bort

Hi,

I'm trying to record the optical output from my Polk Xrt12 XM radio tuner on my Audigy Platinum Ex w/kX drivers. The data from the receiver is 24-bit (I'm almost certain) at 44.1khz. I have Audacity set to capture the audio in this format.

Everything seems to work, but when I play back the audio it sounds to me like the 24-bit data has been downsampled to 16-bit. Of course, it's kind of hard to tell, as XM radio's quality isn't all that great. But assuming I am correct, then I need to figure out whether it's during the recording phase or the playback phase that these bits are getting dropped.

So here are my questions:

1. Is it, in fact, possible to record Direct SPDIF in 24-bit/44.1khz on an Audigy Platinum eX (SB0090)?
2. Assuming the answer to #1 is yes, is it possible to play back the 24-bit/44.1khz audio through the same card without resampling to 16-bit?

Thanks a bunch,
bort.

dj_stick

it may be possible to record, not certain - check the docs on the kX website

as for playback, it WILL get resampled and dithered to 16/48

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bort

Thanks for your help. I RTFM before posting, but I can't find anything in the docs that confirms/denies the ability to do bit-accurate recording in 24-bit on an SB0090. Hopefully someone has a definite answer on that.

bort.

dj_stick

Direct Recording Guide

It states there you can create a direct copy of what you are recording - so i guess the only way to find out is to try it for yourself

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bort

In my first post I explained that I have tried this, but that the audio sounds dithered when I play it back. Since you've told me that all audio I play will, in fact, be dithered to 16-bit, how can I test to see whether the audio I've captured is really 16- or 24-bit?

I've read the Digital Recording Guide several times already, but as the numbers 16 and 24 do not appear anywhere in it, it does not really help to answer my question.

bort.

dj_stick

you can check it with your recording program, or play back on a different system (if possible)

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bort

Well of course, Audacity thinks it's recording 24-bit sound. But I could also make Audacity think it's recording 32-bit sound. So this means nothing.

Unfortunately, I have no other systems with 24-bit sound cards (although I don't think this solution would provide 100% certainty anyway).

So basically, my original first question still remains: Does anyone know if the Audigy Platinum eX (SB0090) can record 24-bit audio in bit-accurate mode? Or is there a way to analyze a "24-bit" wave file to see if the highest 8 bits have been dropped?

bort.

dj_stick

you can analyze the resultant track, check to see if the aliasing is 16bit steps, or 24bit


one way to do this is to create a "fadeout" and as the music is fading out crank the volume slowly

if you hear the level dropping in steps, it's 16bit, if it sounds smooth, it's 24bit - however you'll need a 24bit playback capable card

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bort

Which, as you know, I don't have.

Is there a way to do this by examining the waveform itself or running it through some sort of utility?

bort.

Max M.

don't bother - AFAIR direct spdif recording is 16 bit only - i wonder why Direct Recording Guide doesn't mention this