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Re: Problem with AudioQueueOfflineRender in iOS4
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Re: Problem with AudioQueueOfflineRender in iOS4


  • Subject: Re: Problem with AudioQueueOfflineRender in iOS4
  • From: infrequent <email@hidden>
  • Date: Fri, 25 Jun 2010 09:40:47 +0100

Zach,

I'm doing pretty much the same thing and it's working here on iOS4
final (2G iPod).  The only issue I encountered was the offline queue
running out of samples, so I make a second call to
AudioQueueOfflineRender() where the first call returned fewer packets
than the size of my remoteIO playback buffer.  But aside from that
it's working well for a variety of different buffer sizes.

rgds

Pierre

On Thu, Jun 24, 2010 at 9:27 PM, Zachary Kulis <email@hidden> wrote:
> Hi all,
>
> I finally installed XCode 3.2.3 and the iOS4.0 SDK today, and I'm
> experiencing some very strange behavior with the AudioQueueOfflineRender
> API. I am using the API to decode MP3 files on-the-fly into PCM data.
> This strategy has worked fine in OS 2.2.1-OS 3.2. After upgrading my
> iPhone to iOS4, however, the AudioQueueOfflineRender() function
> occasionally reports that it has decoded 0 frames, even though no error
> code is returned and there are plenty of enqueued packets ready for
> decoding (approximately 1.5 seconds of compressed audio enqueued).
>
> The really odd thing is that if I put a do {}
> while(numFramesRendered==0) around this AudioQueueOfflineRender()
> function call, the decoder eventually decodes the requested frames.
> However, strange things start to happen after about 5-10 seconds into
> the audio stream; the sound quality deteriorates and random
> crackling/static is present in the decoded PCM data. As time progresses,
> the audio quality continues to deteriorate, until finally a loud
> squealing sound develops (almost like feedback), and the decoded audio
> is completely obscured.
>
> I've tried running the same code on my iPod Touch 2G (which is currently
> running OS 3.1.2), and everything seems fine. The problem only occurs
> under iOS4.0, regardless of which OS I target for deployment in XCode
> (i.e., even if I target OS 3.1.2 in XCode, the problem still occurs on
> my iPhone).
>
> Any help/insight would be greatly appreciated.
>
> Thanks,
> Zach
>
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References: 
 >VoiceProcessingIO - echo cancellation issues (From: Zachary Kulis <email@hidden>)
 >Re: VoiceProcessingIO - echo cancellation issues (From: Raphaël - Mancing Dolecules <email@hidden>)
 >Re: VoiceProcessingIO - echo cancellation issues (From: Zachary Kulis <email@hidden>)
 >Re: VoiceProcessingIO - echo cancellation issues (From: Raphaël - Mancing Dolecules <email@hidden>)
 >Problem with AudioQueueOfflineRender in iOS4 (From: Zachary Kulis <email@hidden>)

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