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Re: achieving very low latency
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Re: achieving very low latency


  • Subject: Re: achieving very low latency
  • From: Dave Fernandes <email@hidden>
  • Date: Wed, 04 Jul 2012 14:43:37 -0400

Sub-ms latency on a Unix-based OS? I'd be surprised if that were possible. I think you would need an RTOS, though you may prove me wrong. Are there any Arduino or NI cards that allow you to download the waveform to the card and play it from there based on a pushbutton "start" signal to the card?

On 2012-07-04, at 2:28 PM, Daphne Ippolito wrote:

> I've tried buffers of 32 bytes, and I still get ~30 ms of delay. I
> don't think I can go much lower than that? I am using an only slightly
> revised version of the sample code from the Learning Core Audio book.
>
> -Daphne
>
> On Wed, Jul 4, 2012 at 2:18 PM, Robert Martin <email@hidden> wrote:
>> Use smaller buffers?
>>
>> On Jul 4, 2012, at 11:42 AM, Daphne Ippolito wrote:
>>
>>> In the experiment, a physical pushbutton is pressed (the old system used a
>>> National Instruments card to record this; I am using an Arduino) that plays
>>> a sound. I am referring to latency as the time between when the physical
>>> button is pressed and when the sound outputs from the audio jack. I have
>>> been measuring this with an oscilloscope.
>>>
>>> With Core Audio, I have not been able to get this time gap lower than 30
>>> ms. I have tested the Arduino independently and it is not contributing more
>>> than 1 ms of delay.
>>>
>>> This is my first time programming with audio, so I am still a bit unclear
>>> on how it works. I've been told that I can't have more than 10 ms delay
>>> between when the pushbutton is pressed and when the sound leaves the
>>> speakers, and preferably less than 1 ms.
>>>
>>> Any advice on how I can accomplish this?
>>
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References: 
 >achieving very low latency (From: Daphne Ippolito <email@hidden>)
 >Re: achieving very low latency (From: Paul Davis <email@hidden>)
 >Re: achieving very low latency (From: Daphne Ippolito <email@hidden>)
 >Re: achieving very low latency (From: Robert Martin <email@hidden>)
 >Re: achieving very low latency (From: Daphne Ippolito <email@hidden>)

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