QuickTime 3 Reference

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Exporting Data from Sources Other Than Movies

This section describes new functions provided by movie data export components that allow applications to export data from sources other than movies.

MovieExportAddDataSource

The function allows you to define a data source for use with an export operation performed by MovieExportFromProceduresToDataRef .

pascal ComponentResult MovieExportAddDataSource (MovieExportComponent ci, OSType trackType,
                     TimeScale scale, long *trackID, MovieExportGetPropertyUPP
                     getPropertyProc, MovieExportGetDataUPP getDataProc, void *refCon)
ci
Identifies the Movie Toolbox's connection to your component.
trackType
Specifies the type of media provided by this data source. This will normally correspond to a QuickTime media type such as VideoMediaType or SoundMediaType .
scale
Specifies the TimeScale for time values passed to getDataProc parameter. If the source data is being taken from a QuickTime track, this value will typically be the media's TimeScale .
trackID
Contains an identifier for the data source. This identifier is returned from the call.
getPropertyProc
Specifies a callback function that provides information about processing source samples.
getDataProc
Specifies a callback function the export component uses to request sample data.
refCon
Passed to the procedures specified in the getPropertyProc and getDataProc parameters.

DISCUSSION

Before starting an export operation, all the data sources must be defined by calling MovieExportAddDataSource once for each data source.

RESULT CODES

To be provided
 

MovieExportFromProceduresToDataRef

The MovieExportFromProceduresToDataRef function exports data provided by MovieExportAddDataSource to a location specified by dataRef and dataRefType .

pascal ComponentResult MovieExportFromProceduresToDataRef (MovieExportComponent ci, Handle
                     dataRef, OSType dataRefType)
ci
Specifies the movie component for the export operation.
dataRef
Specifies the data reference for the export operation.
dataRefType
Specifies the type identifier for the data reference specified by dataRef .

DISCUSSION

Movie data export components that support export operations from procedures must set the canMovieExportFromProcedures flag in their component flags.

Typically dataRef contains a Macintosh file alias and dataRefType is set to rAliasType .

RESULT CODES

To be provided
 

MovieExportGetPropertyProcPtr

You use MovieExportGetPropertyProcPtr to return parameters that determine the appropriate format for the output data.

typedef pascal OSErr (*MovieExportGetPropertyProcPtr)(void *refcon, long trackID, OSType
                     propertyType, void *propertyValue);
refCon
Contains the value passed to MovieExportAddDataSource in the refCon parameter.
trackID
Specifies the value returned from MovieExportAddDataSource .
propertyValue
Contains a pointer to the location of the requested property information.
propertyType
Specifies the property being requested. All currently defined property types are listed in Table 11-1 .
 

Table 1 Currently supported property types

Property

Type

Track Type
scSoundSampleRateType
 		UnsignedFixed
 		sound
scSoundSampleSizeType
 		short
 		sound
scSoundChannelCountType
 		short
 		sound
scSoundCompressionType
 		OSType
 		sound
meWidth
 		Fixed
 		video
meHeight
 		Fixed
 		video
scSpatialSettingsType
 		SCSpatialSettings
 		video
scTemporalSettingsType
 		SCTemporalSettings
 		video
scDataRateSettingsType
 		SCDataRateSettings
 		video

DISCUSSION

The function defined by MovieExportGetPropertyProcPtr type is passed to MovieExportAddDataSource to define a new data source for an export operation. For example, a video export operation may call the function to determine the dimensions of the destination video track.

If the function doesn't have a setting for a requested property, it should return an error. The export component provides a default value for the property based on the source data format. For example, if no values for video track width and height properties were provided by the callback function, the dimensions of the source data would be used.

RESULT CODES

To be provided
 

MovieExportGetDataProcPtr

You use the function defined by MovieExportGetDataProcPtr to define a data source for an export operation.

typedef pascal OSErr (*MovieExportGetDataProcPtr)(void *refCon, MovieExportGetDataParams
                     *params);

The sample request is made through a parameter block. The data structure used is shown below.

