From: Ray <email@hidden>
Subject: Re: Dual streams, archiving?
To: "Michael Wood, Cincinnati" <email@hidden>
On QT you will need to run an encoder for each stream. There have been
multiple posts on how to run more than one encoder on a single Mac.
Personally I like to run things on two Macs instead of one because I
like the redundancy. I would recommend you go grab a mini and use it
for the low band encoder. Split the signal to both boxes and give the
viewers two links. Or sniff the viewers bandwidth at time of
connection
and send them to the high or low based on their connection speed.
Ray Harris
Ray, don't know about the archiving part, but we've been running 2
copies of QT Broadcaster encoding live audio at two different rates for
almost two years now, without any problems. And this is in the same
XServe as apache and QTSS. It has proven to be a very robust system.
The same box also streams hundreds of on-demand streaming and HTTP
movies for curriculum support. This is 24/7, 365 days/year, with close
to 50 thousand hits at our college radio station. http://video.conncoll.edu/wcni/wcni_live.html
If anyone needs directions, there is a link at the bottom of the page..
(by the way, we are moving our server tomorrow, so it will be down for
about 4 hours)
Pash has written on this board how to do it with video.
QT Broadcaster for us is a very stable program, even when run in
multiple instances, and it has never frozen or failed. You do have to
watch your CPU utilization with all the above programs, of course.
However, on a 933 MHz G4 with 1 gig of ram, here's how much 3
simultaneous copies of QTB use, on average:
32kbps AAC audio stream, mono from iMic, 32 KHz, best encoding: 12% CPU
64kbps AAC audio stream, stereo from iMic, 32 KHz, best encoding: 18%
CPU
300kbps MPEG4 video from firewire input, 320x240, 10 fps, with 20 kbps
AAC 16 KHz audio, mono (fine for dialogue): 27%
A Mac mini would do the above with no problem, and could even support
more live encoding.
It would be overkill to have two computers, each one just encoding one
audio stream, in my opinion. In one 24 hour test, we had 5 copies of
QTB running, four encoding two different USB audio sources at two
different data rates, and one encoding firewire video/audio. No
problems.
However, I agree on the importance of redundancy. If we were doing
mission-critical stuff (I can now totally rebuild our configuration on
another computer in 60 minutes using NetRestore), I would set up two
computers with the same QTB configurations on each one, and have one
standing by to use if the first one fails.
I did notice one small problem with QT Broadcaster, after about 20 days
the compressed audio starts to sound "cripsy". We then just quickly
quit and reopen each instance. Have not had the time to track this
down.
Also, Wirecast allows you to encode multiple different data rate
streams (including video) without having to make multiple copies.
Cheers,
Frank Fulchiero
Digital Media Specialist
Connecticut College
