Re: Info on HALLab telemetry window?
Re: Info on HALLab telemetry window?
- Subject: Re: Info on HALLab telemetry window?
- From: Jeff Moore <email@hidden>
- Date: Wed, 16 Aug 2006 14:28:47 -0700
Both of the situations you describe indicate that your driver is
likely not generating time stamps that accurately describe what the
hardware is doing.
Your A case symptoms are what I'd expect to see from a driver that has
a very jittery clock but doesn't have a large enough safety offset.
Your B case seems to be ignoring the hardware in it's time stamps.
This leads to the HAL drifting away from where the hardware really is.
So basically, you need to figure out a way to generate better time
stamps. Perhaps you should describe your hardware and how your driver
works, especially how it deals with time stamps. I might be able to
help you increase the accuracy.
On Aug 16, 2006, at 2:20 PM, peoplestank wrote:
Hi Jeff-
Thanks for your response. From the basic info plus
some other archived posts on HALLab I have been able
to figure out a few things about the driver I'm
developing:
1) I can generate time stamps in my driver from
either the output or the input streams
a) When I use the output, I get generally smooth
audio except for occasional glitches, but the "rate"
parameter in HALlab fluctuates quite a bit. There are
no overloads (red lines) recorded.
b) When I use the input, rate is spot on 1.000000
for the entire duration, but I get frequent glitches
along overload/red-lines periodically.
Anything come to mind. I can post a screenshot of
case b) with one of the overloads opened for detailed
info, or should I mail that off-list?
Thanks!
--- Jeff Moore wrote:
On Aug 15, 2006, at 4:59 PM, peoplestank wrote:
Is there any documentation explaining the data
in the HALLab
telemetry window.
There is no documentation, per se, but you do have
the source code
right there on your machine. That plus knowing that
the telemetry is
logging events that happen during a work cycle of
the IO thread, you
can figure a lot of it out.
You can also ask questions here. I'm happy to help
you interpret the
telemetry.
Also, I can't figure out how to enable the latency
tracing function
(which is really what I'm looking for), any help?
HALLab has to be run as root to enable the latency
tracing.
--
Jeff Moore
Core Audio
Apple
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--
Jeff Moore
Core Audio
Apple
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