struct MovieExportGetDataParams {
    long                    recordSize;
    long                    trackID;
    TimeScale               sourceTimeScale;
    TimeValue               requestedTime;
    TimeValue               actualTime;
    Ptr                     dataPtr;
    long                    dataSize;
    SampleDescriptionHandle desc;
    OSType                  descType;
    long                    descSeed;
    long                    requestedSampleCount;
    long                    actualSampleCount;
    TimeValue               durationPerSample;
    long                    sampleFlags;
};
typedef struct MovieExportGetDataParams MovieExportGetDataParams;
refCon
Contains the value passed to MovieExportAddDataSource in the refCon parameter.
recordSize
Contains the total size in bytes of the MovieExportGetDataParams structure. This is provided to allow for additional parameters to be added safely in the future.
trackID
Specifies the data source. The trackID is returned when the data source is added by calling MovieExportAddDataSource .
sourceTimeScale
Specifies the TimeScale for this data source. This value is the same TimeScale that is passed to MovieExportAddDataSource .
requestedTime
Specifies the time of the media requested by the exporter. The TimeScale is the same one specified when adding a data source with MovieExportAddDataSource .
actualTime
Specifies the time actually referred to by the returned media data. This value is provided by MovieExportGetDataProcPtr, and is usually the same as requestedTime .
dataPtr
Contains a 32-bit pointer to the media data.
dataSize
Specifies the size in bytes of the data pointed to by dataPtr.
desc
Contains a SampleDescriptionHandle describing the format of the data pointed to by dataPtr . For video data, this is an ImageDescriptionHandle . For sound data, this is a SoundDescriptionHandle .
descType
Specifies the type of SampleDescriptionHandle . For example, if SampleDescriptionHandle is ImageDescriptionHandle, descType is set to VideoMediaType .
descSeed
Specifies which SampleDescriptionHandle represented by the current value of desc . Some data sources contain different kinds of data at different times. For example, a video data source may contain both JPEG and uncompressed raw data. Whenever the data source switches from one type of data to another, change descSeed to notify the exporter. In the case of an export operation that is providing its source data from a QuickTime movie track, descSeed is equal to the sample description index of the sample being returned.
requestedSampleCount
Specifies the number of samples the exporter can work with. The function can return more or fewer samples than requested. For video, this value is always 1.
actualSampleCount
Specifies the number of samples actually returned. The function must fill in this field.
durationPerSample
Specifies the duration of every sample returned. For sound data, durationPerSample always contains 1. For video data, durationPerSample contains the duration of the returned sample, expressed in the TimeScale defined when the data source was created.
sampleFlags
Contains the flags for the returned samples. The only defined flag is mediaSampleNotSync , which is usually only returned for frame-differenced video sample data. The function must fill in this field.

DISCUSSION

The function defined by the MovieExportGetDataProcPtr type is passed to MovieExportAddDataSource to define a new data source for an export operation. The function is used by the exporting application to request source media data to be used in the export operation. For example, in a video export operation, frames of video data (either compressed or uncompressed) are provided. In a sound export operation, buffers of audio (either compressed or uncompressed) are provided.

The data pointed to by dataPtr must remain valid until the next call to this MovieExportGetDataProcPtr function. The MovieExportGetDataProcPtr function is responsible for allocating and disposing of the memory associated with this data pointer.

RESULT CODES

To be provided
 

MovieExportToDataRef

MovieExportToDataRef allows an application to request that data is exported to a data reference, instead of to a file.

pascal ComponentResult MovieExportToDataRef(MovieExportComponent ci, Handle dataRef, OSType
                     dataRefType, Movie theMovie, Track onlyThisTrack, TimeValue startTime,
                     TimeValue duration)
ci
Identifies the Movie Toolbox's connection to your component.
dataRef
Contains a handle to a data reference indicating where the data should be stored.
dataRefType
Specifies the type of the data reference. For exporting to a file, the dataRef will be a Macintosh file alias and the dataRefType will be rAliasType .
theMovie
Identifies the movie for this operation. This movie identifier is supplied by the Movie Toolbox. Your component may use this identifier to obtain sample data from the movie or to obtain information about the movie.
onlyThisTrack
Identifies a track that is to be converted. This track identifier is supplied by the Movie Toolbox. If this parameter contains a track identifier, your component must convert only the specified track.
startTime
Specifies the starting point of the track or movie segment to be converted. This time value is expressed in the movie's time coordinate system.
duration
Specifies the duration of the track or movie segment to be converted. This duration value is expressed in the movie's time coordinate system.

MovieExportGetSettingsAsAtomContainer

The MovieExportGetSettingsAsAtomContainer routine retrieves the current settings from the movie export component.

pascal ComponentResult MovieExportGetSettingsAsAtomContainer (                          MovieImportComponent
ci,
                    QTAtomContainer *settings);
ci
The movie export component instance.
settings
The address where the newly-created atom container should be stored by the call.

DISCUSSION

The caller is responsible for disposing of the returned QTAtomContainer.

MovieExportSetSettingsFromAtomContainer

The MovieExportSetSettingsFromAtomContainer routine sets the movie export component's current configuration from the passed settings data.

pascal ComponentResult MovieExportSetSettingsFromAtomContainer (
                    MovieExportComponent ci,
                    QTAtomContainer settings);
ci
The movie import component instance.
settings
This contains a QTAtomContainer reference to the settings.

DISCUSSION

The settings QTAtomContainer may contain atoms other than those expected by the particular component type or may be missing certain atoms. The function will only use settings it understands.

© 1997 Apple Computer, Inc.

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