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Setting custom stream properties

Media files are opened with a set of default values based on the media file type. When you change any of the values for a media file, these changes are saved for that file in the current project only. If you want to change the default settings for a particular type of video file whenever that type of file is used, click the Save settings to video profiles for future auto-detection button () to the right of the Stream list. This adds an entry to a file called vegas video profiles.ini that can be referenced for future use.

The following properties appear in the Stream properties section of the Media tab:

•If the file has more than one stream of the given type, you can choose the particular stream for which you want to view properties from the Stream drop-down list.

•The Attributes, Format, and Frame rate boxes display basic information about the file.

•Choose an option from the Field order drop-down list to control how the video field order is handled on a television monitor. Choose None (Progressive) for video to be viewed on a computer monitor. For DV output, choose Lower Field First. If the output is jittery or shaky, or your hardware’s manual specifies it, choose Upper Field First. For more information, see Interlacing and field order on page 371.

•While you can choose a different value from the Pixel aspect ratio drop-down list, this value should always match the source video’s properties.

•The option selected in the Alpha channel drop-down list determines how transparency is handled in a file. The default alpha channel setting for most video files is None. PNG image files can have an alpha channel that is automatically detected. The options in this drop-down list are described below.

Alpha channel option

Description

Undefined

Because the image format provides no alpha channel information, this

 

setting ignores any alpha channel information in the file.

None

Either there is no alpha channel or there is an alpha channel but it’s

 

completely opaque (solid).

 

 

Straight (unmatted)

Transparency information is maintained in only the alpha channel. Alpha

 

information must be applied to the RGB channels before compositing.

Premultiplied

The standard method of handling alpha information. Transparency

 

information is maintained in the alpha and RGB channels, and the image is

 

ready for compositing. No RGB component exceeds the alpha value.

 

 

Premultiplied (dirty)

Similar to Premultiplied, but RGB components may exceed the alpha

 

value. This option is used mainly for images created by 3D applications

 

involving compositing of 3D images over a non-solid color image

 

background.

 

 

Modifying output properties

You can adjust final output properties when you render your movie. For more information, see Creating custom rendering settings for AVI files on page 312.

USING ADVANCED VIDEO FEATURES

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