Re: Problem with AudioQueueOfflineRender in iOS4
Re: Problem with AudioQueueOfflineRender in iOS4
- Subject: Re: Problem with AudioQueueOfflineRender in iOS4
- From: Doug Wyatt <email@hidden>
- Date: Thu, 01 Jul 2010 17:22:19 -0700
There are some quite well known apps using offline rendering without issues like that. It is very possible and correct for the API to return zero frames depending on the timing of your pushes and pulls (buffer enqueues and calls to AudioQueueOfflineRender). Please be very specific about what you're doing (most ideally in the form of self-contained example in a bug report).
The feedback may be another issue I've heard of recently and may be unique to a certain (type of?) accessory. What hardware are you using?
# sent from my iPhone
On Jul 1, 2010, at 8:31, Zachary Kulis <email@hidden> wrote:
> 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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