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Re: Trouble recording using the AUHAL unit.
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Re: Trouble recording using the AUHAL unit.

  • Subject: Re: Trouble recording using the AUHAL unit.
  • From: "Dave O'Neill" <email@hidden>
  • Date: Mon, 11 Jan 2016 10:38:24 -0800
I use TPCircularBuffer written by Michael Tyson,  it uses a memory mirroring technique described by Mike Ash.  I have a post on StackOverflow where I give a quick example for iOS (implementation is same for OS X).

Mike ash - https://mikeash.com/pyblog/friday-qa-2012-02-03-ring-buffers-and-mirrored-memory-part-i.html
TPCircularBuffer - https://github.com/michaeltyson/TPCircularBuffer
StackOverflow post - http://stackoverflow.com/questions/30691684/whats-the-reason-of-using-circular-buffer-in-ios-audio-calling-app/30698791#30698791

On Mon, Jan 11, 2016 at 10:07 AM, Alexander Bollbach <email@hidden> wrote:
but essentially, the ring buffer functions as a method of temporarily holding the audio samples in memory from the rendering function in the realtime thread and than quickly reading those samples for some other purpose elsewhere?  using the timestamp to coordinate what exactly?  and wouldn't the ring buffer eat its tail eventually if the realtime callback was dumping sample data into the ring buffer faster than i could write it to disk?  I'm sorry but i find this just a bit difficult to negotiate in my head.

On Mon, Jan 11, 2016 at 12:43 PM Paul Davis <email@hidden> wrote:
On Mon, Jan 11, 2016 at 12:15 PM, Alexander Bollbach <email@hidden> wrote:
thinking a little more,  given that i'm recording an arbitrarily long amount of audio, preallocating a buffer will not be possible, right?  Is that where a circular buffer comes in?  would I use the much used CARingBuffer?  If so, could I get some intuition about the timestamps.  I've followed chapter 8 of Chris Adamson's Learning Core Audio book and I sort of have a sense for using a RingBuffer but i'm not entirely clear on the concept of the timestamps you pass into it.

Yes you need a ringbuffer.

I can't comment further because my audio software is cross-platform so I'm not familiar with the infrastructure offered by OS X or iOS.
 

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References: 
 >Trouble recording using the AUHAL unit. (From: Alexander Bollbach <email@hidden>)
 >Re: Trouble recording using the AUHAL unit. (From: Paul Davis <email@hidden>)
 >Re: Trouble recording using the AUHAL unit. (From: Alexander Bollbach <email@hidden>)
 >Re: Trouble recording using the AUHAL unit. (From: Alexander Bollbach <email@hidden>)
 >Re: Trouble recording using the AUHAL unit. (From: Paul Davis <email@hidden>)
 >Re: Trouble recording using the AUHAL unit. (From: Alexander Bollbach <email@hidden>)

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