CD-Text
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CD-Text is an extension of the
The specification for CD-Text was included in the
Storage
The CD-Text information is stored in the subchannels R to W on the disc. This information is usually stored in the subchannels in the lead-in area of the disc, where there is roughly 5 kilobytes of space available. It can also be stored on the main program area of the disc (where the audio tracks are), which can store about 31 megabytes.[1] Since the R to W channels are not used in the Red Book specification of audio CDs, they are not read by all CD players, which prevents some devices from reading CD-Text information.[1]
Format
CD-text data is defined in a scattered manner between MMC-3 and Sony documentation. The below uses GNU libcdio's description.[4]
On the lowest level, CD-text is stored in 18-byte "pack" units; this part is defined in MMC-3 Annex J. Each pack consists of 4 bytes of header (type indicator, track number reference, sequential counter, block number and character position indicator [BNCPI]), 12 bytes of payload, and 2 bytes of CRC. The type indicator ranges from 0x80 to 0x8F, the 13 defined values being:[5]
| Type | Keyword | Description | Section | Format |
|---|---|---|---|---|
| 0x84 | ARRANGER | Name(s) of the arranger(s) | Any | Character |
| 0x83 | COMPOSER | Name(s) of the composer(s) | Any | Character |
| 0x86 | DISK_ID | Disc Identification information | Disk | Binary |
| 0x87 | GENRE | Genre Identification and Genre information | Disk | Binary |
| 0x8e | ISRC | International Standard Recording Code of each track | Track | Character |
| 0x85 | MESSAGE | Message from the content provider and/or artist | Any | Character |
| 0x81 | PERFORMER | Name(s) of the performer(s) | Any | Character |
| 0x82 | SONGWRITER | Name(s) of the songwriter(s) | Any | Character |
| 0x80 | TITLE | Title of album name or track titles | Any | Character |
| 0x88 | TOC_INFO | Table-of-content information | Disk | Binary |
| 0x89 | TOC_INFO2 | Second table-of-content information | Disk | Binary |
| 0x8e | UPC_EAN | UPC/EAN code of the album | Disc | Character |
| 0x8f | SIZE_INFO | Size information of the block | Any | Binary |
The BNPCI is used to define information that does not fit in one pack. This can be text or binary data. The BNCPI also indicates whether the text is single-byte or
For block types listed above as "character" (per MMC-3), the payload is a simple null-terminated string. (MMC-3 is written confusingly here – it describes the encoding as "ASCII" in the pack type table despite mentioning the BNCPI flag modifying its behavior later.) The descriptions of the binary fields are vague, but the developers of GNU libcdio has either matched them to sections of MMC-3 or written new descriptions based on Sony's sample.[4]
Another layer of encoding specification is found at this payload level, in the SIZE_INFO block. Here the first byte may be used to indicate the encoding,
See also
References
- ^ a b c Unofficial CD Text FAQ.
- ^ Approved Compact Disc Logo configurations.
- ^ IEC 61866:1997 Audiovisual systems – Interactive text transmission system (ITTS).
- ^ a b c d CD Text Format, in GNU libcdio documentation. Provides references to MMC-3 and Sony standards.
- ^ MMC-3 Draft R10G
External links
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