HTTP Live Streaming Presentation

HTTP LIVE STREAMING A review of Apple’s new streaming specification

andrewsblog.org — andrew@fecheyr.be

STREAMING MEDIA • On-Demand • Popular

vs Live

Solutions:

• RTP/RTSP

Open protocol but has firewall issues • Adobe

Flash Media Streaming Proprietary, high client cpu usage on some platforms

HTTP LIVE STREAMING

HTTP LIVE STREAMING • Originally • The • Pure

developed by Apple for its iPhone platform

specification is an IETF Internet-Draft HTTP delivery

• No

firewall issues

• No

special server needed (any web server will do)

ARCHITECTURE • Server

component

• Distribution • Client

component

software

ARCHITECTURE Server media encoder

Distribution stream segmenter

MPEG 2 transport stream

A/V input

Index file

.ts

HTTP

Client

ARCHITECTURE Server media encoder

• Media stream segmenter

MPEG 2 transport stream

A/V input

•

encoder

Outputs an MPEG-2 Transport Stream

• Stream

Segmenter

•

Cuts the stream in small files of equal duration

•

Creates/updates an .m3u8 index files

ARCHITECTURE Server media encoder

Distribution stream segmenter

MPEG 2 transport stream

A/V input

Index file

.ts

HTTP

Client

ARCHITECTURE • Distribution •

Ordinary web server or web caching/proxy system

•

Serves index file & stream segments

Distribution

Index file

.ts

HTTP

• Client Client

•

Fetches index file

•

Fetches stream segments in sequence

FEATURES • On-Demand • Content

Streaming (VOD) and Live Streaming

Protection

• Encryption: AES-128, key

files listed in index file

• Key

files served by HTTP or HTTPS, can be protected by own session-based authentication scheme

• Stream

alternatives and Failover protection

STREAM ALTERNATIVES Main Server Alt. A Index file

Index file

• Different .ts

Alt. B Index file

.ts

Alt. C Index file

.ts

•

eg: high quality for Wifi medium quality for 3G low quality for Edge

•

Client switches automatically

• Failover

Backup Server Backup Index file

bandwidths for varying network connections or devices

.ts

alternative(s) as Backup

.M3U8 INDEX FILE • Extension • Simple

of .m3u playlist file (by Nullsoft for Winamp)

example #EXTM3U #EXT-X-MEDIA-SEQUENCE:0 #EXT-X-TARGETDURATION:10 #EXTINF:10, http://media.example.com/segment1.ts #EXTINF:10, http://media.example.com/segment2.ts #EXTINF:10, http://media.example.com/segment3.ts #EXT-X-ENDLIST

.M3U8 INDEX FILE • Extension • Simple

of .m3u playlist file (by Nullsoft for Winamp)

example duration of segments #EXTM3U #EXT-X-MEDIA-SEQUENCE:0 #EXT-X-TARGETDURATION:10 #EXTINF:10, http://media.example.com/segment1.ts #EXTINF:10, http://media.example.com/segment2.ts #EXTINF:10, http://media.example.com/segment3.ts #EXT-X-ENDLIST end of on-demand video

in seconds

segment urls

.M3U8 INDEX FILE • More

complex example #EXTM3U #EXT-X-KEY:METHOD=AES-128,URI="https:// priv.mycompany.com/key" #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=200000 http://ALPHA.mycompany.com/lo/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=200000 http://BETA.mycompany.com/lo/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=500000 http://ALPHA.mycompany.com/md/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=500000 http://BETA.mycompany.com/md/prog_index.m3u8

.M3U8 INDEX FILE • More

complex example

encryption method and key url

#EXTM3U #EXT-X-KEY:METHOD=AES-128,URI="https:// priv.mycompany.com/key"

200kbps alternatives 500kbps alternatives

#EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=200000 http://ALPHA.mycompany.com/lo/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=200000 http://BETA.mycompany.com/lo/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=500000 http://ALPHA.mycompany.com/md/prog_index.m3u8 #EXT-X-STREAM-INF:PROGRAM-ID=1, BANDWIDTH=500000 http://BETA.mycompany.com/md/prog_index.m3u8

no X-ENDLIST so it is a Live stream

failover alternatives

CRITICAL COMPARISON

CRITICAL COMPARISON • Ease

of setup

• Compatibility • Client

& Server Performance

• Features • Ease • Cost

of distribution

CRITICAL COMPARISON

Tested @ http://streaming_test.andrewsblog.org

EASE OF SETUP • HTTP

Live Streaming

•

Apple toolkit (~5 min) easy, fast and complete, but only available for MacOS

•

Open Source toolchain (~15 min) FFMpeg+Ruby+C: for *nix, flexible but experimental

• RTP/RTSP

with Darwin Streaming Server (~1.5 hours)

•

Install & configure server, conflict with web server if running on port 80

•

Required to ‘hint’ media files

COMPATIBILITY HTTP Live Streaming

RTP/RTSP

Flash Media

Safari 4.0.4, MacOS 10.6.2

✔

✔

✔

FireFox 3.5.7, MacOS 10.6.2

external player

external player

✔

Chrome 4.0.249, MacOS 10.6.2

external player

external player

✔

FireFox 3.5,Vista SP1

✖

external player

✔

IExplorer 8,Vista SP1

✖

external player

✔

iPhone 3.1.2

✔

✖

redirected*

* YouTube automatically sends an alternative HTTP Live Stream to iPhone users.

