Re: [Libcdio-devel] CD-Text patches

[Thomas Schmitt]

Hi,

Robert William Fuller wrote:
> CD-Text IS specified in older MMC standards.  Specifically, try
> "mmc3r10g.pdf".  It has an "Annex J" that describes the format of
> CD-Text. 

Leon Merten Lohse wrote:
> That is indeed the best documentation you can find other than cdrecords.
> But it is still kind of superficial. libcdio already supported most of
> the fields described there. Unfortunately you will not find any 
> information about the structure of binary CD-Text fields like genre or 
> size_info there.

I have read this several times in the past but failed to make much
sense out of it. Especially i hate this sentence:
  "The data format of RAW Sub-channel is explained in ."

But my core problem is that this appendix is very condensed and i
have no example of a CD with text.


Robert William Fuller wrote:
> I am not sure why the newer MMC standards omitted it.

MMC-5 and MMC-6 point to the Philips CD-DA specification. They only
mention the READ TOC/PMA/ATIP command by which one can obtain CD-TEXT
from the Lead-In, and the READ CD command by which one can obtain
it from other regions. With the latter it mentions "P-W Sub channel"
but i cannot spot how to select it for reading (only "R-W Sub channel",
which is not the same).

I have to confess that the whole sub channel stuff is obscure to me.
Personally i have use for data recording only. The inherited sub
channel writing code in libburn is obviously buggy. So i went on to
DVD and BD writing (which only allows MODE1-ish 2048 byte data blocks).

I do know that CD-TEXT writing can be announced by SEND CUE SHEET
for CD SAO recording. Maybe i could combine info from MMC-3 and MMC-5
if i had some example where i could verify my guesses.
E.g. an overview what CD-TEXT data are stored at what place of a
particular example CD.

So if anybody here has a recipe how to produce such a CD from scratch,
then it would be another step for me towards understanding of this
topic. (Assume i have only a CD burner, a CD-RW, cdrecord or cdrdao.
Anything else would have to be provided by the recipe.)


The topic of CD-TEXT is more or less academic to me. I have been asked
for it a few times, but none of the requesters was willing to assist
me with experiments or examples. None of them even had an own use case
for CD-TEXT.
Nevertheless, it is a constant itch for me that libburn cannot substitute
for cdrecord with that task.


Have a nice day :)

Thomas