Re: CDROM's headphone jack old-fashioned?
On Tue, Jan 07, 2003 at 01:16:09AM +0100, Jean-Marc V. Liotier wrote:
> On Mon, 2003-01-06 at 21:36, Dan Jacobson wrote:
> >
> > Take my "RICOH CD-R/RW MP7080A, ATAPI CD/DVD-ROM drive", which seems
> > to have difficulty often realizing that a cd had been inserted.
> > Anyway, say I retire it. Can it then play CDs without a computer
> > around?
>
> Yes, but the controls are very rudimentary. Plug a power supply into
> your CD drive, put a CD audio in the tray, plug headphones into the
> front panel jack socket, press "play" and you will hear the music.
> Sometimes, pressing "play" continuously will fast forward and pressing
> "play" just once skips one track. To stop, press the "eject" button.
>
> On top of the inconvenience, the output quality will probably suck. But
> nothing stops you from doing it.
Course, this doesn't work with CD-ROMs that only have one button...
The output quality will be exactly the same as that when using the
CD-ROM drive to play CDs when it's built into the computer. In both
cases, the same DAC is used, that in the drive. The analogue signal is
then routed both to the headphone socket on the front of the drive and
the 4-pin connector on the back, which feeds the soundcard.
Some CD-ROMs have a built-in regulator to generate the 5V supply from
the 12V input. This is useful, because you can then run it off a car
battery. If the drive does not have a built-in regulator, a 7805 will
do.
CD-ROM drives often play dodgy audio CDs better than a hi-fi CD
player. The CD-ROM drive reads the CD in bursts at high speed, giving
it more time to retry after an error without making a gap in the music.
To force a CD to be played 'digitally' using the DAC in the soundcard,
I use
cdda2wav -q -e -D/dev/cdrom -N -B 2>/dev/null &
Pigeon
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