Re: [Libcdio-devel] CD-TEXT documentation

[Leon Merten Lohse]

Thank you Thomas!

On Sat, Feb 04, 2012 at 10:06:41AM -0500, Rocky Bernstein wrote:
> > doc/libcdio.texi:
> >
> > Some of its aspects go beyond my own CD knowledge.
> > Nevertheless, i have to question some statements:
> >
> > > The first place the information can be recorded is in the R-W sub
> > > codes in the lead in area of the CD giving a data capacity of about
> > > 5,000 ASCII characters (or 2,500 Kanji or Unicode characters).
> >
> > How was the payload of 5,000 bytes computed ?
> >
> 
> Probably from  http://web.ncf.ca/aa571/cdtext.htm

And this source is as wrong as Wikipedia is.
According to the Sony Tool Docs (DOC08), the whole CD-TEXT size should
not be bigger than 9216 and must not exceed 36864 bytes. This includes
the pack headers and crc information so the actual data size is two 
thirds of it. That gives us a maximum of 6144 bytes of text data minus
3*18 bytes of block information per block. Also a CD-TEXT field should
not exceed 255 bytes.
Unicode is definitely not a part of the CD-TEXT specifications.

> > The highest lead-in start for recordable CD media in my list is
> > 97m 49s 00f which means LBA -9975. Lead-in reaches up to LBA -150.
> > Each sector can take 4 text packs of 12 bytes payload = 471,600 bytes.
> >
> > MMC command READ TOC/PMA/ATIP could retrieve 65,534 bytes from lead-in.
> >
> > A CD-TEXT block can have only 253 payload packs of 12 bytes each.
> > There can be 8 blocks at most. 253 * 12 * 8 = 24,288 bytes.
> >
> > A single block (i.e. one language) can have 253 * 12 = 3036 bytes.

> >
> > Afaik, the format is the same in lead-in and in program area.
> >
> > Is the statement about CD+G particularly about program area or does it
> > apply to lead-in too ?
> >

Program Area CD-TEXT is always mentioned but was as far as I know never
implemented. Imho mentioning it is just confusing.

Regards
Leon