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Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling?
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Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling?


  • Subject: Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling?
  • From: William Stewart <email@hidden>
  • Date: Wed, 10 Feb 2010 11:47:46 -0800


On Feb 10, 2010, at 3:51 AM, uɐıʇəqɐz pnoqɥɒɯ wrote:

Thanks. That's what I thought. However, I am still unclear: MP3 to PCM conversion using extAudioFile goes through the hardware decoder?

No. ExtAudioFile always uses software (except for the case of AAC encoding)


If so, is it possible to tell the software decoder to take over if the hardware decoder is busy?


On Feb 5, 2010, at 10:45 AM, William Stewart wrote:

you can easily tell where the conversion happens.

If there is a difference between your client format and the file format, then a conversion will happen whether you are reading or writing


On Feb 4, 2010, at 1:11 PM, uɐıʇəqɐz pnoqɥɒɯ wrote:


On Jan 4, 2010, at 6:16 PM, uɐıʇəqɐz pnoqɥɒɯ wrote:

Hi. Since my app runs one sound through ExtAudioFieConvert, using performSelectorInBackground, and there will not be any concurrency or re-entrance, can I get rid of all the code that handles thread states and mutex locking, etc.?

I'm writing my own ExtAudioFileConvert with some extras (such as splitting my sound into multiple files) and hate to copy and paste code that I don't quite understand (thread handling).

-mahboud


Hi. I have removed mutexes and have gone with NSOperationQueues to handle my audio conversion. However, I still have a few questions about the Apple iPhoneExtAudioFileConvertTest sample, which I don't seem to find answers to. Maybe the Apple folks can resolve these:

1- Will converting from MP3 to PCM ever cause a read or write to be interrupted? I guess I am asking if hardware encoders/decoders are sed for MP3 to PCM conversion.
2- There is a comment in ExtAduioFileConvert.cpp:


//***** do the read and write - the conversion is done on and by the write call *****//
I believe this to be incorrect. If I am converting from MP3 to PCM, the conversion happens during the read, not the write.


Correct?

Thanks.

-mahboud

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References: 
 >Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling? (From: uɐıʇəqɐz pnoqɥɒɯ <email@hidden>)
 >Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling? (From: William Stewart <email@hidden>)
 >Re: ExtAudioFileConvert.cpp: can I get rid of mutex and thread handling? (From: uɐıʇəqɐz pnoqɥɒɯ <email@hidden>)

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