[AG-TECH] Have we looked at vBrick?

Brian Chee chee at hawaii.edu
Tue May 22 20:35:17 CDT 2001

I've actually done some work with the 2NetFX folks that have an HDTV
decoer board...their system does HDTV at 22.5mb/sec with an MPEG-2

Still pretty pricey....

I'm just in favor of a medium resolution system that allows for muxing of
the sound and the video.  The decoupling of audio seems to be the biggest
bugaboo on the AG.  Going to a hardware decoder is getting pretty cheap
and might prevent frequent upgrades of the AG decoder box....but then
again, I'm still fighting my procurement process to get my last couple
pieces to go live with the present configuration.

/brian chee

University of Hawaii at Manoa
Department of Information and Computer Sciences
Advanced Network Computing Laboratory (ANCL)
1680 East-West Road, Room 311
Honolulu, HI  96822
Voice: 808-956-5797       Email: chee at hawaii.edu
Brian J.S. Chee, CNE/CNI

On Tue, 22 May 2001, Markus Buchhorn wrote:

> At 02:20 PM 22/05/2001 -0500, Robert Olson wrote:
> >At 02:11 PM 5/22/2001 -0500, Bill Nickless wrote:
> >>Remind me: what's the problem with converting to mpeg-2?  Is it the
> >>encode problem (expensive) or the fact that mpeg-2 decode is more
> >>expensive than h.261 decode
> >
> >Price and availability of robust encoders for one. There are latency
> >issues (need to be able to tune the encoder to not do the prediction
> >mechansim that requires a second of buffering to decode) as well; there's
> >not a widely available MPEG2 over RTP library that I know of as well.
> Encoding is CPU-expensive, decoding is reasonably CPU expensive. Latency,
> as Bob mentions, is a hassle, even with the hardware encoder cards unless
> you can convince it to do pure I-frames (i.e. intra-frame compression only,
> or at least back-deltas only), but you pay in bandwidth.
> I have found one mpeg/rtp piece of code (linuxtv.org), and it is pretty
> trivial (and not quite to rfc2250 spec) - it just divides the mpeg stream
> into 188 byte payloads and shunts them off. No frame boundary alignment or
> other rfc2250 "required/recommended" bits. But it seems to work from what I
> have heard. I'm trying to get somebody here to do it properly, I just
> haven't found the right bribe yet :-)
> >WinTV + H261 might not be the best, but you can't yet beat the price and
> >reliability.
> Yep, and it does perform remarkably well.
> I have some new cards here that I'm just starting to play with. "Realtime"
> (we'll see) MPEG2 encoder for under $US1k, decoder for under $US100.
> Neither card does RTP streaming/receiving, but I'm working on that...
> Still, there is a rapidly growing market now that you can get MPEG2 on
> (almost?) one chip.
> MPEG1 would be a nice intermediate option, since you can go to decent
> PAL/NTSC resolution at 30fps within 1.5Mb/s. The h.261 codecs are CIF
> (320x240?), right? and (are designed to) run well under 1.5Mb/s. (it's
> N*64kb/s to support the ISDN world)
> At the lower end, is anybody doing something with H.263 (very low
> bandwidth)? It's a big area of interest now, as MPEG-4 uses it, and the
> PDA/cell-phone companies are very keen on it.
> Conversely, some UWash/Stanford guys are playing with realtime HDTV (40Mb/s
> at tolerable latency, 270Mb/s for pure I-frame low-latency :-) ).
> Point-to-point only so far that I am aware of. There's also an
> internet-draft for raw HDTV over RTP(modified) - 1.48Gb/s :-) Plus I know
> NEC make some big (3 gun) projectors that have 2500x2000 display space
> (around $US10k).
> How flexible is the AG setup to putting in other codecs or indeed other
> video tools?
> Cheers,
>          Markus
> Markus Buchhorn, Faculty of Engineering and IT,          | Ph: +61 2 61258810
> email: markus.buchhorn at anu.edu.au, mail: CSIT Bldg #108  |Fax: +61 2 61259805
> Australian National University, Canberra 0200, Australia |Mobile: 0417 281429

More information about the ag-tech mailing list