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PAC-Rat · Aug 31, 2003, 04:54 PM

Does anyone know of a way to output a cd's audio through the digital output on the cd/dvd-rom drive? I believe OS X reads the audio off the cd as if it was any other data cd. I remember before X (perhaps before OS9), cds were played using the audio connections (analog/digital) on the back of the cdrom. Is there a way to get the drive to do this in OS X?

Back in OS9, I used the digital output to record MiniDiscs from my CDs using the digital optical input on my recorder. Would like to be able to do this again.

Super Glitcher · Sep 1, 2003, 10:05 PM

Have you tried using your audio app in Classic mode to see if it still worked? Other than that maybe experiment with other audio programs or contact the tech support department of the manufacturer of your drive - though I thought that the drive would automatically play the signal through it's analog/digital outs when an audio cd was being played, mine always has- but I haven't tried it in osx though.. weird. You may have to use classic if the osx controller reads the cd's as data.. or.. settle for an analog signal?

booboo · Sep 2, 2003, 11:03 AM

Originally posted by PAC-Rat:
Does anyone know of a way to output a cd's audio through the digital output on the cd/dvd-rom drive? I believe OS X reads the audio off the cd as if it was any other data cd. I remember before X (perhaps before OS9), cds were played using the audio connections (analog/digital) on the back of the cdrom. Is there a way to get the drive to do this in OS X?

Back in OS9, I used the digital output to record MiniDiscs from my CDs using the digital optical input on my recorder. Would like to be able to do this again.

Where did you get the digital output from?

All current Mac's bit-transfer the CD data (whether audio or otherwise)

If the particular CD-ROM drive in your Mac has a digital output, then this will automatically mirror the audio data that is traveling from the ATA connector, and you could conceivably use this, clock sync issues aside.

However, your best bet would probably be a cheap USB to Digital Optical connector, such as those made by Edirol, which are fully supported under OS 9/X.

PAC-Rat · Sep 2, 2003, 08:21 PM

On the cdrom drive, next to the analog audio connector are two pins that output digital audio if the cdroms built-in audio playing "stuff" is being used. Unfortunately, OSX doesn't use the cdrom's audio capabilities, it just reads data off the cd and later converts it to analog for listening. Thus, the digital output on the cdrom does not "mirror" the "audio data" on the ata bus, because it doesn't even know it is audio. Some explanation of how cd audio is handled after OS9 is provided here.

I am aware that usb options are available for purchase, but I have no desire to spend money if I can avoid it. Since the control of the cdrom is done in software, I was hoping for an alternative, i.e. hacked driver, specialized application, etc.

Thanks for the consideration so far.

Do you have any recommendations for usb to digital optical connectors, in the event that no one knows how to do this?

booboo · Sep 2, 2003, 10:08 PM

Originally posted by PAC-Rat:
On the cdrom drive, next to the analog audio connector are two pins that output digital audio if the cdroms built-in audio playing "stuff" is being used. Unfortunately, OSX doesn't use the cdrom's audio capabilities, it just reads data off the cd and later converts it to analog for listening. Thus, the digital output on the cdrom does not "mirror" the "audio data" on the ata bus, because it doesn't even know it is audio. Some explanation of how cd audio is handled after OS9 is provided here.

.....

Do you have any recommendations for usb to digital optical connectors, in the event that no one knows how to do this?

I understand what you're saying but I don't understand the problem you have with it.

I'm not sure that it is 'unfortunate' that audio data is read from the cd in this way - in fact it's likely to be bit-accurate.

Granted, the fact that the digital out on the CD drive isn't supported might be unfortunate (and I am intrigued to learn it's a driver thing) but I suspect that the common in Windows way of doing it - a connection between the digital out and the soundcard's digital in - is far from ideal as there is (probably) no digital clock synchronization, plus most cheap soundcards automatically re-sample to 48KHz, again doing dubious things to your sound quality.

Options are:

1. A new G5 which has built-in digital I/O...or

2. Something like this edirol USB adaptor which are quite cheap here in the UK (�35/$50)

But I don't understand how you got the digital signal from the co-axial outs on the CD (at 44.1KHz) to the Optical digi-in of you MiniDisc (48KHz) to work at all...

Please enlighten.

PAC-Rat · Sep 2, 2003, 10:52 PM

Originally posted by booboo:
But I don't understand how you got the digital signal from the co-axial outs on the CD (at 44.1KHz) to the Optical digi-in of you MiniDisc (48KHz) to work at all...

Pretty simple actually. Only needed a buffer and a LED. Got the info from the MiniDisc Appreciation Page. I mounted the red LED in a toslink enclosure, and just plug a optical cable into it to the MD. The page explains the details. I'm not too sure about the 44.1 kHz to 48kHz thing. But it worked.

In OS9 I used to use the old Apple CD Driver from 8.5-ish and it allowed me to use the circuit to record digitally from the cdrom. But since the newer driver doesn't output to the digital output, this is no more.

Perhaps I shall look into that Edirol...I guess that way I can get MP3s on my MDs too.

A G5...I wish. Still hoping for a GHZ Yikes upgrade...

booboo · Sep 3, 2003, 10:24 AM

Originally posted by PAC-Rat:
Pretty simple actually. Only needed a buffer and a LED. Got the info from the MiniDisc Appreciation Page. I mounted the red LED in a toslink enclosure, and just plug a optical cable into it to the MD. The page explains the details. I'm not too sure about the 44.1 kHz to 48kHz thing. But it worked.

In OS9 I used to use the old Apple CD Driver from 8.5-ish and it allowed me to use the circuit to record digitally from the cdrom. But since the newer driver doesn't output to the digital output, this is no more.

Perhaps I shall look into that Edirol...I guess that way I can get MP3s on my MDs too.

A G5...I wish. Still hoping for a GHZ Yikes upgrade...

Absolutely ingenious. I think I'll have to try a TOS to co-ax converter myself, just to see it work. -)

Meanwhile, it might be worth trying a few old CD playing app's in Classic - or maybe in an even older mac 'emulator' such as Basilisk which will run versions of the Mac OS 8.1 and prior...

PAC-Rat · Sep 3, 2003, 07:39 PM

No success in classic. Doesn't even recognize cdrom. Might try emulator.

booboo · Sep 4, 2003, 10:40 AM

Originally posted by PAC-Rat:
No success in classic. Doesn't even recognize cdrom. Might try emulator.

Apple CD-ROM Extension installed?

tooki · Sep 12, 2003, 10:08 PM

Aside: MiniDisc doesn't use a 48KHz sample rate, it uses 44.1KHz, just like CD. (DAT uses 48KHz.)

Trying to use Classic or an emulator is a ridiculous way to try to get this to work... you're trying to get closer to the hardware by using software that intentionally distances you from the hardware.

The upshot is, on OS X, and OS 9 (as well as the "Borg" version of 8.6 that shipped with the earliest G4 machines) on non-beige Macs, the OS will not use the CD drive's built in audio playback, no matter what you do.

tooki