[asdfeproiu9]

Do USB audio devices resample to 48 kHz, even when outputting in the TOSLink optical format? The Sharp AD-USB1 manual has absolutely no specs, but in the installation instructions part, it mentions:

S/P DIF optical output terminal (square)
Output sampling rate 48 kHz

Does this mean it resamples? I thought that when it outputs optically, it would just leave the signal alone ...

 

[MirandaX]

Quote:

Originally posted by asdfeproiu9 Does this mean it resamples? I thought that when it outputs optically, it would just leave the signal alone ...

Yeah, that's what you'd think. The reality, at least in my experience, is somewhat more complicated. With the M-Audio Sonica (another USB device), I get resampling when using the 1.2.20 drivers on Windows XP, but not when I use the 1.2.05 drivers (older). (On my Windows 2000 machine, however, I was able to use the newer drivers without resampling.)

I can't answer your question specifically about the Sharp unit, but you can test it out yourself if you have a home theatre receiver that supports DTS. Go here:
http://www.avsforum.com/avs-vb/showt...hreadid=247101
and download one of the PCM-encoded DTS sound files. (The first one they link to is the smallest, so it's the easiest download.) Play that back into the receiver. If you get music, it's very likely that no resampling or other munging of the signal is going on. If you get loud clicking sounds, your unit is resampling the signal.

 

[asdfeproiu9]

I don't have a home theatre receiver, unfortunately. Do you know of any other methods? Or do you know of any way other than Kernel Streaming / ASIO to bypass kmixer.sys? Or maybe even modify kmixer.sys to prevent resampling?

 

[MirandaX]

For what it's worth, I've found that kernel streaming doesn't always bypass Kmixer, but it does on some configurations. So much of all this is in the specific driver/OS combination that it's hard to comment.

Would it be possible for you to borrow a friend's receiver for an evening? Hate to suggest it, but it's the easiest way to be sure. Alternatively, you could borrow a DAC that displays what rate its incoming signal is coming in at, but that would only tell you if you have a 44.1kHz or 48kHz signal; it wouldn't answer the question about whether you're getting a 44.1kHz signal but Kmixer is still munging it. There's a guy on AVS forum who has two sound cards and records the digital output from one with the other. He has a program that figures out how many samples delay there is, then shifts the recorded file by that much and compares it with the original file, and verifies that no munging has been done that way. It's a lot of work. The receiver test is still the easiest one. Since the Sharp unit is so small (and it's a convenient USB unit), you could always just bring it over to a friend's place who has a receiver and test it over there. Just be sure that s/he's using the same OS you are.