Mac Dev Center Mac OS X Reference Library Drivers, Kernel, & Hardware: User-Space Device Access Disc Recording Framework Reference

Overview

CD-Text object used in the Disc Recording APIs.

Discussion

CD-Text allows the authors of an audio CD to encode textual information about the CD and its tracks onto the disc. Information such as album name, track names, artist, songwriter, performer, and more can be encoded this way. When a disc containing CD-Text is inserted into a CD-Text aware player, this information is displayed as the CD plays.

CD-Text is only for audio CDs; it does not apply to and does not work on data CDs or DVDs.

Here's a conceptual description of how CD-Text works. The CD-Text information for a disc can contain up to eight blocks of textual information. Each block has an associated language code and character set, and contains a complete set of information about the disc.

	+----------------------------+
	| +------------------------+ |
	| | CD-Text block 1        | |
	| |  - language code       | |
	| |  - character set       | |
	| +------------------------+ |
	|            .               |
	|            .               |
	|            .               |
	| +------------------------+ |
	| | CD-Text block 8        | |
	| |  - language code       | |
	| |  - character set       | |
	| +------------------------+ |
	+----------------------------+
	

In typical use each block of CD-Text contains a different language--English, French, Japanese, Chinese, and so on--although only single-byte encodings are currently supported. It's possible and permissible to have multiple blocks that each contain the same language.

Each block can hold a complete set of information about the disc and its tracks. This information is stored as an array of key-value dictionaries. There is one dictionary per track, with an additional dictionary for the disc/album itself (represented by array index 0). On a disc with n tracks, there will be n+1 dictionaries.

	+----------------------------+
	| CD-Text block              |
	|  - language code           |
	|  - character set           |
	| +------------------------+ |
	| | Index 0 - disc info    | |
	| +------------------------+ |
	| +------------------------+ |
	| | Index 1 - track 1 info | |
	| +------------------------+ |
	| +------------------------+ |
	| | Index 2 - track 2 info | |
	| +------------------------+ |
	|            .               |
	|            .               |
	|            .               |
	| +------------------------+ |
	| | Index n - track n info | |
	| +------------------------+ |
	+----------------------------+
	

Dictionaries for individual tracks contain the textual information to be displayed. This information is strictly limited to the character set specified by the enclosing block, and is likewise assumed to be in the language specified.

	+----------------------------+
	| Track info dictionary      |
	|                            |
	|  Title = "title"           |
	|  Artist = "artist"         |
	|  Performer = "performer"   |
	|            .               |
	|            .               |
	|            .               |
	+----------------------------+
	

For compatibility with the widest range of CD players, text values in CD-Text dictionaries should be 160 bytes or smaller. Since the currently supported character encodings are all single-byte encodings, this means a maximum of 160 characters per entry.

Functions

DRCDTextBlockCreate

Creates a CD-Text block with the provided contents.

DRCDTextBlockCreateArrayFromPackList

Parses raw CD-Text data into DRCDTextBlock objects.

DRCDTextBlockFlatten

Flattens the CD-Text block to determine whether any information will be truncated.

DRCDTextBlockGetProperties

Returns properties of the CD-Text block.

DRCDTextBlockGetTrackDictionaries

Returns the array of track dictionaries for a given block.

DRCDTextBlockGetTypeID

Returns the type identifier for all DRCDTextBlock instances.

DRCDTextBlockGetValue

Returns one specific value for a track.

DRCDTextBlockSetProperties

Sets the properties of the CD-Text block.

DRCDTextBlockSetTrackDictionaries

Sets an array of track dictionaries for a given CD-Text block.

DRCDTextBlockSetValue

Sets one specific value for a track.

Creates a CD-Text block with the provided contents.

extern DRCDTextBlockRef DRCDTextBlockCreate( 
    CFStringRef language, 
    CFStringEncoding encoding) ;  

Parameters

Return Value

A new CD-Text block.

Availability

Introduced in Mac OS X v10.4.

Parses raw CD-Text data into DRCDTextBlock objects.

extern CFArrayRef DRCDTextBlockCreateArrayFromPackList( 
    CFDataRef packs) ;  

Parameters

Return Value

A CFArray object containing DRCDTextBlock objects describing the information in the raw PACKs, or NULL if the data could not be parsed. The caller is responsible for releasing this array.

Discussion

You can use this function to parse any data blob containing CD-Text PACKs, such as the result of DRDeviceReadCDText, or the data returned by the IOKit ioctl DKIOCCDREADTOC with format=5.

The CFData should be sized to fit the exact number of PACKs. Each PACK occupies 18 bytes, and the 4-byte header from a READ TOC command may optionally be included.

Availability

Introduced in Mac OS X v10.4.

