Open-source USB interface: Audio Widget

[abraxalito]

Originally Posted by rsdio

Frankly, it would be a serious risk of resources to develop an open source Windows UAC2 driver when Microsoft might turn around and release one the next day.

But Microsoft doesn't do open source. Perhaps your meaning was Microsoft might release a proprietary one. The real waste of effort that I see is that Windows is last millennium's OS, it pays to invest for the future. We'd do better putting the effort into converting computer audio types over to Linux/Android IMO thereby hastening Microsoft's demise.

[RocketScientist]

@rsdio, there's a big difference between drop outs and devices that "fail to function" as you put it when the bus is overloaded, etc, and subtle changes in SQ which is the issue I'm trying to address. There's no argument from me poor driver code, for example, can cause glitches in the audio. As I said, that's a very black and white problem. It can be readily detected and it either happens or it doesn't.

The jitter issue is the only thing that can potentially alter SQ (assuming a bit accurate data stream). And, in what you've written above, I still don't see where the player software can influence the resulting jitter in the clock of a UAC1 DAC. The 1 mS timing, as I understand it, is derived from the USB host controller clock and controlled by its "firmware"--not the player software.

[abraxalito]

Originally Posted by RocketScientist

The jitter issue is the only thing that can potentially alter SQ (assuming a bit accurate data stream).

Really? Really? Any support or reasoning for this apparent myth?

[rsdio]

Originally Posted by abraxalito

But Microsoft doesn't do open source. Perhaps your meaning was Microsoft might release a proprietary one. The real waste of effort that I see is that Windows is last millennium's OS, it pays to invest for the future. We'd do better putting the effort into converting computer audio types over to Linux/Android IMO thereby hastening Microsoft's demise.

I can't disagree with that.

Note that Windows still doesn't support the full USB-MIDI specification, either.

Don't forget Mac OS X, though. It supports UAC2 and at least the Darwin part of the OS is open source. I haven't looked to see whether the USB drivers are included, but I think they have some drivers.

[rsdio]

Originally Posted by abraxalito

Really? Really? Any support or reasoning for this apparent myth?

I don't understand what you're saying. Digital audio only involves two variables, instantaneous value and sample time. How could anything besides jitter and data accuracy affect the sound quality? The obvious exception would be power supply noise if the audio interface is powered from the USB host, but RocketScientist has already addressed that particular aspect. Note: I may be nit-picking the finer details of some of his posts, but I totally agree with what RocketScientist is saying here.

[borges]

Good observation :-)

The Audio Widget of this thread uses the same code base as the SDR Widget. The web page in my signature contains all relevant links to project sites.

Børge

Originally Posted by rsdio

Thanks, but "I don't do Windows."
At first, I thought you were talking about a UAC2 firmware, and I was about to point out the SDR Widget because it seems to implement that. But, now I realize that you're talking about the host side.

[abraxalito]

Originally Posted by rsdio

I don't understand what you're saying. Digital audio only involves two variables, instantaneous value and sample time.

Yeah that's the theory. But in practice there's more to it than theory.

How could anything besides jitter and data accuracy affect the sound quality? The obvious exception would be power supply noise if the audio interface is powered from the USB host, but RocketScientist has already addressed that particular aspect.

I must have missed something then. Where did he address what I consider to be the main issue in digital audio sound quality (once the theory is correctly handled), common-mode conducted noise? In fact alexlee188 explicitly referred to noise conducted from the PC but RocketScientist deflected that valid point with a totally irrelevant mention of tube amplifiers. What gives?

[audiodesign]

In the WINDKK free package from Microsoft there are source of USB Audio 1.0.

Could be more simple develop ASIO driver instead of UAC2 ?

[qusp]

maybe, but not at all desirable, there simply isnt the bandwidth for a crossover

[audiodesign]

Is possible to modify the .inf file of these XMOS driver to be compatible with the Open-source USB interface ?

LINDEMANN.: USB Drivers