X4

396 MPEG glossary
These two fie
lds are not the same, since two fields are created during the
recording between which a 1/50 of a second gap is evident. Moving objects
can therefore produce artifacts on vertical edges.
Typical interlacing errors
You can use so-called de-interlacing to avoid this type of artifact. De-
interlacing places a picture in between the two fields (interpolated). If you want
to create stationary pictures from movies, then you should definitely use a de-
interlace filter.
In the system settings ("File" menu -> Program settings) you can set the
preview monitor display to use hardware de-interlacing during video recordings
for the video recorder and for display in the arranger.
2. Incorrect field rate
If you move around the series of fields in a movie data stream, then you will
see strong jitter and flicker effects. Picture objects move in a backward
movement – two steps forwards, one back – since a delayed field is shown
before the previous one. This can happen in the processing chain if you export
video material improperly with the wrong field order and then import it into
different material. We use MXV or MPEG "Top field first" format for all analog
recordings ("odd" in other programs).
DV-AVI on
the other hand is saved with “Bottom Field First”.
You can correct the field series for each video object in its object settings. See:
"Menu -> Effects -> Object properties"
P frames and B frames
P frames save only the difference between the current picture and the
preceding I frame. The "P" comes from the term "prediction" which describes
this process.
B frames save the differences between the current picture and the I or P frame
preceding and following. This includes the information that was the same
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