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Re: strange noise when using remoteIO unit for playback and record simutaneously
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Re: strange noise when using remoteIO unit for playback and record simutaneously


  • Subject: Re: strange noise when using remoteIO unit for playback and record simutaneously
  • From: Gregory Wieber <email@hidden>
  • Date: Fri, 07 Mar 2014 07:16:41 -0800

Is your render code respecting the buffer size? I assume you're converting formats correctly -- if you're able to get playback working.

It's possible your code is too intensive for the small buffer. Have you tried using the Accelerate framework where you can to optimize any calculations?

Try getting a line out and recording the glitches -- sometimes the waveform can provides clues as to what's going on.


Sent from my iPhone

> On Mar 7, 2014, at 6:50 AM, Dean Ji <email@hidden> wrote:
>
> I want to build a karaoke app for iOS which takes in the singer’s voice and combines it with the accompaniment track signal back to the speaker. remoteIO is my choice.
>
> I chose to instantiate one remoteIO for playback and another remoteIO for recording. I had tested that the recording and playing back woks well, respectively. However, after combining those together, I get glitch noise whenever someone speck to de microphone.  And I am not sure what the problem is.
>
> The Recording format is 16000Hz, 1ch, 16bit, PCM
> The PlayBack format is   44100Hz, 2ch, 16bit, PCM
>
> The following is what I found:
>
> When combining, the remote IO render call back buffer size become unstable(jump from one value to another), In my case, the bigger value is about 4096 bytes and the small value is about 400 bytes. And I think the bigger value is use for playback and the smaller one is for recording.
>
> It’s really a nasty bug for me. Thanks in advance for your kind response!
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References: 
 >strange noise when using remoteIO unit for playback and record simutaneously (From: Dean Ji <email@hidden>)

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