How Matchback Works
The matchback process refers to the video edit information for your sequence and performs a conversion to create a matching 24-fps cut list.
Because of the difference in frame rates between video and film (30áfps or 25 fps for video versus 24 fps for film), the conversion of video edit points might fall within a film frame, requiring the addition or subtraction of a frame in that edit event in the resulting cut list.
For example, with a ratio of 24 film frames to 30 video frames, a 7-frame video edit corresponds to approximately 5.6 film frames. However, film cuts cannot include partial frames, so the edit must be rounded to 5 or 6áframes.
To make these adjustments, the following occurs during matchback:
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If the total video-sequence duration at the end of each cut is a frame
longer than the film, the system subtracts a frame from the last video
edit. If the video is a frame too short, a frame is added to the last video
edit.
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Where an essential frame was added or subtracted to the beginning or
end of each edit, the system adds matchback information to the cut list,
stating that matchback shortened or lengthened the tail of the clip by
one frame. The assistant editor or negative cutter can use this
information to check the edit.
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Each track in the sequence must be corrected independently because
the start and end points for split edits are different for each track. As a
result, the picture and audio for a matchback video edit might be out of
sync by no more than one frame.
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