13-Mar-2015, 22:22
(This post was last modified: 13-Mar-2015, 22:26 by thumb5.
Edit Reason: Removed statement about USB audio class 2 requiring USB 2.0.
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Hello Stigmater - I'm not sure where you found that information about USB audio, but if you don't mind me saying so, it's rather inaccurate, if not totally misleading.
First of all, it's confusing the USB audio device class specification with the USB (core) specification. USB audio device class 1.0 is not saddled with USB 1.1 but can operate over a USB 2.0 high-speed (480 Mbps) bus.
Secondly, both USB audio class 1.0 and 2.0 support asynchronous transfer. The main advantage of this is nothing to do with absolute data rates. Instead it relates to how small differences in the clock frequencies at each end of the link are dealt with to avoid long-term drift and possible sample loss. Asynchronous protocol allows the peripheral (e.g. DAC) to use its own clock to regulate the flow of data on the USB bus, rather than having to adapt to the clock generated by the host. (That's the gist of it, anyway.)
First of all, it's confusing the USB audio device class specification with the USB (core) specification. USB audio device class 1.0 is not saddled with USB 1.1 but can operate over a USB 2.0 high-speed (480 Mbps) bus.
Secondly, both USB audio class 1.0 and 2.0 support asynchronous transfer. The main advantage of this is nothing to do with absolute data rates. Instead it relates to how small differences in the clock frequencies at each end of the link are dealt with to avoid long-term drift and possible sample loss. Asynchronous protocol allows the peripheral (e.g. DAC) to use its own clock to regulate the flow of data on the USB bus, rather than having to adapt to the clock generated by the host. (That's the gist of it, anyway.)
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