Re: Largest channel input count for any Core Audio Device ?
Re: Largest channel input count for any Core Audio Device ?
- Subject: Re: Largest channel input count for any Core Audio Device ?
- From: Jeff Moore <email@hidden>
- Date: Wed, 29 Sep 2004 12:19:35 -0700
I prolly ought to have thrown a "theoretically" in there somewhere. The
buffer space alone for that many channels would be astonishingly huge.
I can't imagine how long it would take to mix/clip that many channels
in the kernel. You'd need some serious iron to pull it off in real time
=)
At any rate, I hope the point was clear that devices can have a lot of
channels and the theoretical limit is quite large. It's best to design
your UI to accommodate a scrolling view of the channel strips so that
the upper limit doesn't have to be fixed.
On Sep 29, 2004, at 12:03 PM, John Stiles wrote:
Given that we currently use a 32-bit OS, and allocating or connecting
a channel will probably consume at least 1 byte of memory in some way
somehow, isn't 2^32 a more reasonable limit? 2^64 seems a bit too
pedantic--wouldn't want to use UInt64s for everything if we can avoid
it! :)
OTOH, I agree that a limit of 20 is far too low ...
On Sep 29, 2004, at 11:46 AM, Jeff Moore wrote:
If I have the math right, the maximum number of total channels on a
device in a given direction is 2^64. You get this by the fact that
the HAL allows for a device to have up to 2^32 streams each of which
can have 2^32 interleaved channels. (These are the limitations of the
AudioBufferList structure.)
Now, you might say that no device will ever have that many channels,
but you'd be wise to write your code as if it could happen.
On Sep 29, 2004, at 9:44 AM, Mark Gilbert wrote:
Folks.
Does anyone know the coreaudio device with the largest number of
input channels ?
So far, I have found the MOTU 896HD, which registers 20 input
channels.
Does anyone know of any devices with more than 20 input channels ?
I am doing some GUI design and it would be nice to know the max
channels currently available for a single core audio input device.
Thanks
Mark Gilbert.
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