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Re: AudioHardwarePlugIn question
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Re: AudioHardwarePlugIn question


  • Subject: Re: AudioHardwarePlugIn question
  • From: Jeff Moore <email@hidden>
  • Date: Wed, 20 Oct 2004 13:05:19 -0700

Presumably, you have a thread or some other periodic mechanism that is calling out to the IOProcs to provide the data, so I'd start off by looking at that mechanism and be sure that it works and then look at the data the client is giving you to see if they are giving good data.

On Oct 18, 2004, at 6:08 AM, Dirk Musfeldt wrote:

Jeff,

OK, thanks for that basic answer. I implemented the float format now and do
not support hog mode.


I ran the ComplexPlayThru sample and it did not catch any errors. But I
didn't hear anything, though. :-(

What is the easiest way to determine the problem with this implementation?


There are two formats that you have to maintain, the virtual format
(the format that IOProcs see) and the physical format (the format that
your device does IO in). In the non-linear PCM case or the non-mixable
linear PCM case, these two formats are the same. In the case of mixable
linear PCM, the virtual format will always be native endian 32 bit
floats, regardless of what the physical format is. Your plug-in is
responsible for doing any necessary conversions.


Note that the non-mixable formats imply single client access, so you
will need to manage hog mode properly as well. Note also that most apps
won't work with non-mixable formats.


On Oct 14, 2004, at 8:45 AM, Dirk Musfeldt wrote:

Hi all,

I'm doing an AudioHardwarePlugIn.

Which stream formats do i need to support to be of any use?

I tried with

48000.0,
kAudioFormatLinearPCM,
kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsBigEndian |
kAudioFormatFlagIsPacked,
4,
1,
4,
2,
16 // the number of bits in each channel


but this does not give any success. This is the 'natural' format of our
data.


Any advice?



Regards

Dirk


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Regards

Dirk




--

Jeff Moore
Core Audio
Apple


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