Re: Problem with AudioQueueOfflineRender in iOS4
Re: Problem with AudioQueueOfflineRender in iOS4
- Subject: Re: Problem with AudioQueueOfflineRender in iOS4
- From: Zachary Kulis <email@hidden>
- Date: Thu, 01 Jul 2010 11:31:02 -0400
Pierre,
There are other strange things going on with the AudioQueueOfflineRender
API : namely a loud audio feedback sound that is produced whenever an
external microphone is connected, the audio session category is set to
Play and Record, and the hardware codec is used. Also, enabling the
"Play and Record" category and overriding the category to allow mixable
audio also causes a loud audio feedback to be produced when an external
microphone is connected and audio is routed to external speakers. I am
currently speaking with an Apple engineer regarding these issues, and
will keep you posted.
-Zach
> Zach,
>
>
>> 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.
>>
> Big apologies: it turns out I was wrong before. I just experienced
> this today, too. On the particular buffer settings I was using - 1
> sec for the offline render, 16k pingpong for the rio callback - it
> mostly takes around a minute to get there. I just wasn't running it
> long enough. Also, seemingly arbitrary changes to the buffer sizes
> (for both) have a pronounced effect on how long it takes before this
> happens.
>
> I hope I haven't led you on a wild goose chase but unfortunately I
> (temporarily) switched to doing other things shortly after submitting
> that post and only got back to it this morning.
>
> Regards
>
> Pierre
>
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