1. MULTIMEDIA SYSTEMS AND
APPLICATIONS
By S. Baskaran & T. Salim
M.Sc Computer Science,
Department of Computer Science,
Pondicherry University.

2. Data and File Format
• RTF
• TIFF
• RIFF
• MIDI
• JPEG
• AVI video file formats
• MPEG standards.

3. RTF
• The Rich Text Format (RTF) Specification provides a
method of transferring encoding formatted text and
graphics between different output devices, OS and
applications.
• RTF uses the American National Standards Institute
(ANSI), PC-8, Macintosh, or IBM PC character set to
control the representation and formatting of a
document, both on the screen and in print.

4. RTF(cont.)
• RTF files begins with control word "rtfN";
where N is the major version number. An
entire RTF file is consider a group and must be
enclosed in braces. Current version is 1.7,
hence the file will begin with
• {rtf1ansiansicpg1252....} ..

5. TIFF
• TIFF: stands for Tagged Image File Format.
• The support for attachment of additional information (referred to as
“tags”) provides a great deal of flexibility.
1. The most important tag is a format signifier: what type of
compression etc. is in use in the stored image.
2. TIFF can store many different types of image: 1-bit, grayscale, 8-
bit color, 24-bit RGB, etc.
3. TIFF was originally a lossless format but now a new JPEG tag
allows one to opt for JPEG compression.
4. The TIFF format was developed by the Aldus Corporation in the
1980's and was later supported by Microsoft.

6. Resource Interchange File Format
(RIFF)
• This is a file format for multimedia data on PCs. It can
contain bit-mapped graphics, animation, digital audio and
MIDI data.
• The WAV file format is the RIFF format for storing sound
data.
• RIFF (similarly to TIFF - Tagged Image File Format) is a
tagged file format. Tags allow applications capable of
reading RIFF files to read RIFF files by another
application, hence the word interchange in RIFF.
• Other Formats/Players - RealPlayer 7 (Windows NT) with
RealAudio, MP3 (MPEG Audio Layer 3) audio, Midi
players; MP3 players (MP3.com)

7. MP3
• Its full title is MPEG-1/2 Layer 3. It is a format for
compressing sounds which uses a lossy technique that
does not seriously degrade the quality of the sound
because it filters out aspects of the original sound that
the human ear cannot detect. After filtering it then
applies further compression techniques. A form of
coding called Huffman encoding is used to compress
the data once it has been captured.
• One minute of music takes up around 1 MS of space.
MP3 allows compression of CD-quality audio files by
a factor of 12 with little loss in quality. This explains
why it is such a widely used format.

8. MIDI
• The Musical Instrument Digital Interface (MIDI) is a
standard interface used by musical instruments like
keyboards, synthesisers and drum machines which
enables notes played on an instrument to be saved on
a computer system, edited and played back through a
MIDI device.
• The information about the sound is stored in a MIDI
file which the computer can then use to tell the
instrument which notes to play.
• http://www.cool-midi.com/

9. MIDI (Cont.)
• When a MIDI sound is stored in a computer system the
following attributes or properties of the sound are stored:
• Instrument, Pitch, Volume, Duration
• Defines the instrument being played. Each built-in sound on
a MIDI keyboard has an instrument number assigned to it.
When selected the instrument number is saved by the
computer so that, on playback, the notes in the musical
piece are played with the sound of that specific instrument.
• This sets the musical tone of a note which is determined by
the frequency.

10. MIDI (Cont.)
• This controls the loudness or amplitude of the note.
• This determines the length of a note (the number of
beats).
• Tempo Rate is the speed at which the piece of music
is set.

11. Advantages of MIDI
• Allows musical pieces or messages to be exchanged
and edited on different computers.
• It is an easily manipulated form of data. Changing the
tempo is a straightforward matter of changing one of
the attributes.
• A musician can store the messages generated by
many instruments in one file. This enables a musician
to put together and edit a piece of music generated on
different midi instruments with complete control over
each note of each instrument.

