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[Csnd] Re: Re: 24bit->16bit conversion in Csound

Date2008-12-10 18:09
Frommark jamerson
Subject[Csnd] Re: Re: 24bit->16bit conversion in Csound
   Maybe I am doing something wrong.  I will try a few things and see what happens, and if that doesn't work, I will post CSD's and such. 


                Mark 



----- Original Message ----
From: victor 
To: csound@lists.bath.ac.uk
Sent: Wednesday, December 10, 2008 11:31:37 AM
Subject: [Csnd] Re: 24bit->16bit conversion in Csound

I don't follow you. If you open a soundfile with diskin or diskin2, whatever
encoding it is, and then run csound as normal, you will get a perfect
16bit file

Victor

----- Original Message ----- From: "mark jamerson" 
To: "Csound" 
Sent: Wednesday, December 10, 2008 4:56 PM
Subject: [Csnd] 24bit->16bit conversion in Csound


> 
> Hello,
> 
>     During an effort to look into the effects of dither, I was trying to convert 24bit files into 16bit files.  The file used was a mono 1k sine tone generated in Csound, using GEN10, with table size 65536, and an oscil amplitude of 10000.  This file sounded and looked perfect.  Then I tried converting the file to a 16bit file in Csound.  I tried loscil and fout to write a 16bit file.  The result was unacceptable, with what sounded like FM sideband modulation. The spectrum analysis also looked extremely messy, with a bunch of extra noise all over the place.  Next I tried using diskin followed by soundin, figuring it might be a problem with my loscil setup. The same results, exactly.  I know that converting a 24bit file to a 16bit file without using dither will lead to a degradation in sound quality, but this seemed excessive.  In an attempt to verify my concerns, I tried the same sort of experiment in a consumer DAW software, by rendering the same 24bit
> file as a 16bit file, with no dither, and got a much cleaner result.  The new file sounded indiscernable form the 24bit source, but the spectrum analysis confirmed a difference, with extra noise across the spectrum, but not anywhere near the levels of the Csound version.
>    So here's my question:  Does anyone do this sort of conversion in Csound, and get acceptable results, if so what methods do you use?  Also, something I just thought of is that I am using the Float version of Csound, is this possibly the cause of these results (would the double version eliminate this sort of thing)?
> 
> 
> Mark
> 
> 
> 
> 
> 
> 
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