Why is only one USB audio path allowed?

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Why is only one USB audio path allowed?

Post by This Wreckage »

This is no doubt an uninformed (aka stupid) question, but why is only one USB audio path available at one time? I have several synths and a mixer with USB audio outputs but I cannot combine them in my Windows PC. I have to choose which one to use. Clearly, this is not like an SP/DIF digital audio stream. Perhaps someone could explain...
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Re: Why is only one USB audio path allowed?

Post by Hugh Robjohns »

It's because, under Windows, each USB audio connection requires its own driver and there is no facility to synchronise the digital audio sample rates coming from multiple sources through multiple drivers.
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Re: Why is only one USB audio path allowed?

Post by Wonks »

It's a Windows thing.
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Re: Why is only one USB audio path allowed?

Post by blinddrew »

Isn't it technically an ASIO thing rather than a Windows thing?
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Re: Why is only one USB audio path allowed?

Post by The Elf »

Each time this topic comes up I find it incredulous that this one hasn't been solved after all this time. :(
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Re: Why is only one USB audio path allowed?

Post by This Wreckage »

The Elf wrote: Thu Aug 11, 2022 11:29 am Each time this topic comes up I find it incredulous that this one hasn't been solved after all this time. :(

If a solution were to be found, who would provide it? Microsoft? Does Apple architecture allow multiple USB audio streams?
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Re: Why is only one USB audio path allowed?

Post by BigRedX »

Probably not the answer you want to hear but on the Mac it's built-in at system level:

Create an Aggregate Device to combine multiple audio interfaces
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Re: Why is only one USB audio path allowed?

Post by Hugh Robjohns »

It's a handy feature.... but I wonder if anyone has done any performance testing on the 'drift correction' function which is a software asynchronous sample rate converter?
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Re: Why is only one USB audio path allowed?

Post by Jimmy B »

A partial solution might be to use Asio4all to combine the usb inputs.
I say "partial" because I've got it working here on Reaper with a Fender Mustang amplifer (usb output) and a Focusrite audio interface but it seems a bit flaky, with excessive latency and little control of where the audio output goes. However, I can successfully record via both devices at the same time. If you just wanted to record, and monitor using the speakers in the synth, it might be OK.
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Re: Why is only one USB audio path allowed?

Post by resistorman »

Even with a Mac, it's probably better for Ye to use an AI with a lot of I/O :)
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Re: Why is only one USB audio path allowed?

Post by N i g e l »

This Wreckage wrote: Thu Aug 11, 2022 11:36 am
The Elf wrote: Thu Aug 11, 2022 11:29 am Each time this topic comes up I find it incredulous that this one hasn't been solved after all this time. :(

If a solution were to be found, who would provide it? Microsoft? Does Apple architecture allow multiple USB audio streams?

YAMAHA [as in YAMAHA Steinberg ASIO driver]

I believe Apple handles multiple AI because devices are USB class compliant and dont need drivers.

Windows can handle multiple drivers if they are different but it cant handle multiple asio driver instances.

So for instance, I cant use Yamaha USB synth outputs at the same time as a Yamaha guitar amp or Yamaha audio interface.

:madas:

Is this a nail in the coffin of USB microphones ?

In a multitracking scenario, I would only be using 1 device at a time and would be happy to press a hot key to select which driver is in use i.e. which driver is the timing master.
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Re: Why is only one USB audio path allowed?

Post by resistorman »

N i g e l wrote: Thu Aug 11, 2022 6:02 pm Is this a nail in the coffin of USB microphones ?

It's a distinct disadvantage :D I'd be interested in hearing from Mac users that use aggregate USB devices in their everyday workflow. It seems to me that having a single interface with multiple analog inputs or networked digital devices would be the best way to do production?
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