Inside Macintosh: QuickTime /

Chapter 2 - Movie Toolbox / Movie Toolbox Reference

Functions That Modify Movie Properties / Working With Alternate Tracks

GetMediaQuality

The GetMediaQuality function returns a media's quality level value. The Movie Toolbox uses this quality value to influence which track it selects to play on a given Macintosh computer.

pascal short GetMediaQuality (Media theMedia);

theMedia

Specifies the media for this operation. Your application obtains this media identifier from such Movie Toolbox functions as NewTrackMedia and GetTrackMedia (described on page 2-138 and page 2-190, respectively).

DESCRIPTION

The GetMediaQuality function returns the media's quality value. The quality value indicates the pixel depths at which the media can be played. This even applies to sound media. The low-order 6 bits of the quality value correspond to specific pixel depths. If a bit is set to 1, the media can be played at the corresponding depth. More than one of these bits may be set to 1. The following bits are defined:

Bit 0	1 bit per pixel
Bit 1	2 bits per pixel
Bit 2	4 bits per pixel
Bit 3	8 bits per pixel
Bit 4	16 bits per pixel
Bit 5	32 bits per pixel

In addition, bits 6 and 7 define the media's quality level. A value of 0 corresponds to the lowest quality level; a value of 3 corresponds to the highest quality level.

mediaQualityDraft

Specifies the lowest quality level. This constant sets bits 6 and 7 to a value of 0.

mediaQualityNormal

Specifies an acceptable quality level. This constant sets bits 6 and 7 to a value of 1.

mediaQualityBetter

Specifies a higher quality level. This constant sets bits 6 and 7 to a
value of 2.

mediaQualityBest

Specifies the highest quality level. This constant sets bits 6 and 7 to a value of 3.

ERROR CODES

invalidMedia

-2008

This media is corrupted or invalid

SEE ALSO

You can set the quality value of a media by calling the SetMediaQuality function, which is described in the previous section.