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Re: Userland driver: Not enough headroom at first in IO operation.
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Re: Userland driver: Not enough headroom at first in IO operation.


  • Subject: Re: Userland driver: Not enough headroom at first in IO operation.
  • From: Eric Gorouben <email@hidden>
  • Date: Fri, 30 Aug 2013 22:01:36 +0200

As far as I understand, and after measuring the effect of these two parameters on the IO loop, the safety offset is actually the exact extra headroom frames added (inSampleTime ≈ theroretical_SampleTime - safety_offset), while the latency seems to have no effect.
Is this correct?

Thanks
Eric
Le 29 août 2013 à 22:22, Ploytec a écrit :

> Hi,
>
> I frequently can’t get enough headroom at the beginning of a recording. My real sample time is sometimes significantly lower than expected due to jitter, delay or drift.
> The problem is especially acute when the device is aggregated.
> Yet, at startup core audio doesn’t know about this jitter or delay or drift. It expects an amount of available data (buffer size + sample time) just slightly under the theoretical value of available samples (given the sample rate and initial zero host time)
> I’ve tried to play with the latency value or safety offset, but this does not give good results (if any).
> I’ve also tried fancy delays but probably too fancy…
> What am I missing?
>
> Desperately seeking for help!
> Thanks
> Eric
>
>
>
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  • Follow-Ups:
    • Re: Userland driver: Not enough headroom at first in IO operation.
      • From: Brian Willoughby <email@hidden>
References: 
 >Can we safely drop Carbons support for audio units? (From: Stefan Huber <email@hidden>)
 >Re: Can we safely drop Carbons support for audio units? (From: Stefan Gretscher <email@hidden>)
 >Re: Can we safely drop Carbons support for audio units? (From: Stefan Huber <email@hidden>)
 >Userland driver: Not enough headroom at first in IO operation. (From: Ploytec <email@hidden>)

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