SUMMARY: Reading Audio data on Sun CDROM Player

From: Steven Venema (
Date: Sat Feb 08 1992 - 13:32:37 CST

        In my original posting, I inquired about reading data from audio
        CD's using Sun's CD-ROM player. Basically, I was able to read the
        table of contents, but attempts to read the data yielded "I/O Error"
        faults. I suspected that there might be some sort of digital read
        protection that this CD-player provides for audio discs.

        Can anyone confirm/refute this suspicion?

        A sample reply (oilean!

> The Sony cdrom drive firmware doesn't support reading audio data
> directly from the disk. The subcode information on the disk does
> make a distinction between audio and digital data (even though
> it's really all just bits). My guess is that it is a simple form
> of copy protection.

        There was some disagreement as to whether the audio read limitation
        was put into the CDROM drive (a Sony device, I think) or into the Sun
        device driver.

        Several people indicated that the SGI Indigo *CAN* read audio data.

        One person suggested that I try to re-route the audio playback
        from the Sun audio port to somewhere else, thereby "capturing" the
        audio data for later perusal. However, as far as I can tell, the
        CDROM audio playback feature can only work with the headphone jack
        on the front of the CD player--data is never routed through the
        SCSI interface up to the sun for playback via the /dev/audio port.
        If anyone knows differently, please speak up!

        The "xcdplayer" software in the X11R5 contrib software works quite
        well if you want to use your CDROM drive as a audio CD-player. It
        provides a small window control panel for start/stop/track-select/
        eject/etc.... The only problem that I could see was that the
        volume control slider needs to be re-calibrated to map the quite-
        loud range over the full range of the slider. Now all I need is one
        of those cordless headphones....

        If anyone wants my humble "cdtoc" (table-of-contents) and "cdread"
        (read cd track) programs you can grab them via anonymous ftp from or send me email for a copy. The "cdtoc"
        program just lists tracks, min/sec/frames, subcode, etc. The "cdread"
        program doesn't work of course, but might be ported to a SGI Indigo
        fairly easily :-)


        Thanks to the following people for taking the time to reply: (Jeremy Lawrence) (Hal Pomeranz)
        oilean! (Joe McGuckin)
        harvard!scubed!! (Ken Bibb) (David DiGiacomo) (Guy Harris)
        Bernhard.Schneck@Physik.TU-Muenchen.DE (Bernhard Schneck)


                                        Steven Venema
                                        Interactive Systems Design Laboratory
                                        Dept. of Electrical Engineering
                                        University of Washington
                                        Seattle, WA USA


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