overview of why Bit Rate Throttling and Smooth Streaming would never normally be applied to the same content, and then elaborated more on Bit Rate Throttling. In this part, I'll focus more on Smooth Streaming, including the way it self-meters the amount of data delivered to clients.

As noted in Part 1, Bit Rate Throttling takes any existing file, whether video or otherwise, and automatically meters the delivery at the server. On the other hand, Smooth Streaming defines a file format, encoding parameters, server functionality, delivery protocol, and client functionality and heuristics.

Here's a typical basic workflow for on-demand Smooth Streaming:

Content is encoded in multiple GOP-aligned quality levels (bit rates, e.g., 300 kbps, 500 kbps, 750 kbps, 1.1Mbps, 1.5 Mbps, etc.) using either the VC-1/WMA or H.264/AAC codecs, either in multiple files (typically one bit rate per file) or a single file containing all quality levels.
Files are published to a Windows Server running as an IIS Web server, where the free IIS Media Services extensions have been installed and IIS Smooth Streaming has been enabled.
A Smooth Streaming client (perhaps created automatically during the encoding process on Expression Encoder, or using a downloaded template from the free Microsoft Media Platform Player Framework) is published to the IIS server.
An end user clicks on a URL to watch a video, which loads the Smooth-Streaming-capable player.
The player requests a manifest from the server that describes the content and quality levels available.
The server delivers the manifest.
The client requests requests the lowest-quality two-second fragment.
The server finds the requested bit rate video file and matching audio file, pulls out the appropriate two-second GOP from the file(s), wraps it up as a cacheable HTTP file, and sends it to the client.
The client measures the time it takes to download the two-second fragment and ensures that the content plays back without stuttering, determines whether it can download a higher quality level video fragment for the next two seconds, and then requests the next two-second fragment while the current video fragment is still playing.
Repeat steps 8 and 9 until the end of the video is reached.

For those of you who prefer visual learning, the simplified image below for earlier versions of our components (which are all now on version 4) might be useful.

Thus, the key to bandwidth metering in Smooth Streaming is that the client typically requests only one or two fragments (2-4 seconds) ahead of the currently playing video. In essence, it is "just-in-time" video delivery. Like Bit Rate Throttling, should an end user click the Stop button on their player, only a few seconds of video goes unwatched, unlike what happens with traditional fire-and-forget web server downloads.

Bit Rate Throttling and Smooth Streaming - Part 1

chriskno — Wed, 11 Aug 2010 05:39:00 GMT

As more and more people evaluate the features in IIS Media Services, I occasionally get questions about how to use IIS Bit Rate Throttling with IIS Smooth Streaming. In reality, these features work on separate types of content. While they can run at the same time on a server, you would never typically use them on the same files. Both features achieve a metered flow of content, but one regulates the flow using delivery logic on the server, while the other regulates the flow using request logic on the client.

In general, Bit Rate Throttling controls the server download speed of a large file, whether a video, a database, or some other content type. Smooth Streaming, on the other hand, starts with a large video file formatted for Smooth Streaming delivery (e.g., MyVideo.ismv) encoded at several bit rates or quality levels, and typically splits the video into 2-second-long cacheable HTTP files as it is being delivered. In effect, Smooth Streaming does not need Bit Rate Throttling, as the flow of 2-second-long HTTP video fragments is controlled by the just-in-time rate of requests coming from the Smooth Streaming client.

In this post, I'll talk more about Bit Rate Throttling. In a subsequent post, I'll explain Smooth Streaming in a bit more detail.

Bit Rate Throttling takes an existing (typically large) file and reduces the speed at which that file is delivered. While Bit Rate Throttling can be applied to specified file or MIME types of any kind, it was primarily designed to deliver video files, such as myVideo.flv or someVideo.wmv, using progressive download. Progressive download describes the capability of a media player to start playing back a file being delivered from a standard Web server or network share before the whole file is downloaded.

Using the default settings, Bit Rate Throttling does a few things during HTTP delivery of a video file:

Checks the file for information about the encoded buffer size, which is often 3-8 seconds - this is usually the minimum amount of video that has to be downloaded to a player to fill the video buffer and allow the video to start playing back even as downloading the file continues progressively in the background.
Checks the file for the encoded bit rate (e.g., 500 kbps).
Blasts down several seconds of data at full speed, to fill the video buffer and allow a user to start seeing video playback immediately.
Reduces the delivery rate to the encoded bit rate (e.g., 500 kbps) for the rest of the video until either: a) the video finishes downloading, or b) the user performs a seek to another location in the video, which restarts the process at step 3.

The end result is that during progressive download, users only receive a few more seconds of data than they need to view the video, rather than downloading the whole file to them immediately. Especially on social media sites, users often stop playback of videos after watching only the first 10-20%; by using Bit Rate Throttling, you potentially save lots of bandwidth costs by not downloading the other 80-90% of the video that doesn't get watched. As an added benefit, Bit Rate Throttling also keeps the egress path of your server free of fire-and-forget fast-as-possible downloads that could potentially congest the network connection and block other users from getting to your content.

Bit Rate Throttling has some other really useful capabilities, such as:

Dynamic Throttling, which shares bandwidth equally among users accessing a server; and
Programmatic throttling, which allows you to turn Bit Rate Throttling on or off based on criteria you set - for instance, if you run a file download service, perhaps your non-paying users get slower file downloads than your paid subscribers.

Read more about Bit Rate Throttling at http://www.iis.net/BitRateThrottling, and look for Part 2 of this post.

Edit - Part 2 of this post is now available. (8/12/2010)