Re: MOTU 896 vs. MOTU 896HD
Re: MOTU 896 vs. MOTU 896HD
- Subject: Re: MOTU 896 vs. MOTU 896HD
- From: Derk-Jan Hartman <email@hidden>
- Date: Thu, 19 Jan 2006 03:21:53 +0100
On 18-jan-2006, at 21:07, Jeff Moore wrote:
The problem is that you are totally failing to account for the fact
that different devices can have different stream layouts. In fact,
the code you provided shows a common mistake that developers make.
It will only ever affect the first stream on the device. Since the
896 and the 896HD are both multi-stream devices and yet have
different streams layouts, your code doesn't work with them. It
will also fail on devices like the Metric Halo devices where each
channel is in it's own stream.
In order to work correctly with multi-stream, you must manage
format info at the AudioStream level, as opposed to the AudioDevice
level. This means you have to get the stream list from the device
and walk it to discover/change the format on each stream.
Which is exactly the reason why you should use AUHAL where you can
btw. It allows you to use your AudioDevice in a much simpler way,
while you still have support for all the same formats, amounts of
channels, and channel orders.
There are so many ways devices deal with channels and streams, to
support all audio devices directly trough CoreAudio is almost
impossible in my experience. Of course for some specific things, you
simply can't get around it, but I doubt your software is that demanding.
I say use AUHAL over pure CoreAudio where you can, it will save you a
lot of headaches.
DJ
On Jan 18, 2006, at 12:17 AM, Christof Faller wrote:
Dear list,
I have a software that uses N output channels (N = 2...32,
whatever desired).
With the MOTU 896 I can initialize with the code below. When I set
MOTU analog
as default device in Audio MIDI Setup and run this code I will
initialize with
8 channels.
However, the same with the MOTU 896HD gives me only two channels,
despite of
choosing the MOTU "analog", where it shows in the Audio MIDI Setup
8 channels.
Does anyone have a clue why that is? (Also, interestingly the same
method
for audio input works on both, 896 and 896HD).
--
Jeff Moore
Core Audio
Apple
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