Re: Best way to simultaneously decode two compressed mp3 files into LPCM using hardware codec?
Re: Best way to simultaneously decode two compressed mp3 files into LPCM using hardware codec?
- Subject: Re: Best way to simultaneously decode two compressed mp3 files into LPCM using hardware codec?
- From: William Stewart <email@hidden>
- Date: Mon, 27 Sep 2010 12:47:08 -0700
On Sep 27, 2010, at 12:11 PM, cc laan wrote:
> Hi,
>
> This is my first post, and I'm an iPhone developer, so sorry if it's not appropriate to ask iPhone questions here. I just figured my question is still relevant to core audio on osx.
>
> I'm trying to play two mp3 audio files at the same time, but I also need access to raw pcm sample data for signal processing.
>
> I have this working using two AudioQueue's and AQOfflineRender.
>
> The problem is, if I create two AudioQueue's, then I have to set one to use the software decoder which is slower (this might be an iPhone specific constraint.)
Yes, well the SW and HW codecs will certainly have different behaviours.
>
> Is there a recommended way to simultaneously render packets from more than one file into raw samples using only one AudioQueue/AQOfflineRender? (in order to use the hardware decoder for both)
you do first one file and then the next. Most audio codecs have dependencies in the encoded packets that go across the packet boundaries, so you can't interleave them (go one packet then the other from different audio files).
>
> If I could somehow get AQOfflineRender to pull from two different AudioQueueBuffer's that contain compressed packets from separate files, it seems like this would work. I just can't figure out how to coerce the Audio Queue stuff into allowing this.
>
> I also have this working with the ExtAudioFile stuff, but it seems much slower than AQOfflineRender.
ExtAudioFile will use the SW decoder
>
> Thanks for any help,
> -chris
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