Re: I/O Latency (Was: Layman with a mission)
Re: I/O Latency (Was: Layman with a mission)
- Subject: Re: I/O Latency (Was: Layman with a mission)
- From: William Stewart <email@hidden>
- Date: Wed, 13 Oct 2004 16:22:42 -0700
On 13/10/04 3:46 PM, "John Pitcairn" <email@hidden> wrote:
> Bill, Phillipe, thanks for your responses. Again, note I am bcc-ing RME.
>
>> At 12:03 PM -0700 10/13/04, William Stewart <email@hidden> wrote:
>> Given these numbers (RME differences between OS 9 and OS X), I think the
>> real issue is the quality and performance of this driver.
>>
>> I think that is also what Angus/Brian are trying to say - that the
>> fundamental disparity here is NOT an architectural problem in Mac OS X, but
>> rather a specific problem with the RME driver. I don't understand personally
>> why the RME driver cannot get to a similar figure of 192 samples on X -
>> particularly as other manufacturer's devices/drivers show that this is
>> indeed entirely possible.
>
> Can you provide an example of a multichannel device that can achieve
> that sort of latency under OS X? In Logic perhaps?
As previously stated, Logic is adding an additional 60 samples of latency -
you'd need to get a response from them about why this is the case (As I
previously noted, some applications do this deliberately, so we'd have to
hear back from them).
As to drivers that can do this already. M/Audio's PCI card has some good
latency figures as do the MOTU interfaces - I'm sure there are others.
>> I'd suggest following up with RME - a comment/complaint from a user goes a
>> long way...
>
> RME suggest that there are two factors involved - the safety offset
> of the CoreAudio driver (32 each way for the Multiface I think),
> which is not used under ASIO in OS 9, and additional buffering by the
> application (Logic in this case).
Right - but this is a driver they are writing, so the first question I'd ask
them is if this is necessarily that high. This is certainly an area that a
driver writer can have a substantial contribution.
> It was suggested that Logic is using approx 64 samples of additional
> buffering when running in OS X. Would anyone in the know care to
> comment?
Bill
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