Matrox Axio Installation And User Manual page 111

Variable bit rate (VBR)
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based on the complexity of the video. The target data rate you select is
used as the average data rate for the compression.
Min , Target , and Max sliders Use these sliders to select your desired
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data rate. The higher the target data rate you select, the better the video
quality will be. Only the Target slider will be available if you selected
Constant bit rate (CBR)
three sliders will be available so that you can set the minimum, target, and
maximum data rates for the video compression.
¦ Note
Adobe Encore requires CBR-encoded .m2v files longer than about two
minutes to be transcoded. VBR-encoded .m2v files do not require transcoding
in Adobe Encore.
Under GOP Structure , you can customize the GOP structure for the
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MPEG-2 IBP compression as follows:
GOP length
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Pictures).
Subgroup length
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P-frames in the GOP, after the initial I-frame. For example, a subgroup of
3 appears as "BBP," and a subgroup of 2 appears as "BP." The available
subgroup lengths depend on your selected GOP length.
Under Profile , select one of the following MPEG-2 profiles:
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This profile uses 4:2:0 luminance/chrominance sampling and is
4:2:0
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suitable for broadcast transmission and distribution on DVD. You must
select this profile if you're capturing to an .m2v file for DVD authoring.
4:2:2 This profile uses 4:2:2 luminance/chrominance sampling and is
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suitable for high-quality distribution and archiving.
Under Motion Estimation , drag the slider to adjust the quality of the
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motion estimation used for the video compression. The default setting gives
good results for most video. However, if you have a lot of fast motion in your
video, such as fast-paced sports footage, you can get better results by
dragging the slider to the right (towards Slow/High quality ). This improves
the quality of the motion estimation, but decreases the speed of the video
compression. Alternately, if you have mostly slow-paced video, you may
want to drag the slider to the left (towards Fast/Low quality ) to decrease
the quality of the motion estimation and speed up the video compression.
Click OK to save your settings.
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Video is compressed at varying data rates
. If you selected Variable bit rate (VBR) , all
Determines the number of frames in the GOP (Group of
Determines the subgroup length of B-frames and
Selecting your MPEG-2 IBP settings
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