COMPATIBILITY HTTP Live Streaming

RTP/RTSP

Flash Media

Safari 4.0.4, MacOS 10.6.2

✔

✔

✔

FireFox 3.5.7, MacOS 10.6.2

external player

external player

✔

Chrome 4.0.249, MacOS 10.6.2

external player

external player

✔

FireFox 3.5,Vista SP1

✖

external player

✔

IExplorer 8,Vista SP1

✖

external player

✔

iPhone 3.1.2

✔

✖

redirected*

still low

okay

great

* YouTube automatically sends an alternative HTTP Live Stream to iPhone users.

CLIENT PERFORMANCE • Average • Ran

CPU Load from 120 samples taken over 40sec

on a 1.8 Ghz dual core MacBook (MacOS 10.6.2)

CLIENT PERFORMANCE • Average • Ran

CPU Load from 120 samples taken over 40sec

on a 1.8 Ghz dual core MacBook (MacOS 10.6.2)

HTTP Live Streaming

RTP/RTSP

Flash Media

CPU Load Embedded CPU Load External

CLIENT PERFORMANCE • Average • Ran

CPU Load from 120 samples taken over 40sec

on a 1.8 Ghz dual core MacBook (MacOS 10.6.2)

HTTP Live Streaming

RTP/RTSP

Flash Media

16,94% 15,10%

CPU Load Embedded CPU Load External

21,64% 21,28% 78,02% 86,44%

SERVER PERFORMANCE • Concurrency

is the important metric!

• RTP/RTSP: Darwin • Tested • HTTP

with StreamingLoadTool

Live Streaming: Nginx web server

• Tested • Ran

Streaming Server

with ApacheBench

on a FreeBSD 7.2 Virtual Private Server with 128MB Ram

SERVER PERFORMANCE Darwin Streaming Server 60

Success

Errors

Failed

50

Streams

40 30 20 10 0

0

20

40

60

Concurency

80

100

SERVER PERFORMANCE Darwin Streaming Server 60

Success

Errors

Failed

50

Streams

40 30 20 10 0

0

20

40

60

80

Concurency

CPU bound, max 20~40 users

100

SERVER PERFORMANCE Nginx web server 15.000

100%

Mean

Requests > 10s 75%

10.000 7.500

50%

5.000 25% 2.500 0

10

30

50

70

90

Concurrency

110

130

0%

Requests out of time

Mean request time (ms)

12.500

SERVER PERFORMANCE Nginx web server 15.000

100%

Mean

Requests > 10s 75%

10.000 7.500

50%

5.000 25% 2.500 0

10

30

50

70

90

110

130

Concurrency

Network bound, max 80~130 users

0%

Requests out of time

Mean request time (ms)

12.500

EASE OF DISTRIBUTION • Clear • Easy

advantage for HTTP Live Streaming <= only HTTP objects !

to integrate with Content Delivery Networks (CDNs)

• eg: Amazon • Inexpensive

Cloudfront

! $1 = 2500minutes of streaming video

EASE OF DISTRIBUTION • Clear • Easy

advantage for HTTP Live Streaming <= only HTTP objects !

to integrate with Content Delivery Networks (CDNs)

• eg: Amazon • Inexpensive

Cloudfront

! $1 = 2500minutes of streaming video

COST • RTP/RTSP • Free • HTTP

= open standards

Open Source Server: Darwin Streaming Server Live Streaming = open specification

• Open • Adobe • $995

Source toolchain and web servers

Flash Media Streaming Server License - or reverse engineered java implementation

CONCLUSION

HTTP Live Streaming

RTP/RTSP

Flash Media

Protocol Type

standard

standard

proprietary

Server Cost

free

free

$995

Ease of setup

very easy

Okay

?

Compatibility

low

using plugins

very high

Client Performance

great

good

high cpu on some platforms

Server Performance

great, network bound

good, cpu bound

?

Variable bitrates

Built in

some servers

only latest version

Encryption

Built in

?

~ server version

Authentication

by protecting key files

custom module

?

Built in Failover

yes

no

no

Seek delay

~ segments duration

< 2 seconds

4-10 seconds

Ease of distribution

Very easy

?

?

HTTP Live Streaming

RTP/RTSP

Flash Media

Protocol Type

standard

standard

proprietary

Server Cost

free

free

$995

Ease of setup

very easy

Okay

?

Compatibility

low

using plugins

very high

Client Performance

great

good

high cpu on some platforms

Server Performance

great, network bound

good, cpu bound

?

Variable bitrates

Built in

some servers

only latest version

Encryption

Built in

?

~ server version

Authentication

by protecting key files

custom module

?

Built in Failover

yes

no

no

Seek delay

~ segments duration

< 2 seconds

4-10 seconds

Ease of distribution

Very easy

?

?

HTTP Live Streaming

RTP/RTSP

Flash Media

Protocol Type

standard

standard

proprietary

Server Cost

free

free

$995

Ease of setup

very easy

Okay

?

Compatibility

low

using plugins

very high

Client Performance

great

good

high cpu on some platforms

Server Performance

great, network bound

good, cpu bound

?

Variable bitrates

Built in

some servers

only latest version

Encryption

Built in

?

~ server version

Authentication

by protecting key files

custom module

?

Built in Failover

yes

no

no

Seek delay

~ segments duration

< 2 seconds

4-10 seconds

Ease of distribution

Very easy

?

?

embedded devices

low latency

highest compatibility

Thank you