Flattens the CD-Text block to determine whether any information will be truncated.

extern UInt32 DRCDTextBlockFlatten( 
    DRCDTextBlockRef block) ;  

Parameters

Return Value

The number of bytes that will be truncated from the CD-Text block. If this function returns 0, no truncation will occur.

Discussion

When burning your CD-Text information to a CD, Disc Recording will automatically truncate some of the information you've specified if it does not fit.

The size limit for CD-Text is approximately 3K per block. This limit is approximate because of overhead and because duplicate strings can sometimes be combined. The only way to determine the final byte size of a CD-Text block is to ask Disc Recording to flatten it. You can then determine whether truncation will be needed.

Disc Recording's truncation preserves the most important information and provides the simplest user experience. If you do not wish to use Disc Recording's automatic truncation, it is your responsibility to ensure that you provide CD-Text block content that fits.

Following is a simple algorithm to avoid having your CD-Text data truncated:

1. Call DRCDTextBlockFlatten.
2. If the result is 0, no truncation is necessary. Stop.
3. Otherwise, truncation will occur -- edit or remove some data.
4. Repeat.

Availability

Introduced in Mac OS X v10.4.

Returns properties of the CD-Text block.

extern CFDictionaryRef DRCDTextBlockGetProperties( 
    DRCDTextBlockRef block) ;  

Parameters

Return Value

A CFDictionary object containing the properties of the specified CD-Text block. The caller does not implicitly retain the reference, and is not responsible for releasing it.

Availability

Introduced in Mac OS X v10.4.

Returns the array of track dictionaries for a given block.

extern CFArrayRef DRCDTextBlockGetTrackDictionaries( 
    DRCDTextBlockRef block) ;  

Parameters

Return Value

A CFArray object containing immutable dictionaries of CFString objects, each of which contains CD-Text information.

Discussion

Each item in the array is a dictionary, which in turn holds key-value encoded information about a track or disc. Array index 0 holds information about the disc, index 1 holds information about track 1, index 2 holds information about track 2, and so on. The caller does not implicitly retain the reference, and is not responsible for releasing it.

Availability

Introduced in Mac OS X v10.4.

Returns the type identifier for all DRCDTextBlock instances.

extern CFTypeID DRCDTextBlockGetTypeID(
    void) ;  

Return Value

A Core Foundation type identifier.

Availability

Introduced in Mac OS X v10.4.

Returns one specific value for a track.

extern CFTypeRef DRCDTextBlockGetValue( 
    DRCDTextBlockRef block, 
    CFIndex trackIndex, 
    CFStringRef key) ;  

Parameters

Return Value

A Core Foundation type reference reference to a copy of the specified CD-Text block value.

Discussion

This function looks up the value for the specified track index and key, and returns the value. The returned value will be a CFString, CFData, or CFNumber object, or will be NULL if no key was found. The caller does not implicitly retain the reference, and is not responsible for releasing it.

Availability

Introduced in Mac OS X v10.4.

Sets the properties of the CD-Text block.

extern void DRCDTextBlockSetProperties( 
    DRCDTextBlockRef block, 
    CFDictionaryRef properties) ;  

Parameters

Availability

Introduced in Mac OS X v10.4.

Sets an array of track dictionaries for a given CD-Text block.

extern void DRCDTextBlockSetTrackDictionaries( 
    DRCDTextBlockRef block, 
    CFArrayRef array) ;  

Parameters

Discussion

Each item in the array is a dictionary, which in turn holds key-value encoded information about the track or disc. Array index 0 holds information about the disc, index 1 holds information about track 1, index 2 holds information about track 2, and so on.

The incoming strings are automatically modified to conform to the character set specified in the language block. Calling the DRCDTextCopyTrackArray() function immediately after DRCDTextSetTrackArray() returns the modified values, which may not be the same as the ones you passed in but correspond to what will actually be used.

Availability

Introduced in Mac OS X v10.4.

Sets one specific value for a track.

extern void DRCDTextBlockSetValue( 
    DRCDTextBlockRef block, 
    CFIndex trackIndex, 
    CFStringRef key, 
    CFTypeRef value) ;  

Parameters

Discussion

The CD-Text value may be a CFString, CFData, or CFNumber object, but should correspond to the type defined in the description of the key.

If the incoming value is a string, it is automatically modified to conform to the character set of the language block. Calling the DRCDTextCopyValue() function immediately after DRCDTextSetValue() returns the modified value, which may not be the same as the one you passed in but corresponds to what will actually be used.

Setting a value to NULL removes the key from the specified track dictionary.

Availability

Introduced in Mac OS X v10.4.

