Transcript Digital Media Technology : Real World

Digital Media Technology
: Real World Applications
June Bicknese
Table of contents
1. Digital media technology in media production
2. Overview of digital technology and a media server
3. A case study on a production company
- digital technologies applied to kiosk system
architecture
Digital Technology + Media Production
1.
Traditional media production and its shortcomings
- Inconvenience of an analog and linear videotape
- Continuous demand for expanding video tape storage space
- Retrieval of a videotape from a tape library
2.
Advantage of using digital techniques
- Digital tapes are non-linear.
- For storing a digital video, various compression algorithms are used.
- Retrieval is easy, if used with a server.
3.
Current status of migrating from analog to digital
- Commercial playback loops
- Analog/digital editing system such as Avid
Video Server Technology
Processing
• • Editing
• • Compressing
Analog
Digital
& Encoding
Storage
• • Archive
• • Retrieval
Analog
Digital
Input
Media Server
Network
Output
Getting an input

Analog input
1) Analog structure: Luminance(Brightness) + Chrominance(Color)
=> Frame like a picture
=> Series frames as moving images
Frame
=> A VHS tape
2) Digitizing a VHS video
=> Import the analog tape into a digitizing software
=> Digitizing software makes the analog input into the digital format
Frame
=>
0111011101101110100101010001110011……
< Streams of bits >
: instructions to recreate an analog video
=> Transfer the digitized data into an editor

Digital input: directly transferred into an editor
Video Processing

Editing
- Software-specific
- Popular software: Avid Xpress, Avid Composer,
Windows Media Encoder, Quicktime Pro

Compressing
- The method that makes the digital media small
enough to fit through the network
Video Compression

Why do we need compression?
 Successive video images have redundant and repeated
images. So, compression makes the repeated images be
encapsulated in such a way that nearly every piece of
redundant content should be expressed once.
 Since there are some limitations that human can
perceive in visual and auditory systems, digital
compression can take advantage of this fact.
Two types of compression method
(1) Lossless compression:
Data can be compressed and decompressed without losing
any of the original data so that the decompressed data
matches the original data exactly.
(2) Lossy compression:
Data is lost during the compression process and cannot be
recovered during the decompression. The amount of how
much data is lost is depending on what kind of
compression scheme is applied to the data.
Ex) streaming media
Processing- Encoding

Encoding
- The way to put the digital media in the correct
format so that the media can be downloaded or
streamed via network
Storage

What is the ideal disk storage?
Reliable
 Available
 Scalable
 Fault tolerant

RAID Popularity



Disk storage: capacity , cost
Fault tolerance: multiple disk drives appear
as a single storage system. If one of them
fails, other remaining drives can continue to
operate without compromise.
Easy replacement: The failed drive can be
replaced without seriously degrading
ongoing operations.
Common Levels of RAID

RAID 1: Data mirroring
Disk 0
0011
0011
0102
0032
0102
0032
Disk
Mirroring
Disk 1
0011
0102
0032
Common Levels of RAID

RAID 3: Striped array + Parity
Byte
Striping
2113
3210
0123
+
2
3
0
1
2
1
1
1
2
3
0
3
P3
P2
P1
Parity
Drive
Disk 0
Disk 1
Disk 2
Disk 3
Parity
Common Levels of RAID

RAID 5: Striped array + Distributed parity
Block
Striping
0110
3200
2113
3210
0123
+
2110
P3
0123
P5
3200
3210
2102
0110
2113
3000
P4
P1
1110
3200
P2
Rotating
Parity
Disk 0
Disk 1
Disk 2
Disk 3
Disk 4
Digital Archiving

Problem of current analog tape library
: continuous tape expansion -> more space needed
: constant management by tracking all the videos
: time-wasting retrieval of a video clip

Digital media archive
: effective compression -> store videos in smaller storage space
: frequently used data can be stored at fast-accessible storage
seldom-used data can be at less expensive storage
: disk storage and backup -> multiple copies available
: proper network setup -> retrieve data fast
Playing a video over Internet