12. Advantages of MIDI(cont.)
• Produces much smaller file sizes than other sound
formats.
• Because it is digital it is easy to interface instruments,
such as keyboards, to computers. The musician can
store music on the computer and the computer can
then play the music back on the instrument.
• Disadvantage
• Browsers require separate plug-ins to play MIDI files.

13. EXIF
• EXIF (Exchange Image File) is an image format for digital cameras:
1. Compressed EXIF files use the baseline JPEG format.
2. A variety of tags (many more than in TIFF) are available to
facilitate higher quality printing, since information about the
camera and picture-taking conditions (flash, exposure, light
source, white balance, type of scene, etc.) can be stored and used
by printers for possible color correction algorithms.
3. The EXIF standard also includes specification of file format for
audio that accompanies digital images. As well, it also supports
tags for information needed for conversion to FlashPix (initially
developed by Kodak).

14. JPEG
• JPEG: The most important current standard for image compression.
• The human vision system has some specific limitations and JPEG takes
advantage of these to achieve high rates of compression.
• JPEG allows the user to set a desired level of quality, or compression ratio
(input divided by output).
• As an example, Fig. 3.17 shows our forestfire image, with a quality factor
Q=10%.
- This image is a mere 1.5% of the original size. In comparison, a JPEG
image with Q=75% yields an image size 5.6% of the original, whereas
a GIF version of this image compresses down to 23.0% of
uncompressed image size.

15. JPEG image with low quality specified by user

16. JPEG I
• The Joint Photographic Experts Group is a standards
body that developed what is now known as the JPEG
image-encoding format
• Like GIFs, JPEG images are platform independent and
specially compressed for high-speed transfer via
digital communication technologies
• Unlike GIF, JPEG supports tens of thousands of colors
for more detailed, photorealistic digital images
• JPEG uses special algorithms that yield much higher
data-compression ratios. It is not uncommon, for
example, for a 200 kilobyte GIF image (which uses
lossless compression) to be reduced to a 30kilobyte
JPEG image

17. JPEG II
• To achieve that amazing compression, JPEG does lose some
image data
• However, you can adjust the degree of ``lossiness'' with
special JPEG tools, so that although the uncompressed image
may not exactly match the original, it will be close enough
that most people cannot tell the difference
• The JPEG format is nearly universally understood by today's
graphical browsers. Some, most notably Netscape, have a
built-in JPEG decoder
• Others, like Mosaic, invoke an external viewing tool (helper
application) for decoding and displaying JPEG files, which
invariably are stored with a .jpg (or .JPG) filename suffix

18. Comparison of JPEG and GIF
(Cont.)
• You can expect progressive loss of quality each time
you do that, especially with different JPEG quality
settings
• If you must edit a photographic image, work with it
in TIFF or PNG format until it is ready for
publication, then convert it to JPEG for the web
• Go straight from a lossless 24-bit format supported by
your scanner, such as TIFF or PNG, to JPEG
• If a given image cannot tolerate being reduced to 8
bits for GIF or losing precise accuracy for
JPEG, TIFF and PNG are the best options.

19. The Progressive JPEG
• Progressive JPEG is a new variation on the JPEG
image format
• It is like interlaced GIF in that it fade in gradually
instead of being drawn from top to bottom
• This enables the viewer to understand what the image
is about very quickly
• Progressive JPEG is much smoother than progressive
GIF

20. The Video Format
The file format of the video determines:
– Which programs can open and play it.
– How much storage space it occupies.
– How fast it travels over an Internet connection.

21. Video File Formats
• AVI (Audio Video Interleave)
– Windows format, plays in Windows Media Player
– Very good quality, even at smaller resolutions
– Large file size – not recommended for delivering video over
the Internet.
– Popular format for videos stored on a computer.
• MOV (Movie)
– Apple format, plays in the QuickTime Player
– Very good quality
– Popular format for videos downloaded from the Internet.

