Advanced Search

Log In | Not a Member?

Contact ADC

< Previous PageNext Page > Hide TOC

New IIDC Digitizer Functions

Many IEEE-1394-based digital cameras and webcams now support Instrumentation and Industrial Control (IIDC) features that can be accessed by software.

QuickTime 6.4 includes six new functions to communicate with video digitizers that have a subtype of vdSubtypeIIDC ('iidc'):

• VDIIDCGetFeatures places atoms in a QuickTime atom container that specify the current capabilities of a camera and the state of its IIDC features.

• VDIIDCGetFeaturesForSpecifier places atoms in a QuickTime atom container that specify the current state of a single camera IIDC feature or group of features.

• VDIIDCSetFeatures changes the state of a camera’s IIDC features.

• VDIIDCGetDefaultFeatures places atoms in a QuickTime atom container that specify the default capabilities and default state of a camera’s IIDC features.

• VDIIDCGetCSRData reads a camera’s CSR registers directly.

• VDIIDCSetCSRData writes to a camera’s CSR registers directly.

Several data structures that support these functions are new in QuickTime 6.4:

• VDIIDCFeatureAtomTypeAndID provides content for the vdIIDCAtomTypeFeatureAtomTypeAndID atom type, discussed in “Type And ID Atoms”. It contains general information about an IIDC feature and specifies the atom that holds that feature’s current settings.

• The VDIIDCFeatureSettings structure provides content for the vdIIDCAtomTypeFeatureSettings atom type, discussed in “IIDC Settings Atoms”. It contains the VDIIDCFeatureCapabilities and VDIIDCFeatureState structures, which are used to describe various IIDC camera features.

• VDIIDCFeatureCapabilities provides IIDC feature capabilities information for the VDIIDCFeatureSettings structure.

• VDIIDCFeatureState provides IIDC feature state information for the VDIIDCFeatureSettings structure.

• VDIIDCTriggerSettings provides content for the vdIIDCAtomTypeTriggerSettings atom type. It contains the VDIIDCTriggerCapabilities and VDIIDCTriggerState structures, which contain information about a camera’s trigger capabilities and state.

• VDIIDCTriggerCapabilities provides trigger capabilities information for the VDIIDCTriggerSettings structure.

• VDIIDCTriggerState provides trigger state information for the VDIIDCTriggerSettings structure.

• VDIIDCFocusPointSettings provides content for the vdIIDCAtomTypeFocusPointSettings atom type. It contains focus point data.

• VDIIDCLightingHintSettings provides content for the vdIIDCAtomTypeLightingHintSettings atom type. It contains lighting hint data.

IIDC Atoms

The information about IIDC features that a camera might support is contained in a hierarchy of new big-endian QuickTime atom types:

• At the top level, the QuickTime atom container passed into VDIIDCSetFeatures or returned by VDIIDCGetFeatures, VDIIDCGetDefaultFeatures, or VDIIDCGetFeaturesForSpecifier contains a set of atoms of type vdIIDCAtomTypeFeature, one for each feature of the camera being interrogated.

• Each atom of type vdIIDCAtomTypeFeature contains one atom of type vdIIDCAtomTypeFeatureAtomTypeAndID. This atom contains a data structure of type VDIIDCFeatureAtomTypeAndID, which conveys general information about the feature and specifies the type and ID of the atom that conveys that feature’s current settings.

• Each atom of type vdIIDCAtomTypeFeature also contains a Settings atom. This may be an atom of type vdIIDCAtomTypeFeatureSettings, vdIIDCAtomTypeTriggerSettings, vdIIDCAtomTypeFocusPointSettings, or vdIIDCAtomTypeLightingHintSettings, each of which stores a particular class of camera settings.

Details of the new atom types are given in the next sections. To determine the number of features in a particular atom container, you can use this code:

SInt16 featureCount = QTCountChildrenOfType(container,

    kParentAtomIsContainer, vdIIDCAtomTypeFeature);

IIDC Feature Atoms

The top-level atoms in the IIDC atom hierarchy are Feature atoms, of type vdIIDCAtomTypeFeature, the value of which is 'feat'. Zero or more of these atoms are present in the atom container that is passed to the VDIIDCSetFeatures function and returned by the VDIIDCGetFeatures, VDIIDCGetDefaultFeatures, and VDIIDCGetFeaturesForSpecifier functions.

Each Feature atom is a container for atoms that convey information about one IIDC feature of the camera being interrogated or set.

Each Feature atom has two child atoms. The first is a Type and ID atom, of type vdIIDCAtomTypeFeatureAtomTypeAndID, described in the next section. The Type and ID atom identifies a second child atom of the vdIIDCAtomTypeFeature atom, which contains the feature’s current or default setting information. These atoms are described in “IIDC Settings Atoms”below.

Type And ID Atoms

Each feature atom contains one Type and ID atom, of type vdIIDCAtomTypeFeatureAtomTypeAndID ('t&id'). Its ID is 1. The contents of this atom is a VDIIDCFeatureAtomTypeAndID data structure. This structure contains the type of the feature, a type that identifies the general category of the feature (image control, color control, mechanics, or triggering), the feature’s human-readable name, and the type and ID of the Settings atom that contains the feature’s settings.

