Tektronix Video Training

ABR- Adaptive Bitrate Streaming

Karl KuhnSr. Video Applications Engineer

karlku@tek.com

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Why Adaptive Bitrate Streaming ?

• Consumers expect video everywhere on

anything they own

• They expect it to work the first time and every

time

• No second chances

• No long load times

• No buffer wait

• No blockiness or freeze frames tolerated

• IT IS ALL ABOUT QoE

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What is Adaptive Bitrate Streaming ?

• Pull is more efficient than Push technologies

• Last Mile Bandwidth is the unknown factor

• The client side player determines available

bit rate and requests the appropriate content

to meet current bandwidth availability

• Streams “adapt” to available bandwidth to Client

• All the while continuously delivering content

• IT IS ALL ABOUT QoE

• We accept low resolution/blurry

4

High Level Testing Concepts

Quality of Service (QoS)

– Perhaps Totally Transparent to End User

– Error Rates

– Bandwidth

– Transmission Latency

– Jitter

Quality of Experience (QoE)

– The End User Will Notice and The Phone Will Ring

– MANAGEMENT WILL NOTICE

– Long Access Times

– Buffer Wait Times

– Black Frames

– Freeze Frames

– Blockiness

– Slice Errors

– Loudness and Level Issues

– Closed Captioning4

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The Shift to HTTP-Based Delivery

• HTTP-based media delivery has little to no

firewall restrictions because firewalls and routers

regularly pass HTTP

• HTTP media delivery does not require special

proxies or caches.

• ABR file is just like any other file to a web

cache server

• Networking equipment sees ABR traffic as

simple web activity.

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What Adaptive Streaming Technologies are available ?

• There are two fundamental types of adaptive streaming

technologies available

– Non-segmented/fragmented such as H.264/SVC

(Scalable Video CODEC)

– Segmented/Fragmented into Stand alone files

• Apple- HTTP Live Streaming (HLS) - most

popular

• Microsoft Smooth Streaming

• Adobe Flash Dynamic Streaming - least

popular

• DASH - new unified standard

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• DASH- Dynamic Adaptive Streaming on HTTP

• Has the potential to replace existing proprietary technologies:

– Microsoft Smooth Streaming,

– Adobe Dynamic Streaming,

– Apple HTTP Live Streaming (HLS).

• Unified standard would be a boon to content publishers

• Produce one set of files that play on all DASH-compatible devices.

• Other advantages

– Trick modes for seeking, fast forwards and rewind

– Dynamic advertising insertion

MPEG DASH - Dynamic Adaptive Streaming over HTTP

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• Transcode content to each required

output profile

• QoE client depends on having a

number of different profiles

• Deployments use 4 to 16 output

profiles per input.

• Profile will have its own resolution

and bit rate parameters – including

scaling to resolutions suitable for

each client device.

Width Height Bit rate

1280 720 3 Mbps

960 540 1.5 Mbps

864 486 1.25 Mbps

640 360 1.0 Mbps

640 360 750 Kbps

416 240 500 Kbps

320 180 350 Kbps

320 180 150 Kbps

ABR Profiles

Video Transcoding

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ABR -Simplified Architecture

TranscodersFragmenters

(Apple, MS, Adobe)Origin Server

Master

Encoders

Multiple copies

at different bit

rates (1-16

copies)

Same content

split in to small

2 to 10 sec.

files

(fragments)

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Encoder Boundary Point Specification OC-SP-EBP-I01-130118

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Encoder Boundary Point Specification OC-SP-EBP-I01-130118

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Customer Client Content Proxy Edge Cache

Hello! Here is my sub id,

device type, bandwidth

available, session ID.

I would like Superman 3,

please.Sub id, device type,

bandwidth available,

and session ID would

like Superman 3, please

Authentication

Origin Cache

Yes

Do I have the asset?

