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Re: iTunes back door, API, DLL raw sample question
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Re: iTunes back door, API, DLL raw sample question


  • Subject: Re: iTunes back door, API, DLL raw sample question
  • From: William Stewart <email@hidden>
  • Date: Fri, 29 May 2009 14:34:14 -0700

umm... sent this before I'd finished!

For resampling:
The issues in iTunes that gave this a sub-optimal experience have been addressed. The main problem was not the fact of doing the resampling, but the quality of the resampling chosen by iTunes was less than they should have used.


For volume:
Yes, that can still be a problem - but I don't think this is correct to characterise this as an iTunes issue - you can get exactly this kind of problem whenever you do any kind of audio processing that involves (or could involve) adding gain. This is particularly the case with much "rock" or "pop" music over the last few years where it is extremely common to say clipped signals just below max amplitude. There is a straight forward way to turn off any processing of a signal in iTunes and you can just have iTunes output the bits as is (modulo any sample rate discrepancies you introduce)



So, really the only issue is if you want to have iTunes change the sample rate of the device while it plays back. That has its own set of problems, including noticeable glitches and gaps, pops and clicks as many devices do not make these changes well - and with many consumer receivers (which you could connect to via S/PDIF) these changes can be really nasty. Its worth a bug report to request the feature I think.


Bill

On May 29, 2009, at 2:23 PM, William Stewart wrote:


On May 29, 2009, at 1:34 PM, Gordon Rankin wrote:

Gang,

I design high end audio asynchronous usb dac hardware. A lot of customers have found that iTunes while nice may not sound as good as actually playing tracks in pro audio tools. The problem with Pro Audio is one track at a time.

One of the reason's why iTunes does not sound as good is that iTunes takes a snap shot of Audio Midi Setup for the device output in question and resamples to that rate and bit size before it goes out. So you may have a 44.1/16 bit track then a 24/96 track and they will both be resampled to the rate specified in the Audio Midi setup.

The issues in iTunes that gave this a sub-optimal experience This is an old issue in iTunes that has been addressed.


Other problems happen when users forget setting the volume control to 100% and using eq and other sound altering options.

The nice thing about iTunes is there are a bunch of applications for remote access and control as well as the ripping and burning capabilities.

So I had an idea that maybe there was an interface for iTunes were the sample and sample rate info was passed to a DLL or API for processing that we could hijack the sample and out put it to a known device as is without any processing and change the sample rate on the fly. In return to iTunes we would pass the altered sample back as a ZERO so when iTunes passed the sample onto the mixer that it would not interfere or be output as anything.

Anything like that? Anyone interested in helping me out with this?

Thanks
Gordon
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References: 
 >iTunes back door, API, DLL raw sample question (From: Gordon Rankin <email@hidden>)
 >Re: iTunes back door, API, DLL raw sample question (From: William Stewart <email@hidden>)

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