Frame jumps and render glitches using Frame Rate converted footage.

For those of you who are interested I have found some answers:


Firstly after some time-consuming searching:

http://discussions.apple.com/thread.jspa?messageID=6500221&#6500221



And secondly, Philip Hodgett kindly answered my e-mail:

On Mar 24, 2008, at 6:34 AM, Susan Scott wrote:

Hi Philip,
Thanks so much for your article on Ken Stone's site on when to convert
your source and when to edit in the native format. I learnt some new
stuff...so sorry to do this to you but I badly need some advice! I
have footage that is DVCPRO HD 60 converted to 23.98, but because of
space issues the footage has not been copied but as far as I
understand it from the tech support guy running the post on this
project, the 23.98 footage is referencing the original footage.

That sounds nasty. If it's been converted to 23.98 from 60 there has
been serious frame rate conversion going on and there is no way the
23.98 could reference the source footage. Even timecode won't match.

The question is, then "how" was it converted from 60 to 23.98? The
only choices I can think of are:

correctly, using a Terranex or similar frame rate converter;
as slow motion from DVCPRO HD using the Varicam frame rate utility; (a
special speed effect, not something to be used for regular footage)
or some other method which would be bad.

The only thing I can think of, is that the converted REFERENCE clip is
not frame accurate, and hence these issues. The problem is that all
this footage is on the biggest XSAN in the Southern Hemisphere and we
can't copy the footage into the 23.98 format. Plus, this is the first
time I have worked in 23.98 as I usually work in the HDCAM 50i
world...so any advice, tips or workarounds would be greatly
appreciated.

The problem would appear to be that your timeline is trying to
reference frames at 23.98 fps and the footage has 60 frames in that
time, and yet none (other than first frame in a second) would actually
line up. (That's why you need the Terranex or Snell and Wilcox boxes
for frame rate conversions.)

Here's the thing. If you want a 23.98 result, you shoot, edit and
output in 23.98. Shooting in 60p is very inappropriate. My best
recommendation is to suggest finishing the project at 60P and then
having a Terranex conversion done to 23.98.

I seriously doubt you'll get this project working the way it's
currently set up.

If I were brought in professionally to advise on this workflow, I'd
advise starting over and then leave. It's never going to be a smooth
job and it really needs someone knowledgeable and local to set up the
workflow before attempting again.

My constant mantra is that you do NOT shoot a single frame of the
project until the shooting format and frame rate have been tested
through the editing process to the desired output. Only once the
entire workflow has been tested, can production begin on the project.
There are just too many variable that can cause the program to go
astray and end up in a quagmire (as you've sadly found).

Sorry to not have a happier answer for you.

Philip

Philip Hodgetts
President, Intelligent Assistance
"Big Brains for Rent"
www.bigbrainsforrent.com