Re: AudioDeviceRead and timestamps
Re: AudioDeviceRead and timestamps
- Subject: Re: AudioDeviceRead and timestamps
- From: Andrew Kimpton <email@hidden>
- Date: Sat, 21 Jun 2003 09:08:29 -0700
Jeff Moore wrote:
The PlayEffect sample code uses AudioDeviceRead. You can consult that
code for a usage example.
Yep I've looked at that sample - the (subtle ?) difference is that the
AudioDeviceRead timestamps are initialized through the AU Render
Callback timestamps. I'm guessing ultimately that those timestamps come
from a device timestamp, but is that actually the case ?
I think that the root of your problem is that you aren't leaving
enough slop when calculating the input time. The reason why is that
the current time is already too late so you need to back off a bit
(determined by experimentation) before subtracting the safety offset
and the buffer size.
I also see that in the PlayEffect sample you adjust the safety offset by
+16 (with a comment about inadequate safety offsets due to cache
effects). That would have the same effect as above, and indeed I've done
similar in my own code and tried values of 1, 8, and 16 to no avail.
A suggestion another list reader had was to try incrementing sampleTime
myself by 512 (starting from the initial callback value) but I'm not
sure how that would work ?
Thanks for the response Jeff, I may just try and catch up with you at
the lab at WWDC on Wednesday.
Andrew 8-)
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