Constants

kDRCDTextArrangerKey

kDRCDTextCFStringEncodingKey

kDRCDTextCharacterCodeKey

kDRCDTextClosedKey

kDRCDTextComposerKey

kDRCDTextCopyrightAssertedForNamesKey

kDRCDTextCopyrightAssertedForSpecialMessagesKey

kDRCDTextCopyrightAssertedForTitlesKey

kDRCDTextDiscIdentKey

kDRCDTextGenreCodeKey

kDRCDTextGenreKey

kDRCDTextLanguageKey

kDRCDTextMCNISRCKey

kDRCDTextPerformerKey

kDRCDTextSizeKey

kDRCDTextSongwriterKey

kDRCDTextSpecialMessageKey

kDRCDTextTitleKey

kDRCDTextTOC2Key

kDRCDTextTOCKey

extern const CFStringRef kDRCDTextArrangerKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the name of the arranger for a track or, if for the disc info block, for the disc as a whole.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextCFStringEncodingKey;  

Discussion

This is a required property key for a CD-Text block. Its value is a reference to a CFNumber object containing the CFStringEncoding value for the text of the block.

This property should remain constant once a block is created. If you change it after creating a block, the results are undefined.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextCharacterCodeKey;  

Discussion

This is a required property key for a CD-Text block. Its value is a reference to a CFNumber object containing the Red Book character set value for the text of the block.

The value is not a CFStringEncoding or an NSStringEncoding data type and should not be used as such.

This property should remain constant once a block is created. If you change it after creating a block, the results are undefined.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextClosedKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains arbitrary disc information. The text format is arbitrary and is up to the content provider. This information is private and players should not display it to the user of the disc.

In compliance with the CD-Text specifications, this string is always encoded using the kDRCDTextEncodingISOLatin1Modified encoding, regardless of the block's encoding.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextComposerKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the name of the composer for a track or, if for the disc info block, for the disc as a whole.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextCopyrightAssertedForNamesKey;  

Discussion

This is an optional property key for a CD-Text block. Its value is a reference to a CFBoolean object that indicates whether copyright is asserted on the names in the block, which include the values associated with the kDRCDTextPerformerKey, kDRCDTextSongwriterKey, kDRCDTextComposerKey, and kDRCDTextArrangerKey keys.

If this value is not specified, no copyright is asserted for these items.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextCopyrightAssertedForSpecialMessagesKey;  

Discussion

This is an optional property key for a CD-Text block. Its value is a reference to a CFBoolean object that indicates whether copyright is asserted on the block text associated with the kDRCDTextSpecialMessageKey key.

If this value is not specified, no copyright is asserted for the text.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextCopyrightAssertedForTitlesKey;  

Discussion

This is an optional property key for a CD-Text block. Its value is a reference to a CFBoolean object that indicates whether copyright is asserted on the disc or track title associated with the kDRCDTextTitleKey key.

If this value is not specified, no copyright is asserted for this text.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextDiscIdentKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains disc identifying information such as the catalog number and name of the record company, point of sale code, year, and so on. Each item shall be separated by a slash ("/").

In compliance with the CD-Text specifications, this string is always encoded using the kDRCDTextEncodingISOLatin1Modified encoding, regardless of the block's encoding.

This key is valid only for the disc as a whole, namely for array index 0. It is ignored when set in the dictionaries for tracks.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextGenreCodeKey;  

Discussion

A CD-Text block dictionary key whose value, a CFNumber object, contains the numeric code of the genre for the disc as a whole as listed in the CD-Text Genres enumeration.

This key is valid only for the disc as a whole, namely for array index 0. It is ignored when set in the dictionaries for tracks.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextGenreKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the name of the genre for the disc as a whole.

In compliance with the CD-Text specifications, this string is always encoded using the kDRCDTextEncodingISOLatin1Modified encoding, regardless of the block's encoding.

This key is valid only for the disc as a whole, namely for array index 0. It is ignored when set in the dictionaries for tracks.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextLanguageKey;  

Discussion

This is a required property key for a CD-Text block. Its value is a reference to a CFString object containing the ISO 639 language code describing the language for the text of the block. CD-Text allows the concept of an unknown language, which is represented here by an empty string.

You can change a block's language after creating the block.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextMCNISRCKey;  

Discussion

A CD-Text block dictionary key whose value, a CFData object, contains either 13 bytes of Media Catalog Number (MCN, for the disc as a whole) or 12 bytes of International Standard Recording Code (ISRC, for tracks).

This information can also be specified in the burn and track properties. CD-Text simply provides an alternative, possibly redundant, way to encode this information. If the MCN or ISRC data was specified in the properties for the burn or track, this value should be the same. See the descriptions of kDRMediaCatalogNumberKey and kDRTrackISRCKey for more details on the precise format of the data.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextPerformerKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the name of the performer for a track or, if for the disc info block, for the disc as a whole.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextSizeKey;  

Discussion

A CD-Text block dictionary key whose value, a CFData object, contains information about the number of packs and languages associated with each block.

