1 – Confidential 9/21/2015

OTT/ABR Demystified and Monitored

Seth VerMulm

12 September, 2015

2 – Confidential 9/21/2015

IPTV and Internet Streaming Methods

• UDP – Light-weight, connectionless protocol

– No retransmission capabilities

– Usually best for reliable or closed networks

– Primarily used by IPTV providers for delivering video over closed network where QoS can be guaranteed

– Often used for video conferencing over the internet

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IPTV and Internet Streaming Methods

• HTTP Progressive Download – Simplest to implement and by far the most common internet

video delivery method

– Supported by standard webservers - uses ordinary TCP file download

– Supported by nearly all devices and protocols

• Flash, HTML browsers, iPad/iPhone and Android

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IPTV and Internet Streaming Methods

• HTTP Progressive Download (Cont’d) – Full handshake and connection setup

– Playback begins while download is in progress

– It is possible to skip ahead with byte offset download

– Subject to the video stopping and buffering if network condition is poor or changes

– Not favorable for live streaming

– Best for short videos

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IPTV and Internet Streaming Methods

• RTMP/RTSP – RTMP is one of the main delivery methods used for Flash

– Uses TCP/HTTP for a communications channel and UDP for the video delivery

– Requires specialized web server and nearly constant communication between web server and the end device

– Can change the delivered video bitrate while in progress

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Why is HTTP Preferred for Internet Video?

• HTTP media delivery has no issues getting through routers, NAT and firewalls

• HTTP media delivery doesn’t require special proxies or caches

• HTTP data caches can easily and cheaply move content closer to end user or the edge of the network

• It is better to adapt video to HTTP than change the internet to allow video

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Basic OTT Concept

• The same content is encoded into multiple profiles, each with different qualities and bitrates

• Each of the profiles are broken into segments that are time-aligned with the same segments in other profiles

• The receiver downloads a manifest file which points to the locations of each profile/segment

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Basic OTT Concept

• The receiver starts downloading segments from one of the profiles and starts decoding once a few segments are buffered.

• If network bandwidth is too low to sustain the buffer, a lower bitrate segment is downloaded instead

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Basic OTT Concept

• If there is plenty of bandwidth to sustain the buffer, a higher bitrate segment might be downloaded

• The algorithms for determining which segment to download and when to switch to lower/higher bitrate is made in the end-user device

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OTT Benefits

• Uses standard webservers and internet technology

• Fast startups and skip-aheads

• Easy adjustment to changing network bandwidth conditions

• Allows seamless adjustment to Wi-Fi/cellular network switching

• Eliminates the need for a stream to be buffered in the middle of playback

• Allows client to adapt to the content rather than forcing the content provider to guess what the client needs

• Truly supports any device, anywhere

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OTT Drawbacks

• Biggest drawback of OTT is Live latency (up to 30 sec.)

• Potentially harder to ensure QoS

• Provider doesn’t have easy ways to control server bandwidth

• Fragmentation in OTT standards and DRM

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OTT Varieties

• Four main varieties – HLS - Apple

– MSS – Microsoft Smooth Streaming

– HDS – Adobe

– MPEG-DASH

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OTT Varieties

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OTT Varieties - HLS

• HLS = HTTP Live Streaming

• Developed by Apple and first released in May 2009

• Uses MPEG-TS container, H.264 video and MP3, AAC or AC3 Audio

• Supports many DRM types – mainly AES128 is used

• Supported by almost any web/streaming server manufacturer

• Supported by all Apple products and now Android and many other vendors support it

• XML manifest file is .m3u8

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OTT Varieties - HLS

• Top-level manifest file (.m3u8) lists URLs of a set of stream-specific manifest files

• Stream-specific manifest files list the URLs of the individual stream chunks (.ts)

• Each .ts chunk typically contains 10 seconds of the video

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OTT Varieties - MSS

• MSS = Microsoft Smooth Streaming

• Developed by Microsoft for live streaming the 2008 Olympics and productized in 2009 as part of Silverlight

• Uses ISO base media file format (MP4) for container

• H.264 and VC-1 video plus AAC and WMA audio are supported

• Microsoft PlayReady is used for DRM

• Requires IIS webserver for hosting, but can be cached with standard HTTP edge cache server

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OTT Varieties - MSS

• .ismc is the XML manifest file type used for MSS

• Fragments/chunks in MSS are usually 2 seconds in length

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OTT Varieties - HDS

• HDS = HTTP Dynamic Streaming

• HDS was released by Adobe in 2010 as a follow-on to their RTMP Flash streaming

• Uses ISO base media file format (MP4) for container

• H.264 and VP6 video plus AAC and MP3 audio are supported

• Adobe Flash Access is used for DRM

• For the Origin server, requires Adobe Media Server or an Adobe plugin for other web servers – Can be cached with standard HTTP edge cache server

