Re: [Libcdio-devel] CD-TEXT documentation

[Rocky Bernstein]

On Sat, Feb 4, 2012 at 11:25 AM, Leon Merten Lohse <address@hidden>wrote:

> 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.
>

I've removed from libcdio.texi mention of size limits and made note of  the
newly created document.

Again, if this is inaccurate or confusing please jump in and make
suggestions. I have a hard time correlating the discussion above to some
concrete change that will make things clearer or less confusing.




> > > 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
>
>