FYI upsampling issue

I recently realized that upsampling a song can result in clipping, which at first blush may sound bizarre as you’re not changing the volume (it’s due to intersample overs).

So if you upsample, you may want to check the clipping indicator in Roon, and engage headroom management.

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Because of “inter-sample overs”

It’s possible for a totally “in-range” piece of source material “out-of-range” samples after upsampling. The very simple explanation is: when the interpolator “connects the dots” to form a signal at a higher sampling rate, sometimes the new “dots” fall out of range.

This is essentially a defect introduced in the mastering process, and is not a problem with the upsampler. Unfortunately, most software silently ignores these defects, and provide no means to track or manage them.



Agreed, definitely not a Roon issue, just something that cannot be avoided, a mathematical fact.
In fact, without upsampling, and Roon’s clipping indicator, you might not be alerted to the fact that your DAC may clip these ‘intersample overs’.

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It depends when it was mastered and more specifically how it was metered and of course whether the mastering engineer was paying adequate attention and/or had tools to highlight the issue and what if anything was done about it in the quest for loudness.

I have heard of cases posted on forums with ISPs of over +6dB, though never encountered this myself. However, I do think that the default -3dB adjustment is too low and use -6dB myself as I certainly have come across ISPs over 3dB.

I just cut and pasted from the roon knowledge base. I don’t understand any of it. :grinning:

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