Re: Color support for Mac OS...

Jason Williams (streak@ccwf.cc.utexas.edu)
Sat, 11 Jul 1998 16:44:14 -0500 (CDT)


On Thu, 11 Jun 1998, Mark Andrew Nassy wrote:
> also, as i understand some version of 0.97aXXc may have problems
> transmitting audio if u have mac os 8.1, and virtual memory on, and or
> sound out quality higher than 22.050 kHz. :-(

I've never heard of this...If this is the old "OS8/8.1 problem with audio,
I know it's been fixed. If not, then I dunno what it could be. I haven't
heard audio from any of the 0.97X versions, though I know audio has been
heard by me. (At least I think so anyway).

If I remember right, CU encodes/decodes audio at 8 khz, so anything more
than that is just resampled down to 8 khz.

> i dont know if u can obtain a copy of wp 2.x but i think 2.x may allow u to
> view some color videos.

As far as I know, 2.X only allowed you to view SFMC (WP Color)...not sure
it supported any of the PC Cornell 1.0 Indeo codecs and I KNOW it didn't
support MJPEG. (No Mac user I know of would be using 3.X if 2.X supported
MJPEG).

> and not use a "mislabelled" copy as once happened to me u can receive
> h.263, and m-JPEG color video with virtual pc on a 250mhz 604e or faster
> cpu with 46,000+ k preferred memory allotted to vpc and a 28.8 modem
> connection. u can also transmit video using m-JPEG. note: this video is not
> live video.

I didn't realize you could install/uninstall drivers for the PC into
Virtual PC. Sounds cool.

> 1 way to get somewhat live video into win cu and vpc may b to
> use a win application that converts the contents of the win clipboard into
> video that win cu can use.

I was talking to Brian Godette one night about an application that would
do this..I have yet to see one though. There may be "other" uses for it
as well. :)

> an additional alternative is clearphone. it is reported to b able to
> transmit cd quality audio over a modem, transmit voice clearly, and have
> really fast video.

The problem I've heard about clearphone is that it's a TCP conferencing
application. Conferencing with TCP is not really a good thing if you have
ANY packet loss due to the way TCP works (It'll retransmit EVERY packet
that's lost). If you have no packet loss at all, it'll fly. If you do,
it'll be slow as mollasses.

I don't see how you can get "cd quality audio" over a modem. CDs are
44khz at 16-bit. that's 44,000 X 16 = 704,000 bits/second = 704kbps. to
fit that into a 28kbps modem, there would have to be a compression factor
of 25:1. I don't know of any lossless audio compression codecs that can
achieve that kind of compression...especially in real time. But then,
audio compression isn't really my thing. The term "cd quality audio"
implies the codec is built for playing music. Most of the time whenever
I've seen "cd quality audio" for advertising, they're just talking about
voice. The typical talking human voice doesn't even remotely approach the
range capable on a cd. :)

> unfortunately i dont have a url for it handy. one vendor i spoke with at
> macworld is considering replacing wp cu with this application for
> distribution with their mac / win product.

The queston I have..does Clearphone provide a multiconference mode? Or is
it just another one of the point to point programs like many of the PC
ones out there? Is it H.323 compliant? If so, MeetingPoint would help
out somewhat.

--
streak@ccwf.cc.utexas.edu    * Jason Williams -- Austin, Tx.  |     |
streak@mail.utexas.edu       * University of Texas at Austin  | ___ |
streak@cs.utexas.edu         * BS Computer Science             \_|_/
*************** http://ccwf.cc.utexas.edu/~streak/ **************|