Andrew_WOT
Headphoneus Supremus
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- Jan 18, 2004
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There could be semantics of terminology. Traditional isochronous was unstable mess due to clock derived from the packets, what they refer to as asynchronous nowadays is what you describe with external clock on DAC side. It was quite a revolutionary breakthrough when new gen USB DACs started getting equipped with these new receivers. I remember using that external USB dongle from iFiAudio with my Chord DAC to bypass its inferior isochronous receiver, before I upgraded to more modern one (Auralic) that had new type of the receiver onboard.Really?
UAC1 and UAC2 use USB in isochronous mode. That is simply the standard.
When they started with USB audio around 2000 they used the frame rate for synchronization. A pretty jittery solution.
Later (2005?) adaptive mode implementations become popular.
From 2009 on, async become popular.
Today almost all USB audio is USB Audio Class 2 so the bus will be run in isochrone mode with asynchrone synchronization.
If you look at measurements you will see that USB in general outperforms the classic protocols like SPDIF in the jitter departement.
But latency aside, streamers are the cleanest way to get audio out of PC.
Great whitepaper to learn about USB Audio and its history.
https://www.thewelltemperedcomputer.com/KB/USB.html
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