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Topic: Explanation for the difference between Bandcamp and CD version. (Read 1070 times) previous topic - next topic
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Explanation for the difference between Bandcamp and CD version.

I bought the following album as a CD on Bandcamp.
https://biosphere.bandcamp.com/album/inland-delta-2

As far as I can tell, the CD is a professional pressing
with the inside CD ring label handlewithcare.de.

I like to back up my CDs on the PC with EAC Secure
so that I can play them more easily and get a secure copy.

I created spectrograms with the program sox ("sox CD.flac -n spectrogram -o CD.png").
Now I compared the digital Bandcamp version
(which you kindly get with it) with the CD and was amazed to
realize that there is a clear difference in the upper
frequency range of every track.

As if there was some kind of filter on the CD.
I am not an audio expert, but I wanted to find out if anyone knows where the difference comes from?

Despite the fact that the difference on the Spectrograms is relatively clear, I can't hear any difference with a "mid-range headphone  setup".


[Edit]
Bandcamp files are 24bit - 44.1kHz.
I noticed that the thread is probably better placed in https://hydrogenaud.io/index.php/board,1.0.html

Re: Explanation for the difference between Bandcamp and CD version.

Reply #1 –
Quote from: trclst on
I am not an audio expert, but I wanted to find out if anyone knows where the difference comes from?
It's probably shaped dither from the conversion to CD-compatible 16-bit/44.1kHz.

Quote from: trclst on
Despite the fact that the difference on the Spectrograms is relatively clear, I can't hear any difference with a "mid-range headphone  setup".
If I'm reading your spectrograms correctly, the difference is mostly below -90dBFS and above 18 kHz. Most people wouldn't be able to hear that on any setup without turning the volume up to dangerous levels.

Re: Explanation for the difference between Bandcamp and CD version.

Reply #2 –
As said above it looks like shaped dither applied when converting from 24bit to 16bit.
This video explains what dithering does. Don't miss the conclusion at the end.

Digital Show & Tell ("Monty" Montgomery @ xiph.org)
https://youtu.be/UqiBJbREUgU?si=Cb3GFjJz4AuQYqlG&t=695