22. Video File Formats
• MPEG (Moving Pictures Expert Group)
– The standard for compression and storage of audio and motion
video for use on the World Wide Web.
• Creates video small file sizes.
• Popular format for videos downloaded from the Internet.
– Its biggest advantage is that It will play in many different media
players.
• RM (RealMedia)
– Plays in the RealPlayer player.
– Typically contains a movie clip.
– Popular format for streaming video viewed over the Internet.
– Real Player is generally supported by many different computers
and operating systems.

23. Video File Formats
– WMV (Windows Media Video)
• Proprietary video format developed by Microsoft.
• Plays in Windows Media Player.
• Popular format for streaming video viewed over the Internet.
– FLV (Flash Video)
• New file format widely used on the Internet.
• Plays in Adobe Flash Player.
• Very small file size.
• Popular format for streaming video viewed over the Internet

24. MPEG Audio Layer 1
• MPEG (1 and 2) audio allows sampling rate at 44.1
48, 32, 22.05, 24 and 16KHz.
• MPEG filters the input audio into 32 bands.
Audio
12 samples Normalize Perceptual
By scale
384 samples factor coder
Filtering 12 samples
And
downsampling 12 samples

25. MPEG Audio Layer 2
• Layer 2 is very similar to Layer 1, but groups 3 12-
samples together in coding.
• It also improves the scaling factor quantization and
also groups 3 audio samples together in bit
assignment. 36 samples
36 samples
Audio Filtering Normalize Perceptual
By scale
3x384 samples And factor coder
downsampling
36 samples

26. File Format
Mpeg audio puts header in each of the frame, so that they can be
decoded separately.
Bit Scale Bit Scale
Header CRC Allocation
Subband Data Header CRC Allocation
Subband Data
factors factors
Frame 1 Frame 2

27. Other Audio Coding Standards
• MPEG 2 and MPEG 4 ACC (advanced audio coding)
– Not backward compatible
– Use MDCT without bandpass filtering
• Dolby AC3
– MDCT based codec
– Similar to MPEG ACC but uses a different
quantization and coding scheme
– A de-facto standard for DVD and Digital audio in
Movie.

28. MPEG (Moving Pictures
Expert Group)
• Committee of experts that develops video encoding
standards
• Until recently, was the only game in town (still the
most popular, by far)
• Suitable for wide range of videos
– Low resolution to high resolution
– Slow movement to fast action
• Can be implemented either in software or hardware

29. Evolution of MPEG
• MPEG-1
– Initial audio/video compression standard
– Used by VCD’s
– MP3 = MPEG-1 audio layer 3
– Target of 1.5 Mb/s bitrate at 352x240 resolution
– Only supports progressive pictures

30. Evolution of MPEG
• MPEG-2
– Current de facto standard, widely used in DVD
and Digital TV
– Ubiquity in hardware implies that it will be here
for a long time
• Transition to HDTV has taken over 10 years
and is not finished yet
– Different profiles and levels allow for quality
control

31. Evolution of MPEG
• MPEG-3
– Originally developed for HDTV, but abandoned
when MPEG-2 was determined to be sufficient
• MPEG-4
– Includes support for AV “objects”, 3D content, low
bitrate encoding, and DRM
– In practice, provides equal quality to MPEG-2 at a
lower bitrate, but often fails to deliver outright
better quality
– MPEG-4 Part 10 is H.264, which is used in HD-
DVD and Blu-Ray

32. MPEG Container Format
• Container format is a file format that can
contain data compressed by standard codecs
• 2 types for MPEG
– Program Stream (PS) – Designed for reasonably
reliable media, such as disks
– Transport Stream (TS) – Designed for lossy
links, such as networks or broadcast antennas

33. AV Synchronization
• Want audio and video streams to be played back in
sync with each other
• Video stream contains “presentation timestamps”
• MPEG-2 clock runs at 90 kHz
– Good for both 25 and 30 fps
• PCR (Program Clock Reference) timestamps are sent
with data by sender
• Receiver uses PLL (Phase Lock Loop) to synchronize
clocks

34. THANK YOU