> use "RGB" color space to make a Quicktime Movie
On Feb 5, 2010, at 3:07 AM, Job ter Burg (L2B) wrote:
> Sorry, but that is a VERY bad idea.
> It will stretch the 16-235 values in your footage to 0-255, crushing
all blacks below 16, and clipping all whites above 235.
> You will have eliminated all that white details prior to editing, let
alone color correction.
> If you export as 601/709, the levels of the original remain
untouched. 0 remains 0, 12, remains 12, 16 remains 16, 235 remains 235,
245 remains 245, etc.
> Honestly.
> If you export as RGB, you crush/clip and then stretch (0 becomes 16,
12 becomes 16, 12 becomes 16, 16 remains 16, 235 remains 235, 245
becomes 245, etc.)
> IMHO, you only export in RGB when exporting a deliverable that is
meant for viewing on computer monitors, for nothing else. If you are
working in video
color space and will be working in video color space and are delivering
on video color space, the RGB export buttons should remain unchecked
the entire
route.
I reply:
It defies logic and I agree it doesn't make sense, but this method has
worked for me for several years now. To clarify, here's what I've been
doing: I export an Avid DNxHD145 HD clip or sequence using "Same As
Source", "Native Pixel Dimensions" (1920x1080, square pixels), and
using RGB color space to make a self-contained Quicktime Movie. I then
import the Avid QT Movie into FCP (which looks fine when viewed on the
Mac computer monitor). Next, I make a new Apple ProRes422 QT Movie
from the Avid QT by using Media Manager to recompress the Movie onto my
media drive. The original Avid QT Movie can then be removed from the
bin and its source drive can be dismounted and disconnected from the
computer. The recompressed QT (now Apple ProRes422 and existing on my
media drive) can now be imported into a bin and can become a source
clip for editing. The new ProRes422 clip looks EXACTLY like the
original. No gamma shift, no lifted blacks.
HOWEVER, if I do the above exactly in the same way EXCEPT export the
Avid clip/sequence using 601/709 color space, the Avid QT will have
lifted blacks when viewed on the Mac. This is the case even before I
do the recompression. The 601/709 Avid QT will instantly be seen on
the Mac's monitor with lifted blacks. If I continue with the rest of
the procedure described above, the resulting ProRes422 QT will ALSO
have lifted blacks.
THEREFORE, I have always followed this procedure, doing the Avid
export with the color space set to "RGB". It gives the correct
results. If others get different results, I can't explain it. This
procedure has worked for me on every Avid Symphony I've tried it on.
BTW, I own an AJA I/O HD. The output of this video hardware device
also shows the same results as I've described it above, monitored on a
Sony PVM-14M4U and a Tek WFM scope and V scope.
Dennis Degan, Video Editor-Consultant-Knowledge Bank
NBC Today Show, New York
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