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OTT Varieties - HDS

• .f4m is the XML manifest file type used for HDS

• Each presentation is represented by a set-level manifest

• Set-level manifest lists URLs of stream-level manifests

• Stream-level manifests list the URLs of rendition fragments

• Fragments are typically 1-4 seconds in length

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OTT Varieties - MPEG-DASH

• DASH = Dynamic Adaptive Streaming over HTTP

• Standardized by MPEG as ISO/IEC 23009-1 in 2012

• MPEG LA is working to consolidate a patent pool

• Backed and promoted by DASH-IF (Industry Forum) – Microsoft, Netflix, Google, Ericsson, Samsung, Adobe and others

• Very open standard – more of a framework – Supports ISO base media format (MP4) or MPEG-TS for containers

– Supports almost any CODEC for video and audio

– DASH does not specify a DRM method but supports all DRM techniques specified in ISO/IEC 23001-7: Common Encryption

• XML manifest file is called the Media Presentation Description (MPD)

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OTT Varieties - MPEG-DASH

• Media Presentation – Defines the video sequence periods

• Each period includes multiple adaptation sets – video, audio, subtitles, etc.

• Each adaptation set has one or more representations (bitrate/resolution combinations)

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Live vs. VOD OTT

• Streaming live events in OTT is very similar to streaming a VOD asset

• For VOD, all the segments from all the profiles are available on the origin server and the manifest is static

• For Live, as new segments are encoded, they are uploaded to the server and the manifest is updated to include the segments – The oldest segments can be removed (sliding window method)

– Oldest segments can also be kept on the server to allow direct conversion to VOD when the live event is finished

– Keeping the oldest segments on the server also allows late-comers to start viewing at the beginning of the live stream

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OTT Encryption and Content Protection

• Most OTT varieties support AES128 encryption methods – Each variety has its own implementation methods

• The manifest file contains a link to the key server. Decoder requests keys and uses them to descramble

• Geo-fencing is also employed to restrict content to certain countries or locations

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OTT Delivery Equipment

• Live Multi-Bitrate Encoder – Takes live stream and produces variants with multiple bitrates

• File-Based Multi-Bitrate Encoder – Processes video files and produces variants with multiple bitrates

• Slicer/Packager – Processes content into time-

aligned fragments

– Creates manifest files

• Origin Server – Publishing point for the

manifest file and content files

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Content Delivery Networks

• Interconnected system of caching servers

• Usually are geographically dispersed

• Caches the most popular content

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Content Delivery Networks

• Advantages of using a CDN – Reduces load on the origin server

– Reduces strain on internet backbone and interconnects

– Lowers delivery latency

– Saves on data usage costs

– Easier to scale for a large viewing audience

• Akamai, Alcatel-Lucent, Level 3, Limelight Networks are examples of CDN providers

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Common OTT Problems

• Profile alignment issue – Causes glitches when end-device switches to a different profile

• Stale manifest on live streams – As new segments are added in live stream, manifest file must be

continuously updated to include them

• Encryption breakdown – Key server access and out of date keys

• Origin server overload – Too many end-devices requesting highest profile on startup

• CDN caching failures – Out of date cached content or broken URLs

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Monitoring Techniques for OTT

• Profile Alignment Issues – Constantly check profile alignment and alarm on mis-alignment

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Monitoring Techniques for OTT

• Stale Manifest on Live Streams – Manifest age testing checks how long it has been since a

particular manifest file has been updated

– Monitor and alarm if the manifest age is higher than a minute or so

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Monitoring Techniques for OTT

• Encryption Breakdown – Setup monitoring equipment to descramble the OTT services

– Alarming if the service cannot be decoded

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Monitoring Techniques for OTT

• Origin Server Overload or CDN Problems – Monitor the fragment download time for all profiles and alarm if

they are longer than the fragment length

– Monitor and alarm on HTTP 3xx/4xx/5xx issues

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Summary

• OTT is a video delivery method that is rapidly growing in popularity

• There are a lot of benefits to using OTT compared with other internet video delivery methods

• The are multiple competing standards for delivering OTT

• OTT issues are prevalent and can be minimized by a proper monitoring system

• Sencore VideoBRIDGE is one of the best OTT monitoring systems available today

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References • Adaptive Bitrate Technology. Presentation. 2012. Peter Chave, Cisco.

• http://www.jwplayer.com/blog/what-is-video-streaming/ April 2011. Jeroen Wijering.

• IPTV vs Internet TV. Presentation. SMPTE Boot Camp 6, June 2014. Louis Sebastiani, IPTV Project Director, Incospec Communications Inc.

• What is HLS? October 2011. Jan Ozer. http://www.streamingmedia.com/Articles/Editorial/What-Is-.../What-is-HLS-(HTTP-Live-Streaming)-78221.aspx

• What is MPEG-DASH? November 2011. Jan Ozer. http://www.streamingmedia.com/Articles/Editorial/What-Is-.../What-is-MPEG-DASH-79041.aspx

• IIS Smooth Streaming Technical Overview. White Paper. March 2009. Alex Zambelli.

• HTTP Dynamic Streaming Specification V3.0. 2013. Adobe Systems Inc.