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Note: The average bit-rate setting directly controls the size of the encoded file. The
maximum bit-rate setting does not affect the encoded file’s size.
• Maximum Bit Rate slider and field: Choose the maximum bit rate by dragging the slider
or entering a number into the accompanying field. See About Choosing the Bit Rates
for more information. The range available to you depends on the Stream Usage setting.
See Stream Usage for more information.
Note: This slider is only available with the VBR modes and cannot be set lower than
the average bit rate.
• Motion Estimation pop-up menu: This menu is another trade-off between image quality
and processing time, especially if there is a lot of motion in the source file. The three
options in this menu are described below.
Note: Choose a motion estimation mode from the Motion Estimation pop-up menu
that is appropriate for the encoding mode you have selected from the five possibilities
in the Mode pop-up menu. Use the Good motion estimation mode for one pass, the
Better mode for the “One pass VBR” and “Two pass VBR” modes, and the Best mode
for “One pass VBR Best” and “Two pass VBR Best.” Any of the motion estimation modes
work with any of the encoding modes, but these combinations are most suitable.
• Good: The fastest motion estimation setting. This mode does well even with significant
amounts of motion between frames, if the motion has minimal interfield motion
within frames. For example, footage that has been exposed to frame-rate conversion
or other effects processes tends to have little interfield motion. In general, use Good
with the one-pass encoding mode.
• Better: A good general-purpose motion estimation setting. The Better mode provides
good results even with complex interlaced motion. Better works well for almost all
types of interlaced video sources, even shaky footage from hand-held consumer
camcorders. In general, use Better with “One pass VBR” and “Two pass VBR.” If you
are using a progressive video format, the Better mode will do only frame-based
motion estimation, and not field-based motion-vector searching, which is not relevant
for progressive source. In this case the Better mode will run somewhat faster.
• Best: This is the highest-quality motion estimation setting and should be used for
the most demanding and complex motion for interlaced sources. It is slower than
the Better mode. In general, use the Best mode to maximize quality when using “One
pass VBR Best” or “Two pass VBR Best.”
GOP Tab
You use the GOP (group of pictures) tab to select a GOP format, structure, and size. It
contains the following controls. See Understanding GOPs and Frame Types for more
information.
204 Chapter 18 Creating MPEG-2 Output Files