Re: iOS SDK: ExtAudioFileSeek
Re: iOS SDK: ExtAudioFileSeek
- Subject: Re: iOS SDK: ExtAudioFileSeek
- From: Art Gillespie <email@hidden>
- Date: Mon, 28 Nov 2011 14:13:22 -0700
Ah, thanks. Where does one go to get smart about such things? Is there a block size that makes sense for decoding the mp3 to LPCM in chunks rather than decoding the whole file serially before playback?
On Mon, Nov 28, 2011 at 1:20 PM, tahome izwah
<email@hidden> wrote:
Decode to PCM and play in reverse. It might be possible to do it "in
place" with a compressed file but that would be horribly inefficient
(of course depending on your audio block size per decode). MP3
requires previous transform frames to decode the current one so the
decoder will end up seeking in your file quite a bit.
--th
2011/11/28 Art Gillespie <email@hidden>:
> I'm trying to play a file in reverse using ExtAudioFileSeek and I'm seeing
> some strange behavior when the file in question is an mp3.
> Code here:
>
https://gist.github.com/1401245
> With an LPCM or aac file, the reverse playback sounds as I would expect, but
> with an mp3 I get some strange behavior. Here's the audio output
>
http://www.tapsquare.com/art/extaudiofilehatesus/output.wav
> I can't find a pattern to the discontinuities, though there does appear to
> be a weird attenuation (windowing?) just before each bit of zero samples.
> The only sensible thing I notice is that the behavior is deterministic:
> Subsequent passes generate the same discontinuities.
> Any suggestions of how to fix this or work around it greatly appreciated.
> Thanks,
> Art
> --
> art gillespie
> tapsquare, llc
> p.
520.344.0902
> skype. artgillespie
> e.
email@hidden
>
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--
art gillespie
tapsquare, llc
p. 520.344.0902
skype. artgillespie
e.
email@hidden
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