Transcript Low-power Wireless Video System

Low-Power Wireless
Video System
Advisor: Professor Alex Doboli
Students: Christian Austin
Artur Kasperek
Edward Safo
Objective
Ÿ Streams
MPEG4
video from server
through wireless
communication to
the Laptop/PDA
am
tre
Ÿ Running
Video Server
Ÿ Maintains
database
of MPEG4
files
Access Point
ys

Use MPEG-4 video
standard.
Hardware software codesign for low-power
video decoder
implementation.
Server
r
nta
me
ele

802.11B
11Mbit
4
EG
MP
Establish a low-power
wireless client/server
streaming video
system.
Ÿ Running
MPEG-4
Client
Software
Ÿ Running
MPEG-4 Client
Software
PDA
What is MPEG-4 and Why Use It?
What is MPEG-4?


Object based video compression and decoding
standard.
Builds on previous MPEG and H.263 standards.
Why use MPEG-4?


High compression makes streaming over low
bandwidth network practical (e.g. wireless).
Adjustable resolution coding allows for video
continuity/quality trade off.

High bit-rate yields better quality video at the expense of
lost frames…
MPEG-4 Framework
Multimedia
Content
Monitor
Scene Compositor
Audio
Objects
MPEG-4
Client
Framework
Scene
Description
Information
Video
Objects
Audio
decoder
Audio
Streams
Video
Decoder
Scene
Description
Streams
Video
Streams
Sync Layer
Protocol
Independent
Streams
DMIF Layer
Local
Streams
MPEG-4
Data
Streams
Network
Streams
Hardware/Software Co-Design
Design methodology that splits a
computer system’s design between
hardware and software in an effort to
improve some feature of the system.
Partitioning targets low power consumption
in this design.
 Achieved by relocating the functionality of
high power sections of code to specialized
hardware.

Power Intensive Software
Locating code.
 Hardware power profiling.
 Software profiling (e.g. GPROF,
VS).
 Power estimation software (e.g.
SimplePower).
Inverse Discrete Cosine Transform
(IDCT).
 Computational intensive.
 High frequency of memory
accesses.
IDCT
Hardware Implementation
Determine functional units needed to
implement the IDCT.

Multipliers and adders.
Map functional units into hardware to
realize the IDCT.

VHDL description of functional units,
Xilinx FPGA based PCI board.
Hardware Power measurements.
Optimize Hardware for low power.



Add power control logic.
Restructure combinational logic to reduce
glitching.
Increase pipelining.
Goals and Applications
Demonstrate that a low-power wireless video
system is practical.

Design for a power constrained, low bandwidth
PDA.
Applications:

Interactive shopping.


Request video of product information while shopping.
Multimedia preview.

Preview movie before buying or renting; watch music
video while previewing new album.