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QTCompressionOptions Class Reference

Overview

This class represents a set of compression options for a particular type of media. QTCompressionOptions objects are used to describe compression options for different kinds of media. Compression options are created from presets keyed by a named identifier. Preset identifiers are described in the Constants section that describes the Compression Options Identifiers.

Tasks

Creating and Configuring Compression Options

• + compressionOptionsIdentifiersForMediaType:
• + compressionOptionsWithIdentifier:

Receiving Compression Options

• – mediaType
• – localizedDisplayName
• – localizedCompressionOptionsSummary
• – isEqualToCompressionOptions:

Class Methods

compressionOptionsIdentifiersForMediaType:

Returns all of the possible identifiers for the given media type that can be used with compressionOptionsWithIdentifier: on the user’s system.

+ (NSArray *)compressionOptionsIdentifiersForMediaType:(NSString *)mediaType

Parameters

mediaType

A media type used to create compression options.

Return Value

An array of strings that can be used to create compression options with the compressionOptionsWithIdentifier: method.

Discussion

Media types are defined in QTMedia.h.

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

compressionOptionsWithIdentifier:

Returns a compression options object configured for the given identifier.

+ (id)compressionOptionsWithIdentifier:(NSString *)identifier

Parameters

identifier

The identifier for the compression options object.

Return Value

A compression options object with the appropriate compression options.

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

Instance Methods

isEqualToCompressionOptions:

Returns whether the receiver contains options identical to those in the given compression options object.

- (BOOL)isEqualToCompressionOptions:(QTCompressionOptions *)compressionOptions

Parameters

compressionOptions

The compression options of the compression options object.

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

localizedCompressionOptionsSummary

A localized summary of the receiver’s compression options.

- (NSString *)localizedCompressionOptionsSummary

Return Value

A localized string summarizing the receiver's compression options.

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

localizedDisplayName

A short localized name describing the receiver’s compression options.

- (NSString *)localizedDisplayName

Return Value

A localized string appropriate for display in the user interface (in a list of compression options, for example).

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

mediaType

The media type on which the receiver’s compression options should be used.

- (NSString *)mediaType

Return Value

A QuickTime media type, such as QTMediaTypeVideo or QTMediaTypeSound.

Availability

• Mac OS X v10.5 and later.

Declared In

QTCompressionOptions.h

Constants

Compression Options Identifiers

These identifiers can be passed to the compressionOptionsWithIdentifier: class method to get an instance configured with the compression options for that identifier. Each identifier represents a set of options that determine how media will be compressed.

QTCompressionOptionsLosslessAppleIntermediateVideo;
QTCompressionOptionsLosslessAnimationVideo;
QTCompressionOptions120SizeH264Video;
QTCompressionOptions240SizeH264Video;
QTCompressionOptionsSD480SizeH264Video;
QTCompressionOptions120SizeMPEG4Video;
QTCompressionOptions240SizeMPEG4Video;
QTCompressionOptionsSD480SizeMPEG4Video;
QTCompressionOptionsLosslessALACAudio;
QTCompressionOptionsHighQualityAACAudio;
QTCompressionOptionsVoiceQualityAACAudio;

Constants

QTCompressionOptionsLosslessAppleIntermediateVideo

Compresses video using the Apple Intermediate codec at lossless quality.

This is appropriate for an intermediate format for media that requires further processing.

Not available in 64-bit.

QTCompressionOptionsLosslessAnimationVideo

Compresses video using the Animation codec at highest quality and color depth.

This is appropriate for an intermediate format for media that requires further processing.

QTCompressionOptions120SizeH264Video

Compresses video using the H.264 codec using medium bit-rate settings with dimensions no larger than 160x120.

This is appropriate for delivery to low-bandwidth and low-capacity destinations.

QTCompressionOptions240SizeH264Video

Compresses video using the H.264 codec using medium bit-rate settings with dimensions no larger than 320x240.

This is appropriate for delivery to medium-bandwidth and medium-capacity destinations.

QTCompressionOptionsSD480SizeH264Video

Compresses video using the H.264 codec using medium bit-rate settings with dimensions no larger than 720x480.

This is appropriate for delivery to medium and high-bandwidth and medium- and high-capacity destinations.

QTCompressionOptions120SizeMPEG4Video

Compresses video using the MPEG-4 codec using medium bit-rate settings with dimensions no larger than 160x120.

This is appropriate for delivery to low-bandwidth and low-capacity destinations.

Not available in 64-bit.

QTCompressionOptions240SizeMPEG4Video

Compresses video using the MPEG-4 codec using medium bit-rate settings with dimensions no larger than 320x240.

This is appropriate for delivery to medium-bandwidth and medium-capacity destinations.

Not available in 64-bit.

QTCompressionOptionsSD480SizeMPEG4Video

Compresses video using the MPEG-4 codec using medium bit-rate settings with dimensions no larger than 720x480.

This is appropriate for delivery to medium and high-bandwidth and medium- and high-capacity destinations.

Not available in 64-bit.

QTCompressionOptionsLosslessALACAudio

Compresses audio using the Apple Lossless codec.

This is appropriate for an intermediate format for media that requires further processing.

QTCompressionOptionsHighQualityAACAudio

Compresses audio using the AAC codec at 64 kbps per channel.

This is appropriate for delivery of high-quality music and other audio.

QTCompressionOptionsVoiceQualityAACAudio

Compresses audio using the AAC codec at 32 kbps per channel.

This is appropriate for delivery of voice recordings.

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