RE: AudioQueue Services approximate latency?
RE: AudioQueue Services approximate latency?
- Subject: RE: AudioQueue Services approximate latency?
- From: Stéphane Beauchemin <email@hidden>
- Date: Fri, 5 Nov 2010 09:43:59 -0400
- Thread-topic: AudioQueue Services approximate latency?
Hi Eric,
I already try to ask for 16 bit little endian and it doesn't work. In fact you can even find leftover of this if you look in the code, the following line is commented:
FillOutASBDForLPCM(outputASBD, 44100, 2, 16, 16, false, false, false);
With the AudioConverter api you should get the following error when the format is not defined:
kAudioConverterErr_FormatNotSupported = 'fmt?'
In my case, I am getting a 'perm' error.
I haven't found this error code defined anywhere so I am guessing that hardware decoder is not supported thru the AudioConverter service. However, it would be really nice that someone at apple confirm this.
Stephane
-----Original Message-----
From: Eric Wing [mailto:email@hidden]
Sent: November-04-10 2:39 PM
To: Stéphane Beauchemin
Cc: Denis Lebel; email@hidden
Subject: Re: AudioQueue Services approximate latency?
On 11/4/10, Stéphane Beauchemin <email@hidden> wrote:
> Hi Eric,
>
> Here is an example I got from this mailing list. I have modified it to make
> it run on the iPhone. I always get a 'perm' error when trying to use the
> hardware decoder. Using the software decoder if fine however. Am I doing
> something wrong?
>
> Just copy the following in .mm file and import it in an empty iPhone app in
> XCode. You will also need to compile CAAudioBufferList.cpp (with very small
> modifications).
I haven't tried your code. But two quick guesses. First, maybe the
audio session mode is set wrong. But I think solo should work, so
that's probably not it.
Second, you are requesting a floating point format
(kAudioFormatFlagIsFloat). iOS prefers 16-bit signed little endian
samples. It could be that the hardware decoder fails because the
hardware chip is not designed for float.
-Eric
--
Beginning iPhone Games Development
http://playcontrol.net/iphonegamebook/
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