Re: Completely not getting it with AudioBufferList and CASpectralProcessor
Re: Completely not getting it with AudioBufferList and CASpectralProcessor
- Subject: Re: Completely not getting it with AudioBufferList and CASpectralProcessor
- From: William Stewart <email@hidden>
- Date: Wed, 3 Dec 2008 17:51:35 -0800
On Dec 3, 2008, at 4:16 PM, David Preece wrote:
Thanks for this Bill,
On 3/12/2008, at 7:43 AM, William Stewart wrote:
[snip]
Audio Units use a canonical format of de-interleaved audio data -
we wanted to use one standard layout so it would be trivial to pass
audio data from one audio unit to the next. So, all effects will
only generally deal with de-interleaved data.
Makes sense. A quick aside: Can I take it as read that float32 is
the "preferred" format for audio unit chains?
expected is a better word. The only audio units that may take other
formats at this point are converter and output units for the desktop.
Have a look at AUOutputBL in Public Utility - that is robust for
creating an ABL that will represent different "layouts" of linear
PCM in an audio stream basic description
Right, so I can construct one of these using an
AudioStreamBasicDescription (actually a CAStreamBasicDescription
that's cast)
(dont' even have to cast it as a CAStreamBasicDescription is a(n)
AudioStreamBasicDescription)
which is the same stream description I'm setting as the client
format on the source file (via ExtAudioFileSetProperty -
kExtAudioFileProperty_ClientDataFormat). However, whenever I try to
do this with a non-interleaved stream description
(streamDescription.mFormatFlags=kAudioFormatFlagIsNonInterleaved |
kAudioFormatFlagIsFloat) the call fails with error 1718449215 which
does not appear to be documented.
1718449215 == ?fmt
bad format error - there's something wrong with the format you are
trying to set. In the flags above, you probably need to be using the
packet flag as well - if you use CAStreamBasicDescription to construct
your ASBD does that work (it should)?
Am I to take it that I can only extract audio in the interleaved
format? Does this apply to writing as well? Am I to take it that I
should de-interleave manually? - in itself not a problem except for
my dislike of reinventing the wheel.
ExtAudioFile should deal with either I think
Bill
Thanks,
Dave
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