Re: handing audio dropouts with synchronized input and output
Re: handing audio dropouts with synchronized input and output
- Subject: Re: handing audio dropouts with synchronized input and output
- From: Paul Davis <email@hidden>
- Date: Wed, 08 Aug 2012 14:06:46 -0400
On Wed, Aug 8, 2012 at 1:45 PM, Brian Willoughby
<email@hidden> wrote:
Many built-in chip sets are USB. If you are sure that this one isn't, then I assume that the only reason Apple have handled it the way they did is because the clock sources are separate for input and output. If one single clock were used for both, then they'd actually be forced by the CoreAudio design specifications to provide a duplex driver.
The chipset on the motherboard of most intel and related systems is Intel HDA compliant. It is not accessed or controlled via USB, but uses the PCI bus (or variant thereof).
Perhaps you are interpreting my use of "builtin" to mean "drivers builtin to OS X" rather than "devices builtin to your mac".
Read the rest of my email - the part you didn't quote. The crux of this matter is CoreAudio and the way Apple have designed it from the start. USB is just one example of where the actual hardware behavior might not be what an application wants, and thus somewhere the missing pieces must be supplied (even if the pieces come from CoreAudio itself, such as AudioConverter AudioUnits).
The overwhelming majority of pro- and prosumer audio interfaces come with duplex device drivers because they are manufactured to correctly use the same clock source for both directions. My impression is that this is true for most pro- and prosumer USB devices too.
I personally don't consider any device that offers both playback and capture but uses different clocks (let alone different interrupts) to be worth paying any attention to. Unfortunately, Intel HDA has forced a lot of us to pay attention to something that is inherently just a poorly thought out specification, assuming that you care about audio engineering.
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