[cdg123-devs] Extracting CD+G CDs on Linux

[Steve F. <li...@pe...>]

Hi,

I was looking for a CD+G player for Linux and found this project.  I have downloaded
and built libcdg123 and libxmms_cdg123 so the next step was to see if I could get
input data in the right format while reading the CD+G disc on Linux.

I have found the cdrdao command claims to be able to extract sub-channel information
from a CD provided the CD-ROM drive supports this.  In my case the drive did though I
was only able to get this to work in raw mode (option --read-subchan rw_raw).  In
this mode cdrdao appears to write a single file consisting of a series of 2448
sectors each being the 2352 bytes of audio data followed by the 96 bytes of
sub-channel data.

I was able to use the TOC file generated by cdrdao to split the tracks appart
and then splitting the audio and sub-channel data by reading chunks of 2448 bytes
at a time and writing the first 2352 to the audio file and the next 96 to the
sub-channel file.

Playing the resulting files with the XMMS plugin doesn't work though - the SDL
output window cycles between black and blue backgrounds with occasional junk
appearing on the screen.  This makes me think that the format of the .cdg file
may not be the same as the sub-channel data from the disk or that the sub-channel
data may still need rearranging in some way before libcdg123 can process it.

Is there a specification for the .cdg file format available publicly and is an
extract of the .cdg test file available from anywhere?

Steve.