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Re: Crackling audio output with command-line tool
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Re: Crackling audio output with command-line tool


  • Subject: Re: Crackling audio output with command-line tool
  • From: Jeff Moore <email@hidden>
  • Date: Mon, 15 Oct 2007 18:15:38 -0700

Generally, the reason for this behavior is that your tool is missing the real time deadlines for whatever reason. This is likely because the priority of one or more of the threads involved in producing the audio data is getting depressed by the switch into the background. But, you'll have to be a bit more specific about how the tool works before we can give you a better assessment of what might be going wrong.


On Oct 5, 2007, at 11:57 AM, Mihir Sarkar wrote:

Please forgive if this is not the right forum to post this...

I am porting someone else's audio processing code to Mac OS X. The program is written in C and I am building it as a standard (command- line) tool in Xcode. I am using the CoreAudio framework for audio I/ O. When I run the application on Terminal, it sounds fine... until I click on any other window in my desktop environment and Terminal loses focus. Then the sound starts to crackle. There doesn't seem to be any obvious pattern in the way it sounds but it happens somewhat consistently. One hypothesis is that on losing focus the process runs in the background (with a lower priority?) and doesn't get enough cycles to fill up its output buffers. Or it could be a completely different reason. I am just wondering if someone came across something similar and might want to share their experience (and solution or approach) with me.

Please let me know if you need more info on the way I implemented my calls to CoreAudio.

--

Jeff Moore
Core Audio
Apple


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 >Crackling audio output with command-line tool (From: Mihir Sarkar <email@hidden>)

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