This key is for output use only, when reading CD-Text from a disc. It is ignored when specified in a burn.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextSongwriterKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the name of the songwriter for a track or, if for the disc info block, for the disc as a whole.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextSpecialMessageKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains a text message that may be displayed to the user by some players.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextTitleKey;  

Discussion

A CD-Text block dictionary key whose value, a CFString object, contains the title for a track or, if for the disc info block, for the disc as a whole.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextTOC2Key;  

Discussion

A CD-Text block dictionary key whose value, a CFData object, contains additional table-of-contents information.

This key is for output use only, when reading CD-Text from a disc. It is ignored when specified in a burn.

Availability

Introduced in Mac OS X v10.4.

extern const CFStringRef kDRCDTextTOCKey;  

Discussion

A CD-Text block dictionary key whose value, a CFData object, contains table-of-contents information.

This key is for output use only, when reading CD-Text from a disc. It is ignored when specified in a burn.

Availability

Introduced in Mac OS X v10.4.

Typedefs

DRCDTextBlockRef

A reference to DRCDTextBlock instances.

A reference to DRCDTextBlock instances.

typedef const struct __DRCDTextBlock* DRCDTextBlockRef;  

Enumerated Types

CD-Text Encodings

Special CFStringEncoding values supported by the CD-Text format.

CD-Text Genres

Numeric values for audio content genres.

Special CFStringEncoding values supported by the CD-Text format.

enum { 
    kDRCDTextEncodingISOLatin1Modified = kCFStringEncodingISOLatin1, /* 
        ISO-Latin-1, as of Mac OS X 10.5 the appropriate CD-Text variant will now be used */
    kDRCDTextEncodingASCII = kCFStringEncodingASCII /* 7-bit ASCII */
};  

Discussion

The CD-Text format supports only encodings listed here.

As of Mac OS X 10.5 two new encodings are supported, they are kTextEncodingDOSJapanese (kTextEncodingShiftJIS)(CD-Text variant) and kCFStringEncodingUTF8. Note, they do not have a DR defined value as with the previously supported encodings.

These new encodings are intended to be specified along side existing encodings, as to aide in the localization process should multi lingual CD-Text be desired. Support for Shift JIS, while documented in the Red Book specification, may not be supported on most CD-Text capable devices. UTF-8 support is not defined in the Red Book specification and is to be considered a vendor specific enhancement, implementors worried about compatibility should avoid its use.

Numeric values for audio content genres.

enum { 
    kDRCDTextGenreCodeUnknown = 0x0001, 
    kDRCDTextGenreCodeAdultContemporary = 0x0002, 
    kDRCDTextGenreCodeAlternativeRock = 0x0003, 
    kDRCDTextGenreCodeChildrens = 0x0004, 
    kDRCDTextGenreCodeClassical = 0x0005, 
    kDRCDTextGenreCodeContemporaryChristian = 0x0006, 
    kDRCDTextGenreCodeCountry = 0x0007, 
    kDRCDTextGenreCodeDance = 0x0008, 
    kDRCDTextGenreCodeEasyListening = 0x0009, 
    kDRCDTextGenreCodeErotic = 0x000A, 
    kDRCDTextGenreCodeFolk = 0x000B, 
    kDRCDTextGenreCodeGospel = 0x000C, 
    kDRCDTextGenreCodeHipHop = 0x000D, 
    kDRCDTextGenreCodeJazz = 0x000E, 
    kDRCDTextGenreCodeLatin = 0x000F, 
    kDRCDTextGenreCodeMusical = 0x0010, 
    kDRCDTextGenreCodeNewAge = 0x0011, 
    kDRCDTextGenreCodeOpera = 0x0012, 
    kDRCDTextGenreCodeOperetta = 0x0013, 
    kDRCDTextGenreCodePop = 0x0014, 
    kDRCDTextGenreCodeRap = 0x0015, 
    kDRCDTextGenreCodeReggae = 0x0016, 
    kDRCDTextGenreCodeRock = 0x0017, 
    kDRCDTextGenreCodeRhythmAndBlues = 0x0018, 
    kDRCDTextGenreCodeSoundEffects = 0x0019, 
    kDRCDTextGenreCodeSoundtrack = 0x001A, 
    kDRCDTextGenreCodeSpokenWord = 0x001B, 
    kDRCDTextGenreCodeWorldMusic = 0x001C 
};  

Discussion

CD players can use the numeric codes associated with these genres to automatically assign equalizer settings. If no genre code is specified, a value of kDRCDTextGenreCodeUnknown is used.

You can also specify a textual genre description, using the kDRCDTextGenreKey CD-Text dictionary key, to supplement the numeric code. In typical implementations, the textual genre will be visible to the listener regardless of the genre code.