Browse Prior Art Database

Video Data Transfer on Limited Bandwidth Buses

IP.com Disclosure Number: IPCOM000117964D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Kerigan, S: AUTHOR [+2]

Abstract

It would be desirable to attach digital Input/Output (I/O) cameras to Universal Serial Bus (USB) and IEEE 1394 buses. USB has a max data rate of 12 Megabits/sec and the IEEE 1394 has a data rate of 200 Megabits/sec moving to 400 Megabits/sec with todays VLSI. The data rate for digital studio quality video is 168 Megabits/sec, the data rate for video conferencing is typically 6 Megabits/sec.. Some operating systems cannot support USB fully as they are not a real time operating system therefore cannot guarantee the bus bandwidth for 50% availability and connect other devices.

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Video Data Transfer on Limited Bandwidth Buses

      It would be desirable to attach digital Input/Output (I/O)
cameras to Universal Serial Bus (USB) and IEEE 1394 buses.  USB has a
max data rate of 12 Megabits/sec and the IEEE 1394 has a data rate of
200 Megabits/sec moving to 400 Megabits/sec with todays VLSI.  The
data rate for digital studio quality video is 168 Megabits/sec, the
data rate for video conferencing is typically 6 Megabits/sec..  Some
operating systems cannot support USB fully as they are not a real
time operating system therefore cannot guarantee the bus bandwidth
for 50% availability and connect other devices.

      A solution to the above problem of moving uncompressed video
data via a system bus (USB or IEEE 1394) to the system unit where
compression takes place in the hardware or software is to move the
compression into the camera.  This reduces the studio quality
requirement from 168 Megabits/sec to 1.4 Megabits/sec for MPEG1 or 4
Megabits/sec for MPEG2.  The video conferencing requirement reduces
from 6 Megabits/sec to approx 800 kbits per sec..  It also addresses
the problem of the operating system bandwidth allocation as within
both MPEG and H251 compression products the video data blocks are
chained and therefore can be reconstructed at a later time.