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Does downgrading from 24/192 to 16/44.1 hurt?, Vynil rips
krafty
post Apr 2 2013, 19:22
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I was wondering if downgrading, with sox, material with 24-bit and 192kHz samplerate, to 16-bit and 44.1kHz samplerate hurts a lot.
Not that I have noticed anything, but is this a dirty technical procedure?
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DVDdoug
post Apr 3 2013, 01:56
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QUOTE
does down-sample cause it to have artifacts like "horribly distorted" sound as I recollect someone said here that "downsample" was worse than "upsample".
No!!!! I've never heard ANY difference when downsampling to 44.1kHz.

Downsampling throws-away information, and upsampling does not. If you downsample to 8kHz at 8-bits, you WILL notice the quality loss. wink.gif But, 44.1kHz/16-bits is better than human hearing and far-better than analog vinyl. Any information that's thrown-away is mostly noise, perhaps including some supersonic noise. In any case, nothing audible is lost.

Upsampling only the bit-depth is mathematically exact. So, you can go from 16-bits to 24-bits, and it's totally reversible... If you downsample back to 16-bits, you'll get the exact-same bytes. It's sort-of like writing 1000.000 instead of 1000. It takes more space to add zeros after the decimal point, but it doesn't add information. In fact, if you upsample the bit depth you are simply adding zero-bits to a binary number.

That's not generally true if you upsample the sample rate, even if you simply double the sample rate. If you upsample from 44.1kHz to 88.2kHz, and then back down to 44.1, there is interpolation and filtering. And with filtering there is always rounding. These teeny-tiny rounding errors are NOT audible, but the process is not mathematically perfect and the bytes will be different.

Of course, you don't automatically "improve quality" or "add information" when you upsample. The only time I upsample is when I'm going from CD (44.1kHz) to DVD (48kHz). It would also make sense to upsample if you are working on an audio project (mixing, etc.) and most of the project is at one sample rate, but you have one additional file at a lower sample rate. In that case, your DAW (digital audio workstation) will usually automatically re-sample everything to your "project settings".

This post has been edited by DVDdoug: Apr 3 2013, 01:57
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greynol
post Apr 3 2013, 02:16
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QUOTE (DVDdoug @ Apr 2 2013, 17:56) *
If you downsample back to 16-bits, you'll get the exact-same bytes.

Best practice is to use dither when reducing bit-depth in which case the process is not reversible.


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