Re: Accessing audio samples from Audio Queue Buffers
Re: Accessing audio samples from Audio Queue Buffers
- Subject: Re: Accessing audio samples from Audio Queue Buffers
- From: Doug Wyatt <email@hidden>
- Date: Thu, 10 Sep 2009 14:12:03 -0700
Oops, I was just reminded that we *do* have a software MP3 decoder as
of 3.0. I don't know what I was thinking.
sorry for the confusion
Doug
On Sep 10, 2009, at 13:55 , Doug Wyatt wrote:
The new capability in 3.1 is to be able to use the hardware AAC
*encoder*, *only* ... nothing has changed with respect to hardware
decoders. We do have some software decoders available as of 3.0, but
MP3 isn't one of them.
As for the difference in MP3 decode rates, that's interesting. If
you like, file a bug and attach files which illustrate the problem
and we'll investigate.
thanks,
Doug
On Sep 9, 2009, at 17:43 , Steven Winston wrote:
Well in my tests I'm noticing that some audio when encoded with the
exact same format are filling the audioqueueofflinerender buffers at
different rates than other files encoded with the same format. I
didn't investigate too far into this however, it seems like there
must
be some overhead that prevents the callback happening at a more
consistant rate between the files.
So for instance if file A is encoded as a MP3 44.2 khz 16 bit 2 chan
file and file B is also encoded as a MP3 44.2 khz 16 bit 2 chan file
when they are decoding file A might decode at an appreciable rate
slower than file B when using AudioQueueOfflineRender. If that
problem doesn't exist, in the ExtAudioFile, then I can scrap the
external software MP3 decoder in my project.
On Wed, Sep 9, 2009 at 5:33 PM, William Stewart<email@hidden>
wrote:
On Sep 9, 2009, at 5:28 PM, Steven Winston wrote:
That's awesome! However, a question, is this solution going to
suffer
from the same different files of the exact same format decode at
different rates problem?
"same different" - sorry, but I don't understand the problem you are
referring too.
I'll start digging through 3.1 docs and will
eagerly await the further details.
On Wed, Sep 9, 2009 at 5:22 PM, William Stewart<email@hidden>
wrote:
One of the new things in iPhone OS 3.1 is that you can use
ExtAudioFile
to
read and write compressed data where you may need to use a
hardware
assisted
codec (such as AAC encoding) to do so.
Details are forthcoming, including some example code - have a
look in the
tech notes and release notes for the 3.1 release
Bill
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