Audacity Forum

gd2shoe wrote:

We'll see what the Windows elves think.

Fingers crossed.

When they show

I am the main "WIndows elf" here. So you already heard from them.


Gale

gd2shoe wrote:WASAPI is currently useless on my system. It will not record a second track if I've already got one. ("Error opening sound device..." no matter what I've tried.)

You did not give the entire error. If it says that the problem is with playback, then probably you need to make Windows Default Format playback the same as Audacity Project Rate (Exclusive Mode off) or choose a project rate that is a sample rate supported by your playback device (Exclusive Mode on).

And you must restart Audacity after making changes in Windows Sound, or you will get WASAPI error opening in any case.

gd2shoe wrote:I'm not sure if DirectSound upconverts, or delivers 16 bit. It's old enough, I suspect it doesn't

Under DirectSound on Vista and later, even with Exclusive Mode on, Windows will always upconvert to 32-bit float before Audacity even gets the audio. DirectSound (and MME) are emulated on top of WASAPI on those versions of Windows.


Gale

gd2shoe wrote:

Gale Andrews wrote:Also if you want "bit perfection" you won't be able to get that in Audacity on any operating system because it always captures at 32-bit float (that is, upconverts the bit depth).

Are you suggesting Audacity always converts to 32 bit float, and then converts back down to the quality setting? I don't know enough to argue against that, but it seems illogical.

I am not suggesting anything. I am telling you that Audacity always records in 32-bit float. Look at the Audacity source code if you don't believe it.

So yes, if you change to 16-bit quality in Audacity then your recording will be downconverted to 16-bit and dither applied (unless you turned dither off, which is not recommended). As you'll know, there are many advantages to processing in 32-bit float.


Gale

I might have to, but dual boots are a pain, and I have Windows programs I need to run. For that matter, it would be a pain to migrate the macros that make Audacity dance for me over to a different program that runs in Linux. (I actually have a close approximation of punch-and-roll running with Audacity.)

You did not give the entire error. If it says that the problem is with playback, then probably you need to make Windows Default Format playback the same as Audacity Project Rate (Exclusive Mode off) or choose a project rate that is a sample rate supported by your playback device (Exclusive Mode on).

In 2.1.2, it usually said "recording device", but occasionally would say "playback". I never did figure out if there was a pattern to it.

The message has changed slightly in 2.1.3. Now, the 2.1.3 error reads in full: "Error opening sound device. Try changing the audio host, recording device and the project sample rate."

And you must restart Audacity after making changes in Windows Sound, or you will get WASAPI error opening in any case.

Even if you "Rescan Audio Devices"?

Restarting Audacity doesn't fix it at any rate.

Under DirectSound on Vista and later, even with Exclusive Mode on, Windows will always upconvert to 32-bit float before Audacity even gets the audio. DirectSound (and MME) are emulated on top of WASAPI on those versions of Windows.

Ok. So, is there any way to determine which filters/transforms/algorithms Windows is applying, and does it do so before or after converting to 32 bit? (presumably after, but I'm not assuming that it only adjusts volume; you can't always trust MS not to do something dumb.)

As you'll know, there are many advantages to processing in 32-bit float.

Yes, I agree there. I'm not concerned about the conversion to 32 bit. I'm concerned that something is adjusting the actual values in the signal. I want to know what it's doing (preferably why), and whether or not I'd benefit from stopping it.

I was much more concerned when I thought that it was Audacity that was upconverting to 32 bit. That would have meant definite loss of fidelity. Now, It's uncertain. It depends on whatever other voodoo is going on where I can't see it.

gd2shoe wrote:I'm concerned that something is adjusting the actual values in the signal.

Do not use Windows if this matter concerns you. Of course with specific USB devices that have custom USB drivers it is possible there will be no scaling if the drivers are written that way. You cannot guarantee no scaling with a device that uses standard Windows USB Audio Class drivers.


Gale

gd2shoe wrote:

Under DirectSound on Vista and later, even with Exclusive Mode on, Windows will always upconvert to 32-bit float before Audacity even gets the audio. DirectSound (and MME) are emulated on top of WASAPI on those versions of Windows.

Ok. So, is there any way to determine which filters/transforms/algorithms Windows is applying, and does it do so before or after converting to 32 bit? (presumably after, but I'm not assuming that it only adjusts volume; you can't always trust MS not to do something dumb.)

As stated, upconversion to 32-bit float will happen with DirectSound host before Audacity receives the audio.

If you use WASAPI Exclusive Mode (if you could get it going) then Windows should be handing 16-bit audio to Audacity and it will be Audacity that does the upconversion to 32-bit float on capture.


Gale