Web server vs. Video server

Retrieving a video with a metafile

Streaming vs. Downloading

Playing a video on a client browser
Web server vs. Video server


Using a web server only
: If you need small amount of video or audio clips to be
played over the network, your web server doesn’t need to
have a separate video server. Your web server can
accommodate the basic functions of a video server.
Combining a web server and a video server
: If we are considering media production and distribution
of the output over the network, we definitely need a video
server that has higher quality digital services than the web
server.
Retrieving a video with a metafile


Windows Media Metafile
(1) contains the location of the media file
(2) references the media file for playing its video over the network
Why do we need a metafile?
(1) Guide a browser what to do with the requested video link
: metafile will properly link to the media file and the video will be
played accordingly.
(2) Instructs Windows Media Player to go the location and play the
media file accordingly.
(3) Great way to combine a web server and a video server
Retrieving a video with a metafile
Creating a Windows Media Metafile
<ASX version = 3.0>
<ENTRY>
<Ref href = “mms://MediaServer/MyVideo.wmv” />
</ENTRY>
</ASX>
(a) ASX defines the enclosed script as being part of a Windows media
metafile.
(b) ENTRY specifies the digital media
(c) Ref href specifies the URL of the media.
(d) MMS is the Windows Media Streaming protocol.

Retrieving a video with a metafile

The name convention: The name of a metafile corresponds to its
media file.
Ex) Media file: MyVideo.wmv, Metafile: MyVideo.wvx

Adding the metafile on a web page
<HTML>
<HEAD>
<TITLE>Easiest way to play a media on a web</TITLE>
</HEAD>
<BODY>
<A HREF= http://WebServer/MyVideo.wvx >My video</A>
</BODY>
</HTML>
Streaming vs. Downloading
Downloading: copying a file over a network.
(1) Time wait for an entire file to be transmitted
(2) Memory space to store the downloaded file.

Media
file
Original
media file
=>
........ =>
The media file is
divided into multiple
packets to be delivered
over network
Server
Packets of the media file
are delivered to its
destination
Client
Streaming vs. Downloading

Streaming: delivering a file over a network and playing the file instantly.
(1) As soon as enough data are buffered, the video starts to play.
(2) After playing, the file is not stored in memory.
So, no extra memory space is necessary.
Media
file
Original
media file
........
=>
=
The media file is
compressed and
encoded into a certain
bit rate. It is stored at a
server.
Server
=>
Client
Upon the request of the media file,
the file is streamed by sending data
bit rate-by-bit rate.
Streaming vs. Downloading

Intelligent streaming
: It dynamically adjusts the bit rate of streaming video as the network
bandwidth changes. It is beneficial for a video to be streamed via networks
with different bandwidth over the Internet. However, the quality of the video
may be downgraded.
Server
Media
file
........
Original
media file
Server
Server
Encode the media file
with different bit rates
Client
Client
Client
Send the encoded file based on the network bandwidth
Streaming vs. Downloading

Advantage of streaming over downloading
 Real-time playback
 Significantly reduced waiting time
 Only small portion of memory space for buffering
 Cancellation of playback at any time
 Same control options such as play, stop, pause, fast-forward, and rewind.

Disadvantage of streaming over downloading
 Limitation of continuous playback for higher bandwidth than the bit rate
 Possibility of unpredictable long buffering time -> discontinuous playback
 In case of intelligent streaming, the video quality is not as good as its original
file.
Playing a video on a client browser

A media player on a client side decompresses the transmitted data and
converts the digital instructions into analog video or audio form.
0111011101101110……
=>
1101110001110100……
< Streams of bits >

Frame
< Analog video >
Different ways to use a media player
 A link from a web page to a Media Player outside the browser
- Audio or video will be played outside the browser.
- This scheme enables the end user to continue to surf with the browser while
listening/watching the streaming clip.
Playing a video on a client browser

Different ways to use a media player (continued)
 embedding a media player in a web page using OBJECT tags
- This method enables you to integrate the design of the player with that of your
page.
- You can also customize the playback control buttons.

