Dr Nathan Scott (nscott@mech.uwa.edu.au)
Sun, 20 Jun 1999 10:38:36 +0800
Dear Dig-vid,
I've been struggling towards a semi-professional setup for many years now.
All along I've had visions of doing high-quality digital video editing but
it has eluded me so far. Here's a history:
I bought a Quadra 840AV which did 320 x 240 pixels at 15 FPS - not bad for
1993 straight out of the box. Did some ray-traced animation and made a
small promotional movie with Adobe Premiere 4.2.
Then in 1998 I bought a beige G3 tower with the built-in AV. To my
annoyance it was actually a less powerful video grabber than the 840AV! So
I also bought a MiroMotion DC30+, thinking, "now I've got everything".
The MiroMotion card was actually pretty good and for the first time I could
at least read and write a decent PAL signal (i.e. 768 x 576 at 25 FPS). But
again I was frustrated because it soon turned out that the hard disk in the
Mac was only capable of a sustained data transfer rate of about 1.2 Mb/s.
This is not enough for high-quality work and the movie ends up with
noticeable artifacts.
Then a friend gave me a spare FireWire card to try in my trusty beige G3. I
connected up a lovely new XL1 but was horrified with the quality of the
image captured this way - even worse than using the analog MiroMotion card
to capture the same image. Of course the same hard disk limitation was
getting me for the same reason.
So I am just about to buy an Adaptec 2940UW SCSI controller and an 18Gb IBM
Hammerhead disk to put inside my Mac. This pair is rated at 80 Mb/s burst
rate. The best advice I can get about this is that I can expect an actual
sustained data rate of about 30 Mb/s. This is much greater than the 8Mb/s
that the MiroMotion card can produce and it is also greater than the 4Mb/s
I expect the XL1 to produce. Therefore, in theory at least, THIS should be
an awesome combination.
If any of you are still with me, here are the questions:
1) If there is anything wrong with this plan, I would really like to know
about it NOW. If past experience is any guide, I will get the controller
and hard disk working and THEN someone will tell me that - of course - I
need XYZ additional hardware to edit a good-looking movie. In short, is
there some other bottleneck or harware limitation I will discover? Or will
it finally just work?
2) I hear that Adaptec are now producing a cool new "combo" FireWire/SCSI
controller card, the 8945
http://www.adaptec.com/products/overview/aha8945hc.html
HOWEVER it is only rated at 40 Mb/s. So again I need advice: when actually
editing, will I notice a real difference between a card/disk pair rated at
40Mb/s and a card/disk pair rated at 80 Mb/s? Is there any performance
penalty for having the FireWire on a separate card from the SCSI
controller? This is an important question because I would prefer not to use
up two slots when I might be able to get away with just one. BUT I also
want a swift editor.
3) There is a new choice out there: the FireWire drive! The only one I can
find is
http://www.firepower.com/products/FireDrive.html
So - does anyone have one of these, and does it work for DV? I note that
the sustained transfer rate of the largest of these drives is given as "13
to 8" Mb/s. What does that mean? Does it mean they will promise me 13 and
deliver 8? Or should I divide every number in two to make it realistic?
I hope this story will help anyone who is just starting. The message is,
don't expect anyone, even Apple, to sell you a desktop computer that REALLY
edits video straight out of the box. I am fairly certain this applies even
to the otherwise appetising blue/white G3. You MUST also buy additional
harware to eliminate the bottleneck of the relatively slow built-in hard
disk and controller. If I am wrong here I hope someone will correct me.
Regards,
Dr Nathan Scott
Lecturer
Department of Mechanical & Materials Engineering
The University of Western Australia
Western Australia 6907
Rm 220 +61 8 9380 3761
FAX +61 8 9380 1024
Home +61 8 9440 0242
nscott@mech.uwa.edu.au
http://www.mech.uwa.edu.au/dynamics/
This archive was generated by hypermail 2.0b3 on Sat Jun 19 1999 - 19:41:09 PDT