Re: Skipping backward and forward
Re: Skipping backward and forward
- Subject: Re: Skipping backward and forward
- From: "Sean Morrell" <email@hidden>
- Date: Wed, 27 Mar 2002 16:19:47 -0800
email@hidden writes:
>
on 3/27/02 9:08 AM, Sean Morrell <email@hidden> wrote:
>
>
> To track down some anomalies in the audio, I added some debug code to
>
> convertInputSamples and clipOutputSamples. I compare the last sample
>
> frame read or written in a call, to the first sample frame in the next
>
> call. And I find that CoreAudio will sometimes skip ahead in the buffer
>
> from where it last transferred data. This would seem to leave blocks of
>
> the buffer either unread or unwritten. And sometimes CoreAudio jumps
>
> back, reading/writing blocks of samples frames again. Now I'm not for
>
> sure this accounts for my audio anomalies. But can someone verify that
>
> this is normal behavior? If not, under what circumstances does this
>
occur?
>
>
This is normal behavior for a driver to see. Remember, in the driver you
>
are
>
seeing things from a global perspective. This means you are seeing the
>
interactions of multiple instances of the HAL in separate processes that
>
don't know anything about each other.
Would this be normal behavior even when a single application is being
used? Additionally, I don't notice this problem with Daisy. But I do get
these skips using a third party application. CPU Monitor shows the system
60 to 80 percent continuously busy when this application is in use. I
don't know if this is relevant. Also, I don't see a lot of what I'm
calling skips. In running the audio engine for 10 minutes, I might get
anywhere between 1 to 25 skips.
>
>
>
--
>
>
Jeff Moore
>
Core Audio
>
Apple
>
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