Q- Optical Output on decent sound cards (A/D done or not ??)

[1kyle]

I've got a question that I haven't been able to find a decent answer too even with a bit of "Googling"

Assuming you play an HI-MD disc on your computer via SS (just play --don't transfer) and the computer sound card is a high quality one which can play back 24 bits @ 192 khz or whatever and you set the "recording input" to WAV (Or SPDIF) even though you are not actually going to make a recording to your computer

Then my question is this

If I connect the optical OUT of the sound card to the Optical in on to another Minidisc unit (be it HI-MD or the Net-MD versions) how many A/D stages of conversion are there (if any) -- apart from one where you have to have an A/D conversion to actually hear the sound from the speakers.

I'd assume that it works like this

1) ATRAC==>WAV / SPDIF Sonic stage digitally decoding the ist minidisc unit from the USB into the computer sound system. SPDIF should enable "Digital Pass Thru" to the optical output of the Card -- note no DRM at this point (thank goodness)

2)WAV/SPDIF===>ATRAC on the 2nd minidisc player digitally at the Optical In stage of the 2nd minidisc player. (No SCMS or DRM BS stuff either)

Why would the Sound card have to perform another A/D conversion before outputting to the Optical output.

I understand there would have to be an A/D conversion before playing on the computer speakers but in theory the Optical output should just be able to output a WAV signal directly like a CD player with an optical Out.

Have I misunderstood something here.

Surely the whole point of the SPDIF interface is to have direct Optical links without any intervening A/D stage until the final playiut at the Spekers which are of course Analog.

Here's the "Spec" of the Sound Card I'm using.

Technical Specifications

High Signal-to-Noise Ratio (SNR) exceeding 104 dB using high linearity, low distortion 24-bit converters with resolutions of up to 192 kHz

Playback: 24-bit Digital-to-Analog conversion of digital sources at 96 kHz to analog 7.1 speaker output, 192kHz for Stereo DVD-A

Recording: 24-bit Analog-to-Digital conversion of stereo analog inputs at 96 kHz sample rate

Supports Sony/Philips Digital Interface (SPDIF) format of up to 24-bit/96 kHz quality at selectable sampling rate of 44.1, 48 or 96 kHz

Thanks everyone.

[dex Otaku]

If I connect the optical OUT of the sound card to the Optical in on to another Minidisc unit (be it HI-MD or the Net-MD versions) how many A/D stages of conversion are there (if any) -- apart from one where you have to have an A/D conversion to actually hear the sound from the speakers.

On one hand, there is no reliable answer to this question. On another, there are no a/d conversions if you connect everything properly.

The reason there's no reliable answer, though, is that directsound processes almost everything going through your puter audiowise.

Disclaimer: this depends on your sound card and [their] drivers. Some drivers will allow completely unprocessed audio to flow from the source to the output; others, regardless of whether your choose to force digital out or not, thoroughly munge the data by resampling, requantising, &c. The M-Audio Revo 7.1 is a fine example of this: it's impossible [by my experience] to play a DTS audio CD through its coax out and have it decode properly with outboard equipment, for example. [Whatever you try to play gets reframed as 44.1kHz CD audio. Don't ask how many players I've tried this with.]

The end result is that you will never really know if you're getting bit-for-bit copies.

Which isn't really relevant, actually, for two reasons: first, the digital in on all MDs and HiMDs resamples the stream, even if it's already 44.1kHz. Second, if you're recording in atrac/3/plus on the second unit, the 2nd generation of encoding will introduce far more artifacts than proper resampling should.

Another thing to note is that by playing the audio straight from HiMD using SS, SS is doing the atrac/3/plus decoding. It has been argued that SS's decoder is not as accurate as the hardware ones built into MDs/HiMDs, though no one has proved this asof yet.

[shibany69]

And would you know a sound card which wouldn't re-encode signal before it passes through optical out?