Inside Macintosh: QuickTime Components
Some video digitizer components may provide functions that allow applications to control the characteristics of the input analog video signal. This section describes these analog video functions.
The VDGetVideoDefaults function returns the suggested default values for the analog video parameters that can be affected by functions described in this section.
A number of functions affect gamma correction. The VDSetInputGammaRecord and VDGetInputGammaRecord functions work with gamma structures (see Designing Cards and Drivers for the Macintosh Family , third edition, for more information about gamma structures). You can use the VDSetInputGammaValue and VDGetInputGammaValue functions to allow your application to set particular gamma values.
The VDSetBlackLevelValue , VDGetBlackLevelValue , VDSetWhiteLevelValue , and VDGetWhiteLevelValue functions allow applications to work with black levels and white levels in the source video. Black level refers to the degree of blackness in an image. This is a common setting on a video digitizer. The highest setting produces an all-black image; on the other hand, the lowest setting yields little, if any, black even with black objects in the scene. Black level is a significant setting because it can be adjusted so that there is little or no noise in an image. White level refers to the degree of whiteness in an image. It is also a common video digitizer setting.
The VDSetContrast , VDGetContrast , VDSetSharpness , and VDGetSharpness functions allow applications to work with contrast and sharpness values in the source video. The VDGetBrightness and VDSetBrightness functions allow applications to work with the image brightness setting.
The VDSetHue , VDGetHue , VDSetSaturation , and VDGetSaturation functions allow applications to work with hue and saturation settings in the source video.
The VDGetVideoDefaults function returns the recommended values for many of the analog video parameters that may be set by applications.
All video digitizer components must support this function.
pascal VideoDigitizerError VDGetVideoDefaults
(VideoDigitizerComponent ci,
unsigned short *blackLevel,
unsigned short *whiteLevel,
unsigned short *brightness,
unsigned short *hue,
unsigned short *saturation,
unsigned short *contrast,
unsigned short *sharpness);
The VDSetBlackLevelValue function sets the current black level value. Black level values range from 0 to 65,535, where 0 represents the maximum black value and 65,535 represents the minimum black value.
pascal VideoDigitizerError VDSetBlackLevelValue
(VideoDigitizerComponent ci,
unsigned short *blackLevel);
The VDGetBlackLevelValue function returns the current black level value. Black level values range from 0 to 65,535, where 0 represents the maximum black value and 65,535 represents the minimum black value.
pascal VideoDigitizerError VDGetBlackLevelValue
(VideoDigitizerComponent ci,
unsigned short *blackLevel);
Applications can set the black level value by calling the VDSetBlackLevelValue function (described in the previous section). Applications can obtain the recommended black level value by calling the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetWhiteLevelValue function sets the white level value. White level values range from 0 to 65,535, where 0 represents the minimum white value and 65,535 represents the maximum white value.
pascal VideoDigitizerError VDSetWhiteLevelValue
(VideoDigitizerComponent ci,
unsigned short *whiteLevel);
Applications can get the current white level value by calling the VDGetWhiteLevelValue function (described in the next section). Applications can obtain the recommended white level value by calling the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetWhiteLevelValue function returns the current white level value. White level values range from 0 to 65,535, where 0 represents the minimum white value and 65,535 represents the maximum white value.
pascal VideoDigitizerError VDGetWhiteLevelValue
(VideoDigitizerComponent ci,
unsigned short *whiteLevel);
Your application can set the white level value by calling the VDSetWhiteLevelValue function (described in the previous section). Your application can obtain the recommended white level value by calling the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetHue function sets the current hue value. Hue is similar to the tint control on a television, and it is specified in degrees with complementary colors set 180 degrees apart (red is 0°, green is +120°, and blue is -120°). Video digitizer components support hue values that range from 0 (-180° shift in hue) to 65,535 (+179° shift in hue), where 32,767 represents a 0° shift in hue.
pascal VideoDigitizerError VDSetHue (VideoDigitizerComponent ci,
unsigned short *hue);
Your application can obtain the current hue value by calling the VDGetHue function (described in the next section). To retrieve the recommended hue value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetHue function returns the current hue value. Hue is similar to the tint control on a television, and it is specified in degrees with complementary colors set 180 degrees apart (red is 0°, green is +120°, and blue is -120°). Video digitizer components support hue values that range from 0 (-180° shift in hue) to 65,535 (+179° shift in hue), where 32,767 represents a 0° shift in hue.
pascal VideoDigitizerError VDGetHue (VideoDigitizerComponent ci,
unsigned short *hue);
Your application can set the hue value by calling the VDSetHue function (described in the previous section). To obtain the recommended hue value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetSaturation function sets the saturation value, which controls color intensity. For example, at high saturation levels, red appears to be red; at low saturation, red appears pink. Valid saturation values range from 0 to 65,535, where 0 is the minimum saturation value and 65,535 specifies maximum saturation.
