<![CDATA[<body bgcolor="#FFFFFF">
<p><img src="../media/filmstrip.gif" width="302" height="71" usemap="#filmstrip" border="0" >
<map name="filmstrip">
<area shape="rect" coords="260,12,299,58" href="../archives.html" >
<area shape="rect" coords="212,12,259,59" href="../filmsvcs2.html" >
<area shape="rect" coords="172,10,213,57" href="../avid.html" >
<area shape="rect" coords="132,13,171,58" href="../nyc3.html" >
<area shape="rect" coords="88,13,128,57" href="../news.html" >
<area shape="rect" coords="44,12,84,59" href="../telecine.html" >
<area shape="rect" coords="4,12,42,61" href="../filmskool.html" >
</map></p>
<p><b><font color="#330000" face="Arial, Helvetica, sans-serif" size="4">Why final
mixes and other non-field original audio sources cannot be recorded to mag with
100% certainty that they will sync unless sync picture is supplied to us for
examination.</font></b></p>
<p> <font face="Arial, Helvetica, sans-serif"><b>by Jim Erickson</b></font><br>
<br>
Film elements cannot be run at exactly the speed they were originally recorded
at when they are played back in a video environment. This is because the frame
rate of most film elements (24 fps) does <img src="../media/plugs.jpg" width="230" height="158" align="right">not
evenly relate to the frame rate of the video world (29.97 fps).<br>
<br>
Therefore, when a film element (either picture or sound) originally recorded
at 24 fps is played back in the video environment, it cannot be played back
at exactly 24 fps, but rather must be played at 23.98 fps (the closest equivalent
speed that will work in the video world.) This slowed down playback condition
is called "PULLING DOWN."<br>
<br>
Similarly, when a film element originally recorded at 24 fps is played back
in the film environment, it can be played back at exactly 24 fps. This condition
of playing the element at exactly the same speed is called "PULLING OFF"<br>
<br>
Similarly, when a film element originally recorded at 24 fps has already been
PULLED DOWN to play in a video environment (as when it is transferred to a video
tape) and must now be translated back into the film environment (as when one
wishes to make a mag from a videotape of a film transfer), it must be speeded
up again to match back into the film world. This condition of speeding up the
element is called "PULLING UP."<br>
<br>
When we are supplied original sound from the field and are requested to make
a mag from it, we know with almost 100% certainty that the picture it matches
against is a camera that was running at exactly 24 fps. Armed with this knowledge,
we can accurately determine whether to pull down, pull up, or pull off the audio.
Because the frame rate of the picture element is known exactly, all answers
with regard to the audio are known.<br>
<br>
When we are supplied final mix sound for a production, or any sound element
that is not field original, we do not know whether the audio has already been
pulled down, off, or up---or a combination of all three! Why didn't this situation
exist years ago? Because the progression of inexpensive and powerful video-based
sound mixing tools has been extremely rapid. Only 3-4 years ago, one could expect
a final mix to come from a large, well established sound house on full coat
mag film. Thus, the finished mix was a film element, no questions asked. Today,
final mixes often are delivered from the non-linear devices of offline editors.
They might be DATs, DA-88's, or who knows what-----and to match to picture they
might need to be pulled down, off, or up----but usually the answer cannot be
found by simply asking the question of the client. The concept of pull down,
off, or up is unfortunately often an exotic one--even to otherwise experienced
sound people. When the stakes are high, such as when we will be making a mag
from which an optical track will be made, we must be supplied picture to match
to so that we can determine what sort of pulling to do, OR the client must be
sufficiently knowledgeable to give us a command that they are willing to stand
by--"pull down to match to video," "pull off to match to video,"
or "pull up to match to video." Colorlab has already had this question
incorrectly answered by the most experienced of sound house mixers, and feels
that it is best not to ask the question at all. We must have picture to check
sync against if we are to guarantee our mag product in the 1990's.<br>
<br>
<br>
Jim Erickson<br>
Senior Colorist, Colorlab</p>
<p><a href="../telecine.html">Back to Table of Contents</a><br>
</p>
<map name="mmm">
<area shape="rect" coords="255,10,299,63" href="../archives.html">
<area shape="rect" coords="217,8,257,62" href="../filmsvcs2.html">
<area shape="rect" coords="174,11,212,61" href="../avid.html">
<area shape="rect" coords="132,9,170,62" href="../nyc3.html">
<area shape="rect" coords="90,12,127,61" href="../news.html">
<area shape="rect" coords="45,9,90,64" href="../telecine.html">
<area shape="rect" coords="3,9,44,63" href="../filmskool.html">
</map>
</body>]]>