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Re: 30FPS to 24FPS



In a message dated 7/8/99 2:59:06 AM, martin at hollydig.com writes:

<< How do you take DV material (you know, pro-sumer format) shot at 30fps and
use it to edit on an Avid at 24fps?  How do you get it into the Avid? >>

Here are some excellent replies to this question copied from Mike Morgan at 
ILM,
followed by a technote from Michael Phillips at Avid Technology.
__________________________________
In the console, type "pulldown choice" and hit return.

This will enable that video rate choice.  Just remember, the playback of
the captured material will playback at 24fps.  This basically disables
pulldown removal when digitizing within Film Composer and does a frame
for frame capture from tape.  This is used normally for shots that are
layed off to tape at frame for frame, like a film or 24fps digital shot
that does not have pulldown added when layed off to tape, or digitizing
directly from a DDR (disk recorder) that is playing back at 24fps.  

Can be useful and can be very dangerous as well.  Because if you select
video rate, and then forget to deselect it and continue to digitize film
footage with pulldown, then you will have material that plays back
incorrectly.  Use with extreme caution, and make sure that .

BTW, when you quit out of composer and relaunch, it will clear out the
command and video rate will be grayed out once again.


Hope this helps

------------------------
Mike Morgan
Industrial Light + Magic
Editorial
------------------------

All of our work is done at 24fps as well, and all of our shots trade
between the CG world via omf.  If we want to an inhouse transfer of 35mm
to go into the Avid, we  have the option to transfer the film with
pulldown added (thus including 3/2 pulldown to make 24fps=30fps).  The
other option is to transfer the film-to-video frame to frame, one film
frame = one video frame.

At this point, the video tape when played back on a beta deck will
appear to be playing faster because the 24fps film is now playing at
30fps (no pulldown)

In Film Composer, we then digitize at "video rate" instead of
"pulldown".  THis will capture every frame at 30fps, just like in a
30fps project.  However, FC will playback that image at 24fps thus
maintaining its original speed and sync... lost yet?

In order to capture at "video rate":
1. Open the console.
2. type "pulldown choice" on the command line, hit return.
3. go into Film Settings
4. The setting "FILM TO VIDEO TRANSFER" should be defaulted at
'pulldown'.
5. Select "Video Rate" in that setting.

At this point, all digitizing will be done 30fps style, thus no removal
of pulldown since pulldown wasn't included.  After you digitize a clip,
the bin should show that the FPS=24 but the CFPS=30, which means that
the capture frames per second was done at 30, but the project will
playback at 24.  This is useful only when doing transfers of film
(24)-->video (30) --> film comp (24)... the video really acts as the
transfer media, but is not all that useful for a video master to make
dubs and such... so label that tape clearly as "NO PULLDOWN" to avoid
confusion. Also, make sure that you switch back to "pulldown" in the
settings or restart composer to flush out the console command.   The
"video rate" option is normally grayed until the console command
executed.

_______________

30 Frame Capture in a NTSC Film Project
by Michael Phillips


Feature

Version 6.5.lv1 of the Film Composer and Film option software allows 30 
frame capture of film based material into a 24 frame film project. This 
feature is only available once a console command has been entered. Once 
enabled, film to tape transfers that were done without pulldown can now 
be captured directly into a film project. This feature is principally 
for special effects that are generated on a frame to frame basis to tape 
and need to be integrated into the film project. Picture only digitize 
is available when this mode is active. 24 frame and 30 frame capture can 
be edited together in the same sequence.

Console Command

The feature is enabled by typing "pulldown choice" into the console and 
hitting return. You will then be greeted by a warning message "EDL's are 
not supported when capturing at this rate". Click OK.

Procedure

Once the feature is enabled, go to the "film" settings and select "video 
rate" from the transfer speed selector. This will now indicate to the 
system that every frame of video should be digitized. Once digitized, 
the picture will play back at 24fps. The setting must be changed back to 
"film rate" if normal 24 frame capture is desired.

Supported Outputs

Digital Cut:

Digitized media will behave like any other digitized picture. All 
playback of Avid media will depend on Video Slave Driver settings and 
menu selector in the "Digital Cut Window".


VSD 

	Digital Cut
Window 

	Playback Speed 



.99 

	film rate 

	23.976 


1.00 

	film rate 

	24 


.99 

	video rate 

	29.97 (20% faster/ 1 to 1) 


Cutlists:

All Cutlists will be displayed correctly for film based media regardless 
of capture rate. All captured material assumes a 24 frame playback. All 
cutlist tool options are available.


Unsupported Outputs


EDL

The EDL Manager and composition (sequence) currently only understand 
media that has been digitized from a source with a 2/3 pulldown. All 
picture digitized in the 30 frame mode will be off by 20% of the 
duration. EDL's are not intended to work nor are they supported at this 
time.

Caution

Batch digitize is only supported within groups of transfer rates. This 
means that all pulldown transferred material can be digitized together 
and all 30 frame transferred material can be captured together. Capture 
settings are not contained in the clip, so the setting needs to be set 
for each type before digitizing takes place. The only way of identifying 
how the clip was digitized is by looking at the "Pullin" column. 24 
frame captured material will display either A, B, C, or D. 30 frame 
captured material will be blank.

Copyright  1997 Avid Technology, Inc. All Rights Reserved 

---
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