Re: buffer gaps
Re: buffer gaps
- Subject: Re: buffer gaps
- From: Kurt Revis <email@hidden>
- Date: Sun, 19 Oct 2003 12:20:59 -0700
On Sunday, October 19, 2003, at 05:28 AM, Daniel Todd Currie wrote:
I am recording 0.5 second audio samples using a simple HAL IOProc to
be sent to an FFT unit. The audio comes in buffers of 512 frames, but
when I merge the buffers together, there are discontinuities in the
data. I fear that these discontinuities are tainting my FFT results.
Is there supposed to be a "gap" in the buffer data, if so what size?
What can I do to make sure that my data will be as continuous as
possible?
There should not be any gaps or overlaps in the buffers that your
IOProc receives. You could check the timestamps given to your IOProc
and see if they match up to what you expect.
Are you doing a significant amount of work in the IOProc? If
you take too long, CoreAudio will be forced to drop some data. Ideally
you would do as little work as possible in the IOProc -- just copy the
data and get out. You can do the FFT in some other thread.
Also, are you looking at the raw audio samples, or the result of the
FFT? If you are not properly windowing your FFT, you may see some weird
results which could look like "discontinuities". (I'm kind of grasping
at straws here...)
(BTW, my mail sent to <email@hidden> bounced, with the error
"unrouteable mail domain 'dtcurrie.net'. So this is going to the whole
list as well.)
--
Kurt Revis
email@hidden
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| References: | |
| | >buffer gaps (From: Daniel Todd Currie <email@hidden>) |