User guide

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Chapter 11, Using Matrox Vetura Capture and Vetura Playback
3 To apply advanced compression settings, set the options under Compressor.
The default settings for the advanced options provide good results for most
applications. We recommend that you change these settings only when
needed for special purposes.
$ Select your desired Scan pattern:
• Regular Sets the regular zig zag scanning pattern of the AC
coefficient of the DCT block as defined in the ISO/IEC 13818-2 (figure
7-2) specification document.
• Alternate Sets the alternate zig zag scanning pattern of the AC
coefficient of the DCT block as defined in the ISO/IEC 13818-2 (figure
7-3) specification document. Use this setting when capturing video at a
high data rate.
$ Select your desired Rounding type:
• MPEG-2 Rounds the AC coefficient up to the nearest whole number
when calculating the quantization coefficient.
• Matrox custom Truncates the AC coefficients to the lowest whole
number when calculating the quantization coefficient. In some cases,
this setting may yield less artifacts in graphics.
$ From the DC precision list, select the bit-depth precision of the DC intra
block. The higher the DC precision value that’s used to render your video,
the more likely that the DC content will be increased at the expense of the
AC content in the encoded stream. This may result in lowering the overall
quality of the compressed stream at a specified data rate.
$ Select the Force frame-based DCT setting to render macroblocks as
frames rather than as fields. In some cases, graphics will yield less
artifacts if this option is selected.
4 Click OK to save your settings.
Keyboard shortcuts
This section lists the keyboard shortcuts when working with Matrox Vetura
Capture.
Action Keyboard Shortcut
Open preferences window
COMMAND+COMMA
Open Compression Settings window COMMAND+D
Stop capture
ESC