Re: asynchronous change of kAudioStreamPropertyPhysicalFormat
Re: asynchronous change of kAudioStreamPropertyPhysicalFormat
- Subject: Re: asynchronous change of kAudioStreamPropertyPhysicalFormat
- From: Jeff Moore <email@hidden>
- Date: Wed, 21 Dec 2005 17:05:25 -0800
On Dec 21, 2005, at 4:51 PM, Derk-Jan Hartman wrote:
I'll have to find a way around it I guess, with multiple locks
and timeouts.
I did this, and now it works.
Great!
I have one more question, according to a user the Motu 828 mkII
didn't like that i'm trying to set Hog mode. Should I allow for
such a fluke? or should I fail in that case (critical?)? playback
works with DVD player according to the user.
Hog mode is not something a particular device can override or have
any input into. Hog mode is entirely managed by the HAL. In fact,
the only thing the device knows about hog mode is how many clients
are doing IO at any given time. When some process owns hog mode,
it just always happens to be one. The funny thing is that the
IOAudio family will apply a number of optimizations to the signal
flow when there is only one client, regardless of whether or not
that client owns hog mode.
At any rate, the MotU FireWire boxes don't support non-mixable
flavors of LPCM nor do they support AC-3, so I imagine that the
problem you are having is not with hog mode per se, but rather
with the non-mixable/AC-3 stuff. And yes, you should definitely be
prepared to deal with this case.
That said, if it is something to do with hog mode, I'd have to
know a bit more about the circumstances to provide a better answer
since the particular device involved shouldn't matter.
That's always the problem I guess for software developers :D You
don't have all the devices..
True.
Perhaps I should contact MOTU directly. Do you have email-addresses
of their engineers or something which I could try? (off the list of
course)
Sending emails to support is generally a waste of time in my
experience. It was the same for M-Audio. Engineers eager to help,
Support not that much.
Before I went that route, I'd press the user for more information on
the issue. It seems to me that one user report likely means that it
is likely an issue with the user's machine, environment, etc. as
opposed to a particular piece of hardware.
Another thing you can do is create a version of the
AudioReflectorDriver that is configured to look like an 828 and try
things out. (An 828, as it's name implies, has three streams. The
first has 8 channels. The second has 2. The third has either 8 or 2
depending on how the optical port is configured. All the streams only
support mixable, big-endian 24 bit signed integer data at either
44.1k or 48K sample rates. I can't remember offhand if the 24 bit
data is aligned high in 32 bits, but I think it might have been.)
Hopefully in the coming year the devices, api and applications will
all "stable"-out a bit.
I wouldn't bet on it. If anything, devices are going to get weirder
in coming years if you asked me.
Thank you for your time again :D
Happy to help.
--
Jeff Moore
Core Audio
Apple
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