Apple Compressor (4.0) - Manual (Page 175)

Chapter 7 Advanced functions 175
Other reverse telecine issues
Because the goal of reverse telecine is to output progressive 23.98 fps video, all the other options
in the Frame Controls pane are disabled when you choose Reverse Telecine from the Deinterlace
pop-up menu.
When using the Reverse Telecine menu command, consider these issues:
•
Because of the unpredictable nature of the processing when reversing the telecine, segmented
encoding does not work as efficiently as it does when reverse telecine is not being used.
•
If you pause the transcoding process, the transcode must start from the beginning when
you restart it.
Creating PAL video during the reverse telecine process
It’s a common practice to convert 23.98 fps or 24 fps video to PAL’s 25 fps rate by speeding up
the playback by 4 percent. If you’re starting with NTSC 29.97 fps video from a telecine, you can
convert it to PAL video by chaining two Compressor jobs. (For more information about chaining
jobs, see
Chain jobs on page 146.) Create the following two jobs:
•
First job: Apply a setting to the job that performs the reverse telecine process and results
in an NTSC frame size at 23.98 fps. (Although you can apply a setting that also converts the
video to PAL, that format conversion does not use Frame Controls and therefore may not be
of suitable quality.)
•
Second job: Create the second job selecting the first job and choosing Job > New Job With
Target Output. This creates a job that is chained to the output of the first job. You can now
apply a setting that sets the output format to PAL and use the Frame Controls feature to
ensure a high-quality output file.
About the cadence
When film is telecined to NTSC video, it has a constant cadence. This means that the 3:2 pattern
is consistent and uninterrupted. It’s relatively easy to remove the telecine from a constant-
cadence clip because you need only determine the pattern once.
If you take these telecined clips and edit them as NTSC video, the result is a final video file that
has a broken cadence with an inconsistent 3:2 pattern. It’s much more difficult to remove the
telecine from this clip because you have to constantly verify the cadence to make sure you don’t
inadvertently choose incorrect fields when creating the 23.98 fps video.
The Reverse Telecine feature included with Compressor automatically detects broken cadences
and adjusts processing as needed.
About retiming
The retiming controls in the Frame Controls pane have two common uses:
•
Convert video from one frame rate to another: This typically involves converting NTSC video to
PAL frame rates or PAL video to NTSC frame rates. This function uses only the setting of the
Rate Conversion pop-up menu and is automatically configured when necessary.
•
Convert video to a new speed: This can be a matter of playing the existing frames at a different
rate or, in the case of slow-motion effects, it can require generating intermediate frames.