In order to embed the player, add an OBJECT element for the Windows Media
ActiveX control like the following example:
<BODY>
<OBJECT ID = “Player” width =“250” height=“250”
CLASSID = “CLSID:6BF52A52-394A-11d3-B153-00C04F79F116” >
</OBJECT>
Windows Media Player 7.0 Class ID
</BODY>
(More
details are in the article “Adding Windows Media to Web Pages” in msdn )
Playing a video on a client browser
Widows Media Player
Media Player’s original functions
Embedded Media Player
Embedded and controlled functions
Network architecture for digital media

Network requirements for media delivery


The network should be able to deliver multi-media in a time-sensitive manner.
Packet switching vs. Circuit switching
In packet switching, although data can tolerate delays in delivery, audio and video
cannot tolerate time delays.
=> fast packet switching allows control parameters that specify the importance of intime delivery in a network header.
=> Multimedia protocols such as RTP or RTSP

In circuit switching, once virtual circuit is set up, it is remained until the end of
usage and the virtual circuit guarantees fast delivery.


Ethernet and ATM are a good match



Ethernet is used inside the building for data traffic among personal workstation or
desktop
ATM is used for backbone network.
Most of all, Ethernet and ATM are good setup for both of the Internet and
multimedia that have to share the links.
Case study of a media production company

Current status of digital media usage
 In production area, digital media technology has been
used mostly for video editing and commercial
playback. A video server is not used for the production.
 The closest of using digital technology is the kiosk
systems. Kiosk systems are using essential digital
media technology. So, kiosk system can be a good
example of the current applications for digital
technology.
Overview of Kiosk systems

Kiosks are located at the First Union Center. They are used to help the sports
fans and audiences get information about the facilities and events. Kiosk touch
screens are especially popular during a sports game intermission. During the
intermission, people can see the major highlights that just happened during the
game.
Main Concourse
Luxury Suites
Lexus Club
The major applications of a kiosk
• The overall interface design is done in Macromedia Flash movie
Adobe
Illustrator
Adobe
Photoshop
MS
SQL
The major applications of a kiosk



SMS (Systems Management Server) – check the status of all the kiosk
systems and allows us to remotely trouble-shoot all the kiosk systems.
Advantage: Rebooting each kiosk
can be done remotely at one
workstation rather than doing
Luxury
each computer
Suites
S
at its location.
M
Main Concourse
Disadvantage: For remote
S
trouble-shooting, the only
Lexus Club
function is to turn on and
off a kiosk.
The major applications of a kiosk



symantec pcAnywhere – remotely access the server and update the contents of
the server, and to transfer files to the server.
Advantage: we can remotely access the server machines rather than we have to
physically go to each server and update contents.
Disadvantage: Once a user accesses the server with the authorized user name
and password, it lets a user allow any changes the user can make in the server.
First Union Spectrum
Web Server
Video Server
First Union Center
pc
Anywhere
Video Server- Video Server Architecture

Main functions of the media server: storage of videos and streaming
Compressed
digital video
input
 Stores the input in
order in primary disk
array.
Windows
Media Player
requests for
the media file
with the
metafile.
 Retrieve the requested
video file in real time.
 Stream the video
 Transmit the video file
< Windows Media Server >
Streaming
Downloading
Video Server- Getting a new input

Video inputs: game highlights or concert footage
30 seconds to 1 minute 30 seconds long

