Re: AudioServerPlugin: resynchronization
Re: AudioServerPlugin: resynchronization
- Subject: Re: AudioServerPlugin: resynchronization
- From: Jeff Moore <email@hidden>
- Date: Thu, 12 Dec 2013 14:58:32 -0800
Comments inline.
—
Jeff Moore
Core Audio
Apple
On Dec 12, 2013, at 5:46 AM, Bertrand Van Kempen <email@hidden> wrote:
> Hello,
>
> Asking again because I'm still stuck on this one ;-(
>
> I would like to ask the HAL to resynchronize it's PLL on certain condition (i.e. when the external clock has changed).
> To do so, I increment the outSeed value returned by GetZeroTimeStamp but it looks like the HAL just ignores the seed.
Sounds like a bug. Please file it!
> At this point, the only way I find to "force" the HAL to resynchronize it's PLL is to change the sampling rate.
>
> How I have to do?
The general mechanism to interrupt IO is the RequestConfigChange/PerformConfigChange mechanism. You are using that mechanism for your sample rate change, but you don’t have to actually change the sample rate. Your Perform operation could be a no-op.
> Note: I noticed that inIOCycleInfo.mIOCycleCounter is always zero?!?
> the documentation says:
> @field mCycleCounter
> The cycle ordinal number. This number starts at 1 for the first IO cycle and
> increments for each subsequent IO cycle. The count will recycle back to 1
> whenever the IO thread resynchronizes with the hardware.
> Is it a known issue?
No. It is not a known issue. Please file a bug!
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