cdrdao-devel

[Cdrdao-devel] CD+G and raw mode

[Bill M. <mo...@ha...>]

The disclaimer is I know next to nothing about CD+G other than my kids
are trashing their CD+Gs and I want to make a backup.  And I know also
little about the inner secrets of CDs in general.  Then there's my
shell scripting skills....

With that clear, I'm able to make a backup CDR of a CD+G using the
following.  Is this the recommended way?

    #!/bin/sh

    if [ -z "$1" ]; then
        echo "Usage: $0 <discname>"
        exit 0
    fi


    cdrdao read-cd \
        --read-raw \
        --read-subchan rw_raw \
        --device /dev/cdr \
        --datafile "$1.bin" \
        "$1.toc" || exit 0

    echo "Burn use: cdrdao write $1.toc"


Here's my question:  I tried just using

    cdrdao read-cd --read-subchan rw foo.toc

but the resulting CD+G I burned was not playable -- it kind of worked
but the graphics didn't always work and the audio buzzed.

I'm trying to understand why I need to do the --read-raw and
--read-subchan rw_raw.

If I understand correctly, --read-raw says to bypass the error
correction done by the drive -- so any errors in the read are then
transferred to the cdr on the write operation.  Is that correct?  I
would think I would want the error correction.

Or is it not the --read-raw that is making the difference, but the
--read-subchan rw_raw that is required for some reason with CD+G.

Thanks,



-- 
Bill Moseley
mo...@ha...

Re: [Cdrdao-devel] CD+G and raw mode

[Kelvin L. <ke...@us...>]

Bill,

 > Here's my question:  I tried just using
 >
 >     cdrdao read-cd --read-subchan rw foo.toc
 >
 > but the resulting CD+G I burned was not playable -- it kind of worked
 > but the graphics didn't always work and the audio buzzed.
 >
 > I'm trying to understand why I need to do the --read-raw and
 > --read-subchan rw_raw.
 >
 > If I understand correctly, --read-raw says to bypass the error
 > correction done by the drive -- so any errors in the read are then
 > transferred to the cdr on the write operation.  Is that correct?  I
 > would think I would want the error correction.
 >
 > Or is it not the --read-raw that is making the difference, but the
 > --read-subchan rw_raw that is required for some reason with CD+G.


I've also been experimenting with CD+G lately. I've written some tools 
that take the toc/bin generated by cdrdao and encode the tracks to MP3+G 
files. (See http://www.kibosh.org/cdgtools/ for more details).

As I understand it, the choice of rw or rw_raw depends on what modes 
your CD drive supports. In my case, my drive doesn't support rw mode 
(deinterleaved RW subchannel mode), so I can only use rw_raw (raw 
interleaved RW subchannel mode). It may be that your drive only supports 
rw_raw mode, hence your mixed results from rw mode.

That said, I'm surprised that you get any graphics at all if the drive 
doesn't support rw mode. Are you getting the odd glitch or quite serious 
flaws in the graphics?

I haven't looked into the --read-raw option, but I can tell you I don't 
use it here. Have you tried rw mode together with --read-raw to 
establish which option is the important one? I'd be interested to hear 
the results of that.

FYI, I use the following command line:

cdrdao read-cd --driver generic-mmc-raw --device /dev/cdroms/cdrom0 
--read-subchan rw_raw mycd.toc

Cheers,
Kelvin.