#PC to Exabyte?
11 messages in this thread
There's a good public domain / freely distributable tape driver in the Unix
Forum here on CIS. There's also a 'tar' there if you need to make a 'tar'
tape. If you really want Abekas format, you might want to purchase commercial
software from a place like Elastic Reality. Several forum members here have
set up this PD tape driver, myself included, so feel free to ask questions.
John,
re Abekas/Exabyte output. What do you set the gamma at?
Ian.
Offhand, without checking my notes, I think it's 1.6, or whatever the same
value is for any other RGB to NTSC conversion…
I've been using 1.8 gamma for Abekas output.
John Tissavary (LUNA cie, inc)
This is out of the blue, as usual, but Abekas recommends a gamma value of 1.2.
Gus, Are you sure its not 2.2? I think Greg once recommended 2.2 (though maybe
he was refering to PAR). I'm a little nervous because I'm doing my first
broadcast animation and I don't want to have to pay for a tape transfer twice
— or rerender! My contact at the post house wasn't much help, "just do it so
that it looks good on the screen (computer)."
Ian.
John Tissavary has done this quite often so he, better than I, should be able
to tell you the "best" gamma correction. What I'm saying is that the Abekas
expects 4:2:2 component digital video gamma corrected at 1.2. That only means
the "correct" value and doesn't necessary means the "better" value.
Gus:
>> Abekas expects 4:2:2 component digital video gamma corrected at 1.2.
Interesting! We did a bunch of tests for our "It's A Digital World" project,
in which 35mm film was transferred to D-1, run through an Abekas and given to
us for compositing.
It was extremely important that after rendering the images in 3DS and
compositing on the live backgrounds, transferring back to Abekas and on to D-1,
the closest match we had for the background images was 2.2, so that's what we
used for the entire project…
But who knows what really goes on inside those Hollywood studios? :^)
Greg Pyros
1.2?! I remember hemming and hawing over that last year. The lowest I used
was 1.3, and it was darker than hell (but that's what I wanted). For the
regular happy looking logos and stuff I really stick to 1.8. I'll have to do a
test next time and re-evaluate. Maybe lighting the scenes differently and
rendering 1.2 would be better?
John Tissavary (LUNA cie, inc)
I remember that thread quite well. No thanks, not again!<g> When going through
the technical details of the YUV format and how they want the image encoded, I
bumped into this "requirement". My point out of this is that it should be what
you like best. YUV is a very different format from RGB. The luminance is
extracted just like RGB but the chroma is shrunk to 8 bits (giving a 16 bits
per pixel encoding). Well, it's a bit more than that as each two pixels carry
each other's complement… it gets worse… At any rate, just look at the PAR
or a FAST Video Machine. They all use the same exact encoding.
Yeah, that thread was pretty mangy. I basically decided gamma was not some
sort of absolute mandate of the gods, but just another slider for getting stuff
to look better. I'm usually happy with 1.8, though I'll go up or down for
certain looks.
John Tissavary (LUNA cie, inc)