Transcript Web Radio - CS Course Webpages

Web Radio
Stereo Component
To Jog Your Memory..
 High speed access is become more common
in homes and the market for Hi-Fi audio has
always existed. Our project takes streaming
audio via the Internet and makes it available
as a stereo component.
Our Project...
Traditionally people have
listened to the radio over
and RF frequency. With
our implementation,
people will be able to
listen to their favorite
radio station no matter
where they are in the
world.
Accomplishments So Far...
 LCD Interface
– The interface from the parallel port of the
ColdFire board to the LCD is complete
 Setting up Metrowerks
 Wired a Voltage Converter
– We needed from 3.3V to 5V for the ColdFire
evaluation board
More Accomplishments…
 MPEG/Layer 3 Decoding
– Once we eliminated RealAudio as a decoding
option, we turned to MPEG/Layer 3 which has
a lot of documentation available
How Does MPEG/Layer 3 work?
 Without data reduction, digital audio signals consist
of 16 bit samples recorded at a sampling rate more
than twice the actual audio bandwidth (e.g. 44.1 kHz
for Compact Disks). So you end up with more than
1.400 Mbit to represent just one second of stereo
music in CD quality.
 By using MPEG audio coding, you can shrink down
the original sound data from a CD by a factor of 12,
without losing sound quality.
How Does MPEG/Layer 3 work?
 Basically, this is realized by perceptual coding
techniques addressing the perception of sound
waves by the human ear.
 When you look at the sun and a bird passes in front, you
don’t see it because of brightness of the sun. In audio,
strong sounds overshadow the weaker sounds so they don’t
need to be coded.
So How Are We Using It?
 International Standards Organization
(ISO)
– ISO has released public C code to perform the
MPEG/Layer 3 decoding process for Solaris.
We are adding functionality to this code so that
it may be used by the ColdFire board and our
Digital-to-Audio converter to deliver line-out
Flowchart of Decoding Process
TCP/IP streaming
MPEG/Layer 3
audio
While a
bitstream
!= NULL
Read
MPEG/Layer 3
Header
Decode
Audio Stream
Create at
Least 3
Frame
Buffers
Output to Parallel
Port of ColdFire
5307 so that
Digital-to-Audio
conversion process
can start
Original Schedule...
Component
LCD interface
Network interface
RealAudio decoding
Audio decompression
Digital-to-Audio
conversion
RCA line out
Integration
Testing
Final Presentation
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Updated Schedule...
Component
LCD interface
Network interface
MPEG L-3 decoding
Digital-to-Audio Conv.
RCA line out
Integration
Testing
Final Presentation
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Mid-term Summary
 Level of Difficulty in implementation
–2
 Coordination Among Team Members
–1
 Support From the Lab
–2
References...
 Introduction to TCP/IP –
– gopher://gopherchem.ucdavis.edu/11/Index/Internet_aw/Intro_t
he_Internet/intro.to.ip/
 MPEG/Layer 3 Information
– http://www.mp3tech.org
 Motorola –
– http://www.motorola.com
References...
 483 Home Page –
– http://www.cs.tamu.edu/courseinfo/cpsc483/common/
 Analog Devices –
– http://www.analogdevices.com