Re: IOAudioDevice and Sample Rate Deviation
Re: IOAudioDevice and Sample Rate Deviation
- Subject: Re: IOAudioDevice and Sample Rate Deviation
- From: Jeff Moore <email@hidden>
- Date: Fri, 13 Jun 2003 16:13:33 -0700
This is the property you would use in a call to
AudioDeviceGetProperty() to retrieve the actual sample rate as
determined by the time stamps your driver provides. It's talked about
in <CoreAudio/AudioHardware.h>.
On Friday, June 13, 2003, at 4:09 PM, Dirk Musfeldt wrote:
Jeff,
could you please point me to the definition of
kAudioDevicePropertyActualSampleRate ?
As long as your time stamps reflect the variance and your safety
offset
is set large enough to account for the jitter and any physical access
issues, the HAL will track any variance in the actual sample rate of
your device. This is reflected in kAudioDevicePropertyActualSampleRate
as well as in the duration of the IO cycle for the HAL's clients.
On Friday, June 13, 2003, at 2:51 PM, Dirk Musfeldt wrote:
Hi all,
I have a PCI device and a IOAudioDevice that handles the sound input.
Do I have to care about deviations from the nominal sample rate?
I have a deviation of 0.7 Hz (on my card in my Mac) and I have the
assumption that this leads to the sound distortions I observe. If my
write
head is constantly faster than the read head something will go wrong
sooner
or later.
Does the Audio HAL care for this kind of deviation? It is not stated
directly but that was my understanding of the documentation.
If it does not care for this how should I care?
--
Jeff Moore
Core Audio
Apple
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
Mit freundlichen Gr|_en
Dirk Musfeldt
Meilenstein Mac OS Software
Neue Strasse 5
D-31582 Nienburg
Tel: +49 (0) 5021 91 24 44
Fax: +49 (0) 5021 91 24 45
<http://www.meilenstein.de/>
--
Jeff Moore
Core Audio
Apple
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.