IIDC Settings Atoms

Most IIDC features can be expressed by VDIIDCFeatureSettings data structures. Three, however, require VDIIDCTriggerSettings, VDIIDCFocusPointSettings, or VDIIDCLightingHintSettings data structures, as shown in the following listing:

vdIIDCFeatureHue                = 'hue ', // Uses VDIIDCFeatureSettings

vdIIDCFeatureSaturation         = 'satu', // Uses VDIIDCFeatureSettings

vdIIDCFeatureSharpness          = 'shrp', // Uses VDIIDCFeatureSettings

vdIIDCFeatureBrightness         = 'brit', // Uses VDIIDCFeatureSettings

vdIIDCFeatureGain               = 'gain', // Uses VDIIDCFeatureSettings

vdIIDCFeatureIris               = 'iris', // Uses VDIIDCFeatureSettings

vdIIDCFeatureShutter            = 'shtr', // Uses VDIIDCFeatureSettings

vdIIDCFeatureExposure           = 'xpsr', // Uses VDIIDCFeatureSettings

vdIIDCFeatureWhiteBalanceU      = 'whbu', // Uses VDIIDCFeatureSettings

vdIIDCFeatureWhiteBalanceV      = 'whbv', // Uses VDIIDCFeatureSettings

vdIIDCFeatureGamma              = 'gmma', // Uses VDIIDCFeatureSettings

vdIIDCFeatureTemperature        = 'temp', // Uses VDIIDCFeatureSettings

vdIIDCFeatureZoom               = 'zoom', // Uses VDIIDCFeatureSettings

vdIIDCFeatureFocus              = 'fcus', // Uses VDIIDCFeatureSettings

vdIIDCFeaturePan                = 'pan ', // Uses VDIIDCFeatureSettings

vdIIDCFeatureTilt               = 'tilt', // Uses VDIIDCFeatureSettings

vdIIDCFeatureOpticalFilter      = 'opft', // Uses VDIIDCFeatureSettings

vdIIDCFeatureTrigger            = 'trgr', // Uses VDIIDCTriggerSettings

vdIIDCFeatureCaptureSize        = 'cpsz', // Undefined settings

vdIIDCFeatureCaptureQuality     = 'cpql', // Undefined settings

vdIIDCFeatureFocusPoint         = 'fpnt', // Uses VDIIDCFocusPointSettings

vdIIDCFeatureEdgeEnhancement    = 'eden'  // Uses VDIIDCFeatureSettings

vdIIDCFeatureLightingHint       = 'lhnt'  // Uses VDIIDCLightingHintSetting

The types and IDs of the Settings atoms that contain these data structures are the following:

// Atom type and ID that contains the VDIIDCFeatureSettings struct

vdIIDCAtomTypeFeatureSettings       = 'fstg',

vdIIDCAtomIDFeatureSettings         = 1

// Atom type and ID that contains the VDIIDCTriggerSettings struct

vdIIDCAtomTypeTriggerSettings       = 'tstg',

vdIIDCAtomIDTriggerSettings         = 1

// Atom type and ID that contains the VDIIDCFocusPointSettings struct

vdIIDCAtomTypeFocusPointSettings     = 'fpst',

vdIIDCAtomIDFocusPointSettings       = 1

// Atom type and ID that contains the VDIIDCLightingHintSetting struct

vdIIDCAtomTypeLightingHintSettings   = 'lhst',

vdIIDCAtomIDLightingHintSettings     = 1

A Typical IIDC Atom Hierarchy

To take a specific example, suppose you called VDIIDCGetFeatures, passing an instance of a video digitizer of subtype vdSubTypeIIDC. You might receive back a QuickTime atom container in which you find the following atoms:

vdIIDCAtomTypeFeature    = 'feat'

    vdIIDCAtomTypeFeatureAtomTypeAndID    = 't&id'

    vdIIDCAtomIDFeatureAtomTypeAndID      = 1

        feature     = vdIIDCFeatureShutter            // shutter feature

        atomType    = vdIIDCAtomTypeFeatureSettings

        atomID      = 1

    vdIIDCAtomTypeFeatureSettings    = 'fstg'

    vdIIDCAtomIDFeatureSettings      = 1

vdIIDCAtomTypeFeature    = 'feat'

    vdIIDCAtomTypeFeatureAtomTypeAndID    = 't&id'

    vdIIDCAtomIDFeatureAtomTypeAndID      = 1

        feature     = vdIIDCFeatureFocus              // focus feature

        atomType    = vdIIDCAtomTypeFeatureSettings

        atomID      = 1

    vdIIDCAtomTypeFeatureSettings    = 'fstg'

    vdIIDCAtomIDFeatureSettings      = 1

vdIIDCAtomTypeFeature    = 'feat'

    vdIIDCAtomTypeFeatureAtomTypeAndID    = 't&id'

    vdIIDCAtomIDFeatureAtomTypeAndID      = 1

        feature     = vdIIDCFeatureTrigger            // trigger feature

        atomType    = vdIIDCAtomTypeTriggerSettings

        atomID      = 1

    vdIIDCAtomTypeTriggerSettings    = 'tstg'

    vdIIDCAtomIDFTriggerSettings     = 1

In this example, the VDIIDCGetFeatures function tells you that the camera served by the video digitizer component passed to it reports on three IIDC functions: shutter, focus, and trigger. Data on the shutter and focus features can be retrieved from VDIIDCFeatureSettings structures in vdIIDCAtomTypeFeatureSettings atoms. Data on the trigger feature can be retrieved from a VDIIDCTriggerSettings structure in a vdIIDCAtomTypeTriggerSettings atom.

< Previous PageNext Page > Hide TOC

Did this document help you? Yes: Tell us what works for you. It’s good, but: Report typos, inaccuracies, and so forth. It wasn’t helpful: Tell us what would have helped.

	Get information on Apple products. Visit the Apple Store online or at retail locations. 1-800-MY-APPLE Copyright © 2007 Apple Inc. All rights reserved. | Terms of use | Privacy Notice