User Manual

Mixing Frame Rates and Field Motion Types
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Behavior of Mixed Rate Material at Different Video Quality Settings
Be aware of the following if you work with mixed rate clips when you use the Draft Quality, Best
Performance, or DNxHD Native video quality options:
• You do not see an accurate pulldown cadence when you field-step through material where
pulldown is inserted. This is a limitation of Timewarp and Motion Adapter effects when you
work in draft qualities. If you switch to Full Quality, or render the Motion Adapter effects,
the pulldown cadence is correct.
• Playback of clips whose frame rate do not match the sequence frame rate might be jumpy
when you use Draft Quality. To achieve smooth playback, you can either use Full Quality or
render the motion adapters for the relevant clips.
Transcoding Mixed Rate Material
You can transcode clips of any edit rate, including clips that you have edited into a sequence, to
any resolution available within your current project.
You might need to transcode mixed-rate material as part of common workflows like
offline/online conversion or creation of a QuickTime reference movie. You also might want to
transcode mixed-rate material in order to homogenize your sequence and transfer it to an editing
application that cannot conform mixed-rate sequences, such as an Avid DS version older than
10.3, or an older Media Composer application. You can also use transcoding for general clip
conversion tasks such as removing 2:3 pulldown from 29.97i sources (to generate 23.976
sources), or generating NTSC material from a PAL source.
Once the transcode process completes, you can edit with the clips directly, or you can batch
capture or import if you have access to original sources at the new rate. The transcoded material
uses the project’s edit rate, so the new clips no longer require motion adapters when you edit
them into sequences in the same project type. When existing material in a sequence is transcoded
across edit rates, your Avid editing application automatically removes motion adapters and
adjusts Timewarp effects.
Your Avid editing application creates new clips whose duration and start and end timecode
matches the original clips as closely as possible and which are as compatible as possible with the
project’s edit rate. However, due to roundoff error, you might see minor variations in clip
duration or in frame offset information that could result in such issues as minor audio/video
differences (for example, slips of 1 or 2 frames).
In some cases, the last frame of a transcoded clip might be offline. Avid recommends using
non-zero handles when you transcode sequences with mixed-rate clips to minimize the chance of
seeing offline frames.
You should check transcoded sequences carefully and adjust any variations from the original
sequences that are not acceptable to you, for example, by trimming.