Re: dvd burner can't read cds
On Thu, 11 Feb 2010 03:13:11 -0500 (EST), Leonardo Canducci wrote:
> Stephen Powell wrote:
>> First thing to check: Is the activity light on the drive flashing on
>> and off at regular intervals? On my system, it's on for about 0.5
>> seconds, then off for about 0.5 seconds, just like clockwork.
>> If you don't see that, then either the device never received the
>> play command or it doesn't support it.
>
> I doesn't flash. Drive starts spinning when cd is loaded but doesn't
> spin when I try to play the disc and returns some error.
>
You probably know much of this already, but for the sake of others
listening in ...
There are two basic ways of playing audio CDs: the analog way and
the digital way. And it's not always obvious which method your
CD player uses. The original way is the analog way. The program
sends a "play" command to the CD drive. The CD drive
reads the digital data from the audio CD, does the digital-to-
analog conversion inside the drive itself, and sends an analog
audio signal via the audio cable to the "CD" input of the sound
card. This audio cable only has three wires: right channel,
left channel, and ground. (Sometimes an extra ground wire is
also present, so that each channel has its own ground wire.)
No data is sent across the I/O bus!
>From the point of view of the host processor, host memory,
and I/O bus, nothing is happening during the play operation.
The sound card is simply functioning as an amplifier. Older CD
players, such as cdplay in the
cdtool package, use this method. If all you want to do is
listen to an audio CD, this is by far the most efficient way
to do it.
The newer way is the digital way. The program basically treats
the audio CD as digital data. Digital data is read from the audio
CD and transferred across the I/O bus to host
memory. This digital data is then sent to the regular sound
port (PCM port) of the sound card, which is a second data
transfer across the I/O bus. This method obviously uses more
computer resources than the analog way, but also allows for
more flexibility. For example, sections of audio data from
a CD can be captured and put into a .wav file by the program.
This is called "ripping". This method is used in most
of the newer media players. I'm pretty sure that Windows
Media Player in recent releases of Windows uses this method.
The manufacturers of CD drives gain certain economies of
scale if the same basic CD drive can be used in both digital
computers and consumer CD players. Consumer CD players require
the analog method. Therefore, the analog circuitry is present.
But with DVD players, it may be a different story. It wouldn't
surprise me if some DVD drives don't have this analog circuitry
and therefore don't support the traditional "play" command
for audio CDs. For this type of drive, you may have to use
a media player that uses the digital, or "ripping" method.
If you're sure that cdplay is addressing the right drive,
you get an error message, and you don't see the activity
light on the drive flash on and off at regular intervals,
it's a pretty good indication that the drive doesn't support
the "play" command. The fact that it works in Windows doesn't
mean anything unless you are sure that the media player that
you're using in Windows is using the analog method.
Here's one way to be sure. Play a CD in Windows. While
the CD is playing, unplug the audio cable, either at the
drive end or the sound card end. If sound suddenly
disappears, the media player is using the analog method.
If you continue to hear sound, it's using the digital method.
If you can get the analog method to work under Windows, then
chances are that cdplay was not talking to the correct drive
under Linux. Either that or the drive uses some type of
non-standard command set that the Windows media player
understands but cdplay, which follows the industry standard
command set, does not.
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