Process of getting a new video file
 Shoot videos with the analog camera
 Transfer the videos as composite or component inputs into
Avid Xpress
 A component input separates analog video signal into three different elements of red,
green, and blue(RGB) and uses three different cables, so that they produce better image
quality.
 A composite input combines all of three elements and use one cable so that it is easier
to import the input but has less image quality.
Video Server- Getting a new input
 Digitize the analog inputs
Frame
=>
0111011101101110100101010001110011……
< Streams of bits >
 Compress the video with 2-to-1 compression algorithm and save it as
motion-JPEG
Higher
compression
: Less space
More artifacts
2 to 1
3 to 1
……..
20 to 1
Lower
compression
: More space
Better looking
<Avid Xpress Compression Algorithm>
Video Server- Getting a new input
• Motion JPEG
‣ JPEG is a standard for compressing and storing digital images. Motion-JPEG extends
this standard by supporting videos.
‣ In motion-JPEG, each frame in the video is stored with the JPEG format, and
compresses each video field separately, returning the resulting JPEG bit streams
consecutively in a single frame.
JPEG 1
Frame 1
Frame 3
Frame 2
Frame 1
<Analog
Moving
Images>
01110111011011
Frame 2
JPEG 2
Frame 3
JPEG 3
10100101010001
0111011101101110
1001010100010100
1010100011
01001010100011
<Compressed into a series of JPEGs>
<Motion-JPEG>
Video Server- Getting a new input
• Avid Xpress for digitizing and compressing
JPEG 1
Frame 1
Frame 3
Frame 2
Frame 1
<Analog
Moving
Images>
Transfer into
Avid Xpress
01110111011011
Frame 2
JPEG 2
Frame 3
JPEG 3
10100101010001
01001010100011
(1) Digitizing
(2) Compression into a series of JPEGs
with 2-to-1 compression
011101110110111010010
101000101001010100011
<Motion-JPEG>
Video Server- Getting a new input
 The motion-JPEC file is changed into .omfi file. The file is exported from
Avid Xpress and imported into Windows Media Cleaner.
• OMFI file as a universal compressed file format
‣ Motion-JPEG has no universal decoding algorithm standard. This means
that a motion-JPEG file may produce different results on different
applications. In video imaging, transporting a compressed video in its native
compression format between different applications may require common
denominator.
‣ For this reason, omfi is used as the interchange of digital media data
between different platforms or applications. OMFI means Open Media
Framework Interchange, a registered trademark of Avid Technology, Inc. It is a
standard format of the interchange of digital media data among heterogeneous
platforms.
Video Server- Getting a new input
 In the Windows Media Cleaner, encode it as a Windows Media file
• Windows Media Cleaner for encoding
0111011101101110100
101010001010010101
000110110111010010
101000101101110100
101010001011011101
001010100011000101
101110100101010....
<OMFI File>
Encoding for
media
streaming
<Windows Media File>
Video Server- Getting a new input
 Save the digital video clip as a media file(.wmv) and create its
metafile(.wvx) in a notepad.
<ASX version = “3.0”>
<Entry>
<Ref Href = “Path” />
</Entry>
</ASX>
 Transfer the metafile(.wvx) into the web server and media file(.wmv) into
the media server
Metafile
Video
Editing
Station
Web Server
Video Server
Media file
Video Server-uploading video during game

During the game, if there is a memorable moments, the highlight is uploaded
into the video server so that audience can see it again during the intermission.
This uploading is almost like real-time updating, but it takes about 5 minutes
after the actual event.
 All games are recorded into Avid Xpress.
 Once there is a good highlight, it is edited and exported into the Windows
Media Cleaner.
 In the Cleaner, encode it as a Windows Media file
 Save it as a Windows Media file and Windows object file.
 Transfer the wvx and wmv files into the two different server machines.
Video Server- Storage


