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Hi-Rez Highway

How to check for fake 24 bit depths?

91.119.170.215

A few years ago somebody (I think it was even in this forum) discovered that certain music files being offered as HiRez (e.g. 24 bits*96 kHz) on an audiophile website (that all of you know and use) were not really recorded in 96 kHz but seemingly upsampled later. Nevertheless their price tag was HiRez.

Now, even though selling upsampled music as original hirez is not an honest business model, there are ways to check downloads for this kind of cheating.

However, recently I noticed offers of so-called hirez files in 24 bit * 44.1 kHz. These may look like hirez due to their higher bit depth, but

1) are they worth the premium on the price? And

2) How can one check if these files were not up-decimated from 16 bit to 24 bit to resemble a hirez recording? Are there tests for the original bit depth as there are tests for the original sample frequency?

Thanks.

Follow Ups:

RE: How to check for fake 24 bit depths? - Russell 11:30:01 03/24/14 (3)
This question has been asked before on sites such as computeraudiophile.com, and as far as I'm aware, there's no easy way for consumers to check whether all bits of a 24-bit audio file are being fully utilized or have simply been 'up-decimated' or just padded with 0's. I do know that some record labels, such as BIS, recorded in 24/44.1 (and released those recordings on SACD) for years. Those BIS 24/44.1 files are available for download via eClassical. (They've recently switched to 24/96 for most/all of their recordings.) Same thing with Harmonia Mundi. 24/44.1 is still better than 16/44.1, so while it might not be fully hi-res, it's still better than CD.

As far as passing off upsampled files as 'hi-res' goes, I think that issue is largely over. Once that was exposed a few years ago, I think the labels have been a lot more careful. I make a point of spot-checking each of my hi-res downloads, and I haven't found any 'fake' hi-res files in quite a while now.

Russell
- RE: How to check for fake 24 bit depths? - treefrog 13:25:43 03/25/14 (0)
  Thanks, I found a thread on this issue and currently try to check this out.
- RE: How to check for fake 24 bit depths? - reuben 05:07:28 03/25/14 (1)
  'I make a point of spot-checking each of my hi-res downloads, and I haven't found any 'fake' hi-res files in quite a while now.'
  
  How do you perform the check?
  
  -reub
  - RE: How to check for fake 24 bit depths? - Russell 16:37:59 03/25/14 (0)
    I use Audacity (free) to check the frequency spectrum of a music file. (It also does a good job with showing the file's dynamic range.) I check for the presence of frequency content above 22kHz (the upper limit of a 44.1kHz file). The graph also shows any extraneous noises/signals. For most/all 24/96 files I've downloaded lately, the graphs are very clean and show frequencies extended well beyond 22kHz. With 'fake' hi-res files, there's a very obvious brick wall at 22kHz (or 24kHz, for 48kHz-originated files) and empty space above. As I mentioned before, I haven't seen anything like that for a long time now.
    
    Russell
    - http://audacity.sourceforge.net (Open in New Window)

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