X4

392 MPEG glossary
http://pro.magix.com
LFE filter: The LFE filter is a low pass filter, which lets through only the lowest
frequencies. If you are dubbing a project in Samplitude/Sequoia, and have
applied the LFE filter, you can switch off this function here, since this filtering
has already been accomplished.
MPEG glossary
Motion estimation
Motion estimation is a further element for reducing data used in MPEG
encoding.
Motion estimation also occurs in the B and P frames. The image difference that
still exist after prediction (view page 397) are examined. Complex algorithms
are used
to search for an original occurrence of the macro block in the
reference frame of each macro block of the P or B frame (these are units of
2x2 blocks specially combined for this purpose), which have been moved
either by movement or by camera pan. They can then be left out in the P and B
frame. Only the information by how far and to where the macro block has been
moved is saved instead. This vector is called the motion detector.
In the General encoder settings (view page 387), you can specify the quality of
the final MPEG video. This factor
also influences the time required for
encoding. The longer it takes, the better the quality.
Bit rate
MPEG is a format used for storage and transferring. With older formats (e.g.
AVI) you could predict that 20 seconds of movie would result in 20 MB of data.
The file size is this a direct measurement of quality.
This is different for MPEG: The amount of data available can be used differently
for different display modes. 20 MB can be 4 seconds of DVD Video or 5
minutes Internet streaming in thumbnail format. The quality of an MPEG video
is measured by the width of the created data stream, the bit rate. This is the
amount of the transmitted data per time unit; it is stated in kBit/s or bit per
second.