RAID level 5 – RAID 5 allows three or more drives to stripe the data across
drives. Even two drives can function well.
Video Naming in the Web and Video Servers
 Video name: team name / show name + purpose + number in order
For example, the first Flyers history video is named as flyhis01.wvx in
database and flyhis01.wmv in the video server.
 There are subvideos. These are smaller video files than video files. It is
used when somebody comments on a particular game or play that happened. It
is played with the main video clip. The processes of uploading and retrieving a
subvideo file are same as the video ones.
Video Server- Storage
Video
VideoID (PK)
Date
Description
Team
EventID
History
Highlights
Profile
Community
Filename
PlayerID
Subvideo
SubVideoID (PK)
VideoID (FK)
Description
Filename
<Video and Subvideo tables
at the database in the web server>
Video Server- Storage
<Video>
VideoID
Date
Description
Team
……
Filename
……
1005
5/19/1974
1st Stanley Cup
Flyers
……
flyhis05
……
<Subvideo>
SubVideoID
VideoID
Description
Filename
2004
1005
Clarke
flyper04
2005
1005
MacLeish
flyper05
2006
1005
Parent
flyper06
<An example of Video and Subvideo tables
at the database in the web server>
Video Server- Digital Archive

Tape backup is done every night

At the end of the season, most of the used videos
are removed
Video Retrieval

Process of retrieving a video clip from the Windows Media Server
 A user clicks on the video icon
A video is
selected by
a user.
Video Retrieval
Action script
Flash
at kiosk
Embedded
Media
Player
 Request the metafile with video
id
ASP
as
Middleware
 Get the requested metafile
Video
(Subvideo)
table in the
Web Server
 Reference the video using its metafile
Video Server
 Play the video by streaming
<Process of retrieving a video>
Video Retrieval

Metafile: Windows Media Protocol + Windows Media Server + video folder +
media file.
A single file retrieval

<ASX version = “3.0”>
<Entry><ref href = mms://ctc_wms/video/sixgre03.wmv /> </Entry>
</ASX>
Multiple file retrieval

<ASX version = “3.0”>
<Entry> <ref href = mms://ctc_wms/video/flyhis05.wmv /> </Entry>
<Entry> <ref href = mms://ctc_wms/video/flyper04.wmv /> </Entry>
<Entry> <ref href = mms://ctc_wms/video/flyper05.wmv /> </Entry>
<Entry> <ref href = mms://ctc_wms/video/flyper06.wmv /> </Entry>
</ASX>
Video Retrieval
The metafile has been
sent to Windows Media
Server. It opens and
references the actual
media file in the video
server.
As soon as the enough data is arriving, the embedded Windows Media
Player decompresses the digital file, transforms it into analog format,
and plays it by streaming.
Video Retrieval



If there are multiple requests from multiple clients, the server do multistreaming
The server usually can multi-stream
<Video Server>
videos more than 200 streams,
considering the total of around 150
flyhis05.wmv
kiosk
kiosks.
flyper04.wmv
No Intelligent streaming
flyper05.wmv
a. It provides a poor quality video
kiosk
b. Streaming uses the dedicated
flyper06.wmv
network between two buildings. So,
the bandwidth can be considered
sixgre03.wmv
kiosk
as a constant.
Multiple Streaming
How-to: streaming video

Recommended web site:
For doing simple media streaming over the Internet, check
out the web site,
http://catalyst.washington.edu/catalyst/how-to/digitalvideo
There are specific instructions depending on which
application you are using. RealMedia, QuickTime, and
Media Cleaner Pro.

For Windows Media Encoder, check out msdn library.
Network Architecture for video
Network Architecture for video

RTSP (Real Time Streaming Protocol)
: RTSP is an application-level protocol for control over the real-time data
delivery. It is associated with the port 554. Sources of data can be audio, video,
or live data feeds. This protocol is designed to cope with bandwidthdemanding and real-time streams.
Video Server
Kiosk Client
Media file
+ RTSP
Windows
Media Player
TCP
Frame Relay
Gateway
TCP
IP
IP
IP
Ethernet
Physical
Ethernet
<RTSP’s Video Delivery Method>
References
The End of the Presentation
Any questions or comments?