All things related to multicast

["Lawrence A. Rowe" <>]

Hi -

Many of you know that we have developed programs to stream production
quality audio and video over the Internet using RTP encapsulation and an
inexpensive MJPEG capture board for Linux ($400). Our goal was to
produce television-quality streams, that is, 60 fields per second of
full-sized 4:2:2 video images and stereo 16-bit audio at up to 48 KHz.
Experiments on Internet2 show that we can stream audio/video across
country with a latency around 100 msecs from capture to playback. The
system, called RTPtv, was used in a Berkeley MIG Seminar at the end of
last semester, see      
http://bmrc.berkeley.edu/courseware/cs298/hsmig.html
for details on that webcast including pointers to pages that describe
the technology and link to the software that you can download.

The student who developed this software, Matt Delco, has now finished
his masters report that describes the design and implementation of the
system.  The report goes into exhausting details about the problems we
faced using the board, encapsulating the video in the new MJPEG RTP
payload, including the use of restart markers and variable quantization
tables (that's right, the board produces bounded bit rate video by
varying the quantization table every field - it changes the scale factor
but we had to deduce the scale factor given the table), implementing
solid audio/video synchronization that will work for 24 hours, and
conceal lost packet errors.  You can get a copy of the paper at
        http://www.bmrc.berkeley.edu/research/publications/2001/161/
We plan to revise the paper into a form that we can submit to a journal,
but I wanted to give folks a copy to read since I know many of you are
interested in the details of how the system works and I promised to send
you the report when it was done.

Comments appreciated.  And, watch for more announcements of special
Berkeley MIG Seminars this fall.  We're working on some RGB capture
technology that we hope to deploy this fall along with the RTPtv system
that will significantly improve the quality of the seminars.

Enjoy!
        Larry
-- 
Professor Lawrence A. Rowe          Internet:  

Computer Science Division - EECS       Phone: 510-642-5117
University of California, Berkeley       Fax: 510-642-5615
Berkeley, CA 94720-1776            URL: http://bmrc.berkeley.edu/~larry