pascal VideoDigitizerError VDSetSaturation
(VideoDigitizerComponent ci,
unsigned short *saturation);
Applications can get the current saturation value by calling the VDGetSaturation function (described in the next section). Applications can obtain the recommended saturation value by calling the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetSaturation function returns the current saturation value, which controls color intensity. For example, at high saturation levels red appears to be red, while at low saturation red appears pink. Valid saturation values range from 0 to 65,535, where 0 is the minimum saturation value and 65,535 specifies maximum saturation.
pascal VideoDigitizerError VDGetSaturation
(VideoDigitizerComponent ci,
unsigned short *saturation);
Your application can set the saturation value by calling the VDSetSaturation function (described in the previous section). To obtain the recommended saturation value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetBrightness function sets the current brightness value, which controls the overall brightness of the digitized video image. Brightness values range from 0 to 65,535, where 0 is the darkest possible setting and 65,535 is the lightest possible setting.
pascal VideoDigitizerError VDSetBrightness
(VideoDigitizerComponent ci,
unsigned short *brightness);
Your application can get the current brightness value by calling the VDGetBrightness function (described in the next section). To obtain the recommended brightness value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetBrightness function returns the current brightness value, which reflects the overall brightness of the digitized video image. Brightness values range from 0 to 65,535, where 0 is the darkest possible setting and 65,535 is the lightest possible setting.
pascal VideoDigitizerError VDGetBrightness
(VideoDigitizerComponent ci,
unsigned short *brightness);
Your application can set the brightness value by calling the VDSetBrightness function (described in the previous section). To obtain the recommended brightness value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetContrast function sets the current contrast value. The contrast value ranges from 0 to 65,535, where 0 represents no change to the basic image and larger values increase the contrast of the video image (that is, increase the slope of the transform).
pascal VideoDigitizerError VDSetContrast
(VideoDigitizerComponent ci,
unsigned short *contrast);
Your application can obtain the current contrast value by calling the VDGetContrast function (described in the next section). To retrieve the recommended contrast value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetContrast function returns the current contrast value. The contrast value ranges from 0 to 65,535, where 0 represents no change to the basic image and larger values increase the contrast of the video image (that is, increase the slope of the transform).
pascal VideoDigitizerError VDGetContrast
(VideoDigitizerComponent ci,
unsigned short *contrast);
Your application can set the contrast value by calling the VDSetContrast function (described in the previous section). To obtain the recommended contrast value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetSharpness function sets the sharpness value. The sharpness value ranges from 0 to 65,535, where 0 represents no sharpness filtering and 65,535 represents full sharpness filtering. Higher values result in a visual impression of increased picture sharpness.
pascal VideoDigitizerError VDSetSharpness
(VideoDigitizerComponent ci,
unsigned short *sharpness);
Your application can obtain the current sharpness value by calling the VDGetSharpness function (described in the next section). To retrieve the recommended sharpness value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetSharpness function returns the current sharpness value. The sharpness value ranges from 0 to 65,535, where 0 represents no sharpness filtering and 65,535 represents full sharpness filtering. Higher values result in a visual impression of increased picture sharpness.
pascal VideoDigitizerError VDGetSharpness
(VideoDigitizerComponent ci,
unsigned short *sharpness);
Your application can set the sharpness value by calling the VDSetSharpness function (described in the previous section). To obtain the recommended sharpness value, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDSetInputGammaRecord function allows an application to change the active input gamma data structure. Gamma structures give applications complete control over color filtering transforms.
pascal VideoDigitizerError VDSetInputGammaRecord
(VideoDigitizerComponent ci,
VDGamRecPtr inputGammaPtr);
The VDGetInputGammaRecord function allows your application to retrieve a pointer to the active input gamma structure. Gamma structures give applications complete control over color filtering transforms and are therefore more precise than the gamma values that can be set by calling the VDSetInputGammaValue function (described in the next section).
pascal VideoDigitizerError VDGetInputGammaRecord
(VideoDigitizerComponent ci,
VDGamRecPtr *inputGammaPtr);
The VDSetInputGammaValue function sets the gamma values. These gamma values control the brightness of the input video signal. Your application can implement special color effects, such as turning off specific color channels, by calling this function.
pascal VideoDigitizerError VDSetInputGammaValue
(VideoDigitizerComponent ci,
Fixed channel1,
Fixed channel2,
Fixed channel3);
Your application can retrieve the current gamma values by calling the VDGetInputGammaValue function (described in the next section). To obtain the recommended gamma values, your application can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).
The VDGetInputGammaValue function returns the current gamma values. These gamma values control the brightness of the input video signal.
pascal VideoDigitizerError VDGetInputGammaValue
(VideoDigitizerComponent ci,
Fixed *channel1, Fixed *channel2,
Fixed *channel3);
Your application can set the gamma values by calling the VDSetInputGammaValue function (described in the previous section). To obtain the recommended gamma values, you can call the VDGetVideoDefaults function (described on VDGetVideoDefaults ).