Internet Technologies

Streaming Media

- and an exercise

Allan HammershøjResearch Assistant, CMIallan@cmi.aau.dk

Thursday, April 23, 2009

Preparation Each group should have at least one computer with the following

software installed: VLC 0.8.6i

http://www.videolan.org/mirror-geo.php?file=vlc/0.8.6i/win32/vlc-0.8.6i-win32.exe

MP4box for streaming (the file has to be hinted) http://www.videohelp.com/download/MP4Box-0.4.5.zip

Darwin Streaming Server (patched by me to work with all Windows versions)

available for download here: http://imi.aau.dk/~allan/dss.rar Unpack it (using WinRAR), so the path to the software is: c:\Program Files\

Darwin Streaming Server In this folder run: Install.bat (on Vista run it is as administrator)

Perl interpreter- For windows, choose: http://downloads.activestate.com/ActivePerl/Windows/5.10/ActivePerl-5.10.0.1004-

MSWin32-x86-287188.msi

Remember to restart Windows afterwards

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Agenda Streaming terms

Streaming

Examples of streaming

The exercise

A little help

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Hardware for interpreting digital content Television

DVB-(C/S/T)

IP-TV

Handheld devices Mobile phone

3G

DVB-H

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Streaming

o Streaming: A client logs onto a server and requests a video/audio stream

o Prerecorded & Liveo Takes up no disk space (memory buffering)o No problem with Digital Right Managements

(no local storing)

o Content must be adapted to bandwidth

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Streaming (cont.)

o Streaming servero Interactivity

o Stored content (if hinted) can be fast forwarded to the wanted timecode

o Adapting to bandwidtho Depending on the clients network, the datastream can be

adapted to the bandwidtho Rely on QoS

o Quality of Service (QoS) refers to the capability of a network to provide better service to selected network traffic over various technologies

o Dedicated bandwidtho Controlled jittero Reduced latencyo Priority for one or more flows does not make other flows fail

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Streaming (cont.)

Content delivery On-Demand Live

Unicast (one server where all clients connect to) Splitting (one server send to other servers where clients

connect to) Multicast (standardized way of distributing data to a large

network like the Internet by routing the same packages to all users)

Simulated live Like the three options in live but with prerecorded material

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The protocols of Streaming Streaming also is based on a bunch of protocols like

everything else relating to the Internet RFC 2326 – RTSP: Real Time Streaming Protocol RFC 4566 - SDP: Session Description Protocol RFC 2974 – SAP: Session Announcement Protocol RFC 3261 - SIP: Session Initiation Protocol RFC 3550 - RTP: Real-Time Transport Protocol RFC 3550 – RTCP: Real-time Transport Control Protocol RFC 3551 - RTP Profile for Audio and Video

Conferences with Minimal Control The RFC’s can be found on: http://www.faqs.org/rfcs/

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Network structure (the real ”layer cake”)

Layer definition Layer 1 is not included because it is simply the raw copper,

radio frequency or optic fiber

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RTSP – Real-Time Streaming Protocol The streaming ”remote control”

Method Description

Options Get available methods

SETUP Establish transport

ANNOUNCE Change description of media object

DESCRIBE Get description of media object

PLAY Start playback, reposition

RECORD Start recording

REDIRECT Redirect client to new server

PAUSE Halt delivery, but keep state

SET-PARAMETER Device or encoding control

TEARDOWN Remove state

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SDP – Session Description Protocol The ”menu card” from the server

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RTP – Real-time Transport Protocol The ”data stream” but more than just plain data

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RTCP – Real-time Transfer Control Protocol Used in both RTP & SDP

Overview:

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Single streaming session

Streaming server

Client

Client request file info (RTSP)

Server send SDP-file (RTSP)

Client initialize and send connection info

Option: Send one or more possible suggestions

Server send connection accept Option: Look through

suggestions and accept one of the solutions. Then the client can send an connection accept. If none can be accepted then server sends connection refused

Client send RTP-request (RTSP)

Server send RTP accept (RTSP) and streams RTP on configured port

Option: Client send information on RTCP

(statistics on connection)

RequestSend SDPRequest RTPRTPRTCPConnection info

Connection accepted

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Live streaming (ex. video conference)

RTSP/SIP/SAP/RTP

RecorderPresentation

Capture/encodingStreaming server

Clients

RTSP/SIP/SAP/RTP

RTSP/SIP/SAP/RTP

Picture/Sound

Unicast (RTP)

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Multicast streaming

In many ways the same as single sessions

SIP – Session Initiation Protocol SIP invitations used to create sessions carry session descriptions that

allow participants to agree on a set of compatible media types

SIP makes use of elements called proxy servers to help route requests to the user's current location, authenticate and authorize users for services

SIP is an agile, general-purpose tool for creating, modifying, and terminating sessions

SAP – Session Announcement Protocol Info of the session being broadcasted is periodically sent to a known

address and port to subscribers within the same scope of the broadcast

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A little calculus Video:

Frame rate (frames/s) frame width (pixels) frame height (pixels) color depth (bits/pixel) duration (s) = total video file size (bit)

Sound: Sampling resolution (bit/sample) sampling frequency

(Hz) no. of channels duration (s) = total audio file size (bit)

Total media file size Video + Sound

Questions

Thank you for your attention

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The exercise 1. Step – Try Darwin Streaming Server (DSS) with Quicktime/VLC using rtsp

Use the example files from DSS in the folder: “Movies”

2. Step - Play with VLC and transcode non-live/live video to H.264/AAC Experiment with different frame rates and bit rates. Identify the lowest acceptable

setting to be used with a mobile phone (352x288 resolution)

3. Step – Create a batch-script to transcode to a file using VLC with chosen settings from step 2

4. Step – Insert a semi transparent group logo in the top right corner

5. Step – Prepare it for streaming with the container format 3gp using MP4box

6. Step – Use DSS to stream the file from step 4 to a client (if possible a mobile phone using WIFI) (mandatory)

7. Step – Generate an SDP-file with live input using VLC (optional)

8. Step – Stream the live content to a mobile phone (if possible) using DSS (optional)

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A little help Using VLC in command line mode:

http://www.videolan.org/doc/play-howto/en/ch04.html

Common errors: Using VLC command line with spaces in names, remember ”” Be sure that you use {} in the right amount On the streaming server computer, open port 554 (and 1220 to remote control the streaming

server) in the firewall

Using MP4box: mp4box -hint -flat -add “<source filename>#1:fps=15.000" -add "<source filename>#2" -

3gp -new “<dest filename>.3gp“ The fps means frames per second and has to be edited to match the actual fps in the file

being prepared for streaming. In the example above the video is encoded with 15 fps

Encoding to H.264/AAC using VLC: vcodec=h264,vb=320,venc=x264{keyint=50,no-

cabac,bframes=0,level=13,ref=1,me=hex,subme=5,no-b-adapt,ratetol=10,aq-mode=0,aq-strength=0.75,partitions=none,direct=auto},fps=25,maxwidth=320,maxheight=176,deinterlace

acodec=mp4a,ab=64,channels=1,samplerate=22050

Generating an SDP-file with VLC and put it in the main folder of DSS: :rtp{dst=127.0.0.1,port-video=11030,port-audio=11032,ttl=3,mp4a-latm,sdp="file://C:\

Program Files\Darwin Streaming Server\Movies\vlc_live.sdp"}

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