NoSend manifest file

(XML)

Profile 2 of Superman 3,

to session ID, please

Profile 2 of Superman 3,

to session ID, please

Process manifest file

Request asset file Transfer file to Edge

Cache

Transfer file

segment

Here is your file,

enjoy

Here is your file,

enjoy

Measure download

speed and begin

playback

ABR- Walk through the initial process

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Active ABR Monitoring Overview:

Network Loading and Simulation

Origin Server Load Aware

– Max load per Origin Server

– Many One to One or Round Robin

Validates Origin Server file structure integrity

– Manifest syntax

– Profile

– Playlist validity

– Bitrates and requested throughput.

Programmable Alerts for key metrics

– Manifest Alerts

– Changed, fetch failure.

– Syntax flaw

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Active ABR Monitoring Overview:

Decrypt and Decode content

– Acquire Decryption Keys - Enable decoding

– Validate decode-ability of encrypted content

– Provide visual validation of assets

Expand and Improve Alerting

– Expand alerts to meet user needs

– Full configuration capability

– Alert Template configuration

– Real time status information

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Passive ABR Monitoring Overview:

Strengths Passive ABR

– 10G available throughput

– Non-Intrusive. No load on infrastructure

– Provides specific information per viewer

– Provides real time data on asset views including profile

switches

– Minimal Setup: Probe discovers traffic.

– Tracks viewer bitrate switching

Weaknesses Passive ABR

– Requires special network interface (passive tap or span port)

– Must have traffic. Can’t monitor unviewed assets

– Can’t control path of monitoring

– Probe can’t ask questions.

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– HTTP response status code columns:

• Show the reponses to HTTP requests for a particular

URL

– 100s: Informational. This class indicates a provisional

response, consisting of the Status-Line and optional

headers.

– 200s: Success. The action requested by the client was

received, understood, accepted and process successfully.

– 300s: Redirection. Further action needs to be taken by

the user agent to fulfill the request.

– 400s: Client Error. The client seems to have

erred. Except when responding to a HEAD request, the

server should include an entity containing an

explanation of the error situation, and whether it is a

temporary or permanent condition.

– 500s: Server Error. The server failed to fulfill

an apparently valid request.

Media Set Status: HTTP Status Codes

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Identifying Compression Artifacts

Over-compressed picture

High quality picture

Monitoring QoE ABR

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Media Set Detail Report: Statistics & Graphs

• Fragment Load Bitrate: This is the fragment size / fragment load

time

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Media Set Detail Report: Statistics & Graphs

• Fragment Load Time: This is the time measured between when the

HTTP header for a fragment is detected and when enough bytes

have been received to equal the fragment size.

Fragment Load Latency: This is the time between when a request is

made for a fragment (at the socket level) and when the HTTP header

for the fragment is detected.

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Port Statistics

• Allows for reviewing/exporting the Port statistics at the URL level

collected for the reporting period. Measurements include:

– Bitrate

• Shows the measured bitrate of the URL stream.

– Manifest Bitrate

• The sum of all stated bitrates from the manifest for all of the active

representations on the Media Set.

– Non-Manifest Bitrate

• Shows the difference between Total Observed Transport Bitrate and

Manifest Bitrate.

– HTTP Error Count

• Displays a count for each of the HTTP Status Codes received.

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Program Statistics

• Allows for reviewing/exporting the statistics collected for the

reporting period against the ABR content being monitored.

Measurements include:

– ABR Fragment Size/Duration

• Average fragment size being received.

– ABR Fragment Load Time

• Time measured between when the HTTP header for a fragment is

detected and when enough bytes have been received to equal the

fragment size.

– ABR Fragment Load Bitrate

• This is the (fragment size / fragment load time)

– ABR Fragment Load Latency

• Is the time between when a request is made for a fragment (at the

socket level) and when the HTTP header for the fragment is

detected.

– ABR HTTP Status

• Percent of each HTTP Status code present.

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ABR- Adaptive Bitrate Streaming

Karl KuhnSr. Video Applications Engineer

karlku@tek.com