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Frame rate

Frame rate is important in determining the quality and size of the final media file. The appropriate frame rate is determined by the final destination of the movie. See your video capture card’s manual for more information. The final rendered multimedia file can have a different frame rate from the project itself.

Field order

Video that is displayed on a television monitor is interlaced. This means that every frame of video is actually composed of two fields, each of which is made up of half of the lines that make the final frame. These two fields are woven together in alternate lines, but which of the two fields is displayed first can be important. Choose None (progressive scan) to ignore interlacing for video to be displayed on a computer. For video on a television, most hardware supports Lower Field First. If the output is jittery or shaky on a television, or your hardware’s manual specifies it, choose Upper Field First.

Pixel aspect ratio

A pixel is a single picture element or dot on a television or computer screen. Computers display pixels as squares: 1.0. Televisions display individual pixels as rectangles: 0.909, 0.899, or anything other than square. Using the wrong pixel aspect ratio can result in distortions or stretching of the video. Select the aspect ratio for the final movie’s destination. Consult your hardware manual if you are in doubt about the appropriate ratio. The pixel aspect ratio and frame size determine the frame’s aspect ratio.

Video format

Codec, which stands for COmpressor/DECompressor, is the mathematical algorithm used to compress a media file. The codec directly determines the size and quality of the movie, as well as its compatibility with various playback devices. The final destination for the movie dictates the choice of codec. Many of the codecs used for specific rendering formats are updated periodically by their creators. For information about specific codecs, contact the codec’s manufacturer.

Each codec is a small program that may have additional custom controls used to fine tune the output. Click Configure to adjust these parameters manually.

Quality slider

If the codec you choose in the Video format drop-down list supports it, use this slider to adjust the quality of the compression applied by the codec.

Interleave every

This control allows you to specify how often the audio and video streams are interleaved. Interleaving relates directly to how the data is saved in the file. For example, during the rendering process, the audio data is written in between the video data based on the frame setting that you specified. Interleaving allows for optimal playback of the AVI file.

Keyframe every

If the codec you choose in the Video format drop-down list supports compression keyframes, select this option to set compression keyframes to adjust the quality of the compression. More keyframes typically produce higher quality video, but a larger file size (and thus a higher data rate).

Data rate

If the codec you choose in the Video format drop-down list supports a data rate ceiling, select this option and enter a maximum data rate for the final file.

Render alpha channel

If the codec you choose in the Video format drop-down list supports alpha channel transparency, select this option to save this information with the file.

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SAVING, RENDERING, AND PRINTING PROJECTS